A High-Performance Digitally Controlled LC Oscillator for Ku-Band Applications

A 13.5-15.5 GHz low phase noise digitally controlled LC VCO, designed in a 0.25 mum BiCMOS technology, is presented in this paper. The resonant circuit of the VCO uses a high performance radio-frequency differential binary-weighted switched capacitor array (RFDSCA) to cover the 2 GHz tuning band with a continuous tuning voltage of 5 V. The RFDSCA circuit was optimized using a new automated synthesis method in order to guarantee a VCO with minimum phase noise. The VCO presents a typical phase noise of -116 dB/Hz @ 1MHz and a maximum tuning sensitivity of 165 MHz/V. The VCO core works with a voltage supply of 3 V and has a current consumption of 5 mA. The results demonstrate the feasibility of implementing and using high performance RFDSCAs as digital tuning elements at operating frequencies up to tens of gigahertz.