CMOS on-chip active RF tracking filter for digital TV tuner ICs

Abstract

Digital TV (DTV) is developed rapidly nowadays since it enables broadcasters to offer television with better picture and sound quality. It can also offer multiple programming choices. The tuner, as a key element of DTV, converts received RF signals into digital signals, which can be further processed for the sound and picture. Various existing digital TV standards, such as advanced TV systems committee-terrestrial (ATSC-T), Open Ca-ble, digital video broadcasting terrestrial (DVB-T), and DVB-C cover a wide range of operating frequencies, from 48 to 860MHz. This broadband character presents many technical challenges in the design of DTV tuners, including harmonic mixing, image rejection, dynamic range, and linearity. The bottlenecks in selectivity and linearity performances of DTV tuners arise mainly from TV broadcasting environments with wide range signal strength. Therefore, the rejection of unwanted channel signals and harmonics is the main design concern of tun-ers. This problem has been resolved by the adoption of an RF tracking filter. In typical silicon tuner architecture, the tracking filter is located between the LNA and a mixer. In this dissertation, several design techniques for high performance on-chip RF tracking filter are proposed. Firstly, two version low band RF tracking filters which work in the frequency range from 48 to 300 MHz are introduced. For first version, a highly linear tunable G??m-C type active harmonic rejection filter (HRF) design is presented. The proposed HRF architecture can provide gain, center frequency, and quality factor tuning. Moreo-ver, by simultaneously changing the transistor sizes and bias currents of the unit Gm-cell, good linearity over the whole frequency range can be achieved. For second version, a low power and highly linear CMOS active track-ing band-pass filter is presented. In this design, a transconductor linearization technique based on a method of dynamic source degenerated differential pair is a...