Direct conversion receiver with high conversion gain and wide tuning range in 0.18 um CMOS

This paper describes the design of a high conversion gain wide tuning range direct-conversion receiver in 0.18 um CMOS technology. The receiver is built in differential topology with a single-ended input for better connection with the antenna. The integration is composed of a RF buffer amplifier with single to differential conversion function, a cross-coupled VCO and a double balanced mixer. The amplifier is built of two cascode stages and an active balun employing a RC a feedback network for gain and phase flatness improvement. The cross-coupled VCO realize more than 20% tuning range with a three bit control. The phase noise is better than -112dBc/Hz at 1MHz offset at 4.0GHz. Current bleeding technology is used in the double balanced mixer for convention gain improvement. 3.1mm × 1.1mm die area is consumed for the integrated receiver with all DC/RF pads included. It achieves 21dB conversion gain, -10.5dBm P1dB and -9dB maximum output power.