Low Phase Noise and Wide Tuning Range VCO Using the MOS Differential Amplifier with Active Load

We demonstrate the design of a novel voltage-controlled oscillator (VCO), which is based on a metal-oxide-semiconductor field-effect transistor (MOS) differential amplifier with active load. This VCO achieves low phase noise and wide tuning range. The phase noise is –120 dBc/Hz at 600 KHz offset from a 1.216 GHz carrier frequency. This value is comparable to that of a LC-based integrated oscillator. The operating frequency can be tuned from 117 MHz to 1.216 GHz with the supply voltage varying from 1.3 V to 3.3 V. Therefore, the tuning range is about 90.38% which is larger than most of the LC and ring oscillator. The VCO circuit, which is constructed using a standard 0.35 μm CMOS technology, occupies only 26.25 × 7.52 μm die area and dissipated 10.56 mW under a 3.3 V supply voltage.