Design and Investigation of Tunable Gyrator Resonance Circuit Implemented on AMS 0.35μm Process

— The paper considers some basic problems in the design of tunable fully differential gyrator resonance circuit. First is presented briefly the theory of the parallel gyrator tank with emphasizing on the effects from the amplifier imperfections. Then is considered the design of a single stage operational transconductance amplifier (OTA) with source degeneration for better linearity. It is demonstrated by simulation that wide range of variation of OTA’s gm with preserving the linearity can be achieved by using of an architecture, consisting of several parallel connected differential cells with different gms. They are switched on and off and the designed amplifier has 3 cells with gm of 50, 100 and 200μS. The resonance frequency of the gyrator tank, created with two such amplifiers, can be increased 7 times. The Q-factor of the tank is also tunable by negative resistances in parallel to the OTA outputs. Key-Words: active filters, gyrator, programmable filters; operational transconductance amplifiers, CMOS, nonlinear distortion.