A resistor-less amplifying circuit includes a plurality of resistor-less cells. Each cell includes a plurality of MOS transistors. Each cell generates a differential output equal to ΔVGS of two MOS transistors with a magnitude of the differential output controlled by a control voltage generated by a differential amplifier coupled to a feedback loop around a cell. In one embodiment, the resistor-less amplifying circuit is a part of a bandgap voltage reference circuit. In another embodiment, the resistor-less amplifying circuit is part of a temperature sensor circuit.