CMOS Transistors Based First-Order Voltage-Mode All-Pass Filter with Tunable Transformation Possibility

Abstract

In this paper, a novel complementary metal-oxide semiconductor (CMOS) transistors based first-order voltage-mode all-pass filter is proposed. The filter circuit employs six metal-oxide semiconductor (MOS) transistors and minimal number of passive components, i.e., a resistor and a capacitor. The core of the proposed filter is a CMOS inverting amplifier with unity gain. The proposed circuit exhibits some attractive features such as compact design, high input impedance and ability to provide non-inverting and inverting all-pass responses simultaneously. Additionally, it does not require any kind of passive element matching constraints. Furthermore, by replacing the passive resistor with an active negative channel metal-oxide semiconductor (NMOS) transistor, the proposed filter is enriched with the much-desired feature of tunability. The theoretical behavior is tested and demonstrated by carrying SPICE simulations using TSMC 0.18[Formula: see text][Formula: see text]m level-7 CMOS process parameters.