LMH6401_16 Datasheet, PDF (18/48 Pages) Texas Instruments – LMH6401 DC to 4.5 GHz, Fully-Differential, Digital Variable-Gain Amplifier

LMH6401
SBOS730A – APRIL 2015 – REVISED MAY 2015
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8.6 Noise Figure
This test is done by matching the input of the LMH6401 to a 50-Ω noise source using a 1:2 balun (see
Figure 46), with the noise figure being referred to the input impedance (R_S = 100 Ω). As noted in Figure 46, an
Agilent E4443A with NF features is used for the testing.
8.7 Pulse Response, Slew Rate, and Overdrive Recovery
For time-domain measurements, the standard EVM is driven through a balun again to convert a single-ended
output from the test equipment to the differential inputs of the LMH6401. The differential outputs are directly
connected to the oscilloscope inputs, with the differential signal response calculated using trace math from the
two separate oscilloscope inputs.
8.8 Power Down
The standard EVM is used for this test by completely removing the shorting block on jumper JPD. A high-speed,
50-Ω pulse generator is used to drive the PD pin, which toggles the output signal on or off depending upon the
PD pin voltage.
8.9 VOCM Frequency Response
The standard EVM is used for this test. A network analyzer is connected to the VOCM input of the EVM and the
EVM outputs are connected to the network analyzer with 50-Ω coaxial cables. The network analyzer analysis
mode is set to single-ended input and differential output, and the output common-mode response is measured
with respect to the single-ended input (Scs21). The input signal frequency is swept with the signal level set for
100 mV (–16 dBm). Note that the common-mode control circuit gain is approximately one.
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