Class of potentiometers and analog circuits for linearly mixing signals

(Independent) An active and powered electronic circuit module for linearly mixing two or more input signals, at least one of said input signals being differential, and compensating the amplitude of the mixed output for amplitude variations due to phase cancellations between the two said input signals, based upon a either a mechanical 3-gang pot or three digital pots, comprised of:

• a. a first pot gang or digital pot, designated as Pga, associated with a first input signal, the circuits associated with said Pga effectively multiplying said first input signal by a first function, −1≤Q(x)≤1, where 0≤x≤1 is the physical fractional rotation of a mechanical pot, or the normalized virtual rotation of a digital pot, and said Q(x) is a pseudo-sine function with Q(0)=−1, Q(½)=0 and Q(1)=1, followed by a first buffer amplifier of gain one, designated as Buff1;
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• b. a second pot gang or digital pot, designated as Pgb, associated with a second input signal, the circuits associated with said Pgb effectively multiplying said second input signal by a second function, 0≤R(x)≤1, where said R(x) is a pseudo-cosine function, orthogonal to said Q(x), with R(0)=R(1)=0 and R(½)=1 , followed by a second buffer, designated as Buff2, of gain G, such that any deficiency in said Pgb circuits that makes R(½)<1 is eliminated;
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• c. a third pot gang or digital pot, designated as Pgc, acting as part of the feedback circuit of a summer/compensator circuit, in which said summer/compensator adds the output signals of the first two said circuits using said Pga and Pgb, and at least partially compensates for amplitude variations in said mixed first and second input signals, due to phase cancellations between said first and second input signals, the compensation being due to variations in the gain of said summer/compensator circuit due to the action of said Pgc, such that the output amplitude of said summer/compensator circuit remains relatively level with variations in x, compared to its input;
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• d. said circuit module with three pot gangs or digital pots being designed so that more than one such circuit module may be combined to accommodate three or more of said input signals;
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• e. said orthogonal signals, Q(x) and R(x), respectively form the basis for approximate full-cycle sine and cosine functions, apsin and apcos, for the approximate and practical calculation of forward and reverse spectral transforms of said input signals and said output signals, using a programmable processor with at least the basic four math functions, add, subtract, multiply and divide.