Design Of Reconfigurable Filter For IoT

Due to the broad application prospects in industrial,consumer electronics and military,wireless sensor networks have been widely concerned.Low-pass filter and complex band-pass filters are used as components of RF transceiver chips in wireless sensor network nodes,whose ability to select useful frequency signals and suppress interference signals will affect the performance of the entire RF transceiver.In order to save chip area,designing reconfigurable filters that can realize both low-pass and complex band-pass functions has important research value and significance.A reconfigurable filter that can realize dual functions of low-pass and complex band-pass through the reconstruction circuit is designed in the thesis.In order to meet the different requirements of the RF transceiver for the filtering function in the transceiver link,a fourth-order low-pass filter architecture is obtained by cascading two MFB-type Biquads.Then,after the frequency shift,the architecture of the complex band-pass filter is obtained,and the analog switch is controlled by the SPI to realize the switching of the filtering function.Finally,the system architecture of the reconfigurable filter is obtained,which realizes the reconfigurable function and saves the chip area.In order to reduce the complexity of RC parameter design in active RC filter design,a method assisted by MATLAB is proposed to make the calculation of RC parameters in the filter design process fast and accurate.The manual frequency calibration circuit is designed to avoid the influence of process and temperature on the frequency characteristics of the filter,so that the performance of the filter is more guaranteed.Based on the TSMC 55nm RFCMOS process,the circuit schematic and layout are designed.After the simulation verification and tape-out verification,the module area is0.4*0.5mm~2.The test results show that the circuit power consumption is about 0.6m W under the 1.2V power supply voltage.When working in the low-pass state,the passband gain is about-0.3d B,the bandwidth is 1.45MHz,the input IIP3 is 14.02d Bm,and the rejection ratio at 4MHz is 22.2d B.When working in the complex bandpass state,the passband gain is about 14.92d B,the bandwidth is 2.9MHz,the image rejection ratio is 21.5dB,and the input IIP3 is 9.03dBm.