Linear Technology DC1705A Quick setup guide

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DEMO MANUAL DC1705A
DESCRIPTION
LTC6946
Ultralow Noise and Spurious Integer-N
Frequency Synthesizer with Integrated VCO
DC1705A features the LTC
®
6946, an ultralow noise and
spurious integer-N frequency synthesizer with integrated
VCO. The VCO uses no external components and is inter-
nally calibrated without external system support.
There are three versions of the DC1705A, one for each
version of the LTC6946. The DC1705A-A contains the
LTC6946-1, the DC1705A-B incorporates the LTC6946-2
and DC1705A-C uses the LTC6946-3.
Each DC1705A provides 50Ω SMA connectors for the
reference frequency input, fREF, the reference output buffer
(REF OUT), and the differential RF output (RF+and RF–).
A DC590 USB serial controller board is used for SPI com-
munication with the LTC6946, controlled by the supplied
PLLWizard™ software.
Design files for this circuit board are available at
http://www.linear.com/demo
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
PLLWizard and QuikEval are trademarks of Linear Technology Corporation. All other trademarks
are the property of their respective owners.
Figure 1. Proper Measurement Equipment Setup

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DEMO MANUAL DC1705A
PARAMETER INPUT OR OUTPUT PHYSICAL LOCATION DETAILS
3.3V Power Supply Input 3.3V and GND Banana Jacks Low Noise and Spur-Free 3.3V, 115mA
5V Power Supply Input 5V and GND Banana Jacks Low Noise and Spur-Free 5V, 45mA
REF+IN, Reference Frequency Input J1 SMA Connector Low Noise 10MHz or 100MHz*, 6dBm into 50Ω
(Note 1)
REF OUT, Buffered Reference Output J3 SMA Connector Frequency = fREF, 0dBm
RF+and RF–Two Outputs J4 and J5 SMA Connectors Frequency: 900MHz*, Power: 0dBm, Frequency
Range: Depends on the version of the LTC6946
device – refer to Table 1, Step Size: 200kHz*
Loop Bandwidth – Set by Loop Filter Component Values 47kHz*
* These frequencies are for the DC1705A pllset files included with PLLWizard.
Note 1: A low noise 10MHz or 100MHz reference frequency, such as the Wenzel 501-04608A or 501-04516D OCXO, is recommended. If using a different
frequency, make sure to update the fREF and R_DIV boxes under the System tab in PLLWizard so that fPFD is still 1MHz. For example, if a 20MHz clock is
used, fREF should be changed to 20MHz and R_DIV to 20. REF BST and FILT under the System tab in PLLWizard might need to be changed if the reference
frequency and/or power is different than what is recommended in the table above. More information can be found in the LTC6946 data sheet.
Table 1. DC1705A Options and Frequency Ranges
ASSEMBLY VERSION PART NUMBER VCO FREQUENCY RANGE (GHz) OUTPUT DIVIDER SETTINGS
DC1705A-A LTC6946IUFD-1 2.240 to 3.740 Integers 1 through 6
DC1705A-B LTC6946IUFD-2 3.080 to 4.910 Integers 1 through 6
DC1705A-C LTC6946IUFD-3 3.840 to 5.790 Integers 1 through 6
TYPICAL DC1705A REQUIREMENTS AND CHARACTERISTICS
QUICK START PROCEDURE
The DC590 and PLLWizard application are required to
control the DC1705A through a personal computer (PC).
DC590 Configuration
The DC590’s QuikEval™ drivers must be installed before
the DC590 will be able to communicate with the LTC6946.
To configure the DC590, follow the procedure below, start-
ing with step 1. If you have already installed the DC590
software previously, skip to step 5.
Note: Once the QuikEval software is installed, the applica-
tion does not need to be executed to run PLLWizard or to
control the DC1705A.
1. Do Not plug in the DC590 before running the installation
program.
2. Download the QuikEval installation program from
http://www.linear.com/software.
3. Run the QuikEval installation program and follow the
on-screen instructions. More detailed installation infor-
mation may be found in the DC590’s Quick Start guide.
4. Exit the QuikEval program once the installation is com-
plete, as it is not needed to run the PLLWizard software.
5. Place the DC590 jumpers in the following positions:
JP4 EE Must be in the “EN” position.
JP5 ISO ”ON” must be selected.
JP5 SW ”ON” must be selected.
JP6 VCCIO “3.3V” must be selected. This sets the SPI
port to 3.3V operation.
6. Connect the DC590 to one of your computer’s USB
ports with the included USB cable.

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DEMO MANUAL DC1705A
Figure 2. DC590 Jumper Locations
QUICK START PROCEDURE
PLLWizard Installation
The PLLWizard software is used to communicate with
the LTC6946 synthesizer. It uses the DC590 to translate
between USB and SPI-compatible serial communications
formats. It also includes advanced PLL design and simula-
tion capabilities. The following are the PLLWizard system
requirements:
• Windows Operating System: Windows XP,
Windows 2003 Server, Windows Vista, Windows 7
• Microsoft .NET 2.0 or later
• Windows Installer 3.1 or later
• Linear Technology’s QuikEval and DC590 hardware
Microsoft .NET
You must have Microsoft .NET 2.0 or later installed on
your computer. PLLWizard will not run without it. Note
that with Windows Vista and Windows 7 have at least
version 3.5 pre-installed.
To manually determine your version of .NET using Win-
dows XP, click Start Menu →Settings →Control Panel
→Add or Remove Programs.
Depending upon your .NET version, choose one of
two PLLWizard setup programs, downloaded from
http://www.linear.com/software.

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DEMO MANUAL DC1705A
QUICK START PROCEDURE
Figure 3. PLLWizard Screenshot
Either setup program will automatically install Microsoft
.NET if a compatible .NET version is not found. But, the
installation source depends upon which file you down-
loaded from Linear Technology’s website. You should pick
one of the following two choices, depending upon your
version of .NET.
Table 2. PLLWizard Installation File
FILE .NET 2.0 SOURCE
PLLWizardSetup.exe Latest Version Downloaded from Microsoft
PLLWizardSetup_net20.exe 2.0 SP2 Included (Much Larger File Size)
• Choose PLLWizardSetup if you have .NET 2.0 or later,
have Windows Vista or Windows 7, or if you have less
than .NET 2.0 but want the latest .NET installed.
• Choose PLLWizardSetup_net20 if you have less than
.NET 2.0, and want faster installation (no additional
Microsoft downloads are needed, but the file size is
much larger).
The setup file will verify and/or install Microsoft .NET and
install PLLWizard. Refer to the Help menu for software
operation.

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DEMO MANUAL DC1705A
QUICK START PROCEDURE
DC1705A Configuration
1. Connect an appropriate reference frequency source (at
J1) and signal analyzers (at J4 and/or J5) using the
SMA connectors (see Figure 1 and the Typical DC1705A
Requirements and Characteristics table).
2. Choose theMUTE jumpersetting:JP1 - GND/3.3VMUTE
position. Select GND to mute the RF output, 3.3V to
un-mute.
3. Connect the GND, 3.3V and 5V banana jacks to a power
supply and apply power (see Figure 1 and the Typical
DC1705A Requirements and Characteristics table).
4. Connect the DC590 to the DC1705A with the provided
ribbon cable.
5. Run the PLLWizard application.
6. In PLLWizard, click File →Load Settings and point to
the appropriate pllset file. For example, if you are using
a 10MHz reference with a DC1705A-B to evaluate the
LTC6946-2, load the “DC1705A-B (LTC6946-2) 10MHz
Ref.pllset” file found in the PLLWizard installation direc-
tory (typically Program Files →LTC →PLLWizard →
Set Files).
The red LED on DC1705A should turn on indicating that
the loop is locked at 900MHz.
You can then change the values of N_DIV and/or O_DIV
in PLLWizard to change the output frequency.
Troubleshooting
If the red LED does not illuminate, follow the instructions
below:
1. Verify that you are able to communicate with the
DC1705A. The bottom status line in PLLWizard should
read “LTC6946” and “Comm Enabled.” Refer to PLL-
Wizard’s Troubleshoot and Help if not.
2. Verify that the 3.3V and 5V have the correct voltages
on them and that the reference frequency is applied to
the REF+IN SMA input.
If the red LED is on but you cannot detect an RF output,
make sure jumper JP1 is at the 3.3V position. Run Help →
Troubleshoot in PLLWizard if the problem is not resolved.
DC1705A Reconfiguration
You can redesign the frequency plan of the DC1705A using
PLLWizard. You can change the loop filter components
as found using PLLWizard by reinstalling the loop filter
components shown in Figure 4.
Figure 4. DC1705A Components and Connections

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DEMO MANUAL DC1705A
PARTS LIST
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
DC1705A General BOM
1 1 CI1 Capacitor, X7R 0.022μF 50V 5% 0603 AVX 06035C223JAT2A
2 1 CI2 Capacitor, COG 6800pF 50V 5% 0805 Murata GRM2195C1H682JA01D
3 1 CP Capacitor, COG 2700pF 50V 5% 0603 Murata GRM1885C1H272JA01D
4 4 C1, C8, C9, C18 Capacitor, X7R, 1μF, 16V, 10%, 0805 TDK, C2012X7R1C105K
5 2 C2, C10 Capacitor, Tantalum, 330μF, 10V, 10%, 7343 AVX, TPME337K010R0035
6 2 C6, C11 Capacitor, X7R, 470pF, 50V, 10%, 0402 AVX, 04025C471KAT2A
7 4 C7, C12, C15,
C19
Capacitor, X7R, 0.01μF, 16V, 10%, 0402 AVX, 0402YC103KAT2A
8 C13, C14, C17,
C22, C23,
Capacitor, X5R, 0.1μF, 10V, 10%, 0402 TDK, C1005X5R1A104K
8 C24, C25, C26
9 1 C16 Capacitor, X7R, 2.2μF, 16V, 10%, 0805 TDK, C2012X7R1C225K
10 2 C20, C21 Capacitor, NPO, 100pF, 50V, 5%, 0402 TDK, C1005C0G1H101J
11 1 D1 LED, Red Panasonic, LN1251CTR
12 4 E1, E2, E5, E8 Jack, Banana Keystone, 575-4
13 1 E3 Turret, Testpoint, 2501 Mill-Max, 2501-2-00-80-00-00-07-0
14 1 JP1 Headers, 3 Pins 2mm Ctrs. Samtec TMM-103-02-L-S
15 1 XJP1 Shunt, 2mm Ctrs. Samtec 2SN-BK-G
16 4 J1, J3, J4, J5 Connector, SMA 50Ω EDGE-LAUNCH E. F. Johnson, 142-0701-851
17 1 J2 Connector, Header, 14-Pin, 2mm Molex, 87831-1420
18 2 L1, L2 Inductor, Chip, 68nH, ±5%, 0402 Coilcraft, 0402 HPH-68NXJL
19 1 RZ Resistor, Chip, 453 1/10W 1% 0603 NIC, NRC06F4530TRF
20 1 R1 Resistor, Chip, 51.1Ω, 1/16W, 1% 0402 NIC, NRC04F51R1TRF
21 1 R3 Resistor, Chip, 330Ω, 1/16W, 1% 0402 NIC, NRC04F3300TRF
22 1 R4 Resistor, Chip, 15Ω, 1/16W, 1% 0402 NIC, NRC04F15R0TRF
23 4 R5, R6, R7, R13 Resistor, Chip, 200k, 1/16W, 1% 0402 NIC, NRC04F2003TRF
24 2 R8, R9 Resistor, Chip, 4.99k, 1/16W, 1% 0402 NIC, NRC04F4991TRF
25 3 R10, R11, R12 Resistor, Chip, 100Ω 1/16W, 5%, 0402 NIC, NRC04J101TRF
26 2 U2, U3 IC, Dual Buffer SC-70 6-Lead Fairchild Semi. NC7WZ17P6X
27 1 U4 IC, Dual Transceiver SC-70 6-Lead NXP 74LVC1T45GW
28 4 4 Corners Standoff, Nylon, 0.5, 1/2" Keystone, 8833 (SNAP ON)
DC1705A-A
1 1 DC1705A General BOM DC1705A
21U1 IC Synthesizer QFN-28 4mm ×5mm Linear Technology Corporation, LTC6946IUFD-1
DC1705A-B
1 1 DC1705A General BOM DC1705A
21U1 IC Synthesizer QFN-28 4mm ×5mm Linear Technology Corporation, LTC6946IUFD-2
DC1705A-C
1 1 DC1705A General BOM DC1705A
21U1 IC Synthesizer QFN-28 4mm ×5mm Linear Technology Corporation, LTC6946IUFD-3

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DEMO MANUAL DC1705A
SCHEMATIC DIAGRAM

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DEMO MANUAL DC1705A
SCHEMATIC DIAGRAM
Note: The buffers shown on sheet 2 of 2 of the schematic are used to protect the LTC6946 when communicating to it starts
before powering it up. There is no need for such circuitry if the SPI bus is not active before powering up the LTC6946.

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DEMO MANUAL DC1705A
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
LAYOUT
The top metal layer of the DC1705A is shown here as an example of good PCB layout for the LTC6946.

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DEMO MANUAL DC1705A
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
[phone] ●FAX: [phone] ●www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2011
LT 1211 REV A • PRINTED IN USA
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