Orthogonal least squares algorithms for training multi-output radial basis function networks

A voltage comparator suitable for use in an analog-to-digital converter such as a successive-approximation converter which is comprised of a plurality of capacitively cascade-connected inverters to generate an output signal of a logic level 1 or 0 according to the relationship between the magnitudes of two analog input voltage signals to be compared. A bias circuit for impressing a bias voltage on the inputs of the inverters comprises first and second MOS transistor resistor elements connected in series across a power source and a third MOS transistor which is connected in parallel to the second MOS transistor, and whose gate is supplied with a control voltage so that the inverters are respectively biased to the optimum operation point for comparison through adjustment of the control voltage. With another embodiment of this invention, the respective inverters are automatically biased to the optimum operation point for comparison by detection of the bias voltage of inverters.