I want to build a sigmoid function circuit using any of op-amps/diodes/resistors. The input will be one voltage \$x\$ into the sigmoid circuit. The output of the circuit should be: $$\frac1{1+e^{-x}}$$
The output range will be between 0 and 1 V. I looked online but could not find something that is doing this operation (or close) with the exponent. What would the circuit look like?
