In this paper, a highly-linear CMOS transconductor for use in tracking low-pass Gm-C filters employed III digital TV tuners IS proposed. In order to improve the linearity of the proposed transconductor at the wide VHF/UHF frequency bands, a new linearization technique based on parallel operation of auxiliary transconductors in triode and subthreshold regions is proposed. Based on the proposed transconductor, a third-order elliptic low-pass Gm-C filter is designed and simulated in a standard 0.18-um CMOS technology. The cutoff frequency of the filter is tunable from 50MHz to 300 MHz. Simulation results show that the designed filter provides a maximum in-band output referred third-order intercept point of 21.5 dBm while drawing an average current of 106 mA from a supply voltage of 1.8 V.

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