LMH2832 Datasheet, PDF (17/46 Pages) Texas Instruments – LMH2832 Fully Differential, Dual, 1.1-GHz, Digital Variable-Gain Amplifier

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Setup Diagrams (continued)
LMH2832EVM-50
VS+ = 5 V
LMH2832
SBOS709A – JULY 2016 – REVISED JULY 2016
50
Agilent E4443A
with 50-Ÿ 2XWSXWV
346B
Noise Source
MABA011038
(1:3, zo = 50 Ÿ)
0.1 µF
INPx
SMA
0.1 µF ^INMx
10
½ LMH2832
10
OUTPx ⁴⁰
OUTMx ₄₀
0.1 µF
ETC1-1-13T
(1:1, zo = 50 Ÿ)
SMA
0.1 µF
50
Agilent E4443A
with 50-Ÿ ,QSXWV
SPI
GND
USB
Figure 44. Noise Figure Test Setup
Copyright © 2016, Texas Instruments Incorporated
8.2 ATE Testing and DC Measurements
All production testing and dc parameters are measured on automated test equipment (ATE) capable of dc
measurements only. Some measurements (such as voltage gain) are referenced to the output of the internal
amplifier and do not include losses attributed to the on-chip output resistors. The Electrical Characteristics values
specify these conditions. When the measurement is referred to the amplifier output, the output resistors are not
included in the measurement. If the measurement is referred to the device pins, then the output resistor loss is
included in the measurement.
8.3 Frequency Response
This test is done by running an S-parameter sweep on a 4-port differential network analyzer using the standard
EVM with no baluns; see Figure 41. The inputs and outputs of the EVM are connected to the network analyzer
using 75-Ω coaxial cables with the input ports set to a characteristic impedance of 75 Ω, and the output ports set
to a characteristic impedance of 50 Ω.
The frequency response test with capacitive load is done by soldering the capacitor across the LMH2832 output
pins. In this configuration, the on-chip, 10-Ω resistors on each output leg isolate the capacitive load from the
amplifier output pins.
8.4 Distortion
The standard EVM is used for measuring both the single-tone harmonic distortion and two-tone intermodulation
distortion; see Figure 42 and Figure 43, respectively. The distortion is measured with differential input signals to
the LMH2832. In order to interface with 50-Ω, single-ended test equipment, 50-Ω to 75-Ω impedance matching
pads followed by external baluns (1:2, z_o = 75 Ω) are required between the EVM output ports and the test
equipment. These baluns are used to combine two single tones in the two-tone test plots as well as to convert
the single-ended input to differential output for harmonic distortion tests. The use of 6-dB attenuator pads on both
the inputs and outputs is recommended to provide a balanced match between the external balun and the EVM.
8.5 Noise Figure
This test is done by matching the input of the LMH2832 to a 50-Ω noise source using a 50-Ω to 75-Ω impedance
transformation pad followed by a 1:2 balun (Figure 44), with the noise figure being referred to the input
impedance (R_S = 150 Ω). As noted in Figure 44, a Keysight Technologies™ E4443A with NF features is used for
the testing.
Copyright © 2016, Texas Instruments Incorporated
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