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A full CMOS seventh-order linear phase filter based on-biquads with a 3-dB frequency of 200 MHz is realized in 0.35-m CMOS process. The linear operational transconductance amplifier is based on complementary differential pairs in order to achieve both low-distortion figures and high-frequency operation. The common-mode feedback (CMFB) employed takes advantage of the filter architecture; incorporating the load capacitors into the CMFB loop improves further its phase margin. A very simple automatic tuning system corrects the filter deviations due to process parameter tolerances and temperature variations. The group delay ripple is less than 5% for frequencies up to 300 MHz, while the power consumption is 60 mW. The third-harmonic distortion is less than 44 dB for input signals up to 500 mV pp. The filter active area is only 900 200 m 2. The supply voltages used are 1.5 V.

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A CMOS 80-200-MHz fourth-order continuous-time 0.05 equiripple linear phase filter with an automatic frequency tuning system is presented. An operational transconductance amplifier based on transistors operating in triode region is used and a circuit that combines common-mode feedback, common-mode feedforward, and adaptive bias is introduced. The chip was fabricated in a 0.35-m process; filter experimental results have shown a total harmonic distortion less than 44 dB for a 2-V pp differential input with a single 2.3-V power supply. The group delay ripple is less than 4% for frequencies up to 1.5. The frequency tuning error is below 5%.

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