Applied To The Sensor Low Distortion Gm-c Filter

Since integrated circuit came out half-century ago, there has been significant growth in the area. Compare to digital circuit, analog circuit suffers more from process, noise and so on. So, analog circuit design strongly depends on designer's experience. Continuous analog filter, as one of the most important parts of analog integrated circuit, has also become hot research spot. It is basis of many high technologies, like intelligent computer, sensor, etc. From architecture, it can be split into two categories. One is MOSFET-C filter. The other is gm-C filter. gm-C filter is different from MOSFET-C. It adopts OTA (Operational Transconductance Amplifier) as its component, not traditional operational amplifier. It constructs current-control system, which has the advantages of high-frequency, convenient tuning.The paper adopts the gm-C structure, realizing a 4 order low-pass Bessel filter. Furthermore, I will do some improvement to overcome its flaw. Finally, we will design its layout. The filter includes the components, like OTA, Op-Amp, and Reference. All these components will be designed strictly under the environment of Cadence IC series tools. OTA's linearity is improved by compensation technique, without sacrificing input swing range. The OTA shows THD<-110dB@1V. Op-Amp adopts folded-cascode structure. Its bandwidth can reach 100M, and PM can reach about 76deg. All the designs in the paper adopt 0.35μm CMOS process under the supply voltage of 5V.