A tunable RF front-end receiver for cognitive radio applications

In this paper, a tunable RF front-end sensing receiver for overlay cognitive radio applications is presented. The WLAN IEEE 802.11 g commercial wireless standard key specifications are targeted in the proposed receiver. The design includes a tunable filter-antenna, low-noise amplifier, tunable bandpass filter, single-ended balanced mixer, and a variable gain IF (Intermediate Frequency) amplifier. Prototypes of the aforementioned blocks are fabricated, measured, and assembled to test the reception of the built receiver. For different carrier frequencies in the 2.4-2.485 GHz vicinity, a 20-MHz down-converted signal is shown at the IF output of the receiver.