An injection-locked 8.5 GHz VCO with decade-wide programmable locking range in SiGe BiCMOS

Abstract

This paper presents a low-noise subharmonically injection-locked VCO with programmable locking range. A pulse generator with programmable duty cycle converts the external reference signal into a narrow pulse that locks the VCO. Record low phase noise of -115 dBc/Hz at 100 kHz offset is achieved by combining a low-noise CML pulse generator with a cross-coupled VCO. The VCO features programmable locking range from 10 to 500 MHz. Fabricated in a production SiGe BiCMOS technology, the circuit demonstrates record low phase noise, both at close-in and far-out frequency offsets from the carrier.