A reconfigurable analog baseband circuit for WLAN,WCDMA,and Bluetooth in 0.35μm CMOS is presented. The circuit consists of two variable gain amplifiers（VGA） in cascade and a Gm-C elliptic low-pass filter（LPF）. The filter-order and the cut-off frequency of the LPF can be reconfigured to satisfy the requirements of various applications. In order to achieve the optimum power consumption,the bandwidth of the VGAs can also be dynamically reconfigured and some Gm cells can be cut off in the given application.Simulation results show that the analog baseband circuit consumes 16.8 mW for WLAN,8.9 mW for WCDMA and only 6.5 mW for Bluetooth,all with a 3 V power supply.The analog baseband circuit could provide -10 to ＋40 dB variable gain,third-order low pass filtering with 1 MHz cut-off frequency for Bluetooth,fourth-order low pass filtering with 2.2 MHz cut-off frequency for WCDMA, and fifth-order low pass filtering with 11 MHz cut-off frequency for WLAN,respectively.
A dual-band reconfigurable wireless receiver RF front-end is presented, which is based on the directconversion principle and consists of a low noise amplifer （LNA） and a down-converter. By utilizing a compact switchable on-chip symmetrical inductor, the RF front-end could be switched between two operation frequency bands without extra die area cost. This RF front-end has been implemented in the 180 nm CMOS process and the measured results show that the front-end could provide a gain of 25 dB and IIP3 of 6 dBm at 2.2 GHz, and a gain of 18.8 dB and IIP3 of 7.3 dBm at 4.5 GHz. The whole front-end consumes 12 mA current at 1.2 V voltage supply for the LNA and 2.1 mA current at 1.8 V for the mixer, with a die area of 1.2 × 1 mm^2.
