Monolithic VCO design in standard CMOS technology

Abstract

The noteworthy expansion in telecommunication systems, such as cellular telephony, demands continuous efforts toward the improvement of radio-frequency(RF) circuit performance at ever-increasing levels of integration. The transceiver solutions that fully integrate low-noise amplifiers (LNA``s), mixers, voltage-controlled oscillators (VCO``s), and transmit modulators already exist. Moreover, the rigid noise and spurious emissions requirements for cellular communications system, such as GSM, DCS, and PCS, need to be achieved with even lower power-consumption levels. Especially, the VCO is the most important block of the frequency synthesizer and RF front-ended transceiver because it operated at a high frequency and requires a low phase noise. The VCO is the element of the frequency synthesizer that determines its overall quality. The main characteristics of a VCO are its normalized phase noise and tuning range. Usually, they go in opposite direction and thus there is a delicate tradeoff observed. Beside, the quadrature output of a VCO is demanded in image-rejection receiver or direct-conversion transceiver. The VCO has been demanded for many capabilities. Recently, especially, finding out the solution of how to obtain lower noise characteristic, how to generate quadrature signal, and how to get wide tuning range feature, has been hot issue. In this thesis, we describe three points, such as wide tuning, quadrature output generation, and low phase noise characteristics in monolithic VCO based on standard CMOS technology. In order to solve the problem about tuning range of VCO, a monolithic VCO topology is presented that use binary-weighted accumulation-mode MOS capacitors to expand the tuning range. The measured tunable range of the implemented VCO is 1.56~2.71 GHz (74%). And then, for function of quadrature generation, a new quadrature VCO with body effect is proposed. The proposed VCO can generate quadrature signal supplementary current and additional active devi...