LMH3401 Datasheet, PDF (18/48 Pages) Texas Instruments – LMH3401 7-GHz, Ultra-Wideband, Fixed-Gain, Fully-Differential Amplifier

LMH3401
SBOS695A – AUGUST 2014 – REVISED DECEMBER 2014
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8.6 Distortion
The standard EVM is used for measuring single-tone harmonic distortion and two-tone intermodulation distortion.
All distortion is measured with single-ended input signals; see Figure 53. In order to interface with single-ended
test equipment, external baluns are required between the EVM output ports and the test equipment. The Typical
Characteristics plots were created using Marki™ baluns, model number BAL-0010. These baluns are used to
combine two tones in the two-tone tests. For distortion measurements the same termination must be used on
both input pins. When a filter is used on the driven input port, the same filter and a broadband load is used to
terminate the other input. When the signal source is a broadband controlled impedance, then only a broadband
controlled impedance is required to terminate the unused input.
8.7 Noise Figure
The standard EVM is used with a single-ended input and the Marki balun on the output. The noise figure is
based on an active input match provided by the on-chip resistor network.
8.8 Pulse Response, Slew Rate, Overdrive Recovery
The standard EVM is used for time-domain measurements. The input is single-ended while the differential
outputs are routed directly to the oscilloscope inputs. The differential signal response is calculated from the two
separate oscilloscope inputs. In addition, the common-mode response is also captured in this configuration.
8.9 Power Down
The standard EVM is used with the shorting block on jumper JPD removed completely. A high-speed, 50-Ω pulse
generator is used to drive the PD pin while the output signal is measured by viewing the output signal (such as a
250-MHz sine wave).
8.10 V_CM Frequency Response
The standard EVM is used with R_cm+ and R_cm– removed and a new resistor installed at R_tcm = 49.9 Ω; C17. A
network analyzer is connected to the V_CM input of the EVM and the EVM outputs are connected to the network
analyzer with 50-Ω coaxial cables. Set the network analyzer analysis settings to single-ended input and
differential output. Measure the output common-mode 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 one.
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