SIGNALCORE SC5309A User manual

©2018 Rev 2.0
1
General Information
Table of Contents
1 General Information ...............................................................................................................................4
Warranty ..........................................................................................................................................4
Copyright & Trademarks ..................................................................................................................4
International Materials Declarations................................................................................................5
CE European Union EMC & Safety Compliance Declaration.............................................................5
Warnings Regarding Use of SignalCore Products .............................................................................6
2 Physical Description................................................................................................................................7
Unpacking.........................................................................................................................................7
Setting Up the Device.......................................................................................................................7
Front Interface Indicators and Connectors ......................................................................................8
Signal Connections ................................................................................................................8
Device LED Indicators ..........................................................................................................10
Communication and Supply Connection .............................................................................10
Mini-USB Connection ..........................................................................................................11
Reset Button (Pin Hole) .......................................................................................................12
3 Functional Description..........................................................................................................................13
Overview ........................................................................................................................................13
The Signal Chain .............................................................................................................................14
The RF Input ........................................................................................................................14
The Input Path Switch..........................................................................................................15
The RF Path..........................................................................................................................15
The First Mixer and IF1 Path................................................................................................15
The Second Mixer and IF2 Path...........................................................................................17
The Third mixer and IF3 Path...............................................................................................17
Signal Chain Configurations.................................................................................................17
The LO Module...............................................................................................................................19
The Reference Clocks ..........................................................................................................19
The First Local Oscillator (LO1)............................................................................................20
The Second Local Oscillator (LO2) .......................................................................................20
The Third Local Oscillator (LO3)...........................................................................................20
The Interface Module.....................................................................................................................21
4Hardware Registers .................................................................................................................22

Rev 2.0 | SC5309A & SC5310A Hardware Manual SignalCore, Inc.
2
SC5309A & SC5310A Hardware Manual
Configuration Registers..................................................................................................................22
Register 0x01 INITIALIZE......................................................................................................23
Register 0x02 SYSTEM_ACTIVE............................................................................................24
Register 0x10 RF_FREQUENCY ............................................................................................24
Register 0x11 IF_FREQUENCY..............................................................................................24
Register 0x12 RF_AMP ........................................................................................................25
Register 0x13 ATTENUATOR................................................................................................25
Register 0x14 SIGNAL_PATH................................................................................................26
Register 0x15 CONFIG_AUTO_GAIN....................................................................................26
Register 0x16 STORE_DEFAULT_STATE ...............................................................................28
Register 0x17 DEVICE_STANDBY .........................................................................................28
Register 0x18 REFERENCE_CLOCK.......................................................................................28
Register 0x19 REFERENCE_DAC...........................................................................................29
Register 0x1A FREQ_PLAN_PARAM.....................................................................................29
Register 0x1B SYNTH_MODE (2 Bytes)................................................................................30
Register 0x1C SYNTH_SELF_CAL..........................................................................................30
Register 0x1D USER_EEPROM_WRITE.................................................................................31
Query Registers..............................................................................................................................31
Register 0x20 GET_DEVICE_PARAM....................................................................................32
Register 0x21 GET_TEMPERATURE .....................................................................................32
Register 0x22 GET_DEVICE_STATUS....................................................................................33
Register 0x23 GET_DEVICE_INFO........................................................................................34
Register 0x24 CAL_EEPROM_READ .....................................................................................34
Register 0x25 USER_EEPROM_READ...................................................................................35
Register 0x26 SERIAL_OUT_BUFFER....................................................................................35
Device Parameters Data and Format...................................................................................36
Device Information Parameters and Format.......................................................................37
5 Communication Interfaces......................................................................................................................1
Communication Data Format...........................................................................................................1
USB Interface....................................................................................................................................1
Control Transfer ....................................................................................................................1
Bulk Transfer .........................................................................................................................1
SPI Interface .....................................................................................................................................2

©2018 Rev 2.0
3
General Information
Writing the SPI Bus................................................................................................................3
Reading the SPI Bus ...............................................................................................................3
RS232 Interface................................................................................................................................4
Writing to the Device Via RS232............................................................................................4
Reading from the Device Via RS232 ......................................................................................5
PXI Express .......................................................................................................................................5
Setting Up the PCI to Serial Bridge ........................................................................................5
Writing to the Device.............................................................................................................6
Reading from the Device .......................................................................................................6
6 Calibration ..............................................................................................................................................7
Calibration EEPROM Map.................................................................................................................7
Absolute Conversion Gain ................................................................................................................8
Gain Through the RF Conversion Path..............................................................................................8
Applying Calibration ..............................................................................................................8
Revision Table..............................................................................................................................................10

Rev 2.0 | SC5309A & SC5310A Hardware Manual SignalCore, Inc.
4
SC5309A & SC5310A Hardware Manual
1General Information
Warranty
This product is warranted against defects in materials and workmanship for a period of three years
from the date of shipment. SignalCore will, at its option, repair or replace equipment that proves to
be defective during the warranty period. This warranty includes parts and labor.
Before any equipment will be accepted for warranty repair or replacement, a Return Material
Authorization (RMA) number must be obtained from a SignalCore customer service representative
and clearly marked on the outside of the return package. SignalCore will pay all shipping costs
relating to warranty repair or replacement.
SignalCore strives to make the information in this document as accurate as possible. The document
has been carefully reviewed for technical and typographic accuracy. If technical or typographical
errors exist, SignalCore reserves the right to make changes to subsequent editions of this document
without prior notice to possessors of this edition. Please contact SignalCore if errors are suspected.
In no event shall SignalCore be liable for any damages arising out of or related to this document or
the information contained in it.
EXCEPT AS SPECIFIED HEREIN, SIGNALCORE, INCORPORATED MAKES NO WARRANTIES, EXPRESS OR
IMPLIED, AND SPECIFICALLY DISCLAIMS ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR A
PARTICULAR PURPOSE. CUSTOMER’S RIGHT TO RECOVER DAMAGES CAUSED BY FAULT OR
NEGLIGENCE ON THE PART OF SIGNALCORE, INCORPORATED SHALL BE LIMITED TO THE AMOUNT
THERETOFORE PAID BY THE CUSTOMER. SIGNALCORE, INCORPORATED WILL NOT BE LIABLE FOR
DAMAGES RESULTING FROM LOSS OF DATA, PROFITS, USE OF PRODUCTS, OR INCIDENTAL OR
CONSEQUENTIAL DAMAGES, EVEN IF ADVISED OF THE POSSIBILITY THEREOF. This limitation of the
liability of SignalCore, Incorporated will apply regardless of the form of action, whether in contract
or tort, including negligence. Any action against SignalCore, Incorporated must be brought within
one year after the cause of action accrues. SignalCore, Incorporated shall not be liable for any delay
in performance due to causes beyond its reasonable control. The warranty provided herein does not
cover damages, defects, malfunctions, or service failures caused by owner’s failure to follow
SignalCore, Incorporated’s installation, operation, or maintenance instructions; owner’s
modification of the product; owner’s abuse, misuse, or negligent acts; and power failure or surges,
fire, flood, accident, actions of third parties, or other events outside reasonable control.
Copyright & Trademarks
Under the copyright laws, this publication may not be reproduced or transmitted in any form,
electronic or mechanical, including photocopying, recording, storing in an information retrieval
system, or translating, in whole or in part, without the prior written consent of SignalCore,
Incorporated.
SignalCore, Incorporated respects the intellectual property rights of others, and we ask those who
use our products to do the same. Copyright and other intellectual property laws protect our

©2018 Rev 2.0
5
General Information
products. Use of SignalCore products is restricted to applications that do not infringe on the
intellectual property rights of others.
“SignalCore”, “signalcore.com”, and the phrase “preserving signal integrity” are registered
trademarks of SignalCore, Incorporated. Other product and company names mentioned herein are
trademarks or trade names of their respective companies.
International Materials Declarations
SignalCore, Incorporated uses a fully RoHS compliant manufacturing process for our products.
Therefore, SignalCore hereby declares that its products do not contain restricted materials as
defined by European Union directive 2002/95/EC (EU RoHS) in any amounts higher than limits stated
in the directive. This statement assumes reliable information and data provided by our component
suppliers and may not have been independently verified through other means. For products sold
into China, we also comply with the “Administrative Measure on the Control of Pollution Caused by
Electronic Information Products” (China RoHS). In the current stage of this legislation, the content of
six hazardous materials must be explicitly declared. Each of those materials, and the categorical
amount present in our products, are shown below:
鉛
Lead
(Pb)
汞
Mercury
(Hg)
镉
Cadmium
(Cd)
六价铬
Hexavalent
Chromium
(Cr(VI))
多溴联苯
Polybrominated
biphenyls
(PBB)
多溴二苯醚
Polybrominated
diphenyl ethers
(PBDE)
✓
✓
✓
✓
✓
✓
A ✓indicates that the hazardous substance contained in all of the homogeneous materials for this
product is below the limit requirement in SJ/T11363-2006. An Xindicates that the particular
hazardous substance contained in at least one of the homogeneous materials used for this product
is above the limit requirement in SJ/T11363-2006.
CE European Union EMC & Safety Compliance Declaration
The European Conformity (CE) marking is affixed to products with input of 50 - 1,000 Vac or 75 -
1,500 Vdc and/or for products which may cause or be affected by electromagnetic disturbance. The
CE marking symbolizes conformity of the product with the applicable requirements. CE compliance
is a manufacturer’s self-declaration allowing products to circulate freely within the European Union
(EU). SignalCore products meet the essential requirements of Directives 2004/108/EC (EMC) and
2006/95/EC (product safety) and comply with the relevant standards. Standards for Measurement,
Control and Laboratory Equipment include EN 61326 and EN 55011 for EMC, and EN 61010-1 for
product safety.

Rev 2.0 | SC5309A & SC5310A Hardware Manual SignalCore, Inc.
6
SC5309A & SC5310A Hardware Manual
Warnings Regarding Use of SignalCore Products
(1)
PRODUCTS FOR SALE BY SIGNALCORE, INCORPORATED ARE NOT DESIGNED WITH COMPONENTS NOR TESTED
FOR A LEVEL OF RELIABILITY SUITABLE FOR USE IN OR IN CONNECTION WITH SURGICAL IMPLANTS OR AS
CRITICAL COMPONENTS IN ANY LIFE SUPPORT SYSTEMS WHOSE FAILURE TO PERFORM CAN REASONABLY BE
EXPECTED TO CAUSE SIGNIFICANT INJURY TO A HUMAN.
(2)
IN ANY APPLICATION, INCLUDING THE ABOVE, RELIABILITY OF OPERATION OF THE SOFTWARE PRODUCTS CAN
BE IMPAIRED BY ADVERSE FACTORS, INCLUDING BUT NOT LIMITED TO FLUCTUATIONS IN ELECTRICAL POWER
SUPPLY, COMPUTER HARDWARE MALFUNCTIONS, COMPUTER OPERATING SYSTEM SOFTWARE FITNESS,
FITNESS OF COMPILERS AND DEVELOPMENT SOFTWARE USED TO DEVELOP AN APPLICATION, INSTALLATION
ERRORS, SOFTWARE AND HARDWARE COMPATIBILITY PROBLEMS, MALFUNCTIONS OR FAILURES OF
ELECTRONIC MONITORING OR CONTROL DEVICES, TRANSIENT FAILURES OF ELECTRONIC SYSTEMS
(HARDWARE AND/OR SOFTWARE), UNANTICIPATED USES OR MISUSES, OR ERRORS ON THE PART OF THE USER
OR APPLICATIONS DESIGNER (ADVERSE FACTORS SUCH AS THESE ARE HEREAFTER COLLECTIVELY TERMED
“SYSTEM FAILURES”). ANY APPLICATION WHERE A SYSTEM FAILURE WOULD CREATE A RISK OF HARM TO
PROPERTY OR PERSONS (INCLUDING THE RISK OF BODILY INJURY AND DEATH) SHOULD NOT BE SOLELY
RELIANT UPON ANY ONE COMPONENT DUE TO THE RISK OF SYSTEM FAILURE. TO AVOID DAMAGE, INJURY,
OR DEATH, THE USER OR APPLICATION DESIGNER MUST TAKE REASONABLY PRUDENT STEPS TO PROTECT
AGAINST SYSTEM FAILURES, INCLUDING BUT NOT LIMITED TO BACK-UP OR SHUT DOWN MECHANISMS.
BECAUSE EACH END-USER SYSTEM IS CUSTOMIZED AND DIFFERS FROM SIGNALCORE'S TESTING PLATFORMS,
AND BECAUSE A USER OR APPLICATION DESIGNER MAY USE SIGNALCORE PRODUCTS IN COMBINATION WITH
OTHER PRODUCTS IN A MANNER NOT EVALUATED OR CONTEMPLATED BY SIGNALCORE, THE USER OR
APPLICATION DESIGNER IS ULTIMATELY RESPONSIBLE FOR VERIFYING AND VALIDATING THE SUITABILITY OF
SIGNALCORE PRODUCTS WHENEVER SIGNALCORE PRODUCTS ARE INCORPORATED IN A SYSTEM OR
APPLICATION, INCLUDING, WITHOUT LIMITATION, THE APPROPRIATE DESIGN, PROCESS AND SAFETY LEVEL
OF SUCH SYSTEM OR APPLICATION.

©2018 Rev 2.0
7
Physical Description
2Physical Description
Unpacking
All SignalCore products ship in antistatic packaging (bags) to prevent damage from electrostatic
discharge (ESD). Under certain conditions, an ESD event can instantly and permanently damage
several of the components found in SignalCore products. Therefore, to avoid damage when handling
any SignalCore hardware, you must take the following precautions:
1. Ground yourself using a grounding strap or by touching a grounded metal object.
2. Touch the antistatic bag to a grounded metal object before removing the hardware from
its packaging.
3. NEVER touch exposed signal pins. Due to the inherent performance degradation caused by
ESD protection circuits in the RF path, the device has minimal ESD protection against direct
injection of ESD into the RF signal pins.
4. When not in use, store all SignalCore products in their original antistatic bags.
Remove the product from its packaging and inspect it for loose components or any signs of damage.
Notify SignalCore immediately if the product appears damaged in any way.
Setting Up the Device
Integration of the SC5309A and SC5310A modules requires attention to maintain effective cooling.
Inadequate cooling can cause the temperature inside the RF housing to rise above the maximum for
this product, leading to improper performance, reduction of product lifespan, or complete product
failure. SignalCore suggests providing moderate airflow across the RF housing. If active cooling is not
an option, use thermal interface materials to bond the RF housing to a larger heatsinking surface (i.e.
a system enclosure). As each device’s integrated system configuration is unique, detailed cooling
options cannot be provided.
A cooling plan is sufficient when the SC5309A and SC5310A on-board temperature sensors indicate a
rise of no more than 20°C above ambient temperature under normal operating conditions.

Rev 2.0 | SC5309A & SC5310A Hardware Manual SignalCore, Inc.
8
SC5309A & SC5310A Hardware Manual
Front Interface Indicators and Connectors
The SC5309A is a PXIe-based RF downconverter with all user I/O located on the front face of the
module.

©2018 Rev 2.0
9
Physical Description
The SC5310A is a serial controlled core module with all user connections on the front face of the
module.
Signal Connections
All signal connections (ports) on the device are female SMA-type. Exercise caution when
fastening cables to the signal connections. Over-tightening any connection can cause permanent
damage to the device.
The condition of your system signal connections can significantly affect measurement accuracy
and repeatability. Connections that are improperly mated, dirty, damaged, or worn can degrade
measurement performance. Clean out any loose, dry debris from connectors with clean, low-
pressure air (available in spray cans from office supply stores).
If deeper cleaning is necessary, use lint-free swabs and isopropyl alcohol to gently clean inside the
connector barrel and the external threads. Do not mate connectors until the alcohol has
completely evaporated. Excess liquid alcohol trapped inside the connector may degrade
measurement performance until fully evaporated (this may take several days).
Tighten all SMA connections to 8.8 in-lb max (100 N-cm max)
RF In
This is the RF input port to the device with nominal impedance of 50 . Its
maximum input power is +27 dBm.
IF2 In
This is the input to the second IF stage of the converter. Its nominal input
frequency is 1250 MHz.
IF Out
This is the IF output of the device with nominal impedance of 50 .
Ref In
This is the 10 MHz refence input to the device, enabling the device to phase
lock its internal clocks to an external reference source. This nominally 50
port is AC coupled. Maximum rated input power is +10 dBm.

Rev 2.0 | SC5309A & SC5310A Hardware Manual SignalCore, Inc.
10
SC5309A & SC5310A Hardware Manual
Ref Out
This is the output reference port of the device, allowing for the export of its
internal reference clocks. The reference frequency is selectable between 10
MHz or 100 MHz. Typical power level is 3 dBm.
Device LED Indicators
These are LED indicator lights for the device, and their functions are listed in Table 1 and Table 2.
Table 1. Status LED Indicator
LED Color
Description
Green
The device is functioning properly in the state that it is programmed for.
Amber
Indicates that all functions are on standby mode.
Red
Indicates that one or more local oscillators are not functioning correctly.
Off
No supply or supply error.
Table 2. Active Indicator
LED Color
Description
Green
An external interface port has accessed the device.
Red
Input supply voltage exceeded.
Off
No current interface access.
Communication and Supply Connection
Figure 1. Power and Digital IO Connector
Power and communication to the SC5310A is provided through a Molex Milli-GridM2.00mm pitch,
30 position, male header connector. Its part number is 87833-3020. A suggested receptacle female
connector is the crimp terminal type 51110-3051 or ribbon type 87568-3093 from Molex. The pin
definitions of this I/O connector are listed in Table 3.
Pinouts are different for different SignalCore products with the same connector type. Please ensure
that mating connectors and cables are wired correctly before connection.
Table 3. Interface connector pin out description
PIN #
Description
1,3,5,7
12V Supply Rail

©2018 Rev 2.0
11
Physical Description
2,4,6,8,10,12,16,20,24,28
GND
9,11,13,14,15
Reserved, Do Not Connect
17,18
Reserved, pull high to 3.3V or DNC
19
, System reset, logic 0 to reset device
21
Device Active, accessed
22
PLL status
23
RS232 Baud Rate / SPI Mode Select
25
Device select for SPI
26
SPI Clock
27
TX/MOSI. TX (DTE) for RS232 or MOSI for SPI
29
RX/MOSE. RX (DTE) for RS232 or MISO for SPI
30
SRDY. This pin is serial ready for SPI
Mini-USB Connection
This is a mini-USB Type B connector for USB communication with the device using the standard
USB 2.0 protocol (full speed) found on most host computers. The pinout of this connector, viewed
from the front, is shown in the following table.
PIN #
USB Function
Description
1
VBUS
Vcc (+5 Volts)
2
D-
Serial Data (neg)
3
D+
Serial Data (pos)
4
ID
Not Used
5
GND
Device Ground (also tied to connector shell)
Figure 2. Proper Removal of Latching-Style Ribbon Cable Connectors

Rev 2.0 | SC5309A & SC5310A Hardware Manual SignalCore, Inc.
12
SC5309A & SC5310A Hardware Manual
Reset Button (Pin Hole)
Behind this pin hole is the reset button, which is only available on the SC5310A. Using a pin to
lightly depress this momentary-action push button switch will cause a hard reset to the device,
putting it back to its default settings. All user settings will be lost. System reset capability can also
be accessed through the communication header connector.

©2018 Rev 2.0
13
Functional Description
3Functional Description
Overview
The SC5310A uses USB as its primary interface with an optional SPI or RS232 interface. The SC5309A
is a PXIe version of the product.
The downconverter assembly consists of three module parts:
•The Signal Conversion Module contains the mixers, filters, signal amplifiers, and attenuators. This
module is referred to as the “signal chain”.
•The Synthesized Local Oscillator Module contains the 3 synthesized LO signals and the reference
signal circuitry.
•The Power Conditioning and Digital Control Board contains the supply switchers that generate
the needs rails for the RF modules and an onboard MCU that provides both the computation
engine and interface between the user and the RF modules.
The figure below shows how the modules relate to each other.
Figure 3. Simplified Block Representation of the Downconverter Assembly Module
The downconverter has a maximum of three conversion stages. The first converted intermediate
frequency (IF) stage is called IF1, whose signal is converted from the RF input signal. The second
converted stage is called IF2, and the third converted stage is IF3. The converted signals in each stage
are derived by mixing their respective input signal with their local oscillator (LO) signal. This mixing
process results in many products and the desired product at each IF stage is picked out using band-
pass filters. Signals that appear inside the passband of the filter will be passed through, while those
that are outside the passband are suppressed. Generally, the farther an unwanted signal is away
from the filters the better it is suppressed. Unwanted signals that are close to the passband or inside
the passband are called spurious signals (or ‘spurs’ for short). Because of the wide bandwidth of the
Signal Conversion Module
Synthesized Local Oscillator Module
Supply Conditioning and Digital Control/Interface
RF Input
Ref In
Ref Out
Digital IO Supply
IF Output
IF2 Input
LO1 Output

Rev 2.0 | SC5309A & SC5310A Hardware Manual SignalCore, Inc.
14
SC5309A & SC5310A Hardware Manual
IF filters there are input RF frequency regions as well as IF output regions where the number and
level of spurs are higher than typical, making those regions unsuitable for high dynamic range
applications.
The input tunable range of the downconverter is from ≈100 kHz to 2.5 GHz, while the output tunable
IF3 range is from ≈10 MHz to 100 MHz. The RF is tuned using the first local oscillator (LO1) and IF3 is
tuned with LO3. IF3 is tunable from 15 MHz to 140 MHz.
The frequency accuracy and stability of the device is derived from an onboard Temperature
Controlled Crystal Oscillator (TCXO) with accuracy better than 500 ppb. For better accuracy and
stability, the downconverter can lock to an external reference of higher precision.
The Signal Chain
The conversion module contains the mixers, filters, amplifiers, and attenuators used to convert,
purify, and maintain the amplitude of the signal, all the way from the input of the device to its output.
This cascade of signal conversion and conditioning stages is often referred to as the signal chain,
which is shown on the system block drawing in Figure 4.
The RF Input
All RF connectors are high quality female stainless steel SMA types rated to 18 GHz of operation.
The RF port is AC coupled with a 0.1 broadband capacitor as indicated in Figure 4. The input
frequency range at this port is less than 100.0 kHz to greater than 2.5 GHz. The upper limit to which
the device tunes to above 2.5 GHz varies slightly from unit to unit depending on the limits of the
oscillator circuitry. The usability of the upper out-of-bounds region depends on the roll-off
response of the RF elliptic filter and the IF1 mixer.
Figure 4. Block diagram of the signal conversion module of the downconverter assembly
R
I
LR
I
L
R
I
L
LO1
3.625-6.125
GHz
LO2
3.32GHz
DSA
IF3ATTEN2
This is alowpass
filter with the
option for a
bandpass
IF2_BPF1,
BW= Option
IF3
MIXER
RF
PREAMP IF1BPF
CF=3.625 GHz
BW=100 MHz
IF2LPF
500 MHz
IF2_BPF0,
CF=305GHz
BW=20 MHZ
DSA
IF3ATTEN1
DSA
RF ATTEN2
DSA
RF ATTEN1
IF1 CF = 3.625 GHz
IF2 CF=305Hz
BYPASS IF3
CONVERSION
PATH
RF IN
IF OUT
User
programmable
components
Fixed components
IF3 Freq =~10-100 MHz
RF Freq = 100kHz to 2.5 GHz
From LO Module
BYPASS
CONVERSION
PATH
ELLIPTIC
LPF IF2
MIXER
IF1
MIXER
Device
controlled
components
LO3
420 MHz MHz
220 MHz MHz

©2018 Rev 2.0
15
Functional Description
The Input Path Switch
Immediately following the capacitor is an RF switch to selectively direct the RF signal down two
paths:
1. The default is the conversion path where the RF signal is converted to a final IF.
2. The alternative path is directly to the IF port, bypassing all means of frequency conversion. For
lower RF frequency that can be digitized directly by a digitizer at the IF port, this path provides
the convenience. Another reason for choosing this path for lower frequencies is that converting
low RF to an IF may result in more unwanted spurs at the IF output.
When the conversion path is bypassed, the conversion path and the internal LO are disabled by
powering down.
The RF Path
The first device in the RF conversion path is a step attenuator with 1 dB step resolution. This
attenuator (RF_ATTEN) is used to control the signal level at the mixer or at the RF preamplifier. If
the RF level at the input of these devices is relatively large with respect to their input compression
points, the signal would experience greater nonlinear effects, distorting its waveform, and
producing large spurious 3rd intermodulation distortion effects.
Following RF_ATTEN is a switchable RF amplifier that can be switched into the signal path to
improve the device sensitivity, effectively lowering the device noise figure. In other words, the
effective input noise level of the device is lowered when this amplifier is enabled. Turning on this
amplifier is recommended to improve the signal-to-noise dynamic range (DRSNR) when expected
signal levels are lower than -30 dBm. The typical maximum gain of the downconverter without the
amplifier enabled is +30 dB. When the amplifier is enabled, its additional +15 dB will boost the
typical maximum gain to +45 dB.
The attenuator (RF_ATTEN2) following the amplifier switch is used together with RF_ATTEN1 to
control the level at the input of the mixer. Unless the input level is very high, and the attenuation
range of RF_ATTEN1 is exhausted, RF_ATTEN2 is not commonly used except when the RF amplifier
is enabled. RF_ATTEN1 and RF_ATTEN2 provide 60 dB of attenuation range, which is enough to
keep the device in the linear mode of operation even for signal levels near the maximum
recommended value of +27 dBm.
Between RF_ATTEN2 and the mixer is the RF elliptic low pass filter. This filter cuts off just above
2.7 GHz and has better than 75 dB of rejection for frequencies above 3.6 GHz. This suppresses
back-travel LO leakages to better than -100 dBm (typically -120 dBm) at the input RF port. Another
function of this filter is to provide superior suppression of RF image frequencies. The lack of
suppression of these RF images could result in mixing with LO1 and appear as spurious components
in the IF.
The First Mixer and IF1 Path
The first mixer (IF1 mixer) of the downconverter is very critical as it sets the dynamic ranges of the
device for both the signal-to-noise and third order IMD (DRIMD) dynamic ranges. The DRSNR and
DRIMD are directly related to the mixer input compression point (IP1dB) and to the input third-order

Rev 2.0 | SC5309A & SC5310A Hardware Manual SignalCore, Inc.
16
SC5309A & SC5310A Hardware Manual
intercept point (IIP3). The IIP3 of the mixer is typically better than +18 dBm, and its P1dB is better
than 5 dBm. In applications that require better signal linearity, it is recommended that the level at
the mixer input is kept at -20 dBm or less. Typically, the IMD is better than -75 dBc for two -20 dBm
tones at the mixer. Increasing the level at the mixer improves SNR of the IF output signal at the
expense of linearity.
Another important characteristic of the mixer is the LO-IF isolation and LO-RF isolation. The higher
the isolation, the lower the leakage LO signal is at the RF and IF ports. The IF1 mixer is driven with
a ≈+20 dBm LO1 signal and the LO-IF isolation is about 45 dB, resulting in a -25 dBm LO1 leakage in
the IF1 path. If the RF signal level at the mixer is -20 dBm and the mixer conversion loss is -8 dB,
the converted IF1 signal is -28 dBm. For this case, the LO leakage is greater than the converted IF
signal. For most of the RF input range, the LO1 leakage is not an issue because the first IF filter (IF1
BPF) will suppress it. Furthermore, when the leakage passes through the IF2 bandpass filters, it will
be further suppressed. However, when the downconverter turns to lower frequency, especially
when the RF is near the value of the bandwidth of these filters, the LO1 becomes an unwanted
spur.
The frequency relationship between the three ports of the mixer is given as:
As RF approaches 0 Hz, LO -> IF, resulting in the LO leakage being inside the passband of the filter.
The filters are not able to optimally reject leakages inside their passband or within their filter slope.
This LO1 leakage will mix with the converted IF1 signals or with LO2 to produce higher order
unwanted in-band spurs that could be large enough to affect the recovery of signal data. These
intermodulation spurs are usually not so easy to determine and deal with. Having high linearity
components helps maintain these spurs at acceptable levels. The linearity in these modules keeps
these types of 3rd order effects at typically less than -60 dBc. In addition, the LO leakage is a known
signal that shows up as the DC value when the final IF spectrum is digitized and processed. For
lower RF frequencies it is recommended to switch the RF directly to a digitizer at the IF port instead
of putting it through the conversion stages. The user should determine whether the application
can tolerate LO leakages, what the effects will be, and decide on the most appropriate route to
take.
The first IF (IF1) frequency is centered typically at 3.675 GHz with a minimum bandwidth of 100
MHz. This center frequency may be adjusted programmatically from 3.675 GHz to ± 50 MHz offset.
The default center frequency is set at the factory at the time of calibration to compensate for shifts
in the IF1 and IF2 filter responses due to fabrication variations. Another advantage of setting the IF
frequency higher is to place it closer to the filter slope region, providing better LO1 leakage
suppression.
This stage of conversion is an up conversion rather than a down conversion. This broadband
architecture simplifies the input RF and IF1 sections to achieve:
1. Superior image rejection without the use of multiple RF bandpass filters.
2. Great RF suppression and isolation in the IF2 passband without multiple IF and LO frequency
bands.

©2018 Rev 2.0
17
Functional Description
The disadvantage of this approach is the requirement of high IF1 and LO1 frequencies which places
demanding phase noise requirements on the LO1 synthesizer.
The Second Mixer and IF2 Path
The second IF (IF2) is typically centered at 305 MHz and has settable range with 5 MHz steps. The
relationship between LO2, IF1, and IF2 is:
IF1 and IF2 are settable with the condition that LO2 must be tuned in 5 MHz steps and have a range
less than ± 50 MHz.
The converted IF2 signal out of the mixer is passed through a 500 MHz filter to suppress IF1 and
LO2 leakages. The IF2 LPF is not aggressive, so converted LO1 leakages that are close to the IF1
frequency may appear at relatively high values in the IF2 path. After IF2 LPF, the signal passes
through the selectable bandpass filters BPF0 and BPF1, whose frequency bandwidths are
dependent of the customer option for IF BW. These filters may shape the final BW of the device
for low IF frequencies because there are limited filter selections. If there is a need for further signal
shaping, an external LPF or BPF will need to be placed after the IF OUT port. This signal will be
converted to IF3 via the third IF3 mixer.
For low RF signals, BPF1 can optionally be fitted with a narrow 100 kHz BW filter to suppress LO
leakages, especially for those frequencies that are less than the BW of BPF0.
The Third mixer and IF3 Path
The third IF (IF3) is tunable from ±5 MHz to ±100 MHz, as LO3 is tuned from 220 MHz to 420 MHz
in 5 MHz steps. The negative value of IF3 indicates that the spectrum is inverted with respect to
the RF input spectrum. When spectral inversion is selected, LO3 tunes below IF2 and it tunes above
for no spectral inversion. There is an LPF filter in this stage to provide filtering of IF2 and LO3
leakages as well as harmonics of the IF3 signal.
Attenuators IF3_ATTEN1 and IF3_ATTEN2 are used to set the output amplitude of IF3. Attenuation
should be applied to IF3_ATTEN2 first and any overflow of more than 30 dB is then applied to
IF3_ATTEN1. However, if better linearity is needed, apply the first 6 dB to IF3_ATTEN1 and then
the rest to IF3_ATTEN2.
Signal Chain Configurations
Recommended signal chain configurations are provided below for various application scenarios.
These are strictly recommendations and not indicative of the downconverter function limitations;
users will need to adapt the device to their own applications.
Low Input RF
If the RF value is on the order of the bandwidth of the narrowest filter, significant LO leakage
may appear at the IF output. Placing an external IF filter will provide further suppression of the
leakage that appears outside of the passband. If the external digitizer can handle the RF directly,
then the RF signal should be switched to the IF port directly, bypassing conversion.

Rev 2.0 | SC5309A & SC5310A Hardware Manual SignalCore, Inc.
18
SC5309A & SC5310A Hardware Manual
Converted Signals
Selecting the narrower filters in the IF2 stage improves the leakage spurs, and allows for lower
frequencies at both IF and RF. For example, IF3 could be set to lower for a narrow BW IF2 filter
without the risk of possible increase of in-band spurs arising from LO2-LO3 intermodulation or
having significant LO leakages even when the device is tuned for RF as low as 5 MHz.
The final IF3 LPF is only a 5th order Chebyshev filter so the rejection slope is not particularly
aggressive. This means the harmonic rejection is not as effective for some applications, especially
when IF3 is low. It is recommended that an external filter be used to further suppress these
harmonics.
Dynamic Range Setting
There are 2 sets of digital step attenuators to control the conversion gain of the downconverter.
The first set consists of RF_ATTEN1 and RF_ATTEN2 and the second set consists of IF3_ATTEN1
and IF3_ATTEN2. All attenuators, except for IF3_ATTEN2, have 30 dB range and 1 dB step.
Attenuator IF3_ATTEN2 has 30 dB range and 0.25 dB step.
To set the downconverter for better sensitivity or better SNR, the gain should be shifted to the
RF input path of the device, before the mixer. The RF pre-amplifier should be enabled if necessary
and/or RF attenuation reduced. The IF3 attenuator is then used to adjust the final IF output level.
The drawback is that the signal level starts off higher as it enters the first mixer as well as the
subsequent components. As a result, the apparent linearity of the device is lower.
To set the device for better linearity, the gain should be shifted to the output IF3 path (after the
third mixer) and reduced in the RF path. The signal power level at the first mixer should be lower
than -20 dB for improved linearity. Since the input signal is low, the relative SNR will be lower.
But, as the first mixer and subsequent components experience lower power levels, the apparent
linearity of the device is improved.
When the device gain is balanced well, the device can achieve SNR better than 130 dBc/Hz while
maintaining IMD3 levels close to 80 dBc. These numbers are representative of converters used
in large box high end spectrum analyzers. When the device is optimized for best SNR, typical
values better than -150 dBc/Hz can be achieved, and when the device is optimized for sensitivity,
the input spectral noise floor is typically lower than -160 dBm/Hz. The flexible use of these
attenuators allows the downconverter to achieve better than 190 dB of measurement dynamic
range.

©2018 Rev 2.0
19
Functional Description
The LO Module
The local oscillator (LO) module contains three local oscillators, the reference clocks, and the
calibration EEPROM as shown in Figure 5.
Figure 5. Block diagram of the local oscillator
The Reference Clocks
The base clock of the downconverter is a 10 MHz Voltage Controlled Temperature Controlled
Crystal Oscillator (VCTCXO) with an initial accuracy better than 500 ppb once the device has
reached a stable temperature. Its initial accuracy is set at the factory via an on-board 14-bit voltage
reference DAC. This DAC is accessible for dynamic accuracy calibration. The other reference is a
100 MHz Voltage Controlled Crystal Oscillator (VCXO) which is phase locked to the base reference
whenever an external reference source is not used.
When an external reference is selected as the base clock by enabling the device to phase lock to it,
the effect only occurs when the presence of this reference is detected. In other words, although
the device is programmed to lock externally it will not attempt to do so until the reference signal
is detected at the input reference port. Notice, both the reference clocks will attempt to lock to
the external source. Having the VCXO lock directly to the external source has the advantage of
utilizing the close-in phase noise of the source; it is best to assume that the external source is
superior to the internal base. Although the internal VCTCXO is not used when an external reference
100M PLL
REF DETECT
10
To Signalchain Module
ENABLE
LO3LO2
LO1
TCXO PLL Programmable
component
REF
IN
REF
OUT Fixed
component
LO Section
Reference
Section
CAL EEPROM
This manual suits for next models
1
Table of contents
Other SIGNALCORE Media Converter manuals