Abstract: A digitally controlled impedance driver circuit including a number of fingers, some of which having FETs and series resistors sized in binary or other differential ratios, and some of the higher power FETs being sized in equal ratio and perhaps sharing a series resistor. A DCI controller circuit periodically determines a configuration of the DCI driver circuit that would result in the DCI driver circuit approximating a target impedance. Each time the DCI controller circuit does this, a comparator determines if the impedance of the DCI driver circuit should be increased or decreased. A noise attenuation circuit turns off (or on) only one of the high power fingers if the controller circuit determines that more (or less) impedance is needed even if turning off (or on) only one of the fingers would not result in the configuration of the DCI driver circuit determined by the controller circuit.

Abstract: A complementary differential amplifier includes two differential amplifiers. Each differential amplifier includes two input FETs (or bipolar transistors) having gate terminals coupled to the input terminals of the complementary differential amplifier. Two current load p-type field-effect transistors are each coupled in series between one voltage source and a drain terminal of a respective input FET. A current source FET is coupled in series between a common source terminal of the two input n-type field-effect transistors and a low voltage source. Only two FETs are needed to bias all of the current load and source FETs. A complementary folded cascode stage as well as an inverter stage may also be included.