Described examples include multistage amplifier circuits having first and second forward circuits, a comparator or sensor circuit coupled to sense a signal in the second forward circuit to identify nonlinear operation or slewing conditions in the multistage amplifier circuit, and one or more sample hold circuits operative according to a sensor circuit output signal to selectively maintain the amplitude of an amplifier input signal in the second forward circuit and/or in a feedback circuit in response to the sensor circuit output signal indicating nonlinear operation or slewing conditions in the multistage amplifier circuit. Certain examples further include a clamping circuit operative to selectively maintain a voltage at a terminal of a Miller compensation capacitance responsive to the comparator output signal indicating nonlinear operation or slewing conditions.

A Programmable-Gain Amplifier (PGA) has programming steps that are linear when expressed in Decibels (linear-in-dB). A Recursive Current Division (RCD) resistor network generates currents that are selected by programmable switches to connect to a summing node input of an amplifier. A feedback resistor is connected across the summing node and the amplifier output. The resistor network has only three resistance values regardless of the number of currents selectable as programming steps. The value of a third resistor is set equal to the equivalent resistance of a second resistor in parallel with a series connection of a first resistor and the third resistors. Each final cell in the resistor network is equivalent to the third resistor, allowing recursive division of adjacent currents. The ratio of adjacent currents remains constant for all cells. Recursive Current Division (RCD) produces linear-in-dB programming steps. Floating switches are avoided since switches connect to ground.

A semiconductor integrated circuit includes a first pad provided on one end side of a first resistive element and one end side of a second resistive element externally provided, a second pad provided on a different end side of the first resistive element, a third pad provided on a different end side of the second resistive element and one end side of a third resistive element externally provided, an operation amplifier, a first signal line, wired between an output terminal of the operation amplifier and the first pad, a second signal line wired between an inverting input terminal of the operation amplifier and the second pad, a third signal line wired between the inverting input terminal of the operational amplifier and the third pad, a first ESD protection element, provided to the first signal line, a fourth signal line, through which a voltage signal of the first pad.

An amplifier circuit can include an amplifier and a resistor network coupled to the amplifier. The resistor network can include a range resistor coupled in parallel to a resistor string, and one or more switches coupled to the resistor string. The resistor network can be used to calibrate gain and common mode rejection ratio (CMRR) of the amplifier circuit.

A Programmable-Gain Amplifier (PGA) has programming steps that are linear when expressed in Decibels (linear-in-dB). A Recursive Current Division (RCD) resistor network generates currents that are selected by programmable switches to connect to a summing node input of an amplifier. A feedback resistor is connected across the summing node and the amplifier output. The resistor network has only three resistance values regardless of the number of currents selectable as programming steps. The value of a third resistor is set equal to the equivalent resistance of a second resistor in parallel with a series connection of a first resistor and the third resistors. Each final cell in the resistor network is equivalent to the third resistor, allowing recursive division of adjacent currents. The ratio of adjacent currents remains constant for all cells. Recursive Current Division (RCD) produces linear-in-dB programming steps. Floating switches are avoided since switches connect to ground.

An integrated circuit amplifier configurable to be either a programmable gain amplifier or an operational amplifier comprises two output blocks, one output block is optimized for programmable gain amplifier operation, and the other output block is optimized for operational amplifier applications. A common single input stage, input offset calibration and bias generation circuits are used with either amplifier configuration. Thus duplication of the input stage, offset calibration and bias generation circuits are eliminated while still selectably providing for either a programmable gain amplifier or operational amplifier configuration.

The present disclosure provides an integrating circuit and a signal processing module. The integrating circuit comprises an operational amplifier; an integrating capacitor, coupled to an output terminal and a first input terminal of the operational amplifier; and an adjustable resistance module, coupled between the first input terminal of the operational amplifier and an integrating input terminal of the integrating circuit. The adjustable resistance module receives a plurality of first control signals, to adjust a resistance value of the adjustable resistance module. The present disclosure may realize the noise brought by sidelobe to enhance the SNR, and reduce the power consumption and complexity of the overall circuit.

Some embodiments include apparatus and methods using an integrator in a loop filter of a sigma-delta analog-to-digital converter (ADC), a digital-to-analog converter (DAC) located on a feedback path of the ADC, the DAC including output nodes coupled to input nodes of the integrator, and a comparator including input nodes to receive signals from output nodes of the integrator, and an output node to provide information during calibration of the DAC.

A switched-capacitor circuit comprising a differential operational amplifier and a feedback circuit is described. In some embodiments, the feedback circuit may be configured to provide a reference voltage that is insensitive to temperature and/or process variations. In some embodiments, the feedback circuit may be configured to mitigate the time delay associated with one or more capacitors of the switched-capacitor circuit. The switched-capacitor circuit may be controlled by a pair of control signals. During a first phase, one or more capacitors may be charged, or discharged, through an input signal. During a second phase, the electric charge of the one or more capacitors may be retained.

Described examples include multistage amplifier circuits having first and second forward circuits, a comparator or sensor circuit coupled to sense a signal in the second forward circuit to identify nonlinear operation or slewing conditions in the multistage amplifier circuit, and one or more sample hold circuits operative according to a sensor circuit output signal to selectively maintain the amplitude of an amplifier input signal in the second forward circuit and/or in a feedback circuit in response to the sensor circuit output signal indicating nonlinear operation or slewing conditions in the multistage amplifier circuit. Certain examples further include a clamping circuit operative to selectively maintain a voltage at a terminal of a Miller compensation capacitance responsive to the comparator output signal indicating nonlinear operation or slewing conditions.