An amplifying device includes a main amplifier; a first feedback circuit coupled between an input terminal of the main amplifier and an output terminal of the main amplifier; an input coupling circuit coupled between the input terminal of the main amplifier and a first node; and an amplifying feedback circuit coupled between the output terminal of the main amplifier and the first node, wherein the first feedback circuit and the amplifying feedback circuit are negative feedback circuits.

The present disclosure relates to chopper amplifier circuits with inherent chopper ripple suppression. Example implementations can realize a doubly utilized chopper amplifier circuit that is a current-saving circuit with a wake-up function that is capable of providing a self-wake signal in order to change into a fast, low-jitter/low-latency mode, and to provide a wake-up signal for a sleeping microprocessor or a system in response to signal changes.

The present disclosure relates to chopper amplifier circuits with inherent chopper ripple suppression. Example implementations can realize a doubly utilized chopper amplifier circuit that is a current-saving circuit with a wake-up function that is capable of providing a self-wake signal in order to change into a fast, low-jitter/low-latency mode, and to provide a wake-up signal for a sleeping microprocessor or a system in response to signal changes.

Amplifying circuitry configured such that when a detection circuit detects an abnormal state in which the level of signals input to a main amplifying circuit exceeds a normal range, a control circuit sets the state of integration of signals in the integration circuit to a default state. When the detection circuit detects the abnormal state and then detects that an operating state returns to a normal state in which the level of signals input to the main amplifying circuit is included in the normal range, the control circuit cancels the setting of the default state in the integration circuit.

A chopper amplifying circuit employing a negative impedance compensation technique, including a differential input end, a first-level chopper switch, a first-level amplifying circuit, a second-level chopper switch, a second-level amplifying circuit, a negative impedance converting circuit, a negative feedback unit, an input capacitor, and a differential output end, is provided. The differential input end is connected to the first-level chopper switch. An output terminal of the first-level chopper switch is connected to the first-level amplifying circuit through the input capacitor. The first-level amplifying circuit is connected to the second-level chopper switch, which is connected to the second-level amplifying circuit. The second-level amplifying circuit is connected to the differential output end, and is also connected to a feedback input end of the first-level amplifying circuit through the negative feedback unit. The negative impedance converting circuit is parallel-connected to a signal input end of the first-level amplifying circuit.

A high CMRR current monitoring circuit includes a first stage that receives a current sense signal, a voltage across a current sense resistor in series with an output of a class-D amplifier. First stage is powered by at least one floating supply and/or reference that tracks the amplifier output. First stage applies gain to the current sense signal to generate an intermediate signal. A second stage receives the intermediate signal and is powered by a ground-referenced supply and provides an amplified representation of the current sense signal. The floating supply is supplied by a capacitive-coupled power source driven by the ground-referenced supply. The second stage output may be a voltage relative to ground or a digital signal. The intermediate signal may be a current, digital signal, or amplified version of the current sense signal voltage. The first stage may be a transconductance amplifier and the second stage a transimpedance amplifier.

A high CMRR current monitoring circuit includes a first stage that receives a current sense signal, a voltage across a current sense resistor in series with an output of a class-D amplifier. First stage is powered by at least one floating supply and/or reference that tracks the amplifier output. First stage applies gain to the current sense signal to generate an intermediate signal. A second stage receives the intermediate signal and is powered by a ground-referenced supply and provides an amplified representation of the current sense signal. The floating supply is supplied by a capacitive-coupled power source driven by the ground-referenced supply. The second stage output may be a voltage relative to ground or a digital signal. The intermediate signal may be a current, digital signal, or amplified version of the current sense signal voltage. The first stage may be a transconductance amplifier and the second stage a transimpedance amplifier.

A differential operational transconductance amplifier, or DOTA, intended to be used in zero-drift precision operational amplifiers as chopper amplifier stage is disclosed. The DOTA is configured to function with a low-voltage power supply and to have good performance based on circuitry configured to provide a constant gain over a range of common-mode voltages, or VCM. The DOTA further includes bias circuitry configured to respond to the common mode voltage in order to prevent large currents, which can result from the constant gain circuitry, from negatively affecting performance. The DOTA further includes current sources that are configured to prevent temperature variations from negatively affecting performance. The DOTA further includes VCM-driven bias voltages used to optimize the operating point of the differential output stage. The DOTA uses input and input replica transistors having medium threshold voltage, which results in capability to operate at low supply voltages.

A differential operational transconductance amplifier, or DOTA, intended to be used in zero-drift precision operational amplifiers as chopper amplifier stage is disclosed. The DOTA is configured to function with a low-voltage power supply and to have good performance based on circuitry configured to provide a constant gain over a range of common-mode voltages, or VCM. The DOTA further includes bias circuitry configured to respond to the common mode voltage in order to prevent large currents, which can result from the constant gain circuitry, from negatively affecting performance. The DOTA further includes current sources that are configured to prevent temperature variations from negatively affecting performance. The DOTA further includes VCM-driven bias voltages used to optimize the operating point of the differential output stage. The DOTA uses input and input replica transistors having medium threshold voltage, which results in capability to operate at low supply voltages.

A thermally-isolated-metal-oxide-semiconducting (TMOS) sensor has inputs coupled to first and second nodes to receive first and second bias currents, and an output coupled to a third node. A tail has a first conduction terminal coupled to the third node and a second conduction terminal coupled to a reference voltage. A control circuit applies a control signal to a control terminal of the tail transistor based upon voltages at the first and second nodes so that a common mode voltage at the first and second nodes is equal to a reference common mode voltage. A differential current integrator has a first input terminal coupled to the second node and a second input terminal coupled to the first node, and provides an output voltage indicative of an integral of a difference between a first output current at the first input terminal and a second output current at the second input terminal.