A method and circuit for improving linearity of a folding or flash
analog-digital-converter (ADC) circuit. Averaging resistors connect
outputs of each of a bank of first pre-amplifiers. A series adjustment
resistor is placed between each node connecting the output of a first bank
pre-amplifier and the associated averaging resistor, and the input of each
of a second bank pre-amplifier. An adjustment current is injected through
the adjustment resistor during a calibration. A permanent value for
adjustment current is determined such that an effect of offset errors is
substantially minimized.
