CMOS baseband filter for WCDMA integrated wireless receivers

A new second-order lowpass filter based on a single CMOS fully differential current conveyor is presented. Developed from the Sallen-Key highpass filter, the proposed filter is AC coupled and provides programmable gain. Moreover, the filter exhibits low noise, high linearity and low power, making it suitable for implementing the baseband filter of a WCDMA direct-conversion wireless receiver. A WCDMA filter having a programmable bandwidth around 2.1 MHz, a variable gain range of 50 dB and a DC notch below 2 kHz using passive components below 5 kW for resistors and 20 pF for capacitors is implemented. Experimental and simulation results obtained from fabricated chips are included.