A circuit includes first and second transistors, an adaptive bias current source circuit, and an adaptive resistance circuit. The first transistor has a control terminal and first and second current terminals. The control terminal of the first transistor being a first input to the circuit. The second transistor has a control terminal and first and second current terminals, and the control terminal of the second transistor is a second input to the circuit. The first and second inputs are differential inputs to the circuit. The adaptive bias current source circuit is coupled to the second current terminal of the first transistor. The adaptive resistance circuit is coupled between the second current terminal of the second transistor and the adaptive bias current source circuit.

A Low Dropout Regulator (LDO) with Less Quiescent Current in the Dropout Region is described, including an error amplifier configured to compare a reference voltage to an LDO output voltage across a resistive divider, a current mirror configured to mirror a first output of the error amplifier to a first and second output of the current mirror, and a comparator configured to compare the LDO output voltage to a second output of the error amplifier, which has been compared to the second output of the current mirror, and configured to output a control voltage to the error amplifier, where a low quiescent current is maintained when an LDO input voltage is near or less than the LDO output voltage.

A circuit for increasing an output direct-current level of a transimpedance amplification stage in a TIA (Trans-Impedance Amplifier) includes a transimpedance amplification stage, a differential amplification stage, a level boosting unit, and a DC-restore loop. An input terminal of the transimpedance amplification stage is used for inputting a photocurrent signal. An output terminal of the transimpedance amplification stage is directly connected to an input terminal of the differential amplification stage.

The present technology relates to a comparator that can easily modify operating point potential of the comparator, and an imaging device. A pixel signal output from a pixel, and, a reference signal with changeable voltage are input to a differential pair. A current mirror connected to the differential pair, and a voltage drop mechanism allowed to cause a predetermined voltage drop is connected between a transistor that configures the differential pair, and a transistor that configures the current mirror. A switch is connected in parallel to the voltage drop mechanism. The present technology can be applied, for example, to an image sensor that captures an image.

In described examples, an amplifier can be arranged to generate a first stage output signal in response to an input signal. The input signal can be coupled to control a first current coupled from a first current source through a common node to generate the first stage output signal. A replica circuit can be arranged to generate a replica load signal in response to the input signal and in response to current received from the common node. A current switch can be arranged to selectively couple a second current from a second current source to the common node in response to the replica load signal.

An amplifier with an input stage comprising: a first current mirror; a first input differential pair; a first current source; a second current source; a second input differential pair, wherein the first input differential pair and the second input differential pair receive a reference voltage; a second current mirror; and a voltage control transmission circuit. An extra current path in the first current mirror is formed and a current flowing through the extra current path flows through the second current mirror to a ground when the reference voltage is higher than a first predetermined value. Also, an extra current path in the second current mirror is formed and a current flowing through the extra current path in the second current mirror flows to the first current mirror when the reference voltage is lower than a second predetermined value.

A differential amplifier circuit includes a first transistor, a second transistor, a field effect transistor (FET) connected between the first transistor and the second transistor, a first current source connected to the first transistor, a second current source connected to the second transistor, and a control circuit. The first transistor and the second transistor generate a differential output signal in accordance with an input signal and a reference signal. The control circuit includes a first resistor and a second resistor connected in series between the drain and the source of the FET, a center node between the first resistor and the second resistor, a third resistor connected between the gate of the FET and the center node, and a variable current source. The variable current source supplies a control current to the third resistor in accordance with a gain control signal. The control circuit controls on-resistance of the FET.

A MOSFET has a current conduction path between source and drain terminals. A gate terminal of the MOSFET receives an input signal to facilitate current conduction in the current conduction path as a result of a gate-to-source voltage reaching a threshold voltage. A body terminal of the MOSFET is coupled to body voltage control circuitry that is sensitive to the voltage at the gate terminal of the MOSFET. The body voltage control circuitry responds to a reduction in the voltage at the gate terminal of the MOSFET by increasing the body voltage of the MOSFET at the body terminal of the MOSFET. As a result, there is reduction in the threshold voltage. The circuit configuration is applicable to amplifier circuits, comparator circuits and current mirror circuits.

A variable current trans-impedance amplifier (TIA) for an ultrasound device is described. The TIA may be coupled to an ultrasonic transducer to amplify an output signal of the ultrasonic transducer representing an ultrasound signal received by the ultrasonic transducer. During acquisition of the ultrasound signal by the ultrasonic transducer, one or more current sources in the TIA may be varied.

A MOSFET has a current conduction path between source and drain terminals. A gate terminal of the MOSFET receives an input signal to facilitate current conduction in the current conduction path as a result of a gate-to-source voltage reaching a threshold voltage. A body terminal of the MOSFET is coupled to body voltage control circuitry that is sensitive to the voltage at the gate terminal of the MOSFET. The body voltage control circuitry responds to a reduction in the voltage at the gate terminal of the MOSFET by increasing the body voltage of the MOSFET at the body terminal of the MOSFET. As a result, there is reduction in the threshold voltage. The circuit configuration is applicable to amplifier circuits, comparator circuits and current mirror circuits.