Electronic circuit for digital control of the parameters of the frequency amplitude response in switched-capacitance active filters

摘要

The invention relates to the complex electronic circuit which resolves the problem of digital control of the parameters of the frequency amplitude response in active switched-capacitance filters. The circuit in question also resolves the problem of the continuous displacement (adjustment) of the complex frequency amplitude responses on the frequency axis, without changing the parameter of the slope (selectivity) of this same response. Via the choice of construction parameters, it has been possible to obtain a continuous displacement of the frequency amplitude response with the lower and higher extreme values in a proportion of 1:10. The circuit is intended to be integrated into electroacoustic appliances, used to process articulation faults and to re-educate hearing, as well as to teach foreign languages, by the verbotonal method. By combining several filters, it is possible, in these appliances, to achieve an optimal complex frequency amplitude response which, with the aid of the circuit mentioned above, can be very precisely adjusted by continuous displacement, on the frequency axis, in the widest band (1:10) or in some reduced band. This reduced band can be graduated into parts of the octave or into levels of displacement about the nominal cutout frequency of the filters (e.g. for the reduced diapason: +/- 1/4 of an octave, or +/- 20%). The invention also resolves the problem of the luminous indication of offsets in cutoff frequencies of the response of the filters with respect to the nominal values. From the point of view of construction, the circuit consists of a voltage-controlled high-frequency oscillator (VCO), of frequency dividers (decade and binary) and of voltage comparators, and the whole thing, according to the theoretical diagram, is represented in Figure 1. IMAGE