Comb Generator Basics
This page covers Comb Generator basics and mention low phase noise comb generator vendors or manufactures. Application note covering how to use comb generator for EMC site testing or RFI testing.
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.
Application note-How to use comb generator
Figure-2 depicts radiated emission test (EMI) using radiated comb generator.
Figure-3 depicts conducted emission test (EMC) using conducted 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.
|Specifications||Model 7112 features|
|Frequency Range||300 MHz to 700 MHz|
|Power Range||25 dBm to 29 dBm|
|Harmonics||Upto max. frequency of 20 GHz|
|Phase noise||Ultra Low|
|Package type||Coaxial, Surface Mount|
low phase noise comb generator vendors/manufacturers
Following are the popular comb generator vendors or manufacturers.
|Company||Comb Generator Model|
|Picosecond Pulse Labs|| Model 7112 , low phase noise comb generator
|Com-Power Corporation||CGO-501, CGO-505, CGO-515|
|COBHAM (Aeroflex Company)||GaAs Comb Generators|
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