A method and device for continuous-time filtering in digital cmos process

摘要

In a digital CMOS process neither resistors nor linear capacitors are available and it is not possible or simply not practical to design continuous-time filters using traditional methods. It has therefore been proposed to utilize current mirrors to realize filtering functions in a voltage-to-current converter when designing continuous-time filters for sampled data systems in digital CMOS processes. The pole frequency is therefore determined by the transconductance of an MOS transistor (6) and the capacitance of a capacitor (8) seen at its gate. In this application, a generalized method of designing continuous-time filters in digital CMOS process and methods of cascading have been proposed to reduce the spread of the pole frequencies.