Disclosed herein are transconductance circuits, as well as related methods and devices. In some embodiments, a transconductance circuit may include an amplifier having a first input coupled to a voltage input of the transconductance circuit, and a switch coupled between an output of the amplifier and a second input of the amplifier.

In an embodiment an amplifier includes a first MOS transistor having a drain connected to an output of the amplifier and a source coupled to a first node configured to receive a first power supply potential, a first capacitive element connected between an input of the amplifier and a gate of the first MOS transistor, a first current source connecting the drain of the first MOS transistor to a second node configured to receive a second power supply potential and a resistive element and a second capacitive element connected in parallel between the gate and the drain of the first MOS transistor, the resistive element including a switched capacitor.

Methods and devices used in mobile receiver front end to support multiple paths and multiple frequency bands are described. The presented devices and methods provide benefits of scalability, frequency band agility, as well as size reduction by using one low noise amplifier per simultaneous outputs. Based on the disclosed teachings, variable gain amplification of multiband signals is also presented.

The present invention provides an amplifier circuit, wherein the amplifier circuit includes an input terminal, a capacitor, an amplifier, a feedback circuit and an aliasing tone cancellation circuit. The input terminal is configured to receive a first input signal. The capacitor is coupled to the input terminal. The amplifier is configured to receive the input signal through the capacitor to generate an output signal. The feedback circuit is coupled between an input node and an output node of the amplifier, and is configured to generate a feedback signal according to the output signal, wherein the feedback circuit includes a storage block including a switched-capacitor. The aliasing tone cancellation circuit is coupled between the input terminal of the amplifier circuit and the input node of the amplifier, and configured to generate a signal to cancel or reduce an aliasing tone of the feedback signal according to the input signal.

The invention relates to an electrical circuit in the form of a transimpedance amplifier stage, and to a method for operating this circuit. The invention furthermore relates to a circuit containing at least one signal amplifier that has at least one output connection, at least one input connection or at least one pair of differential input connections and at least two voltage supply connections, one of which may also be an earth or ground connection, wherein the signal amplifier has at least one additional connection that is connected internally to at least one of the input connections or the input connection via at least one further component, for example a diode.

The present disclosure provides for process and temperature compensation in a transimpedance amplifier (TIA) using a dual replica via monitoring an output of a first TIA (transimpedance amplifier) and a second TIA; configuring a first gain level of the first TIA based on a feedback resistance and a reference current applied at an input to the first TIA; configuring a second gain level of the second TIA and a third TIA based on a control voltage; and amplifying a received electrical current to generate an output voltage using the third TIA according to the second gain level. In some embodiments, one or both of the second TIA and the third TIA include a configurable feedback impedance used in compensating for changes in the second gain level due to a temperature of the respective second or third TIA via the configurable feedback impedance of the respective second or third TIA.

A negative impedance circuit includes: a differential circuit stage; a positive feedback path from an output of the differential circuit stage to a first input of the differential circuit stage; and a negative feedback path from the output of the differential circuit stage to a second input of the differential circuit stage. The negative feedback path includes a first transistor, and a unitary gain path from the output of the differential circuit stage to the second input of the differential circuit stage, the unitary gain path coupled to ground via a reference impedance. The positive feedback path includes a second transistor. The first and second transistors are coupled in a current mirror arrangement and have respective control electrodes configured to be driven by the output of the differential circuit stage, where the negative impedance circuit causes a negative impedance at the first input of the differential circuit stage.

Circuits and methods for improving the noise figure (NF) of an amplifier, particularly an LNA, in high-gain modes while improving the IIP3 of the amplifier in low-gain modes. The source of an amplifier common-source FET is coupled to circuit ground thorough a degeneration circuit comprising a two-port inductor and a bypass switch coupled in parallel with the inductor. A switched feedback circuit is coupled between the gate of the common-source FET and a feedback node in the amplifier output signal path. During a low gain mode, the inductor is entirely bypassed and the enabled feedback circuit lowers the input impedance of the common-source FET and reduces the gain of the amplifier circuit, essentially eliminating the need for a degeneration inductor. During a high gain mode, the source of the common-source FET is coupled to circuit ground through the inductor and the feedback circuit is disabled. Other gain modes are supported.

The present invention discloses an audio processing circuit, wherein when the audio processing circuit determines that a signal being processed is a small signal, an output stage uses a regulated supply voltage provided by a voltage regulator, and the output stage uses an open-loop structure to reduce noise of an output audio signal; and when the audio processing circuit determines that the signal being processed is a large signal, the output stage directly uses the supply voltage without using the regulated supply voltage, and the output stage uses a closed-loop structure to reduce the total harmonic distortion of the output audio signal. By using the present invention, the audio processing circuit can have a good performance indicator with a small chip area design.

A circuit device includes an analog front-end circuit that receives a target signal is input, and a processing circuit that performs arithmetic processing based on an output signal from the analog front-end circuit. The analog front-end circuit includes a plurality of comparator circuits that compare the voltage level of the target signal to a plurality of threshold voltages and output a plurality of comparison result signals. The processing circuit obtains the transition timing of the target signal based on the comparison result signals and delayed-time information of the analog front-end circuit.