A single-chip CMOS IF-band converter design for DVB-T receivers

This paper describes a CMOS single chip IF-band converter (IFC) which is applied in the analog front end circuitry of DVB-T receivers. The proposed IFC is composed of a down-conversion mixer, an automatic gain controller (AGC), and an anti-aliasing filter (AAF). The down-conversion mixer uses a current folded-mirror technique which converts a 36 MHz intermediate frequency (IF) input into a 4.5 MHz baseband signal. The AGC loop applies a novel digital VGA (variable gain amplifier) basing on a gm-boosting DVGA (digital VGA). A total of three tunable gain stages are cascaded to provide a 70 dB dynamic range. A temperature-compensated 6th order transconductance-C (Gm-C) filter with digitally tunable bandwidth (6, 7, 8 MHz) is used to constitute the proposed anti-aliasing filter (AAF). Moreover, a temperature-compensated circuitry is used to neutralize the AAF’s bandwidth drifting caused by the temperature variation.