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A sixth-order low-pass g m-C filter for fiber-optic electrical dispersion compensation receivers cascades three biquads permitting a reduction of group delay variation down to 10 ps. A cutoff frequency is tuned from 1.6 to 3.2 GHz by using two methods, namely, changing gm and switching a CMOS varactor's polarity. Output third-order intercept point reaches 13.1 dBm and total harmonic distortion is below -40 dB at 0.9 V pp-diff output. The continuous time filter is implemented in a 0.18-??m SiGe process, it occupies 0.17 mm2 on a 3.2 ?? 3.7 mm2 test chip and consumes 0.3 W from a 3.3-V supply.