AMPLIFIER HAVING CONTROLLABLE INPUT IMPEDANCE

An amplifier circuit includes a circuit input, and a circuit output. An inverter, including first and second MOS transistors is connected between first and second supply voltages, and has an inverter input connected to the circuit input, and an inverter output, which provides an inverter output current corresponding to a circuit input voltage. A first resistive element comprises a third MOS transistor and a fourth MOS transistor of opposite conductivity types, and each having their gate and drain terminals connected to the inverter output and the circuit output, and having their respective source terminals connected to respective ones of the first and second supply voltages. A second resistive element includes a fifth MOS transistor and a sixth MOS transistor of opposite conductivity types, and each having its drain-source path connected between the circuit output and the circuit input, and having its gate connected to a respective voltage source.