Abstract: A reconfigurable analog baseband circuit for WLAN, WCDMA, and Bluetooth in 0.35 μm 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 base- band circuit consumes 16.8 mW for WLAN, 8.9 mW for WCDMA and only 6.5 mWfor 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.

Key words: analog integrated circuits