Location:Training / Power Supply / How to Measure Power Supply Rejection Ratio(PSRR)How to measure power supply rejection ratio / How to Measure Power Supply Rejection Ratio (PSRR)

Discusses methods for measuring power supply ripple rejection (PSRR) of linear regulators.

The output impedance of many signal generators allows the use of matched characteristic impedance cables (50 ohms is common). For low current LDOs (<50mA) this is not a problem, but as the LDO current increases, the DC voltage drop across the output resistor may be excessive. For example, an LDO operating at 200mA in series with a 50-Ohm signal generator results in a 10V DC voltage drop and 2W of power consumption. This will exceed the DC voltage and power ratings of many signal generators.