A method for operating an input-cell comprises: receiving a sensor input signal, a digital-bias first control input and a second control input and, using a first resistor network to apply an analog pull-up bias to the sensor input signal when the bias of the first control input is in a first digital state. To provide a path for at least a portion of the first resistor network to a ground to cause the first resistor network to apply a pull-down bias to the sensor input signal when the bias of the first control input is in a second digital state. Receiving a voltage reference and an input waveform signal; using a second resistor network to apply to the input waveform signal to a comparator when the bias of the second control input is in a first digital state and, to apply a biased and attenuated input waveform signal to the comparator when the bias of the second control input is in a second digital state. Comparing the biased sensor input signal to the waveform applied by the second resistor network to determine an input-cell output, so that the input-cell can convert the sensor input signal to a time-based parameter.