In one implementation, a circuit can include a reference pin and an operational amplifier that can include an output pin, an inverting input pin and a non-inverting input pin. The inverting input pin can be electrically coupled to the output pin via a first impedance and to the reference pin via a second impedance. The non-inverting input pin can be electrically coupled to the reference pin via a third impedance and can be configured to receive a detection signal. The reference pin can be configured to receive a detection reference signal associated with the detection signal.

Methods and apparatus for providing adaptive biasing to power amplifiers. Adaptive bias circuits are configured to provide sharp turn on and/or current clamping to improve the efficiency of a power amplifier over a wide input signal bandwidth. Sharp turn on may be achieved using a subtraction technique to subtract outputs from multiple detectors. Clamping may be achieved using MOSFET device characteristics to pull the device from the triode region into the saturation, subtraction techniques to subtract the outputs from multiple detectors, and/or by using circuit devices, such as diodes.

A front-end amplifier circuit for receiving a biological signal includes a signal channel. The signal channel amplifies the biological signal to generate a detection current and includes a capacitive-coupled transconductance amplifier. The capacitive-coupled transconductance amplifier amplifies the biological signal with a transconductance gain to generate a first current.

Methods and systems for vector combining power amplification are disclosed herein. In one embodiment, a plurality of signals are individually amplified, then summed to form a desired time-varying complex envelope signal. Phase and/or frequency characteristics of one or more of the signals are controlled to provide the desired phase, frequency, and/or amplitude characteristics of the desired time-varying complex envelope signal. In another embodiment, a time-varying complex envelope signal is decomposed into a plurality of constant envelope constituent signals. The constituent signals are amplified equally or substantially equally, and then summed to construct an amplified version of the original time-varying envelope signal. Embodiments also perform frequency up-conversion.

Provided is a current generation circuit including a first terminal to be connected to a first external circuit; a second terminal to be connected to a second external circuit; a first resistor in which a potential is generated by the first external circuit connected through the first terminal; a second resistor in which a potential is generated by the second external circuit connected through the second terminal; a first amplifier circuit including a first positive input terminal to which the potential generated in the first resistor is supplied, and a first negative input terminal to which the potential generated in the second resistor is supplied; and a first MOS transistor having a gate connected to an output terminal of the first amplifier circuit, a source connected to the first negative input terminal, and a drain connected to a first differential current terminal.

A data output device is provided. The data output device includes a converter circuit configured to generate a conversion signal based on an output signal; a boosting circuit configured to generate a boosting signal based on the output signal; and an output circuit configured to generate the output signal based on an input signal and a feedback signal, the feedback signal being based on the conversion signal and the boosting signal.

An industrial control I/O module for interfacing with industrial control equipment, such as sensors and actuators, can be configured to dynamically provide differing resistances in each channel as may be required for reliably achieving particular modes of operation in the channel. Providing differing resistances in such channels flexibly allows different modes in the channel to provide universal I/O capability. Modes of operation could include, for example, digital output, digital input, analog output, analog input and the like, in the same channel, but at different times. In one aspect, a processor or voltage divider can be used to control an amplifier, with feedback, driving a transistor in a channel to dynamically adjust resistance in the channel by selectively biasing the transistor to achieve a resistance in the channel suitable for the selected mode.

A differential amplifier circuit includes a first and second amplifiers that output a differential signal in a radio-frequency band, a first inductor having a first end connected to an output end of the first amplifier, a second inductor having a first end connected to an output end of the second amplifier, a choke inductor connected to second ends of the first and second inductors, a first and second capacitors, and a switch that connects the second capacitor in parallel to the first capacitor or terminates a parallel connection of the first and second capacitors. A resonant circuit formed by connecting the first or second inductor in series with the first capacitor has a different resonant frequency from a resonant circuit formed by connecting the first or second inductor in series with the parallel-connected first and second capacitors. These resonant frequencies correspond to second harmonic frequencies of the differential signal.

Low-noise optical differential receivers are described. Such differential receivers may include a differential amplifier having first and second inputs and first and second outputs, and four photodetectors. A first and a second of such photodetectors are coupled to the first input of the differential amplifier, and a third and a fourth of such photodetectors are coupled to the second input of the differential amplifier. The anode of the first photodetector and the cathode of the second photodetector are coupled to the first input of the differential amplifier. The cathode of the third photodetector and the anode of the fourth photodetector are coupled to the second input of the differential amplifier. The optical receiver may involve two stages of signal subtraction, which may significantly increase noise immunity.

Techniques for improving current sensing via a shunt resistance are provided. In an example, an apparatus for sensing current can include a substrate, and a plurality of metal layers stacked on the substrate and separated from the substrate and from each other by an insulation material. In certain examples, a first one or more metal layers can form a sense resistance configured to pass current between a source and a load, and a second one or more metal layers can form one or more gain resistances coupled to the sense resistance and configured to couple to a current sense amplifier. In some example, a metal layer can include portions of both the sense resistance and the gain resistance to compensate for environmental anomalies, material anomalies or manufacturing anomalies.