An active R filter using CMOS transistor arrays
S. V. Naimpally · International Journal of Electronics · 1976
A versatile state variable active R filter is described, which uses only resistors and CMOS transistor arrays as the circuit elements. The CMOS array can be used to produce either an integrator or an inverting amplifier depending on the power supply voltage. The design equations are very simple and with some modifications, the filter can be used to realize any biquadratic voltage transfer function in a straightforward manner.