Design of A Tunable Low-pass Active Filter for Communication

In this paper, a integrator as a basic block of the low-voltage(2.5V) active filter for communication system are proposed. The integrator is composed of the CMOS complementary circuit which can extend transconductance of an integrator. Therefore, the unity gain frequency which is determined transconductance is increased about two times larger than that of the conventional continuous-time integrator. And then frequency and gain of the integrator can be controlled with simple tuning circuit. Finally, tunable low-pass active filter is designed with double-poly double-metal CMOS process.