Cutoff frequency correction circuit of filter

Abstract

The invention discloses a cutoff frequency correction circuit of a filter. A jump function increased from a first voltage to a second voltage is input to the correction circuit. The correction circuit comprises a primary passive filter, a first comparator, a second comparator, a counter, a digital block and a filter, wherein the primary passive filter integrates the jump function to obtain a third voltage; when the third voltage is higher than a set first reference voltage, the first comparator outputs a high-frequency signal; the second comparator is used for outputting high-frequency signals in a first period from the moment of applying the second voltage to the moment that the first comparator outputs the high-frequency signal; the counter is used for counting the number of the reference clocks input in the first period; the digital block is used for calculating the time constant variation rate of the filter by using the number of the reference clocks counted by the counter, and generating a correction code capable of correcting the time constant variation rate; and the filter is used for correcting cutoff frequency according to the correction code of the digital block. The correction circuit can increase the cutoff frequency regulating speed so as to shorten the operation preparation time of a system comprising the filter and increase the ratio of the occupied area of the digital block to the cutoff frequency accuracy.

Description

technical field [0001] The present invention relates to a filter cut-off frequency correction circuit using a digital method, in particular to a filter cut-off frequency correction circuit, which calculates the distorted time constant change rate according to the engineering variation (variation) embodied in the semiconductor, and according to The rate of change of the time constant is digitally corrected for the cut-off frequency. Background technique [0002] Electronics is generally the field of transmitting, receiving or processing signals. Therefore, when other unnecessary signals are mixed in the process of signal transmission, it is only necessary to filter out the original signal that needs to be transmitted through the filter, especially the analog filter, whose function is: before the signal is transmitted to the digital signal processing circuit, the It becomes a clean signal with only the required information. [0003] Since the cut-off frequency of the filter ...

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Problems solved by technology

[0010] However, since this technique needs to repeat the above-mentioned series of processes until the cutoff frequency is reached, there is a problem that it takes too long for the filter to fully filter out the state of the signal

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