A Gunn diode based surface mount 77 GHz oscillator for automotive applications

Gunn diode cavity oscillators are currently used in the majority of ACC 77 GHz radar systems. These are bulky and normally require to be individually tuned. A substrate based voltage controlled oscillator has been developed, still using a Gunn diode; which has small size, is surface mount packaged and which retains the superior performance of a Gunn based oscillator over MMIC solutions. A good performance over temperature is achieved, due to the use of hot electron injection in the Gunn diode and the oscillator is voltage tuned by employing a varactor diode. The design, construction and performance are presented of a planar circuit based VCO which is suitable for high volume production.