An amplifier includes an input transistor pair connected to amplifier input nodes, a complementary transistor pair connected to a common bias, amplifier output nodes connected to the input transistor pair and the complementary transistor pair, and variable capacitors connected between the complementary transistor pair and the amplifier output nodes.

A tunable filter is described where the frequency response as well as bandwidth and transmission loss characteristics can be dynamically altered, providing improved performance for transceiver front-end tuning applications. The rate of roll-off of the frequency response can be adjusted to improve performance when used in duplexer applications. The tunable filter topology is applicable for both transmit and receive circuits. A method is described where the filter characteristics are adjusted to account for and compensate for the frequency response of the antenna used in a communication system.

An amplifier system with high gain, compact size, and extended bandwidth is disclosed. The amplifier system includes one or more inputs configured to receive one or more input signals and a pre-driver configured to receive the one or more input signals. The pre-driver may comprise source connected FETs which create a virtual ground and may include inductors which cancel or counter parasitic capacitance of the FETs. The pre-driver amplifies the one or more input signals to create one or more pre-amplified signals, which are provided to a voltage divider network configured to reduce a DC bias voltage of the one or more pre-amplified signals, while maintaining a wide bandwidth range. An amplifier receives and amplifies the output of the voltage divider network to create amplified signals. The amplifier may comprise mirrored FET pairs in a common source configuration and a common gate arrangement.

An image sensor and electronic apparatus comprise a pixel circuit configured to generate an analog signal; a vertical signal line configured to convey the analog signal from the pixel circuit; an analog amplifier circuit configured to receive the analog signal via the vertical signal line and generate an amplified signal; and a tail current boost circuit configured to modify an instantaneous gain bandwidth product of the analog amplifier circuit by temporarily modifying a tail current of the analog amplifier circuit.

Sampling circuits and methods for sampling are provided. In a first operating phase, sampling capacitors are coupled to inputs, and in a second operating phase, to a common-mode signal.

Techniques for shielding wearable surface electromyography (sEMG) devices are described. According to some aspects, an sEMG device may comprise amplification circuitry comprising at least a first differential amplifier and at least two sEMG electrodes electrically connected to the amplification circuitry. The device may further comprise at least one auxiliary conductor not electrically connected to the amplification circuitry, wherein the at least one auxiliary conductor is configured to be electrically coupled to a wearer of the wearable device, and an electromagnetic shield surrounding the wearable device at least in part and electrically connected to the at least one auxiliary conductor.

An amplifier includes: a first input transistor connected to a first input, a first output, and a power source or a ground, a second input transistor connected to a second input, a second output, and the power source or the ground; a first replica transistor connected to the first input, a detection node, and the power source or the ground; a second replica transistor connected to the second input, the detection node, and the power source or the ground; and a bias transistor connected to a bias voltage, the detection node, and the power source or the ground.

The present invention provides a circuit having a filter with an amplifier circuit for filtering and amplifying an input signal to generate an output signal, wherein a corner frequency of the filter is adjustable to control a settling time of the output signal.

Techniques for monitoring a distortion signal of a power amplifier circuit, where the output of a distortion monitoring circuit includes little or no fundamental signal and closely represents the actual distortion of the amplifier circuit of a wired communications system. The power amplifier circuit can generate a distortion feedback signal that does not affect the power amplifier's output power capability, e.g., no inherent loss in the fundamental output of the amplifier. That is, using a distortion monitor circuit, the power amplifier circuit can resolve a distortion feedback signal from the intended output signal of the output power amplifier circuit.

An operational amplifier includes a single-stage amplifier and a current controller. The single-stage amplifier receives an input signal, and amplifies the input signal to generate an output signal, wherein the single-stage amplifier includes a voltage controlled current source circuit that operates in response to a bias voltage input. The current controller receives the input signal, and generates the bias voltage input according to the input signal.