A 1.8V high dynamic range CMOS Gm-c filter for portable video systems

A 4th order, 5 MHz, lowpass Butterworth Gm-c filter has been combined with a low noise low-voltage amplifier to form a lowpass filter for video applications. In this filter an improved transconductor and a powerful method is used to adjust the transconductance gain for tuning application. A continuous variable gain current-to-current converter is used to tune the transconductor value. The THD of the filter is -77 dB for 1 V/sub ppd/ input signal. Input referred noise is 40 nV//spl radic/Hz in the worst case. All the circuits are designed based on a 0.25 /spl mu/m CMOS process technology with a single 1.8 V supply.