RF comb Generator | Using comb generator for EMC,RFI testing

This page covers RF Comb Generator basics and describes how to use comb generator for EMC testing or RFI testing. It lists manufacturers of low phase noise RF comb generators.

Comb generator is the signal generator which produces harmonics of its input signal. Output spectral components are spaced at equal intervals. For example if input is Fin, it will produce +/-K*Fin, where in 'K' ranges from 1, 2, 3 and so on. Frequency spectrum in the analyzer looks similar to teeth of comb, hence it is known as comb generator.

Figure-1 depicts function of comb generator. As we know EMI refers to Electromagnetic Interference. EMC refers to Electromagnetic Compatibility. Refer EMI and EMC basics. Comb generator is used for EMI test as well as EMC test.

The other wide use of comb generator is in broadband frequency synthesizers. These synthesizers generate high frequency output referenced to low frequency source. This highly stable high frequency output further used as frequency reference input in PLL circuit.

Using comb generator for EMC testing or RFI testing

Figure-2 depicts radiated emission test (EMI) using comb generator.

Figure-3 depicts conducted emission test (EMC) using comb generator.

It is very easy to use comb generator, just connect the port with the antenna and it will start radiating.

Low Phase Noise Model No-7112 from Picosecond Pulse Labs is high performance comb generator. The comb generator works over input frequency range and power range. Following are the silent features of comb generator.

Manufacturers of low phase noise RF comb generators

Following are the popular vendors or manufacturers of low phase noise RF comb generators.

Test and Measurement Equipments

RF and Wireless Terminologies