High frequency CMOS Gm-C bandpass filter with automatic on-chip tuning

A fourth-order CMOS transconductance-C (Gm-C) bandpass filter with on-chip automatic frequency tuning for wireless receiver filtering applications is proposed. A linearized transconductance (Gm) cell is designed and optimized for phase error cancellation. The center frequency of the filter is locked to an external reference frequency using an Adaptive Gain Phase-Locked Loop (AGPLL). The purpose of the AGPLL technique is to provide a short locking time which is under 50 clock cycles, it decreases the filter time response. The power supply of the proposed design is 2.2 volts and the whole circuit has been implemented in 0.35 um CMOS technology available through the Canadian Microelectronics Corporation (CMC).