Low-power CMOS differential LC-VCO and QVCO design with low phase noise

Abstract

This thesis presents newly proposed VCO and QVCO architectures which are a current reused CMOS a differential LC-VCO and a QVCO with coupling capacitor. the new differential LC-VCO replaces one of the NMOSFETs of the conventional differential LC-VCO with a PMOSFET. Basically suggested structure can be superior to conventional NMOS differential LC-VCO on two aspects; power consumption and phase noise. for the verification of the suggested idea, the proposed LC-VCO is implemented in 0.18 $\mum$ CMOS technology with the conventional. for 2GHz application. Measured phase noise results show -103dBc/Hz at 100KHz offset while dissipating 1 mW from 1.25V supply. QVCO with coupling-capacitor technique is proposed newly. By positioning of coupling transistor below the switching stage, new QVCO eliminates nonlinear effect of the coupling transistor. In addition, coupling-capacitor technique develops lower phase noise as well as lower phase error. To compare performance of conventional QVCOs, three types of QVCO which base on same bias condition and resonator, are implemented on 0.18 $\mum$ CMOS technology for 1.7~1.8GHz application. Measured phase noise of QVCO with noise filtering represents -110dBc/Hz at 100KHz. The QVCO consumes 3.4mA current from a 1.3V supply.