We have released a new line injector for PSRR (power supply rejection ratio), DC-biased inductor, and DC-DC converter input impedance testing.

The J2121A is especially suited to high power applications. It can be used with input bus voltages up to 400V and supply up to 20A. It supports testing up to a 1MHz bandwidth and works with any vector network analyzer (VNA).

“The higher power of the J2121A provides support to military and satellite buss applications. It is a unique product in the test marketplace. With its regulated voltage output the line injector allows all types of PSRR and impedance measurements,” according to Steve Sandler, Picotest CEO.

While popular ‘Bode plot’ injection transformers are very wideband adapters, they are not useful for measuring ripple rejection (PSRR) of a power supply or even an opamp. This is because the attributes that make the injection transformer perform so well for stability analysis also result in a transformer that is intolerant of DC current. Even very small DC currents (5mA or less) can greatly reduce the signal capacity or even totally saturate the transformer. For this reason, the popular Picotest line injector J2120A, and now the J2121A, are essential test adapter for power supply PSRR testing.

The line injector allows the user-provided DC supply voltage to be modulated by the network analyzer source signal (oscillator). The J2121A line injector output is regulated and provides a fixed voltage drop of 750mV from the input bus voltage fed into the injector. Connecting the J2121A output and the power supply output to the VNA allows you to measure power supply rejection ratio. The line injector can also be used to measure the input impedance of a power supply or the inductance of an inductor. The J2121A conveniently includes an isolated current sense monitor output that can be connected to the VNA, replacing the need for current probe.

J2121A High Power Line Injector