An apparatus, comprising an input transformer; a first differential transistor pair configured to receive a first back gate bias voltage; a second differential transistor pair configured to receive a second back gate bias voltage; a cross-coupled neutralization cap comprising PMOS or NMOS transistors and configured to receive a third back gate bias voltage; and an output transformer. A method of fixing at least one back gate bias voltage to impart a desired capacitance to the transistors of at least one of the first differential transistor pair, the second differential transistor pair, or the neutralization cap. The apparatus and method may provide a power amplifier having improved linearity and efficiency.

An operational amplifier circuit is provided. The operational amplifier circuit includes a differential input stage circuit and a loading stage circuit. The differential input stage circuit includes an input circuit, a voltage maintaining circuit, and a current source. The input circuit includes a first input transistor and a second input transistor, for receiving a first and a second input signals, respectively. The voltage maintaining circuit includes a first branch circuit and a second branch circuit. The first branch circuit is coupled to the first input transistor for receiving the first input signal, and the second branch circuit is coupled to the second input transistor for receiving the second input signal. The current source is coupled to the first input transistor and the second input transistor. The loading stage circuit is coupled to the voltage maintaining circuit.

A differential amplifier circuit includes a differential pair including a first field-effect transistor (FET) and a second FET, a first current source that generates a current which flows in the first FET and the second FET, and an output circuit that outputs an output voltage corresponding to a difference between a gate voltage of the first FET and a gate voltage of the second FET in accordance with an operation of the differential pair. A back gate of the first FET is connected to a gate of the first FET, and a back gate of the second FET is connected to a gate of the second FET. A first feedback voltage corresponding to the output voltage is input to the gate of the second FET.

An instrumentation amplifier including a pair of input amplifiers, each including an input transistor and a feedback current amplifier configured to amplify and feedback an error current from the input transistor. The arrangement can enable a current efficient solution where the amplifier can operate with very low input signals that are close to, or potentially below ground, without requiring a negative power supply voltage.

In one example an amplifier includes a bias circuit, an open-loop gain stage including a first PMOS having a gate coupled to a first node, a source coupled to a second node, a drain coupled to a third node, and a bulk coupled to the bias circuit, a second PMOS having a gate coupled to a ground node, a source coupled to the second node, a drain coupled to a fourth node, and a bulk coupled to the bias circuit, a first NMOS having a drain and a gate coupled to the third node and a source coupled to a fifth node, a second NMOS having a drain coupled to the fourth node, a gate coupled to the third node, and a source coupled to the fifth node, an adjustable resistor coupleable between the third and fourth nodes, and a buffer stage coupled to the open-loop gain stage.

A differential circuit includes a differential pair and a back gate bias circuit. The differential circuit includes a first MOS transistor and a second MOS transistor provided between a first power supply line, to which a first power supply voltage is applied, and a second power supply line, to which a second power supply voltage is applied. The back gate bias circuit applies a bias voltage closer to the first power supply voltage than source potentials of the first MOS transistor and the second MOS transistor to back gates of the first MOS transistor and the second MOS transistor.

A novel comparison circuit, a novel amplifier circuit, a novel battery control circuit, a novel battery protection circuit, a power storage device, a semiconductor device, an electronic device, and the like are provided. The semiconductor device includes a capacitor, a first amplifier circuit including a first output terminal electrically connected to a first electrode of the capacitor, and a second amplifier circuit including an input terminal, a second output terminal, a first transistor, and a second transistor; a second electrode of the capacitor is electrically connected to the input terminal; the input terminal is electrically connected to a gate of the first transistor and one of a source and a drain of the second transistor; one of a source and a drain of the first transistor is electrically connected to the second output terminal; the second transistor has a function of supplying a potential to the input terminal and holding the potential; and a channel formation region of the second transistor includes a metal oxide containing at least one of indium and gallium.

A circuit includes a first switch assembly having a first input node and a first output node, and a second switch assembly having a second input node and a second output node. The circuit further includes a third switch assembly an operational amplifier, and a buffer. The third switch assembly has a third input node and a third output node. The third input node is coupled to the second output node, and the third output node is coupled to the first output node. The buffer has a buffer input and a buffer output. The buffer input is coupled to an input stage of the operational amplifier. The buffer output is coupled to the third switch assembly.

An apparatus includes a digital-to-analog converter (DAC) and an independently controlled biasing circuit coupled to the DAC. The DAC includes at least a first transistor and a second transistor, where the first and second transistors are configured to provide output signals for the DAC. The biasing circuit includes a third transistor having a body coupled to the third transistor source and this source is coupled to a first transistor body and to a second transistor body of the first and second transistors of the DAC. A current loop is coupled to the source and the drain of the transistor of the biasing circuit that maintains a substantially same value of current in the biasing circuit as in the DAC.

A current feed-back instrumentation amplifier (CFIA) comprises a differential pair with degeneration for amplifying small differential voltages in the presence of large common-mode voltages. The CFIA includes input and feedback transconductors and a trimming circuit that trims the back-bias voltages of the transistors in each transconductor. The trimming circuit includes a plurality of selectable resistors disposed in the signal path of the tail current in each transconductor. Each of the plurality of selectable resistors has a switch coupled to it. When a switch is closed, only the resistors up to the respective switch are in the signal path of the bulk-to-source voltage of the differentially paired transistors. The resistor trimming circuit reduces the mismatch between transconductances of the respective differential pair transistors, in turn reducing mismatch of the overall transconductances of the transconductors, and thereby reducing the CFIA's gain error.