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.