A 65nm CMOS 1-to-10GHz tunable continuous-time low-pass filter for high-data-rate communications

In this work the Gm-C topology is adopted for its merits at high frequencies. In this technique, two critical parameters should be accounted for: the accuracy of the Q factors of the pole pairs (for correct transfer function) and parasitic capacitances (for maximal cut-off frequency). The former point is influenced by the phase shift of the integrators compounding the filter in the neighborhood of the filter's edge frequency. This phase error is due to two antagonistic effects which are the integrator's finite DC gain and its high-frequency poles/zeros.