A current detection circuit has a differential amplification circuit that outputs a differential output current dependent on a voltage difference between input terminals and first and second feedback circuits that output a detection current in response to the differential output current and form a feedback path to each input terminal of the differential amplification circuit. First and second MOS transistors that generate voltages dependent on respective source-drain voltages at a time when drain currents in a forward direction and a backward direction flow through an output MOS transistor are connected to respective input terminals of the differential amplification circuit.

An amplifier that amplifies a differential signal includes first and second input terminals for receiving two input signals; first and second diodes each including an anode and a cathode, the anodes being electrically connected to the first and second input terminals; first and second bias current sources being respectively electrically connected to the cathodes of the first and second diodes; an operational amplifier connected to the cathode of the first diode and the cathode of the second diode and configured to amplify a differential signal between signals generated at the cathodes of the first and second diodes; a capacitive element being electrically connected between an input and an output of the operational amplifier; and a differential amplifier provided between the operational amplifier and the first and second input terminals and configured to amplify the two input signals. The first and second bias current sources include a current mirror circuit.

Radio Frequency (RF) amplifiers with voltage limiting using non-linear feedback are presented herein. According to one aspect, an RF amplifier comprises an amplifier circuit having an input terminal and an output terminal and a non-linear feedback circuit having an input terminal and an output terminal. The input terminal of the non-linear feedback circuit is connected to the output terminal of the amplifier circuit and the output terminal of the non-linear feedback circuit is connected to the amplifier circuit to reduce the gain of the amplifier circuit when an RF voltage swing present at the input terminal of the non-linear feedback circuit exceeds a predefined threshold. In one embodiment, the output terminal of the non-linear feedback circuit is connected to the input terminal of the amplifier circuit. In another embodiment, the output terminal of the non-linear feedback circuit is connected to a bias circuit of the amplifier circuit.

A sensor amplifier arrangement includes an amplifier having a signal input to receive a sensor signal and a signal output, and a feedback path that couples the signal output to the signal input, wherein the feedback path includes an anti-parallel circuit of diodes, and a voltage divider including a first and a second divider resistor and a voltage divider tap between the first and the second divider resistor, wherein the voltage divider couples the signal output to a reference potential terminal, and the voltage divider tap is coupled to the anti-parallel circuit of diodes and the anti-parallel circuit of diodes is coupled to the signal input.

An amplifier circuit (AC) for amplifying an output signal (OS) of a capacitive sensor (M) comprises a first input terminal (AIN) to receive the output signal (OS) of the capacitive sensor (M) and a second input terminal (BIN) to receive a bias voltage (Vbias) of the capacitive sensor (M). The amplifier circuit (AC) comprises an amplifier (A) for amplifying the output signal (OS) and a control circuit (CF) arranged in a feedback loop (FL) of the amplifier (A) being configured to control a DC voltage level at an input connection (A1) of the amplifier (A). A bias voltage sensing circuit (BVS) senses a change of the level of the bias voltage (Vbias) at the second input terminal (BIN) and changes the bandwidth of the feedback loop (FL) in dependence on the sensed change of the level of the bias voltage (Vbias).

A structure having: a plurality of field effect transistors (FETs) connected between a common input and a common output, each one of the field effect transistors comprises: a source region, a drain region, and a gate electrode for controlling carriers through a channel region of a transistor region of the structure between the source region and the drain region; a plurality of diodes, each one of the diodes being associated with a corresponding one of the plurality of FETs, each one of the diodes having an electrode in Schottky contact with a diode region of the corresponding one of the FETs. The gate electrode and the diode electrode extend along parallel lines. The source region, the drain region, the channel region, and a diode region having therein the diode are disposed along a common line.

A method for improving the linearity of a radio frequency power amplifier, a compensation circuit (307) for implementing the method, and a communications terminal with the compensation circuit (307). In the method, a compensation circuit (307) is connected between a base (a3) and a collector (b3) of a transistor of a common emitter amplifier (306), in order to neutralize the impact of a variation in capacitance between the base (a3) and the collector (b3) of the transistor (306) according to a radio frequency signal. No additional direct-current power consumption is needed, and degradation in performance of other radio frequency power amplifiers can be avoided. The corresponding compensation circuit (307) can be easily integrated with a main amplification circuit, without affecting other performance of the main amplification circuit, and provides high adjustability.

An amplifier that amplifies a differential signal includes first and second input terminals for receiving two input signals; first and second diodes each including anode and cathode, the anodes being electrically connected to the first and second input terminals; first and second bias current sources being respectively electrically connected to the cathodes of the first and second diodes; an operational amplifier connected to the cathode of the first diode and the cathode of the second diode and configured to amplify a differential signal between signals generated at the cathodes of the first and second diodes; a capacitive element being electrically connected between an input and an output of the operational amplifier; and a differential amplifier provided between the operational amplifier and the first and second input terminals and configured to amplify the two input signals. The first and second bias current sources include a current mirror circuit.

A structure having: a plurality of field effect transistors (FETs) connected between a common input and a common output, each one of the field effect transistors comprises: a source region, a drain region, and a gate electrode for controlling carriers through a channel region of a transistor region of the structure between the source region and the drain region; a plurality of diodes, each one of the diodes being associated with a corresponding one of the plurality of FETs, each one of the diodes having an electrode in Schottky contact with a diode region of the corresponding one of the FETs. The gate electrode and the diode electrode extend along parallel lines. The source region, the drain region, the channel region, and a diode region having therein the diode are disposed along a common line.

The invention discloses a nonlinear feedback circuit, which includes at least one diode. The invention also discloses a low noise amplifier using the nonlinear feedback circuit. In the invention, temperature compensation is performed for the gain change of the low noise amplifier based on the negative temperature characteristics of the diode, thereby achieving gain stability. In addition, the nonlinear characteristics of the diode can also provide high-order harmonics for the low-noise amplifier, and the mutual cancellation and addition of high-order harmonics can increase the OIP3 of the low noise amplifier.