In an impedance converter using an electron tube as an active element, output impedance can be made sufficiently low, and the number of circuit elements therefor is decreased and a circuit configuration therefor is made simple. Provided is an impedance converter having an electron tube cathode-follower connected. The impedance converter includes a bias diode that provides a bias voltage to a cathode of the electron tube, high resistance elements that provide a voltage of the bias diode to a grid of the electron tube, a load circuit connected to the electron tube, and a complementary emitter output circuit including two transistors, respective bases of which are connected to one end and the other end of the bias diode.

A graphene microphone preamplifier is a minimalist design working in class A with large quiescent current in a push-pull configuration, with automatic balancing of voltage imbalance.

Semiconductor devices and methods are described wherein temperature dependence of leakage current in at least one pathway of a device is compensated by a resistor in the device. Control of temperature dependent leakage current is particularly useful for silicon nitride devices and for circuits such as cascode circuits. A semiconductor leakage current that increases with temperature may be compensated by a fabricated resistor such as a boron doped polysilicon resistor that is electrically connected to compensate the leakage current in the pathway.

A graphene microphone preamplifier is a minimalist design working in class A with large quiescent current in a push-pull configuration, with automatic balancing of voltage imbalance.

An amplifier arrangement comprising first and second power amplifiers (T1, T2) having drains connected to positive and negative drive voltages, respectively, and gates connected to an input signal. The arrangement further comprises first and second current sensors (1, 2) for detecting first and second drain currents from the power amplifiers, processing circuitry (3) adapted to identify the smallest drain current, and a feedback control loop (5) and means for driving a bias current dependent on a feedback signal through a resistor connected between the input signal and the gate of an inactive one of the first and second power amplifiers. The control loop will keep the idle current constant in the transistor with the lowest current (the inactive transistor). Thereby, the current running in the transistor which does not deliver current to the load will be fixed at a desired value.