Reprogrammable, wide tuning range 1.6GHz CMOS VCO with low phase noise variation

Phase noise can vary dramatically over the tuning range of a VCO, but the published literature often obscures this fact by reporting phase noise measurements at only a small number of selected turning voltages. It is difficult to obtain simultaneously a large tuning range, low phase noise, and small phase noise variation, particularly while accommodating manufacturing and packaging tolerances. This work describes the first use of native EPROM devices (available in every standard CMOS technology) and switched reactances to relax these tradeoffs. In addition to permitting post-packaging compensation for manufacturing variations, the inherent reprogram inability of these cells also enables the rapid prototyping and optional reconfiguration of RF and mixed-signal systems. This technology allows the realization of a fully-integrated oscillator in 0.25mum CMOS with a phase noise variation of under 10dB (compared with 40dB variation in a conventional implementation) over a 1.25GHz to 1.92GHz (42%) tuning range. The oscillator consumes 23mW from a 3V supply while exhibiting a phase noise of better than -93dBc/Hz at 100kHz offset from a nominal 1.58GHz center frequency.