MOSFET-C filters is popular in analog filters, the major reason is the simplicity. They are easily implemented with opamps and have similar architectures to active RC filters [1], this saves much of the design time. The frequency response of analog continuous time filters is determined by resistors, capacitors, inductors or transconductors. However, the process variation, temperature drift and aging, make the integrated RC time constants vary about 30 percent [2]~[3]. We proposed a switched-capacitor tuning circuit , which can be used in MOSFET-C Filter and the novel tuning circuit doesn¡¦t need off chip capacitor. The novel circuit has following advantages (1). Small chip size. (2). Simplicity (3). Low reference clock frequency.

This work analyzes tuning capabilities of different fully integrated active filter topologies. Work only deals with continuous time active filters. Topologies described in this work differ in type of active element and in method of frequency tuning. Techniques of tunning are proved on second order low pass filter. Filter topologies are compared from tunning capabilities and from point of total harmonic distortion. The main building block of all filters is integrator.

Thesis describes analog filters topologies with capability of tuning of the main parameters and the MOSFET-C and switched-capacitor filters are described. With focus to linearity and maximal tuning range optimal topology have been chosen. In work the issue of analog switch design is described and is solved. Design of switched-capacitor low-pass Sallen-key filter in Cadence software was made and simulation results are presented.