Design Of Switched - Capacitor Filter Based On CMOS Process

In signal processing, dual-tone multi-frequency signals in programmed sessions systems, automatic control system plays an important role. The filter in the transmission system dual-tone multi-frequency signal has played a decisive role in filter performance will determine the receiving end dual-tone multi-frequency signal processing effects. Switched capacitor filter in the filter field of good play, which is more suitable for CMOS technology in use in circuit design. As integrated filter mainstream technology, CMOS technology is one of the hot switch capacitor technology can achieve the most effective SoC circuit.Based on this study CSMC 0.5um CMOS technology, the use Cadence simulation software, multi-stage in series and Z-domain synthesis by Biquad were applied to the design of a dual-tone multi-frequency signal reception system sixth-order switched capacitor bandpass filter. The filter in the working voltage of 5V conditions, the clock frequency of 27.3KHz, pass-band frequency of 689 Hz ~ 949 Hz. When the input signal voltage is 200 mV conditions: the cascade method designed filter passband attenuation-0.55 dB, stop-band attenuation-40.98 dB, the overall capacitance value 87.891pF; z-domain synthesis of the switched capacitor filter design passband attenuation-0.39 dB, stop-band attenuation-41.73 dB, the overall capacitance value 65.428 pF. The parameter comparison, the effect of the z-domain filter circuit filter synthesis design better, the capacitance value is smaller, and the use of Cadence simulation software for the z-domain synthesis filter circuit design layout design, its layout area of approximately 66060μm2.