Amplifier power supply rejection ratio or PSRR is typically measured with a network
analyzer. In the case of high power amplifier requires high current and most network
analyzer output impedance is 50 ohm and cannot drive high current. The TS200 Modulated
Power Supply is ideal for amplifier power supply rejection ratio measurements. These
amplifiers are include op-amp, audio amplifiers (class-A, B, AB, D and G), differential
amplifier, and instrumentation amplifier. TS200 can also measure PSRR for unity gain
buffer, digital-to-analog converter, analog-to-digital converter.
Amplifier PSRR measurement is same as LDO PSRR except for a few minor differences.
Please see Figure 1 and refer to the How to Measure LDO PSRR app note, for additional
PSRR measurement details.
As shown in Figure 1 the amplifier input is grounded, either AC or DC ground, for
power supply rejection ratio measurement. Calibrate the setup as shown in Figure
1a with the network analyzer input-A and input-B connected to the same point at the
amplifier’s power supply input. After calibration, move input-B to the amplifier
output as shown in Figure 1b. Then measure PSRR in the same way as LDO PSRR in the