Recently there are many researches of the continuous time filter which has high linearity, low distortion and low power. This paper describes the design of a low frequency band pass filter for a infrared receiver IC using 0.8um BiCMOS technology. The band pass filter is based upon the second biquad gm-c filter which has 38kHz center frequency and high quality factor about 10. The band pass filter is composed of main filter block and center frequency tuning block.
Electronic components must be expected to vary during operation, because of environmental effects, such as temperature changes, humidity, or aging. So the center frequency of the band pass filter is automatically tuned. This paper proposes center frequency tuning method using DC offset method instead of phase locked loop. Due to the new tuning method, the filter size and power consumption are reduced. Total power consumption is about 2 mW for Bipolar and 1.2mW for MOS from a +5V power supply.
