A wide tuning range Gm-C filter for multi-mode direct-conversion wireless receivers

A third-order channel selection filter for multi-mode direct-conversion receiver is presented. The filter is designed based on the Butterworth prototype with the target applications of bluetooth, cdma2000, wideband CDMA, and IEEE 802.11 a/b/g/n wireless LANs. Linear region MOS transistors are used to perform the voltage-to-current conversion. The wide tuning range can be achieved by the translinear loop followed by the linear voltage-to-current converter. Implemented in the TSMC 0.18-mum CMOS process, the measurement results show that the filter can operate with the cutoff frequency of 500 kHz to 20 MHz, and thus meet the requirement of different wireless applications. In the design, the maximum power consumption is 11.1 mW under a 1.2-V supply voltage. The figure of merit (FOM) is favorably compared with the other previously reported works.