DEMO MANUAL DC1765A
LTC6957-1/LTC6957-2
Low Phase Noise, Dual LVPECL or LVDS
Output Buffer/Driver/Logic Converter
Description
Demonstration Circuit 1765A features the
LTC
®
6957-1/
LTC6957-2,
a low phase noise, dual LVPECL or LVDS
output buffer/driver/logic converter.
The DC1765A provides 0.5" spaced SMA connectors for
the differential inputs and outputs. The inputs are termi-
nated to on-board 50Ω resistors. The LVPECL outputs
of the DC1765A-A are individually biased through 130Ω
resistors to ground and then AC-coupled. The transmis-
sion lines are 50Ω, making the outputs suitable to drive
50Ω input impedance instruments. The LVDS outputs
of the DC1765A-B are terminated with 100Ω differential
and are DC-coupled. The DC1765A allows the user to
take advantage of the shutdown and bandwidth selection
features of the LTC6957. The DC1765A can operate with
a single-ended or differential sine wave or square-wave
input signal. Supply the DC1765A with 3.3V and it is
ready to function. The DC1765A offers extra component
population options to make it compatible with different
logic signal types.
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 of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
Figure 1. DC1765A Inputs and Outputs
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DEMO MANUAL DC1765A
Quick start proceDure
The DC1765A is very straightforward to operate. Refer to
Figure 1 for the following discussion.
DC1765A Configuration
1. Apply a low-noise and low-spurious 3.3V supply between
the V+ (E1) and GND (E2) turrets.
2. Connect a low phase-noise (or jitter) single-ended or
differential input signal to IN+ (J1) and/or IN– (J2)
SMA connectors. Refer to the LTC6957 data sheet for
appropriate input signal types and levels.
3. Connect either of the outputs (OUT1, J3 and J4 or OUT2,
J5 and J6) to a high-speed scope, spectrum analyzer or
a signal analyzer to start the evaluation of the LTC6957.
4. Configure the input bandwidth of the LTC6957 with the
use of FILTA (JP1) and FILTB (JP2) jumpers. Follow the
instructions given in the LTC6957 data sheet to choose
the correct bandwidth given an input signal.
5. Shut down an unused output by using jumper SD1 (JP3)
to shutdown OUT1 or jumper SD2 (JP4) to shutdown
OUT2.
DC1765A Reconfiguration
The DC1765A is flexible and allows the connectivity of a
variety of input and output signal types. The DC1765A is
configured as shown in the schematic diagram. However,
the DC1765A allows the installation of different input and
output configurations to adapt to a variety of logic sig-
nals. Refer to the Applications Information section of the
LTC6957 data sheet for all possible connectivity options
that can be implemented by modifying the DC1765A.
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DEMO MANUAL DC1765A
assembly options
Table 1. DC1765A Assembly Options
ASSEMBLY VERSION
DC1765A-A
DC1765A-B
PART NUMBER
LTC6957HMS-1
LTC6957HMS-2
OUTPUT TYPE
LVPECL
LVDS
layout top layer
The top metal layer of the DC1765A is shown here as an example of good PCB layout for the LTC6957-1/LTC6957-2.
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DEMO MANUAL DC1765A
parts list
ITEM
1
2
3
4
5
6
7
8
9
10
11
12
DC1765A-A
1
2
3
4
5
DC1765A-B
1
2
3
4
5
1
4
0
2
1
Z1, Z2, Z3, Z4
R1, R2, R3, R4
R20, R21
U1
DC1765A GENERAL BOM
RES., CHIP, 0Ω, 0603
RES., 0603
RES., CHIP, 100Ω 5%, 0603
IC, LTC6957HMS-2, MS12
DC1765A
VISHAY, CRCW06030000Z0EA
OPT
VISHAY, CRCW0603100RJNEA
LINEAR TECH., LTC6957HMS-2
1
4
4
0
1
Z1, Z2, Z3, Z4
R1, R2, R3, R4
R20, R21
U1
DC1765A GENERAL BOM
CAP., X7R, 0.01µF 50V, 0603
RES., CHIP, 130Ω, 0603
RES., 0603
IC, LTC6957HMS-1, MS12
DC1765A
NIC, NMC0603X7R103K50TRP
VISHAY, CRCW0603130RFKEA
OPT
LINEAR TECH., LTC6957HMS-1
QTY
2
1
1
1
2
4
6
0
2
4
4
4
REFERENCE
C6, C8
C13
C14
C16
E1, E2
JP1, JP2, JP3, JP4
J1, J2, J3, J4, J5, J6
R6, R11, R14
R7, R15
R16, R17, R18, R19
SHUNTS FOR JP1-JP4
PART DESCRIPTION
CAP., X7R, 0.01µF 50V 10%, 0603
CAP., X7R, 0.1µF 50V 10%, 0603
CAP., X5R, 1µF 25V 10%, 0603
CAP., TANT, 22µF 10V, 3528
TESTPOINT, TURRET 0.094"
HEADER 1×3 079
CONN., SMA 50Ω EDGE-LAUNCH
RES., OPT 0603
RES., CHIP, 49.9Ω 1% 0603
RES., CHIP, 330k 1% 0603
SHUNT, .079" CENTER
STAND-OFF, NYLON 0.500
MANUFACTURER/PART NUMBER
NIC, NMC0603X7R103K50TRP
TDK, C1608X7R1H104K
TDK, C1608X5R1E105K
AVX, TPSB226K010R0400
MILLMAX, 2501-2-00-80-00-00-07-0
SAMTEC, TMM-103-02-L-S
E.F. JOHNSON, 142-0701-851
OPT
VISHAY, CRCW060349R9FKEA
VISHAY, CRCW0603330KFKEA
SAMTEC, 2SN-BK-G
KEYSTONE, 8833 (SNAP ON)
DC1765A General BOM
dc1765af
4
5
4
3
2
ECO
GND
E2
D
V+
V+
3.15V - 3.45V
E1
__
3
PRODUCTION
MICHEL A.
08-16-12
REV
REVISION HISTORY
DESCRIPTION
APPROVED
DATE
1
D
C16
22uF
3528 10V
V+
R16
330k
3
2
1
H
L
JP3
R20
R1
OUT1+
SMA-R
J4
OUT1-
SMA-R
Z1
*
R17
330k
SD1
J3
V+
+
V+
C6
0.01uF
R7
49.9
1
2
3
4
5
6
C8
0.01uF
V+
H
L
JP2
FILTB
3
2
1
R18
330k
3
2
1
R19
330k
V+
SD2
H
JP4
L
R15
49.9
FILTB
SD2
GND
7
R3
R21
OUT2+
IN-
8
Z3
OUT2-
IN+
9
OUT1-
V+
10
OUT1+
FILTA
11
R2
SD1
12
C13
0.1uF
C14
1uF
schematic Diagram
OUT1+
J1
IN+
Z2
*
R6
OPT
FILTA
3
H
2
1
L
JP1
*
SMA-R
U1
*
*
*
*
*
*
OUT1-
C
C
R11
OPT
V+
J5
OUT2-
SMA-R
J6
Z4
R4
OUT2-
J2
IN-
R14
OPT
SMA-R
*
*
OUT2+
SMA-R
OUT2+
B
B
*
R1-R4
130 OHM
OPT
0 OHM
100 OHM
0.01uF
OPT
ASSY
U1
Z1-Z4 R20-R21
-A
LVPECL
LTC6957HMS-1
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.
-B
LVDS
LTC6957HMS-2
CUSTOMER NOTICE
APPROVALS
KIM T.
MICHEL A.
A
NOTE: UNLESS OTHERWISE SPECIFIED
TECHNOLOGY
TITLE: SCHEMATIC
1630 McCarthy Blvd.
Milpitas, CA 95035
Phone: (408)432-1900
www.linear.com
Fax: (408)434-0507
LTC Confidential-For Customer Use Only
A
1. ALL RESISTORS AND CAPACITORS ARE 0603.
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A
CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS;
HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO PCB DES.
VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL
APP ENG.
APPLICATION. COMPONENT SUBSTITUTION AND PRINTED
CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT
PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
SIZE
SCALE = NONE
3
LOW PHASE NOISE, DUAL LVPECL OR LVDS OUTPUT
BUFFER / DRIVER / LOGIC CONVERTER
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
4
N/A
DATE:
IC NO.
08/16/2012, 06:45 PM
2
LTC6957HMS-1 / -2
DEMO CIRCUIT 1765A
REV.
3
SHEET 1
1
OF 1
5
DEMO MANUAL DC1765A
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