VCO in Radar Transceiver

Hi All,

I was looking at several papers of radar transceiver that operates at 77GHz to 88 GHz focusing on the VCO and Chirp PLL architecture.

So if we want the output of the VCO to be 77GHz to 88 GHz, all the papers for radar transceivers use VCO with a multiplier to generate frequencies in the range of 77GHz to 88 GHz. (Say 20 * 4 or 38*2 )

What would be the technical reason to use multipliers? why can't we just have an architecture of the VCO that operates at 77 GHz?

Please let me know

That would take a special VCO capable of such frequencies. the multipliers take a much lower frequency and multiply it to your 77-88 Ghz. Gunn oscillators or magnetrons are typical oscillators that can reach these frequencies. In radar these are often followed by a high power puled amplifier or TWT.

Newer radars at 77GHz (automotive collision avoidance/ADAS) use simple oscillators with only 2x multiplier. High speed GaN or SiGe Transistors are used.