Highly Linear Low-Pass G_m − C Filter with Self-Biasing Transconductor for Digital TV Tuner

Abstract

To improve the linearity of the transconductor in digital TV tuner application, a new technique of multiple gated transistors in self-biasing basis is presented. The proposed design decreases the bill-of-material (BOM) and offers less complexity of the structure. In addition, the proposed transconductor with utilizing by third-order Chebyshev introduces low-pass filter with low power consumption and the cutoff frequency of 50-200 MHz. The hybrid tracking low-pass filter is designed to overcome the issue of local oscillator harmonic-mixing for Advanced Television System Committee terrestrial digital TV tuner integrated circuit. The proposed operational transconductor amplifier (OTA) is designed and implemented in 90 nm CMOS technology. The simulation result with the two-tone test at 100 MHz center frequency proves the proposed OTA has 5 dBm Input-referred Third-Order Intercept Point (IIP3) in compare with a single-gate OTA in the third-order Chebyshev filter. The proposed OTA achieves maximum noise figure (NF) of 13 dB and maximum IIP3 of approximately 21.7 dBm at 100 MHz, whereas consuming 18 mA with 1.2 V supply voltage and it shows great improvement.

Keywords: ATSC, Tracking filter, transconductor, self-biasing

JEL Classification: F14, L, O14, C63