| 摘要 |
A predistortion network preceding a continuous-time active MOSFET-C lowpass filter cancels the inherent distortion of the filter over a large portion of its passband. The lowpass filter has resistive feedback and input devices whose ratio controls its transfer function at DC and low frequencies. The predistortion network has resistive feedback and input devices that control its transfer function and that match the input and feedback devices, respectively, of the active filter. Cancellation of distortion results in low distortion operation for signals in the frequency range from DC to a substantial fraction of the passband. As the filter response rolls off at higher frequencies, imperfect cancellation results in distortion performance similar to that without predistortion. The invention reduces large signal distortion of active MOSFET-C filters, which enhances their use in monolithic system with switched capacitor circuits.
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