MOS-only third order butterworth filter with DTMOS tuning technique for high frequency applications

In this paper, a new low-voltage, MOS-only, third order low-pass filter is proposed. The core circuit consists of only three MOSFETs and their parasitic gate to source capacitances as passive elements. Using TSMC 0.18μm technology parameters, the circuit with all biasing elements included consumes just 0.69mW for a cut-off frequency higher than 200MHz under a single supply of 1.8V. Non-ideal effects have been investigated and dynamic threshold voltage MOS (DTMOS) tuning technique has been developed for the filter circuit to suppress the non-idealities. Resulting circuit is capable of operation at high frequencies with low power consumption due to the usage of significantly less number of transistors than conventional active block-based filtering circuits.