A tunable Gm-C narrow-band complex filter for low intermediate frequency receivers

Abstract

In this paper, a new CMOS sixth-order Gm-C complex filter with tunable center frequency, bandwidth and image rejection rate used in low intermediate frequency receiver is presented. The innovations of this paper are as follows: 1. This paper proposes a complex filter with low center frequency and high image rejection ratio. 2. As the requirements of image rejection and narrowband frequency selection, a tunable trans-conductance control circuit is designed. 3.The complex filter realizes the function of adjustable parameters such as center frequency, and is suitable for narrow-band communication network. The simulation results show that the control voltage range of the filter is 0.6V~1.1V, and the corresponding center frequency adjustment range are 108~359 kHz; the bandwidth adjustment range is 181~268 kHz; the image rejection ratio of the filter ranges from 42~72dB, the current consumption range is 2.5~4.4mA, and the operating voltage is 1.8V.