Linear Technology DC1846A Quick setup guide

1
dc1846af
DEMO MANUAL DC1846A
DESCRIPTION
LTC6947
Ultralow Noise and Spurious
Fractional-N Synthesizer
Demonstration circuit 1846A features the LT C
®
6947, an
Ultralow Noise and Spurious Fractional-N Synthesizer.
DC1846A provides 50Ω SMA connectors for the reference
frequency (REF+) and the two single-ended RF outputs
(RF+ and RF–).
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
FracNWizard is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners.
A DC590 USB serial controller board is used for SPI com-
munication with the LTC6947, controlled by the supplied
FracNWizard™ software.
Design files for this circuit board are available at
http://www.linear.com/demo
Figure 1. DC1846A Connections





Frequency
referenceinput,
SMA
ExternalVCO
input,SMA
Differential
outputofVCO
buffer,SMA
3.3VDCsupply,
bananajacks
5VDCsupply,
bananajacks
Ribbon
cable
connection
toDC590
Activeloopfilterop‐
ampDCsupply,turret
U3(VCO)DC
supply,turret
U4(VCOorVCXO)
DCsupply,turret
Enable(pin2)
ofU4(VCOor
VCXO),turret

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dc1846af
DEMO MANUAL DC1846A
QUICK START PROCEDURE
The DC1846A is easy to set up to evaluate the performance
of the LTC6947. Follow the procedure below.
The DC590 and FracNWizard application are required to
control the DC1846A through a personal computer (PC).
DC590 Configuration
Place the DC590 jumpers in the following positions (refer
to Figure 2):
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.
Connect the DC590 to one of your computer’s USB ports
with the included USB cable.
FracNWizard Installation
The FracNWizard software is used to communicate with
the LTC6947 synthesizer. It uses the DC590 to translate
between USB and SPI-compatible serial communica-
tions formats. It also includes advanced PLL design and
simulation capabilities. The following are the FracNWizard
system requirements:
• Windows Operating System: Windows XP, Windows
2003 Server, Windows Vista, Windows 7
• Microsoft .NET 3.5 SP1 or later
• Windows Installer 3.1 or later
• Linear Technology’s DC590 hardware
Figure 2. DC590 Jumper and Connector Locations


JP6
jumpers
J4,ribbon
cable
connection
tothe
DC1846
JP5jumpers
JP4
jumper
J3,USB
connection
toPC

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dc1846af
DEMO MANUAL DC1846A
QUICK START PROCEDURE
Download the FracNWizard setup file at:
www.linear.com/FracNWizard
Run the FracNWizard setup file and follow the instructions
given on the screen. The setup file will verify and/or install
Microsoft .NET and install the FracNWizard. Refer to the
Help menu for software operation.
DC1846A Configuration
1. Connect a 100MHz reference frequency source (at J2)
and signal analyzers to RF+ and/or RF– (at J6 and/or
J7) using the SMA connectors (see Figure 1 and the
Typical DC1846A Requirements and Characteristics
table).
Be sure to terminate any unused RF output with 50Ω, or
poor spurious performance may result.
2. Choose the MUTE jumper setting:
JP1: GND/3.3V - MUTE position. Select GND to mute
the RF output, 3.3V to unmute.
3. Connect the GND, 3.3V, 5V banana jacks and the
V+VCO turret to a power supply and apply power (see
Figure 1 and the Typical DC1846A Requirements and
Characteristics table).
4. Connect the DC590 to the DC1846A with the provided
ribbon cable.
5. Run the FracNWizard application.
6. In FracNWizard, click File -> Load Settings and point
to the “LTC6947_100MHz.fracnset” file.
The red LED on the DC1846A should turn on indicating
that the loop is locked at 2415MHz.
Figure 3. FracNWizard Screenshot

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dc1846af
DEMO MANUAL DC1846A
QUICK START PROCEDURE
DC1846A RECONFIGURATION
Troubleshooting
If the red LED does not illuminate, follow the instructions
below:
1. Verify that you are able to communicate with the
DC1846A. The bottom status line in FracNWizard
should read “LTC6947” and “Comm Enabled”. Refer
to FracNWizard’s Troubleshoot and Help if not.
2. Verify that the 3.3V, 5V and V+VCO have the correct
voltages on them and that the reference frequency is
applied to the REF+ SMA input.
If the red LED is on but you cannot detect an RF output,
make sure the DC1846A jumper JP1 is at the 3.3V position.
Run Help -> Troubleshoot in FracNWizard if the problem
is not resolved.
The DC1846A is flexible and allows the use of a variety of
VCOs and the choice to employ either an active or pas-
sive loop filter. The following covers the hardware recon-
figuration of the DC1846A. Refer to FracNWizard’s Help
and the LTC6947 data sheet to better understand how to
change programmed parameters on the DC1846A.
Installing Different Tunable Devices
The DC1846A permits the use of different tunable oscil-
lators, such as VCOs and VCXOs. There are two different
oscillatorfootprintsontheboard:U3,whichaccommodates
the popular 0.5 ×0.5 in. package, and U4, which accom-
modates another common 14mm ×9 mm package with
four or six pins. An external connectorized VCO can also
drive the LTC6947 through J5. Table 1 gives options to
customize the DC1846’s VCOs. When using an active loop
filter, an additional pole is required in the loop filter to limit
the op amp’s noise contribution to the VCO phase noise.
Selecting Loop Filter Type
The DC1846A can use either an active or a passive loop
filter, depending upon the application. Some VCO tuning
voltage ranges are greater than the LTC6947 charge pump
voltage range (refer to the LTC6947 data sheet). In such
cases, an active loop filter using an op amp can deliver
the required tuning voltage. Table 2 summarizes these
options. FracNWizard helps determine the component
values listed in this table.
Table 1. Oscillator Options
TUNABLE
DEVICE
SELECTION
COMPONENTS
RESISTOR FOR
ADDITIONAL POLE
CAPACITOR FOR
ADDITIONAL POLE POWER
ENABLE PIN OR
REMARKS
U3* C26 ≅100pF, depopulate
R2_F3, C25 and C28*
R2_F2 = 0Ω for passive
loop filter*
R2_F2 = 75Ω for active
loop filter
C3_F2 = Open for passive
loop filter*
Pick C3_F2 such that
1/(2π ×R2_F2 ×C3_F2) ≅
15 × the loop bandwidth in
Hz for active loop filter
Determined by U3
device power supply
specification, up to 24V
applied to V+VCO turret
U4 C28 ≅100pF, depopulate
R2_F2, C25 and C26
R2_F3 = 0Ω for passive
loop filter
R2_F3 ≅75Ω for active
loop filter
C3_F3 = Open for passive
loop filter
Pick C3_F3 such that
1/(2π ×R2_F3 ×C3_F3) ≅
15 ×the loop bandwidth in
Hz for active loop filter
Determined by U4
device power supply
specification, up to 24V
applied to V+VCXO turret
Use EN turret to control
pin 2 of U4 if needed
External C25 ≅100pF, R15 = 0Ω
Ohms, depopulate R13,
C26 and C28
- - - Selection components
are for an active loop
filter. Connect the
external VCO output to
J5. Use CPGAIN to tune
the external device.
*These are the default installation options. For the DC1846A-A, U3 is populated with CVCO55CC-2328-2536 from Crystek

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dc1846af
DEMO MANUAL DC1846A
TYPICAL DC1846A REQUIREMENTS AND CHARACTERISTICS
DC1846A RECONFIGURATION
Table 2. Loop Filter Options
LOOP FILTER
TYPE
SELECTION
RESISTORS
RZ FROM
FRACNWIZARD
CI FROM
FRACNWIZARD
CP FROM
FRACNWIZARD POWER
CPINV BOX,
SYSTEM TAB IN
FRACNWIZARD
Passive R14 and R16 = 0Ω,
depopulate R13 and
R15
RZ_P CI1_P in parallel
with CI2_P
CP_P None Unchecked
Active R13 (except when
using an external
VCO) and R15 = 0Ω,
depopulate R14 and
R16
RZ_A CI1_A in parallel
with CI2_A
CP_A Determined by the
maximum allowed
tune voltage of the
populated VCO (U3
or U4), up to 24V
applied to V+OA
turret
Checked
PARAMETER INPUT OR OUTPUT PHYSICAL LOCATION DETAILS
3.3V Power Supply Input J9 and J10 banana jacks Low noise and spur-free 3.3V,
103mA**
5V Charge Pump Power Supply Input J11 and J12 banana jacks Low noise and spur-free 5V,
22mA**
5V VCO Power Supply Input V+VCO turret Low noise and spur-free 5V,
30mA**
REF+, Reference Frequency Input J2 SMA connector Low noise 100MHz**, 6 to 10dBm
into 50Ω, see Note
RF+ and RF– Tw o Outputs J6 and J7 SMA connectors*** 2328 to 2536MHz** in 190.7Hz**
steps, 0dBm
Loop Bandwidth – Set by loop filter component values 30.7kHz**
**These values are for the “DC1846A_100MHz.fracnset” file and included VCO.
***Any unused RF output must be terminated with 50Ω, or poor spurious performance may result.
Note: A low noise 100MHz reference frequency, such as the Wenzel 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 FracNWizard so that Fpfd
is still 50MHz. For example, if a 250MHz clock is used, Fref should be changed to 250MHz and R_DIV to 5. Ref BST
and FILT under the System tab in FracNWizard 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 LTC6947 data sheet.

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dc1846af
DEMO MANUAL DC1846A
PARTS LIST
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
1 0 CI1_A, C3_F2, C3_F3, CP_A, C14 CAP, 0603 OPT
2 6 CI1_P, C5, C12, C13, C18, C31 CAP, 0603 1.0µF 10% 10V X7R TAIYO YUDEN, LMK107B7105KA-T
3 0 CI2_P, CI2_A CAP, 1206 OPT
4 1 CP_P CAP, 0603 47nF 10% 50V X7R AVX 06035C473KAT2A
5 3 C1, C19, C33 CAP, 7361 47µF 10% 35V, 7361 AVX TAJV476K035RNJ
6 3 C2, C21, C35 CAP, 0805 0.1µF 10% 50V X7R AVX 08055C104KAT2A
7 2 C3, C16 CAP, 7343 330µF 10% 10V TANT AVX TPME337K010R0035
8 9 C4, C6, C11, C30, C36, C39, C41, C43, C44 CAP, 0402 0.1µF 10% 10V X7R TAIYO YUDEN, LMK105B7104KV-F
9 1 C7 CAP, 7343 47µF 10% 20V TANT AVX TAJD476K020RNJ
10 2 C8, C15 CAP, 0402 1µF 10% 16V X5R TDK C1005X5R1C105K
11 4 C17, C23, C34, C45 CAP, 0402 0.01µF 10% 16V X7R AVX 0402YC103KAT2A
12 1 C2_F1 CAP, 0603 33nF 10% 50V X7R AVX 06035C333KAT2A
13 0 C25, C28 CAP, 0402 OPT
14 4 C26, C29, C37, C38 CAP, 0402 100pF 10% 16V NPO AVX 0402YA101KAT2A
15 1 D1 LED, RED PANASONIC LN1251CTR
16 10 E3, E6, E11-E18 TURRET MILL-MAX 2501-2-00-80-00-00-07-0
17 1 JP1 HEADER, 3-PIN 2mm SAMTEC TMM-103-02-L-S
18 4 J2, J5, J6, J7 CONN, SMA 50Ω EDGE-LAUNCH E.F. JOHNSON, 142-0701-851
19 0 J3, J4 CONN, SMA 50Ω Straight OPT
20 4 J9, J10, J11, J12 JACK, BANANA KEYSTONE 575-4
21 1 J13 HEADER, 7 DUAL PIN, 2mm MOLEX 87831-1420
22 0 L1 IND, 0402 OPT
23 2 L2, L3 IND, 0402 68nH 5% COILCRAFT 0402HPH-68NXJLW
24 1 L1_F1 RES, 0805, 0Ω JUMPER VISHAY CRCW08050000Z0EA
25 0 L1_F2, L1_F3 IND, 0805 OPT
26 2 R1_F1, RZ_P RES, 0603 21Ω 1% 1/10W VISHAY CRCW060321R0FKED
27 5 R1, R2, R11, R20, R26 RES, 0402 4.99kΩ 1% 1/16W VISHAY CRCW04024K99FKED
28 1 R4 RES, 0402 330Ω 1% 1/16W NIC NRC04F3300TRF
29 1 R5 RES, 0402 51.1Ω 1% 1/10W VISHAY CRCW040251R1FKED
30 4 R7, R8, R18, R19 RES, 0402 200kΩ 1% 1/16W VISHAY CRCW0402200KFKED
31 4 R9, R14, R16, R2_F2 RES, 0603 0Ω JUMPER VISHAY CRCW06030000Z0EA
32 3 R12, R21, R22 RES, 0402 100Ω 5% 1/16W VISHAY CRCW0402101RJKED
33 0 R13, R15, R2_F3, RZ_A, R31 RES, 0603 OPT
34 0 R23, R24 RES, 0402 OPT
35 5 R25, R27, R28, R29, R30 RES, 0402 0Ω JUMPER VISHAY CRCW04020000Z0EA
36 1 U1 IC, QFN28IUFD-4X5 LINEAR TECH. LTC6947IUFD
37 1 U2 IC, LOW NOISE AMP, SO8 LINEAR TECH. LT1678IS8#PBF
38 1 U3 IC, VCO CRYSTEK, CVCO55CC-2328-2536
39 0 U4 IC, CRYSTAL OSCILLATOR OPT
40 2 U5, U10 IC, DUAL BUFFER, SC70 FAIRCHILD SEMI NC7WZ17P6X
41 1 U8 I.C., Serial EEPROM, TSSOP8 MICROCHIP, 24LC025-I /ST
42 1 U11 IC, DUAL TRANSCEIVER, SOT363 NXP 74LVC 1T45GW
43 1 SHUNT ON JP1 (2&3) SHUNT, 2mm CTRS SAMTEC 2SN-BK-G

7
dc1846af
DEMO MANUAL DC1846A
SCHEMATIC DIAGRAM
1 1
2 2
3 3
4 4
5 5
6 6
7 7
8 8
A A B B C C D D
3.3V
GND
MUTE
VCO
2328 - 2536 MHz
ASSY U3
*
-A CVCO55CC-2328-2536
NOTE: UNLESS OTHERWISE SPECIFIED 1. ALL RESISTORS ARE IN OHMS, 0402 2. ALL CAPACITORS ARE IN MICROFARADS, 0402.
CS
SCLK
SDI
SDO
3.3V
3.3V
3.3V
3.3V 3.3V
5V
V+VCO
V+VCXO
3.3V
V+VCO
3.3V
5V
5V
V+OA
3.3V
REVISION HISTORY DESCRIPTION DATEAPPROVEDECO REV
MICHEL A.PRODUCTION2 01-28-14
__
REVISION HISTORY DESCRIPTION DATEAPPROVEDECO REV
MICHEL A.PRODUCTION2 01-28-14
__
REVISION HISTORY DESCRIPTION DATEAPPROVEDECO REV
MICHEL A.PRODUCTION2 01-28-14
__
SIZE DATE:
IC NO. REV.
SHEET OF
TITLE:
APPROVALS
PCB DES.
APP ENG.
TECHNOLOGY Fax: [phone]
Milpitas, CA 95035 Phone: [phone] McCarthy Blvd. LTC Confidential-For Customer Use Only
CUSTOMER NOTICE
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS; HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL APPLICATION. COMPONENT SUBSTITUTION AND PRINTED CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT PERFORMANCE OR RELIABILITY. CONTACT LINEAR TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE. THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SCHEMATIC
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
SCALE = NONE
www.linear.com
2
01/28/2014, 12:25 PM
12
N/A
LTC6947IUFD
DEMO CIRCUIT 1846A
MICHEL A.
KIM T.
ULTRALOW NOISE AND SPURIOUS FRACTIONAL-N SYNTHESIZER
SIZE DATE:
IC NO. REV.
SHEET OF
TITLE:
APPROVALS
PCB DES.
APP ENG.
TECHNOLOGY Fax: [phone]
Milpitas, CA 95035 Phone: [phone] McCarthy Blvd. LTC Confidential-For Customer Use Only
CUSTOMER NOTICE
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS; HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL APPLICATION. COMPONENT SUBSTITUTION AND PRINTED CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT PERFORMANCE OR RELIABILITY. CONTACT LINEAR TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE. THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SCHEMATIC
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
SCALE = NONE
www.linear.com
2
01/28/2014, 12:25 PM
12
N/A
LTC6947IUFD
DEMO CIRCUIT 1846A
MICHEL A.
KIM T.
ULTRALOW NOISE AND SPURIOUS FRACTIONAL-N SYNTHESIZER
SIZE DATE:
IC NO. REV.
SHEET OF
TITLE:
APPROVALS
PCB DES.
APP ENG.
TECHNOLOGY Fax: [phone]
Milpitas, CA 95035 Phone: [phone] McCarthy Blvd. LTC Confidential-For Customer Use Only
CUSTOMER NOTICE
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS; HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL APPLICATION. COMPONENT SUBSTITUTION AND PRINTED CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT PERFORMANCE OR RELIABILITY. CONTACT LINEAR TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE. THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SCHEMATIC
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
SCALE = NONE
www.linear.com
2
01/28/2014, 12:25 PM
12
N/A
LTC6947IUFD
DEMO CIRCUIT 1846A
MICHEL A.
KIM T.
ULTRALOW NOISE AND SPURIOUS FRACTIONAL-N SYNTHESIZER
+
C16
330uF
7343
10V
+
C16
330uF
7343
10V
C3_F2
OPT 0603
C3_F2
OPT 0603
C3_F3
OPT 0603
C3_F3
OPT 0603
C18 1uF
0603
C18 1uF
0603
E18
EN
E18
EN
C15 1uF C15 1uF
C23
0.01uF
C23
0.01uF
J12 GND J12 GND
C31 1uF
0603
C31 1uF
0603
E12
CPGAIN
E12
CPGAIN
R16 0
0603
R16 0
0603
JP1JP1
R14 0
0603
R14 0
0603
C17
0.01uF
C17
0.01uF
C8
1uF
C8
1uF
J3
CP
OPT J3
CP
OPT
R25
0
R25
0
RZ_P
21
0603 RZ_P
21
0603
+
C33 35V
47uF 7361
+
C33 35V
47uF 7361
J7
RF-
J7
RF-
E13 V+VCO E13 V+VCO
C45
0.01uF
C45
0.01uF
C2
0.1uF
35V
0805
C2
0.1uF
35V
0805
R1
4.99K
R1
4.99K
L1_F3 OPT 0805 L1_F3 OPT 0805
R2_F3
OPT 0603
R2_F3
OPT 0603
J5
EXT VCO IN
J5
EXT VCO IN
CI2_A
OPT 1206
CI2_A
OPT 1206
J4
CPGAIN
OPTJ4
CPGAIN
OPT
C11 0.1uF C11 0.1uF
C12
1uF
0603 C12
1uF
0603
R29
0
R29
0
R2
4.99K
R2
4.99K
C6 0.1uFC6 0.1uF
E3
CP E3 CP
J9
3.3V J9 3.3V
R31
OPT 0603
R31
OPT 0603
R5
51.1
R5
51.1
C38
100pF
C38
100pF
R30
0
R30
0
E15 V+VCXO E15 V+VCXO
+
C1
35V
47uF 7361
+
C1
35V
47uF 7361
CP_A
OPT 0603
CP_A
OPT 0603
R23 OPT R23 OPT
C21 0.1uF
35V 0805
C21 0.1uF
35V 0805
D1
LN1251CTR
RED
D1
LN1251CTR
RED
21
C29
100pF
C29
100pF
C4
0.1uF
C4
0.1uF
C5
1uF
0603
C5
1uF
0603
CI2_P
OPT 1206
CI2_P
OPT 1206
A
B
U2
LT1678IS8
A
B
U2
LT1678IS8
OUTA
1
-INA
2
+INA
3
V-
4+INB 5
-INB 6
OUTB 7
V+ 8
C25 OPT C25 OPT
CI1_A
OPT 0603
CI1_A
OPT 0603
R27
0
R27
0
C30
0.1uF
C30
0.1uF
E11
V+OA
E11
V+OA
CI1_P
1uF 0603
CI1_P
1uF 0603
C2_F1
33nF
0603
C2_F1
33nF
0603
R15 OPT
0603
R15 OPT
0603
E17
GND
E17
GND
J11 5V J11 5V
U4 OPTU4 OPT
VTUNE
1
EN
2
GND
3RFOUT 4
NC 5
VCC 6
J6
RF+
J6
RF+
R24
OPT
R24
OPT
L2
68nH
0402HPH-68NXJL
L2
68nH
0402HPH-68NXJL
U1
LTC6947IUFD
QFN28UFD-4X5
U1
LTC6947IUFD
QFN28UFD-4X5
STAT
2
VCO- 15
CS
3
MUTE
9
SDI
5
V+D
8
LDO
7
RF+
12
RF-
11
GNDA
10
SCLK
4
VCO+ 16
GNDB 17
V+RF
13
REF+
1
BB
14
SDO
6
GNDC 18 GNDD 19
GNDE 20
GNDF 21
GNDG 22
V+VCO 23
GNDH 24
V+CP 25
CP 26
V+REF 27
REF- 28
GND 29
R13 OPT
0603
R13 OPT
0603
U3
*
U3
*
GND 1
VTUNE 2
GND 3 GND 4
GND
5
GND
6
GND
7
GND
8
GND
9
RFOUT
10
GND
11
GND
12
GND 13
VCC 14
GND 15
GND 16
C35
0.1uF
35V 0805
C35
0.1uF
35V 0805
C28
OPT
C28
OPT
+
C3 330uF 7343 10V
+
C3 330uF 7343 10V
C34
0.01uF
C34
0.01uF
L1_F1
0
0805
L1_F1
0
0805
E6
STATUS E6 STATUS
L1_F2
OPT
0805
L1_F2
OPT
0805
C14 OPT 0603 C14 OPT 0603
J2
REF+
J2
REF+
E14 GND E14 GND
L1
OPT
L1
OPT
CP_P 47nF
0603
CP_P 47nF
0603
C26
100pF
C26
100pF
+
C19 35V
47uF
7361
+
C19 35V
47uF
7361
L3
68nH
0402HPH-68NXJL
L3
68nH
0402HPH-68NXJL
R4
330
R4
330
+
C7
20V
47uF
7343
+
C7
20V
47uF
7343
RZ_A OPT
0603
RZ_A OPT
0603
J10
GND J10 GND
C13 1uF
0603
C13 1uF
0603
R1_F1
21
0603
R1_F1
21
0603
R28
0
R28
0
E16 GND E16 GND
C37
100pF
C37
100pF
R2_F2
0
0603
R2_F2
0
0603

8
dc1846af
DEMO MANUAL DC1846A
SCHEMATIC DIAGRAM
Note: The buffers shown on sheet 2 of 2 of the schematic are used to protect the LTC6947 when connected to the DC590 before the LTC6947 is powered
up. There is no need for such circuitry if the SPI bus is not powered before powering up the LTC6947. The EEPROM is for identification and is not needed
to program the LTC6947.
A A
B B
C C
D D
E E
4 4 3 3 2 2 1 1
0603
DC590B SPI INTERFACE
NOTE: EEPROM FOR BOARD IDENTIFICATION
CS SCLK SDI SDO
3.3V
3.3V
3.3V
3.3V
SIZE DATE:
IC NO. REV.
SHEET OF
TITLE:
APPROVALS
PCB DES.
APP ENG.
TECHNOLOGY Fax: [phone]
Milpitas, CA 95035 Phone: [phone] McCarthy Blvd. LTC Confidential-For Customer Use Only
CUSTOMER NOTICE
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS; HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL APPLICATION. COMPONENT SUBSTITUTION AND PRINTED CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT PERFORMANCE OR RELIABILITY. CONTACT LINEAR TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE. THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SCHEMATIC
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
SCALE = NONE
www.linear.com
2
01/28/2014, 12:25 PM
22
ULTRALOW NOISE AND SPURIOUS FRACTIONAL-N SYNTHESIZER
MICHEL A.
N/A
LTC6947IUFD
DEMO CIRCUIT 1846A
KIM T.
SIZE
DATE:
IC NO. REV.
SHEET OF
TITLE:
APPROVALS
PCB DES.
APP ENG.
TECHNOLOGY Fax: [phone]
Milpitas, CA 95035 Phone: [phone] McCarthy Blvd. LTC Confidential-For Customer Use Only
CUSTOMER NOTICE
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS; HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL APPLICATION. COMPONENT SUBSTITUTION AND PRINTED CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT PERFORMANCE OR RELIABILITY. CONTACT LINEAR TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE. THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SCHEMATIC
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
SCALE = NONE
www.linear.com
2
01/28/2014, 12:25 PM
22
ULTRALOW NOISE AND SPURIOUS FRACTIONAL-N SYNTHESIZER
MICHEL A.
N/A
LTC6947IUFD
DEMO CIRCUIT 1846A
KIM T.
SIZE
DATE:
IC NO. REV.
SHEET OF
TITLE:
APPROVALS
PCB DES.
APP ENG.
TECHNOLOGY Fax: [phone]
Milpitas, CA 95035 Phone: [phone] McCarthy Blvd. LTC Confidential-For Customer Use Only
CUSTOMER NOTICE
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS; HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL APPLICATION. COMPONENT SUBSTITUTION AND PRINTED CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT PERFORMANCE OR RELIABILITY. CONTACT LINEAR TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE. THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SCHEMATIC
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
SCALE = NONE
www.linear.com
2
01/28/2014, 12:25 PM
22
ULTRALOW NOISE AND SPURIOUS FRACTIONAL-N SYNTHESIZER
MICHEL A.
N/A
LTC6947IUFD
DEMO CIRCUIT 1846A
KIM T.
R7
200K
R7
200K
WPWP
GND VCC
U10
NC7WZ17P6X
GND VCC
U10
NC7WZ17P6X
1 6
43 52
R8
200K
R8
200K
SDOSDOSCLKSCLKV+DIGV+DIG
R12
100
R12
100
R19
200K
R19
200K
R22 100R22 100
C44 0.1uF C44 0.1uF
GND
DIR
VCC(A) VCC(B)
U11
74LVC1T45GW
GND
DIR
VCC(A) VCC(B)
U11
74LVC1T45GW
1 6
43 52
R18
200K
R18
200K
R26
4.99K
R26
4.99K
GND VCC
U5
NC7WZ17P6X
GND VCC
U5
NC7WZ17P6X
1 6
43 52
R21
100
R21
100
J13
HD2X7-079-MOLEX
J13
HD2X7-079-MOLEX
MOSI/SDA 7
EESDA 9
V+ 1
5V 2
CS 6
SCK/SCL 4
EEVCC 10
MISO 5
EESCL 11
EEGND 12
AUX 14
GND
3
GND
13
GND
8
C36
0.1uF
C36
0.1uF
CSCS
EEGNDEEGND
R9
0
R9
0
SDISDI
EEPROM
ARRAY
U8
24LC025-I /ST
EEPROM
ARRAY
U8
24LC025-I /ST
SDA
5
VCC 8
A0
1A1 2A2 3
GND
4
WP
7
SCL
6
R11
4.99K
R11
4.99K C43
0.1uF
C43
0.1uF
C39
0.1uF
C39
0.1uF
C41 0.1uFC41 0.1uF
R20
4.99K
R20
4.99K

9
dc1846af
DEMO MANUAL DC1846A
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 TOP LAYER

10
dc1846af
DEMO MANUAL DC1846A
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
[phone] ●FAX: [phone] ●www.linear.com
 LINEAR TECHNOLOGY CORPORATION 2014
LT 0514 • PRINTED IN USA
DEMONSTRATION BOARD IMPORTANT NOTICE
Linear Technology Corporation (LT C ) provides the enclosed product(s) under the following AS IS conditions:
This demonstration board (DEMO BOARD) kit being sold or provided by Linear Technology is intended for use for ENGINEERING DEVELOPMENT
OR EVALUATION PURPOSES ONLY and is not provided by LT C for commercial use. As such, the DEMO BOARD herein may not be complete
in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including but not limited to product safety
measures typically found in finished commercial goods. As a prototype, this product does not fall within the scope of the European Union
directive on electromagnetic compatibility and therefore may or may not meet the technical requirements of the directive, or other regulations.
If this evaluation kit does not meet the specifications recited in the DEMO BOARD manual the kit may be returned within 30 days from the date
of delivery for a full refund. THE FOREGOING WARRANTY IS THE EXCLUSIVE WARRANTY MADE BY THE SELLER TO BUYER AND IS IN LIEU
OF ALL OTHER WARRANTIES, EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS
FOR ANY PARTICULAR PURPOSE. EXCEPT TO THE EXTENT OF THIS INDEMNITY, NEITHER PARTY SHALL BE LIABLE TO THE OTHER FOR
ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES.
The user assumes all responsibility and liability for proper and safe handling of the goods. Further, the user releases LT C from all claims
arising from the handling or use of the goods. Due to the open construction of the product, it is the user’s responsibility to take any and all
appropriate precautions with regard to electrostatic discharge. Also be aware that the products herein may not be regulatory compliant or
agency certified (FCC, UL, CE, etc.).
No License is granted under any patent right or other intellectual property whatsoever. LT C assumes no liability for applications assistance,
customer product design, software performance, or infringement of patents or any other intellectual property rights of any kind.
LT C currently services a variety of customers for products around the world, and therefore this transaction is not exclusive.
Please read the DEMO BOARD manual prior to handling the product. Persons handling this product must have electronics training and
observe good laboratory practice standards. Common sense is encouraged.
This notice contains important safety information about temperatures and voltages. For further safety concerns, please contact a LT C applica-
tion engineer.
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