MOSFET-capacitor continuous filter with composite operational amplifier

The authors describe the implementation of the concept of intensive composite operational amplifier (COA) filters, in MOSFET-C continuous-time filters. A general structure of a fully symmetric differential input-differential output COA (DCOA) is proposed. It can be easily realized in MOSFET technology and employed in a fully-balanced filter. The sensitivity analysis of such a filter employing one DCOA is provided. This leads to the conclusion that the range of working frequencies of a fully symmetric filter is twice as large as in the case of an unsymmetric one. An example of a MOSFET-C filter based on the Rauch prototype with one DCOA is discussed to illustrate some advantages of the approach proposed.