DEMO MANUAL DC1591A
LTC6409 High Speed, Low
Noise/Distortion Differential
ADC Drivers
DESCRIPTION
Demonstration circuit 1591A features the
LTC
®
6409
dif-
ferential ADC driver. It incorporates a variety of passive
components to support configurations for varied applica-
tions. On this board, two amplifier circuits are provided.
One is single-ended, the other is a differential input and
output. There is also a calibration circuit to de-embed the
effects of other circuit components.
The LTC6409 is a high-speed differential amplifier with
superior distortion and low noise suitable for demanding
communications transceivers, cellular base-stations, and
other high-speed signal chain applications. These fully-
differential amplifiers accept single-ended or differential
inputs with almost no difference in distortion performance.
Each part has the ability to adjust the output common-mode
voltage without any additional components and flexible
input common-mode ranges, which enable input signal DC
coupling and level-shifting for ADC driving applications.
Design files for this circuit board are available at
http://www.linear.com/demo/DC1591A
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.
QUICK START PROCEDURE
Table 1 shows the function of each SMA connector on the
board. Refer to Figure 1 for the connection diagram and
follow the procedure below:
1. Connect the power supply to V+ and GND as shown in
Figure 1. Typical current consumption of each LTC6409
is about 52mA. Jumper JP1 enables or shuts down
the single-ended amplifier.
2. The power supply voltage range is shown in Figure 1.
Do not exceed the maximum power supply voltage
rating for the parts.
3. Apply an input signal to J1. A low distortion, low noise
signal source with an external high order filter will
yield the best performance. The J1 input is impedance
matched to 50Ω.
4. Observe the output via J2. The output is impedance
matched to 50Ω, suitable for the input of a network or
spectrum analyzer.
Table 1: DC1591A Board I/O Descriptions
CONNECTOR
J1 (IN)
J2 (OUT)
J3 (CAL IN)
J4 (CAL OUT)
FUNCTION
Single-ended Input. Impedance matched to 50Ω, drive
from a 50Ω network analyzer or signal source.
Single-ended Output. Impedance matched to 50Ω, can
be used to drive a 50Ω network/spectrum analyzer input.
Calibration Input. Impedance matched to 50Ω, pairing
with J4 for calibration.
Calibration Output. Impedance matched to 50Ω, pairing
with J3 for calibration to de-embed the effects of other
circuit components.
Differential Inputs. They are impedance matched to
300Ω differentially. Signal can be driven from preceding
receiver signal chain (i.e., Mixer or I/Q Demodulator).
Differential Outputs. They are impedance matched to
100Ω differentially.
Shutdown Jumper. The lower (EN) position enables the
single-ended amplifier circuit, while the upper (DIS)
puts the amplifier into shutdown mode.
Shutdown Jumper. The lower (EN) position enables the
differential amplifier circuit, while the upper (DIS) puts
the amplifier into shutdown mode.
Output Common Mode Adjust. By default, this pin is
self-biasing within U1 and U2. Override this voltage
with other DC voltage source as required.
J5 (IN+)/
J6 (IN–)
J7 (OUT–)/
J8 (OUT+)
JP1 (SHDN1)
JP2 (SHDN2)
E4 (VOCM)
dc1591af
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DEMO MANUAL DC1591A
QUICK START PROCEDURE
V
CC
= 2.7V TO 5.2V
POWER SUPPLY
+
–
IMPEDANCE
MATCHED TO
50Ω
IMPEDANCE
MATCHED TO
50Ω
DC1591A F01
Figure 1. Proper Measurement Equipment Setup
2
dc1591af
DEMO MANUAL DC1591A
ADDITIONAL INFORMATION
The DC1591A demo board is ready for use out of the
box. A single-ended and a differential amplifier circuit are
provided for ease of use and with minimum modification.
DEMO BOARD VERSIONS
Single-Ended Input and Output Configuration
J1:
The single-ended input can be driven from a 50Ω signal
source or network analyzer (usually port 1).
J2:
The single-ended output can be connected to spectrum
analyzer or network analyzer (usually port 2).
Differential Inputs and Outputs Configuration
J5 and J6:
Differential inputs. Typically, signal input to
these ports are from a receiver signal chain such as a
mixer or I/Q demodulator.
J7 and J8:
Differential outputs. These ports can drive
directly into the differential inputs of an ADC.
DRIVING THE INPUTS DC-COUPLED
It is possible to configure the DC1591A inputs differentially
with DC coupling. Transformer T1 should be removed,
and C23 and C24 connections should be replaced with
0Ω resistors. The inputs are now DC-coupled and can be
driven single-ended or differentially (resistor values may
be changed to balance the source impedances, et cetera.
See the product data sheet for more information. Note
input bias currents will flow through the amplifier’s input
resistors if DC1591A is driven DC-coupled.
CHANGING THE OUTPUT COMMON-MODE VOLTAGE
Turret E4 (VOCM) controls the output common mode
voltage of U1 and U2. E4 can be used to level-shift the DC
output voltage for optimum system performance. If used
for this purpose, transformer T2 should be removed, and
C18 and C19 connections can be replaced by 0Ω resistors
to allow the DC bias to reach the output. By default, the
VOCM voltage is self-biased through resistors internal to
the IC’s (U1 and U2).
SCHEMATIC NOTES
Note that transformer T2 and the series resistors at the
amplifier outputs form a 12.6dB attenuation (if the output
has a 50Ω load) that will affect the measured gain of the
demo board. This is done so that the output of DC1591A can
plug directly into a 50Ω network/spectrum analyzer input,
while the amplifier sees a higher 400Ω load impedance.
OUTPUT DRIVE
Each amplifier circuit on the demo board is designed to
have a 50Ω source impedance at its output to facilitate
direct connections to 50Ω terminated test instruments.
ENABLE (SHUTDOWN)
Jumper JP1 and JP2 control the enable function of U1
and U2, respectively, on DC1591A. When set to the EN
position, the part will be on and draws normal operating
current. In the DIS position, the part will be in shutdown
and draws a very small amount of leakage current.
GROUND AND V
CC
CONNECTIONS
DC1591A’s GND connector is not only connected to V– of
the LTC6409, it also serves as the demo board ground.
For best result, a low impedance return path to the power
supply from GND is recommended. Short, low impedance
wires to the V+ and GND connectors of DC1591A will yield
the best performance from the LTC6409.
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DEMO MANUAL DC1591A
PARTS LIST
ITEM
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
QTY
2
2
19
2
2
1
4
3
0
2
2
8
8
0
2
8
6
2
2
2
4
2
1
2
REFERENCE
C1, C5
C2, C6
C3, C7, C11, C14, C15, C16, C18, C19, C20, C21,
C23, C24, C25, C26, C28, C29, C30, C31, C32
C4, C8
C9, C10
C12
C13, C17, C22, C27
E1, E3, E4
E2 (OPT)
JP1, JP2
JP1, JP2
J1, J2, J3, J4, J5, J6, J7, J8
R1, R7, R14, R18, R27, R31, R36, R37
R3, R4
R5, R8, R9, R10, R28, R29, R33, R39
R11, R12, R20, R22, R23, R25,
R17, R30
R21, R24
R34, R40
T1, T2, T3, T4
U1, U2
PART DESCRIPTION
CAP. CHIP, X7R, 100pF, 50V, 10%, 0402
CAP. CHIP, X7R, 0.01μF, 16V, 10%, 0402
CAP. CHIP, X7R, 0.1μF, 16V, 10%, 0402
CAP. CHIP, X5R, 0.47µF, 10V, 10%, 0402
CAP. CHIP, X7R, 1000pF, 25V, 10%, 0402
CAP. CHIP, X5R, 10μF, 10V, 10%, 0805
CAP. CHIP, X7R, 1.3pF, 25V, 10%, 0402
TESTPOINT, TURRET, 0.065" PBF
TESTPOINT, TURRET, 0.065" PBF
HEADER, 3 PINS, 2mm
SHUNT, 2mm CENTER
CON., SMA 50Ω EDGE-LANCH
RES., CHIP, 0Ω 1/16W, 1%, 0402
RES., CHIP, 100Ω 1/16W, 1%, 0402
RES., CHIP, 150Ω 1/16W, 0.1%, 0402
RES., CHIP, 300Ω 1/16W, 1%, 0402
RES., CHIP, 10Ω 1/16W, 1%, 0402
RES., CHIP, 75Ω 1/16W, 1%, 0402
RES., CHIP, 49.9Ω, 1/16W, 1% 0402
TRANS., TCM4-19 SURFACE MOUNT
DIFFERENTIAL AMPLIFIER/ADC DRIVER
FAB, PRINTED CIRCUIT BOARD
STENCIL – TOP & BOTTOM
MANUFACTURER/PART NUMBER
AVX, 04025C101KAT
AVX, 0402YC103KAT
AVX, 0402YC104KAT
MURATA, GRM155R61A474KE15D
AVX, 04023C102KAT
AVX, 0805ZD106KAT
AVX, 04023J1R3ABWTR
MILL-MAX, 2308-2-00-80-00-00-07-0
MILL-MAX, 2308-2-00-80-00-00-07-0
SAMTEC, TMM-103-02-L-S
SAMTEC, 2SN-BK-G
CONNEX, 132357 / 142-0701-851
YAGEO, RC0402FR-070RL
YAGEO, RC0402FR-07100RL
YAGEO, RT0402BRE07150RL
YAGEO, RC0402FR-07300RL
YAGEO, RC0402FR-0710RL
YAGEO, RC0402FR-0775RL
VISHAY, CRCW040249R9FKED
MINI CIRCUITS, TCM4-19
LINEAR TECH., LTC6409UDB
DEMO CIRCUIT # DC1591A
DC1591A
R2, R6, R13, R15, R16, R19, R26, R32, R35, R38 RES., CHIP, 0402 (OPT)
4
dc1591af
5
4
3
2
R5
150 0.1%
ECO
-
2
PRODUCTION FAB
REV
REVISION HISTORY
DESCRIPTION
APPROVED
JOHN C.
1
DATE
06-02-10
C22
1.3pF
E
V+
E
U1
LTC6409UDB
4
9
V+
V+
2
+IN
5
Vocm
-IN
+OUT
7
6
2
3
4
5
-OUT
S
CT
Sd
Pd
6
P
4
1
1
J1
Sd
CT
S
1
2
3
1
IN
2
1
R14
0 Ohm
R1
0 Ohm
SMA
OUT
R2
OPT
C25
0.1uF
C24
R10
C19
R4
100
0.1uF
TCM4-19
1:4 Xfmr by Mini-Circuits
3
T1
0.1uF
C29
0.1uF
C23
0.1uF
R9
150 0.1%
C18
T2
J2
R3
100
6
Pd
SMA
SHDN
4
P
5
4
3
2
SCHEMATIC DIAGRAM
R13
OPT
0.1uF
R12
300
3
TCM4-19
1:4 Xfmr by Mini-Circuits
V+
R15
OPT
E2
VOCM
R16
OPT
SHDN1
DIS
2
3
1
V-
V-
V-
8
10
11
150 0.1%
R11
300
C26
0.1uF
C27
1.3pF
VCM
C32
0.1uF
VCM
E4
C28
0.1uF
R17
10
D
VOCM
D
EN
JP1
R8
150 0.1%
CALIBRATION PATH
C31
T3
6
Pd
P
S
1
CT
CT
2
2
P
Pd
6
4
Sd
S
4
1
3
R21
75
C14
0.1uF
C21
0.1uF
3
Sd
1
J3
C30
0.1uF
C20
C15
R25
300
0.1uF
TCM4-19
1:4 Xfmr by Mini-Circuits
0.1uF
R23
300
0.1uF
R20
300
R24
75
R26
OPT
2
3
4
5
CAL IN
R19
OPT
TCM4-19
1:4 Xfmr by Mini-Circuits
1
R18
0 Ohm
T4
J4
CAL OUT
R22
300
SMA
R27
0 Ohm
C
C
5
4
3
2
SMA
C1
C2
R28
150 0.1%
C13
1.3pF V+
V+
C3
C4
C5
E1
V+
2.7V - 5.25V
R36
0 Ohm
J7
1
100pF
0.01uF
0.1uF
0.47uF
100pF
C6
C9
C12 C11 C10
10uF 0.1uF 1000pF 1000pF
C7
0.01uF
0.1uF
B
B
U2
LTC6409UDB
4
9
V+
V+
J5
1
R31
0 Ohm
R33
150 0.1%
VOCM
5
Vocm
-IN
+OUT
7
6
2
+IN
-OUT
1
R34
50
R35
OPT
R40
50
IN+
R32
OPT
R39
150 0.1%
SHDN
V-
V-
V-
OUT-
2
3
4
5
C8
SMA
E3
GND
0.47uF
3
SMA
C17
1.3pF
8
10
11
5
4
3
2
R38
OPT
R6
OPT
2
3
4
5
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.
J6
1
5
4
3
2
SMA
IN-
R37
0 Ohm
C16
0.1uF
R7
0 Ohm
J8
1
OUT+
SMA
CUSTOMER NOTICE
APPROVALS
PCB DES. NC
APP ENG. JOHN C.
A
TECHNOLOGY
TITLE: SCHEMATIC
SHDN2
DIS
EN
3
2
1
R30
10
1630 McCarthy Blvd.
Milpitas, CA 95035
Phone: (408)432-1900
www.linear.com
Fax: (408)434-0507
LTC Confidential-For Customer Use Only
A
DIFFERENTIAL AMPLIFIER / ADC DRIVER
SIZE
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
R29
150 0.1%
JP2
4
3
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.
N/A
SCALE = NONE
2
IC NO.
DATE:
LTC6409UDB
DEMO CIRCUIT 1591A
Thursday, June 10, 2010
1
REV.
2
SHEET 1
OF
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DEMO MANUAL DC1591A
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