Phase-locked broadband GaAs HBT VCO module for millimeter-wave astronomical local oscillators

A phase-locked broadband GaAs HBT voltage controlled oscillator module is designed, fabricated and tested for the local oscillators in millimetre-wave astronomical heterodyne receivers. The configuration of the local oscillator module is based on the offset phase-locked loop scheme with frequency dividing circuit in the feedback path. Employing closed-loop operation, the system can produce carrier frequencies with negligible reference spur. This system achieves phase noise of -94 dBc/Hz at 1 MHz offset and -104 dBc/Hz at 2 MHz offset, no significant spur observed.