A five-order butterworth low-pass filter with DC offset cancellation for WLAN applications
This paper presents a five-order Butterworth low-pass filter with DC offset cancellation (DCOC) for WLAN Applications in a 65-nm CMOS process. The low-pass filter employs transconductance cell instead of conventional two-stage amplifiers to avoid internal poles which may otherwise cause the reduction of GBW. In order to achieve an appropriate 1-dB bandwidth of the integral filter, extra parasitic capacitances have been carefully considered. The proposed LPF achieves a maximal 1-dB bandwidth up to 80MHz with tunable gain and bandwidth. The LPF consume 4.2mA of current from a 1.2V power supply. A superior 1dB compression point of -2.57dBm is also achieved while with a noise figure of 27.55dB at 20MHz as a result of a good balance between linearity and noise.