DC1774A-C - Demo Manual

DEMO MANUAL DC1774A-C
LTC6431-15
50Ω Gain Block IF Amplifier
DESCRIPTION
Demonstration circuit 1774A-C is a 50Ω gain block IF
amplifier featuring the LTC®6431-15. It is part of the
DC1774A demo board family supporting the LTC643XYY amplifier series. The DC1774A-C is optimized for a
frequency range of 100MHz to 1200MHz and utilizes a
minimum of passive external components to configure
the amplifier for this application.
PERFORMANCE SUMMARY
Because the LTC6431-15 has 50Ω single-ended input
and output impedance, the demo circuit can be connected
directly to most commercially available RF test equipment
for the evaluation.
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.
Specifications are at TA = 25°C, VCC = 5V
Table 1. Typical Demo Board Performance Summary
SYMBOL
PARAMETER
CONDITIONS
VALUE/UNIT
VCC
Operating Supply Range
All VCC Pins Plus +OUT
ICC
Current Consumption
Total Current
Power Supply
4.75V to 5.25V
90mA
OUTPUT
THIRD-ORDER
INTERMODULATION 1
OIM3
(dBc)
SECOND
HARMONIC
DISTORTION 2
HD2
(dBc)
THIRD
HARMONIC
DISTORTION 2
HD3
(dBc)
OUTPUT 1dB
COMPRESSION
POINT
NOISE FIGURE 3
P1dB
NF
(dBm)
(dB)
FREQUENCY
(MHz)
POWER GAIN
S21
(dB)
OUTPUT
THIRD-ORDER
INTERCEPT POINT 1
OIP3
(dBm)
100
15.1
46.6
–89.2
–58.0
–88.0
20.0
3.8
200
15.4
46.7
–89.5
–58.0
–88.0
20.0
3.5
240
15.6
46.7
–89.3
–59.0
–88.0
20.3
3.4
300
15.5
46.6
–89.3
–60.0
–86.0
20.1
3.5
400
15.5
46.1
–88.3
–57.0
–87.0
20.3
3.5
500
15.4
45.3
–86.6
–55.6
–77.0
20.3
3.6
600
15.3
43.5
–83.1
–53.6
–69.0
20.4
3.7
700
15.2
42.2
–80.4
–51.9
–69.0
20.2
3.8
800
15.0
41.1
–78.1
–49.2
–65.0
20.1
4.0
900
14.8
39.5
–74.9
–46.7
–63.0
19.7
4.2
1000
14.7
38.7
–73.3
–45.0
–59
19.3
4.2
1100
14.5
38.0
–71.9
–40.8
–56.8
18.8
4.4
1200
14.3
38.0
–71.9
–38.4
–54.2
18.6
4.6
Notes: All measurements are referenced to J7 (Input Port) and J10 (Output Port).
1. Two-tone test condition: Output power level = +2dBm/tone; Tone spacing = 1MHz.
2. Single-tone test condition: Output power level = +6dBm.
3. Small-signal noise figure.
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1
DEMO MANUAL DC1774A-C
QUICK START PROCEDURE
Demo circuit 1774A-C can be set up to evaluate the performance of the LTC6431-15. Refer to Figures 4 and 5, for
proper equipment connections and follow the procedure
below:
Single-Tone Measurement:
Connect all test equipment as suggested in Figure 4.
1.The power labels of +5V and GND directly correspond
to the power supply. Typical current consumption of
the LTC6431-15 is about 90mA.
2.Apply an input signal to J7. A low-distortion, low noise
signal source with an external high order lowpass filter
will yield the best performance. The input signal is
–10dBm.
3.Observe the output via J10. The measured power at
the analyzer should be about +5dBm.
VCC
(PINS 9, 22)
BIAS AND
TEMPERATURE
COMPENSATION
IN
(PIN 24)
T-DIODE
(PIN 16)
Two-Tone Measurement:
Connect all test equipment as suggested in Figure 5.
1.The power labels of +5V and GND directly correspond
to the power supply. Typical current consumption of
the LTC6431-15 is about 90mA.
2.Apply two independent signals f1 and f2 from SG1 and
SG2 at 240MHz and 241MHz respectively.
3.Monitor the output tone level on the spectrum analyzer.
Adjust signal generator levels such that output power
measures +2dBm/tone at the amplifier output J10, after
correcting for external cable losses and attenuators.
4.Change the spectrum analyzer’s center frequency and
observe the two IM3 tones at 1MHz below and above
the input frequencies. The frequencies of IM3_LOW
and IM3_HIGH are 239MHz and 242MHz, respectively.
For this setup, the Rohde and Schwarz FSEM30 spectrum analyzer was used. This spectrum analyzer has
a typical 20dBm third-order intercept point (TOI). The
Rohde and Schwarz FSU can also be used. The system
as described can measure OIP3 up to 50dBm.
OUT
(PIN 18)
GND
(PINS 8, 17, 23 AND EXPOSED PAD 25)
dc1774ac F01
Figure 1. LTC6431-15 Device Block Diagram
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2
DEMO MANUAL DC1774A-C
QUICK START PROCEDURE
NOMINAL WORKING
FREQUENCY RANGE
18
16
5
|S21| (dB)
14
4
12
10
8
6
4
0
|S11|, |S12|, |S22| (dB)
0
–2
–4
–6
|S21|
–8
–10
–12
|S22| 3
–14
|S11|
–16
–18
–20
–22
|S12|
–24
–26
–28
400
1200
2000
800
1600
FREQUENCY (MHz)
2
1
ECO
__
REV
2
REVISION HISTORY
DESCRIPTION
PRODUCTION
APPROV
JOHN C
dc1774ac F02
Figure 2. Demo Board S-Parameters
Stability
Network
C8
62pF
C1
1000pF
VCC
R2
348
U1
*1
4 DNC
U1=LTC6431-15 5
+OUT
0603
N/C
N/C
VCC
J11
12
N/C
11
VCC
10
9
GND
8
DNC
GND
J10
R17
0
GND 14
DNC 13
DNC
6 DNC
GND
C21
1000pF
T_DIODE 16
DNC 15
7
E6
C22
0.1uF
C3
1000pF
+OUT 18
GND 17
DNC
2 DNC
3 DNC
J18
L1
560nH
DNC 19
0603
DNC 21
DNC 20
0
+IN 24
GND 23
VCC 22
R13
GND 25
J7
+IN
VCC
C7
1000pF
E3
+5V
+5V
C20
1000pF
Figure 3. Simplified Demo Board DC1774A-C Schematic
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
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
5
4
3
APPROVALS
PCB DES.
KIM T.
APP ENG.
JOHN C.
TECHNOLOGY
TITLE: SCHEMATIC
SIZE
N/A
SCALE = NONE
2
DATE:
1630 McCarthy Blvd.
Milpitas, CA 95035
Phone: (408)432-1900 w
Fax: (408)434-0507
LTC Confidential-For Cus
IF AMP/ADC DRIVER
IC NO.
LTC643XIUF FAMILY
DEMO CIRCUIT 1774A-C
Monday, July 16, 2012
dc1774acfa
3
1
SHEE
DEMO MANUAL DC1774A-C
OPERATION
The demo circuit 1774A-C is a high linearity fixed gain
amplifier. It is designed for ease of use. Both the input and
output are internally matched to 50Ω single-ended source
and load impedance which is compatible with most test
equipment. Figure 2 shows the demo board S-parameters.
Figure 3 shows the demo circuit schematic. It requires a
minimum of passive support components. The input and
output DC blocking capacitors (C1 and C3) are required
because this device is internally biased for optimal operation. The frequency appropriate choke (L1) and the
decoupling capacitors (C21 and C22) provide bias to the
RF +OUT node. Only a single 5V supply is necessary for
the VCC pins on the device.
An optional input stability network has been added. It
consists of a parallel 62pF (C8) and 348Ω (R2) input
network has been added to insure low frequency stability.
Table 2 shows the function of each input and output on
the board.
Table 2. DC1774A-C Board I/O Descriptions
CONNECTOR
FUNCTION
J7 (+IN)
Single-Ended Input. Impedance Matched to 50Ω. Drive
from a 50Ω Network Analyzer or Signal Source.
J10 (+OUT)
Single-Ended Output. Impedance Matched to 50Ω. Drive
from a 50Ω Network Analyzer or Spectrum Analyzer.
E3 or J11 (VCC)
Positive Supply Voltage Source.
E6 or J18 (GND) Negative Supply Ground.
ADDITIONAL INFORMATION
The particular element values shown in the demo board
schematic are chosen for wide bandwidth operation.
Depending on the desired frequency, performance may
be improved by the proper selection of these supporting
components.
As with any RF device, minimizing ground inductance is
critical. Care should be taken with the board layout because
of these exposed pad packages. The maximum number of
minimum diameter vias holes should be placed underneath
the exposed pad. This will ensure good RF ground and low
thermal impedance. Maximizing the copper ground plane
will also improve heat spreading and reduce inductance. It
is a good idea to cover the via holes with solder mask on
the back side of the PCB to prevent solder from wicking
away from the critical PCB to the exposed pad interface.
The DC1774A-C is a wide bandwidth demo board but
it is not intended for operation down to DC. The lower
frequency cutoff is limited by on-chip matching elements.
Figure 6 shows the generic PCB schematic for the
LTC643X‑YY amplifier series. The board can be modified for multiple demo board versions. For example,
both DC1774A-A and DC1774A-B demo boards have a
differential amplifier at U1; therefore, the board is using
transformers to transform from differential to single-ended
input and output. Likewise, the DC1774A-C is a singleended demo board; consequently, it uses the LTC6431-15
for single-ended input and output.
Setup and Testing Signal Sources
The LTC6431-15 is an amplifier with high linearity performance, therefore output intermodulation products are
very low. For this reason, it drives most test equipment
and test setups to their limits. Consequently, accurate
measurement of the third-order intercept point for a low
distortion IC such as the LTC6431-15 requires certain
precautions to be observed in the test setup and testing
procedure.
Setup Signal Source
Figure 5 shows a proposed IP3 test setup. This setup has
low phase noise, good reverse isolation, high dynamic
range, sufficient harmonic filtering and wideband impedance matching. The setup is outlined below:
1.High performance signal generators 1 and 2 (HP8644A)
were used in the setup. These suggested generators
have low harmonic distortion and very low phase noise.
dc1774acfa
4
DEMO MANUAL DC1774A-C
ADDITIONAL INFORMATION
2.High linearity amplifiers to improve isolation. It prevents
the two signal generators from crosstalking with each
other and provides higher output power.
3.A lowpass filter to suppress the harmonic contents
from interfering with the test signal.
4.The signal combiner from Mini-Circuits ADP-2-9 combines the two isolated input signals. This combiner
has a typical isolation of 27dB. For better VSWR and
isolation, use the H-9 signal combiner from MA/COM
which features >40dB isolation and a wider frequency
range. Passive devices (e.g., combiners) with magnetic
elements can contribute no-linearity to the signal chain
and should be used cautiously.
input attenuation is increased, then the input power
level was too high for the spectrum analyzer to make a
valid measurement. In other words, the spectrum analyzer 1st mixer was overloaded and producing its own
IMD products. If the IMD reading holds constant with
increased input attenuation, then a sufficient amount
of attenuation was present. Adding too much attenuation will raise the noise floor and bury the intended
IMD signal. Therefore, select just enough attenuation
to achieve a stable and valid measurement.
5.The attenuator pads on all three ports of the signal
combiner will support further isolation of the two input
signal sources. They will reduce reflection and promote
maximum power transfer with wideband impedance
matching.
d.In order to achieve a valid measurement result, the
test system must have lower distortion than the DUT
intermodulation. For example, to measure a +47dBm
OIP3, the measured intermodulation products will be
–90dBc below the –13dBm per tone input level and
the test system must have Intermodulation products
approximately –96dBc or better. For best results, the
IMD or noise floor should be at least –100dBc before
connecting the DUT.
Testing Signal Sources
Testing the DUT
The testing signal should be evaluated and optimized before
it is used for measurements. The following outlines the
necessary steps to achieve optimization:
At this point, the input level has been established at
–13dBm per tone, and the input IMD from the test setup
is well suppressed at –96dBm max. Furthermore, the
spectrum analyzer is setup to measure very low level IMD
components.
a. Apply two independent signals f1 and f2 from signal
generator 1 and signal generator 2 at 240MHz and
241MHz while setting amplitude = –13dBm per tone
at the combined output.
b.Connect the combined signal directly to the spectrum
analyzer (without the DUT).
c. Adjust the spectrum analyzer for the maximum possible
resolution of the intermodulation products amplitude
in dBc relative to the main tone power. A narrower
resolution bandwidth will take a longer time to sweep.
Optimize the dynamic range of the spectrum analyzer by
adjusting input attenuation. First increase the spectrum
analyzer input attenuation (normally in steps of 5dB
or 10dB). If the IMD product levels decrease when the
a. Insert the DUT and output attenuator into the setup,
inline between the signal source and the spectrum
analyzer. The output attenuator should match the DUT
gain.
b.Fine tune the signal generator levels by a small amount
if necessary (<1dB), to keep output power at +2dBm
per tone at the amplifier output.
c. Measure the output IMD level using the same optimized
setup as previous. Based on the output power level of
+2dBm per tone, and knowing the IMD level, OIP3 can
be calculated.
dc1774acfa
5
DEMO MANUAL DC1774A-C
ADDITIONAL INFORMATION
SIGNAL
GENERATOR
ASSY
U1
FREQ
-A
LTC6430AIUF-15
100MHz TO 300MHz
-B
LTC6430AIUF-15 400MHz TO 1000MHz
-C
LTC6431AIUF-15 100MHz TO 1200MHz
DC POWER SUPPLY
GND
V+
(HP8644A)
COAXIAL CABLE
SPECTRUM
ANALYZER
LOWPASS
FILTER
(OPTIONAL)
3dB
ATTENUATION PAD
(OPTIONAL)
ROHDE AND
SCHWARZ
FSEM30
Figure 4. Proper Equipment Setup for Gain and Single-Tone Measurement
dc1774acfa
6
DEMO MANUAL DC1774A-C
ADDITIONAL INFORMATION
SIGNAL
(HP8644A)
GENERATOR 1
ASSY
U1
FREQ
-A
LTC6430AIUF-15
100MHz TO 300MHz
-B
LTC6430AIUF-15 400MHz TO 1000MHz
-C
LTC6431AIUF-15 100MHz TO 1200MHz
DC POWER SUPPLY
GND
V+
AMPLIFIER
(MINI-CIRCUITS, ZHL-2
OR EQUIVALENT)
LOWPASS
FILTER
6dB ATTENUATION
PAD (OPTIONAL)
COAXIAL CABLE
COMBINER
MINI CIRCUIT
ADP-2-9
SPECTRUM
ANALYZER
3dB
ATTENUATION
6dB ATTENUATION
PAD
PAD (OPTIONAL)
APPROXIMATELY
–13dBm/TONE
2dBm/TONE
ROHDE AND
SCHWARZ
FSEM30
15dB
ATTENUATION PAD
(MATCHES DUT GAIN)
LOWPASS
FILTER
AMPLIFIER
(MINI-CIRCUITS, ZHL-2
OR EQUIVALENT)
DUT GAIN APPROXIMATELY 15dB
SIGNAL
(HP8644A)
GENERATOR 2
Figure 5. Proper Equipment Setup for IP3 Measurement
dc1774acfa
7
DEMO MANUAL DC1774A-C
PARTS LIST
ITEM
QTY
REFERENCE
PART DESCRIPTION
MANUFACTURER/PART NUMBER
CAP., X7R, 1000pF, 50V 5%, 0402
AVX, 04025C102JAT2A
DC1774A2 Required Circuit Components
1
4
C1, C3, C7, C20
2
1
C21
CAP., X7R, 1000pF, 50V 5%, 0603
AVX, 06035C102JAT2A
3
1
C8
CAP., COG, 62pF, 16V 2%, 0402
AVX, 0402YA620GAT2A
4
0
C10, C12
CAP., COG, 62pF, 16V 2%, 0402
OPT
5
0
C11, C13, C16-C19
CAP., X7R, 1000pF, 5%, 0402
OPT
6
1
C22
CAP., X5R, 0.1µF, 10V, 10%, 0603
AVX, 0603ZD104KAT2A
7
2
E3, E6
TESTPOINT, TURRET, 0.064"
MILL-MAX, 2308-2-00-80-00-00-07-0
8
0
JP1
HEADER, 2X6, 0.1"
OPT
9
0
JP2, JP3
HEADER, 2X4, 0.1"
OPT
10
0
J5, J6
CONN., SMA 50Ω EDGE-MOUNTED
OPT
11
1
J7
CONN., SMA 50Ω EDGE-MOUNTED
JOHNSON, 142-0701-851
12
0
J9
CONN., SMA 50Ω EDGE-MOUNTED
OPT
13
2
J11, J18
JACK, BANANA
KEYSTONE, 575-4
14
1
L1
INDUCTOR, CHIP, 560nH, 5%, 0603LS-1608
COILCRAFT, 0603LS-561XJLB
15
0
L11, L22
INDUCTOR, CHIP, 1008LS-2520
OPT
16
1
R2
RES., CHIP, 348Ω, 1%, 0402
YAGEO, RC0402FR-07348RL
17
0
R5, R6
RES., CHIP, 348Ω, 1%, 0402
OPT
18
0
R19
RES., CHIP, 0Ω, 5%, 0402
YAGEO, RC0402JR-070RL
DC1774A2-C Required Circuit Components
1
1
DC1774A-2
GENERAL BOM
2
0
C2, C4
CAP., X7R, 1000pF, 50V 5%, 0402
AVX, 04025C102JAT2A
3
0
C5
CAP., X7R, 1000pF, 50V 5%, 0603
AVX, 06035C102JAT2A
4
0
C9
CAP., COG, 62pF, 16V 2%, 0402
AVX, 0402YA620GAT2A
5
0
C14, C15
CAP., X7R, 1000pF, 25V 5%, 0402
AVX, 04023C102JAT2A
6
0
C23
CAP., X5R, 0.1µF, 10V, 10%, 0603
AVX, 0603ZD104KAT2A
7
0
L2
INDUCTOR, CHIP, 560nH, 5%, 0603LS-1608
COILCRAFT, 0603LS-561XJLB
8
0
J8
CONN., SMA 50Ω EDGE-MOUNTED
OPT
9
1
J10
CONN., SMA 50Ω EDGE-MOUNTED
JOHNSON, 142-0701-851
10
0
R1
RES., CHIP, 348Ω, 1%, 0402
YAGEO, RC0402FR-07348RL
11
0
R3, R4
RES., CHIP, 0Ω, 1/16W, 5%, 0603
OPT
12
4
R13, R14, R17, R18
RES., CHIP, 0Ω, 1/16W, 5%, 0603
YAGEO, RC0603JR-070RL
13
0
T1, T2
XFMR, MINI-CIRCUITS
OPT
14
0
T3, T4
XFMR, 2:1
OPT
15
1
U1
IC, IF AMP., QFN24UF-4X4
LINEAR TECH., LTC6431AIUF-15
dc1774acfa
8
DEMO MANUAL DC1774A-C
Figure 6. DC1774A RF/IF AMP/ADC Driver
SCHEMATIC DIAGRAM
dc1774acfa
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 representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
9
DEMO MANUAL DC1774A-C
DEMONSTRATION BOARD IMPORTANT NOTICE
Linear Technology Corporation (LTC) 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 LTC 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 LTC 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. LTC assumes no liability for applications assistance,
customer product design, software performance, or infringement of patents or any other intellectual property rights of any kind.
LTC 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 LTC application engineer.
Mailing Address:
Linear Technology
1630 McCarthy Blvd.
Milpitas, CA 95035
Copyright © 2004, Linear Technology Corporation
dc1774acfa
10 Linear Technology Corporation
LT 0213 REV A • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
●
FAX: (408) 434-0507 ● www.linear.com
 LINEAR TECHNOLOGY CORPORATION 2013
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