A reactance cancelling radio frequency (RF) circuit array is disclosed. The reactance cancelling RF circuit array includes multiple RF circuits each coupled to one or two adjacent RF circuits by one or two pairs of coupling mediums each having a respective length less than one-quarter wavelength. In one aspect, an RF input signal is first split across the RF circuits and then combined to form an RF output signal. As a result, each RF circuit requires a lower power handling capability to process a portion of the RF input signal. In another aspect, each pair of the coupling mediums can cause reactance cancellation in each reactance-cancelling pair of the RF circuits. By coupling the RF circuits via the coupling mediums and enabling splitting-combining among the RF circuits, it is possible to miniaturize the reactance cancelling RF circuit array for improved performance across a wide frequency spectrum.

A matching circuit which can handle a plurality of frequencies is provided. The matching circuit includes a transistor and an inductor. The matching circuit uses capacitance formed between a gate and a source/drain (referred to as capacitance Cgsd below) of the transistor as a condenser. The capacitance Cgsd changes with the voltage of the gate with respect to the source (referred to as voltage Vgs below). The transistor included in the matching circuit is an OS transistor including a metal oxide in a channel formation region. The OS transistor features larger variation in capacitance Cgsd with respect to the voltage Vgs than the MOSFET that uses silicon, which enables the matching circuit to handle alternating-current signals in a wide frequency range.

A circuit for controlling a capacitor having a capacitance adjustable by biasing, including an amplifier for delivering a D.C. bias voltage, having a feedback slowed down by a resistive and capacitive cell.

A reactance cancelling radio frequency (RF) circuit array is disclosed. The reactance cancelling RF circuit array includes multiple RF circuits each coupled to one or two adjacent RF circuits by one or two pairs of coupling mediums each having a respective length less than one-quarter wavelength. In one aspect, an RF input signal is first split across the RF circuits and then combined to form an RF output signal. As a result, each RF circuit requires a lower power handling capability to process a portion of the RF input signal. In another aspect, each pair of the coupling mediums can cause reactance cancellation in each reactance-cancelling pair of the RF circuits. By coupling the RF circuits via the coupling mediums and enabling splitting-combining among the RF circuits, it is possible to miniaturize the reactance cancelling RF circuit array for improved performance across a wide frequency spectrum.

Various embodiments for controlling a resonant frequency of a resonator are described. A system includes at least one resonant circuit and an active variable reactance circuit that controls a resonant frequency of the at least one resonant circuit. The active variable reactance circuit includes an electrically-controllable switching element and a switch controller sub-circuit configured to switch the electrically-controllable switching element at a frequency of a radio-frequency (RF) current or voltage passing through or across a device such that the RF current flowing from a first terminal to a second terminal is substantially sinusoidal.

A reactance cancelling radio frequency (RF) circuit array is disclosed. The reactance cancelling RF circuit array includes multiple RF circuits each coupled to one or two adjacent RF circuits by one or two pairs of coupling mediums each having a respective length less than one-quarter wavelength. In one aspect, an RF input signal is first split across the RF circuits and then combined to form an RF output signal. As a result, each RF circuit requires a lower power handling capability to process a portion of the RF input signal. In another aspect, each pair of the coupling mediums can cause reactance cancellation in each reactance-cancelling pair of the RF circuits. By coupling the RF circuits via the coupling mediums and enabling splitting-combining among the RF circuits, it is possible to miniaturize the reactance cancelling RF circuit array for improved performance across a wide frequency spectrum.

A negative capacitance circuit is connected between a drain and a source of the mixer transistor. With this configuration, the negative capacitance circuit is connected in parallel to a parasitic capacitance generated between the drain and the source of the mixer transistor, and the parasitic capacitance can be canceled out in a wide band by the negative capacitance circuit connected in parallel.

An electronic emulation component for actively emulating a passive electronic component such as a capacitor or inductor having a desired value, comprises a pair of terminals for connection to an external circuit and across which the desired value is to appear, a power convertor, and a passive electronic component of the type to be emulated but having a value different from the value to be emulated and isolated from the pair of terminals by the convertor.

A negative capacitance circuit is connected between a drain and a source of the mixer transistor. With this configuration, the negative capacitance circuit is connected in parallel to a parasitic capacitance generated between the drain and the source of the mixer transistor, and the parasitic capacitance can be canceled out in a wide band by the negative capacitance circuit connected in parallel.

A lumped element directional coupler having an asymmetrical structure. The lumped element directional coupler can be integrated while being compact by using lumped elements, instead of transmission lines, have broadband characteristics through the lumped elements being asymmetrically arranged, and further increase bandwidth by additionally providing a negative capacitor element or, more particularly, a negative capacitor element having loss.