A 2.5-V, 0.35 μm CMOS transconductance-capacitor filter with enhanced linearity

A CMOS transconductance-capacitor (G_m-C) filter with enhanced linearity for low-voltage applications is presented. The proposed design is based on a transconductance amplifier with enhanced linearity. For the elimination of the amplifier harmonic level the compensation principle is used. The transconductor consists of two amplifiers connected in parallel. The input transistors of the first transconductor are working in the saturation region, while the input transistors of the other one are in the triode region. The device was realized as a balanced fifth-order 1MHz low-pass Bessel filter in 0.35μm CMOS technology. The filter operates with a low supply voltage of +2.5 Volt. A comparison shows that the discussed filter provides a higher linearity (from 3 to 8 dB) than known circuits with the exception of the filter based on a degenerated transconductor. But it is noted that there are some difficulties to use the last approach for low-voltage application.