The Design of Double-Positive-Feedback Voltage-Controlled Oscillator

A 24 GHz 1.4-mW double-positive-feedback voltage controlled oscillator (DPF-VCO) has been designed and realized in a 0.13 μm CMOS process. In the proposed DPF-VCO, the concept of double positive feedback loops is adopted to enhance the VCO performance and the current-mode output technique is used to obtain the output current signal. The fabricated DPF-VCO consumes only 0.78 mA, 0.97 mA, and 1.17 mA under the supply voltage of 1, 1.1, and 1.2 V, respectively, and the corresponding measured phase noise is -104dBc/Hz,-112 dBc/Hz,and-115 dBc/Hz at 1 MHz offset frequency. The best FOM of the proposed DPF-VCO is-201 dBc/Hz.