Circuit simultaneously delivers square and square root of two input voltages
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This Design Idea requires inputs from the circuit in a previous Design Idea (Reference 1). IC1 and IC3 are ADG5213 quad switches with individual logic-level control inputs (Figure 1 and Reference 2). With a high input, switches S2 and S3 are open, and switches S1 and S4 are closed. The switches toggle to opposite states with their control inputs low. The circuit is in the idle pretriggered condition. During the initial idle condition before a clock rising-edge trigger, Q is high and, through IC8, holds switches S2 and S3 of IC1 in the open position.
Operation of the circuit is illustrated in Figure 1. For the sake of simplicity, both analog input voltages VX and VY have a value of (3/5)VPEAK; VPEAK represents here a full-scale of both input voltages. The VX, which is compared by IC4 comparator with the linear sawtooth pulse VOUTL produces therefore a pulse width of . Subsequently, the trailing edge of the latter pulse width stops tracking of the quadratic sawtooth voltage VOUTQ at the level of .
Similarly you can connect a cascade of two identical square-rooting channels, which offers you fourth-root function, at output of X channel.
Editor's note: The figures were updated on March 4, 2012.