New monolithic switched-capacitor differentiators with good noise rejection

Inverting and noninverting switched-capacitor (SC) differentiators suitable for integrated-circuit implementation are proposed and analyzed. Their structures are simple, parasitic-free, and less sensitive to offset voltage and power-supply voltage changes. In addition, their fabrication process and operating clocks are fully compatible with conventional SC integrators. Noise analysis shows a good low-frequency noise-rejection capability. The high-frequency noise can be suppressed and does not overdrive the output of the SC differentiators. To demonstrate the application of the SC differentiators in the SC filter, a bandpass differentiator-type biquad is presented. Both the differentiators and the biquad have been fabricated and measured. The differentiation waveforms and the good consistency between the measured and the simulated circuit responses verify the correct operation of the SC differentiators.<
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