Active Filter Design For Wireless Receivers

In recent years,with the rapid development of wireless communication technology and the continuous improvement of circuit integration,low power consumption has been recognized as an important consideration by designers in an increasing number of fields.In communication systems,filters,as important units for processing analog baseband signals,have a significant impact on system performance.Therefore,studying low-power active filters with different structures is of great significance.At present,Bluetooth and UWB systems are widely used in various Io T terminals in various fields such as 5G and intelligent living.This article designs two low-power,bandwidth,and gain adjustable filters that match the indicators of the two.Based on the characteristics of the Bluetooth system,this article designs a twostage cascaded RC active complex filter circuit that can be applied to low to intermediate frequency receivers.At the same time,an automatic calibration circuit is added to reduce the offset of center frequency and bandwidth.Two DCOC circuits are used to solve the direct current offset problem that greatly affects low-frequency signals.Under the 40 nm CMOS process,the circuit was subjected to pre simulation analysis,layout drawing,and post simulation analysis,with a layout area of 530 μm × 305 μm.Through simulation,it can be seen that the RC active complex filter achieves adjustable three gain levels,adjustable center frequencies of 1MHz and 2MHz,and adjustable bandwidth of 0.5MHz and 1.5MHz.At the same time,the image rejection ratio of the circuit is greater than 25 d B,the compression point of-1d B is greater than 10 d Bm,the noise figure is less than 38 d B,and the circuit power consumption is less than 600 μW.Meet the technical design specifications of the Bluetooth system.Based on the characteristics of UWB system,this article designs a dual secondorder Gm-C low-pass filter based on high-speed and high linearity Nauta structure for zero intermediate frequency receivers.The design uses a constant transconductance linear regulator to reduce the impact of power supply voltage and Process corners on the Nauta structure,and uses a simple DCOC circuit to solve the DC offset problem.Under the 40 nm CMOS process,pre simulation analysis,layout drawing,and post simulation analysis were performed on the structure,and the layout area of the structure was 103 μm × 181 μm.The simulation results show that the Gm-C filter can achieve three level gain adjustable,with a bandwidth range of 200 MHz to 480 MHz,a noise figure less than 26 d B,a linearity greater than-4d Bm,and a circuit power consumption less than 730 μW.Meet the technical design specifications of broadband UWB systems.