Design optimization of low phase noise and wide frequency range VCOs

摘要

We propose how to optimize low phase noise and wide frequency range voltage-controlled oscillators (VCOs). The phase noise is in proportion to the square of oscillation frequency, and in inverse proportion to the square of oscillation amplitude. Therefore, the amplitude is usually designed large at desired frequency. But in ease of wide frequency range, optimizing the amplitude in full range is difficult because amplitude is in proportion to the frequency. This paper describes effective circuits and design procedure for this problem. We successfully designed a monolithic VCO with on-chip spiral inductor by using 0.25μm CMOS technology. The simulated frequency range is 1.18GHz to 2.21GHz, and the phase noise are -110dBc/Hz, -107dBc/Hz, and -96dBc/HZ at 100kHz offset from 1.21GHz, 1.54GHz, and 2.21GHz carriers. The VCO dissipates 7mA from a 2.5-V supply voltage.