A 0.18µm CMOS SC lowpass filter for Bluetooth channel selection

The integrated circuit design of a switched-capacitor filter for Bluetooth specifications is described. It was based on the optimum allocation of poles and zeros to generate a transfer function with unequal numerator and denominator orders, so that a direct-form structure with reduced number of opamps and low sensitivity to capacitor ratio errors were obtained. It was designed for implementation in the TSMC 0.18 CMOS process, using differential OTA structures with a dynamic biasing circuit to reduce power consumption. Layout strategies were carefully considered in order to reduce non-ideal effects. With the aid of a computer program, simulations with the extracted parameters were performed to verify the integrated circuit performance.