Wideband voltage controlled oscillators for multi-band multi-standard radios

Abstract

In this thesis, a procedure of designing a wideband, low phase noise VCO is proposed. The sequence is presented step by step, from the frequency planning to topology selection, component selection. By exploring the advantages and disadvantages of each VCO topology and each component, the most suitable topology and components are chosen for each application. A technique for extending the tuning range of inherently narrow tuning range LC VCO is also presented. An all-PMOS wideband, low phase noise VCO is designed to demonstrate the designing procedure. Measurement results shows that the power consumption of this VCO is 8.8 mW from the 1.8 V power supply, the tuning range is from 2.85 GHz to 3.77 GHz, and the phase noise at 1 MHz from the carrier frequency of 3.76 GHz is -122.0 dBc/Hz. To reduce the amplitude variation over a wide frequency tuning range and to ensure a fast and reliable startup against process and temperature variations, combining biasing for optimum noise performance, an automatic amplitude controller is proposed. Measurement results of this all-PMOS wideband VCO with an automatic amplitude controller shows that the current core varies from 4.9 mA to 5.7 mA, the tuning range is from 2.78 GHz to 3.78 GHz, the phase noise performance is better than -122.7 dBc/Hz at 1 MHz for all frequencies of the tuning range, for example the phase noise at 1 MHz from the carrier of 3.77 GHz and 2.78 GHz is -122.7 dBc/Hz and -126.5 dBc/Hz, respectively. Compared to other reported VCOs in terms of a popular figure of merit, very high figure of merit was obtained. The figure of merit ranges from -184.6 to -185.5.