Fig. 3

Computing the signum function. a Block diagram of a circuit to compute the signum function. In computing the square root, the Newtown-Raphson method is used. b Block diagram of a circuit to compute the signum function using the ultrasensitive regime from the covalent modification cycle. c Computation of signum function (i) Input signal. (ii) Output of the signum function. Green dashed-dot line: using combination of operators. Blue dashed line: using ultrasensitive regime from covalent modification cycle