Applied To The Sensor Cmos Low-pass Filter

Since Integrated-Circuits came out half-century ago, filter has become the most popular module in any analog system. There are three different architectures for filter design: Switched-Capacitor filter, Active-RC filter and Gm-C filter which have their own advantages and disadvantages, respectively. In different systems, the proper filters should be selected.With the requirements of projects, a Gm-C filter and a Switched-Capacitor filter are finished in this dissertation.Based on traditional OTA, a new one with mobility compensation is finished. With the opposite sign of the 3rd harmonic distortion, the triodes which work in the triode region combine with the triodes which work in the subthreshold region to improve the THD of the OTA which is about ?70dB. Then, the CMFB and CMFF are both used in the OTA to improve the stability of the common-mode output voltage. Finally, the Gm-Opamp-C structure is adopted to solve the problem of driving the resistor loads of the next stage.Compared with Gm-C filter, Switched-Capacitor filter is used in low frequency area. And the lower the frequency is, the better the Switched-Capacitor filter shows. Based on the Active-RC filter, a Switched-Capacitor filter is finished with the use of simple resistor replacement method. As the aera is only 500μm×500μm, the THD of the filter can reach -82dB.The layouts of a forth-order low-pass Bessel Gm-C filter with 0.5μm process and a second-order low-pass Bessel Switched-Capacitor filter with 0.6μm process are finished in this dissertation. And the layout of the chip which contains the Switched-Capacitor filter is also finished by myself.