A 3rd order low-pass filter with high linearity and tunable in-band attenuation for WiMAX/LTE receiver

Abstract

In this paper, a Gm-C Low-pass filter with high linearity and tunable in-band attenuation for WiMAX/LTE receiver is presented. A linear Gm-cell is proposed and used as a key building block in design of the filter. The linear Gm-cell employs a circuit technique to reduce the nonlinearity of the source follower (SF) stage resulting from unmatched signal swings at the gate and source terminals of the input transistor. The Gm-cell was used to build a biquad bloc, which was utilized to construct a 3rd-order Butterworth low pass filter. The proposed filter consists of a buffer and a biquad stage to form the 3rd-order transfer function. The simulation results of the filter for bandwidth of 10MHz show that the IIP3 of the filter was equal to 29.5 dBm. The minimum in-band noise density was 22.6 nV/√Hz and power consumption was 10.8 mW. The supply voltage of the filter was 1 V.