A Direct-Conversion CMOS RF Receiver Reconfigurable From 2 to 6 GHz

A CMOS direct-conversion receiver with only one signal path is reconfigurable from 2 to 6 GHz in the RF band and from 3.6 to 54 MHz in the channel bandwidth. By employing a voltage feedback in a common-gate low-noise amplifier (LNA), the input matching of the LNA can be reconfigured for each RF band by simply changing the resonant frequency of the load network. The frequency characteristics of the active-RC channel selection filter with an R-2R ladder is automatically tuned by a one-shot tuning circuit. Implemented in 0.18- μm RF CMOS technology, the whole receive path shows 4.6-5.6-dB noise figure while consuming 65-75 mA from a 1.8-V supply depending on the mode of operation.