The mains voltage insertion module J2121A allows the voltage to be modulated on the input side of a DC power supply, for example the way it is used to measure a high suppression of noise from the supply voltage (Power Supply Rejection Ratio / PSRR). The injector module must cover a frequency range that lies below the mains frequency up to the bandwidth of the power supply control loop of the power supply under test.
The mains voltage injector module can only supply electricity. Therefore, the output amplitude can be very clearly influenced by the current requirement caused by capacitive loads. The network analyzer Bode 100 from Omicron Lab has a high selectivity, so that distortions at the outlet of the injector do not influence the measurements. Since this injector can only impress low power, the input signal from the oscillator should be kept as small as possible, but above the noise level.
Measurement of the input impedance:
This mains input voltage injector can be used in conjunction with a current clamp to measure the input impedance of a power supply. The input impedance of a switching power supply or controller is negative and is therefore a stability challenge when an EMI filter is involved. However, this measurement is important for the design, analysis and for the verification process. The current clamp must be set to 1A / V or the results must be adjusted according to a different scaling.