A touchscreen controller includes a set of transmitters for generating transmit signals applied to electrically-conductive transmit lines of a touchscreen panel, and a set of receivers configured to receive the signals via electrically-conductive receive lines that are capacitively coupled to the transmit lines. Each receiver includes an integrator to integrate the received current signal to generate an output voltage used for determining a location, if any, of a finger or object touching the panel. The integrator includes input and output amplification stages, and a feedback capacitor coupled between an input and output of the cascaded amplification stages. The capacitance of the feedback capacitor is configured so that the integrator achieves a desired rejection of a received jammer current signal. To reduce the size of the feedback capacitor, a bypass amplification stage is provided to steer away some of the input jammer current from the input of the integrator.

A differential power amplifier having first and second amplifiers with first and second signal output terminals along with bias circuitry in communication with the first and second amplifiers is disclosed. The differential amplifier further includes a first output clamp coupled to the first signal output terminal and a bias control terminal of the bias circuitry, wherein the first output clamp is configured to limit voltage at the first signal output terminal to a first predetermined voltage magnitude and lower bias current to the first amplifier in response to an overvoltage at the first signal output terminal. A second output clamp is coupled to the second signal output terminal and is configured to limit voltage at the second signal output terminal to a second predetermined voltage magnitude.

In some embodiments, a filtering technique can include a pre-amplifier filter configured to filter a signal, and an amplifier assembly configured to amplify the filtered signal. The filtering technique can further include a filter circuit configured to provide selective filtering of the amplified signal based at least in part on a rejection level of the pre-amplifier filter and a gain of the amplifier assembly.

In a general aspect, a system can include a fully differential amplifier circuit that includes a first amplifier, and first and second feedback paths. The first feedback path can provide a feedback path from a positive output of the first amplifier to a negative input of the first amplifier. The second feedback path can provide a feedback path from a negative output of the first amplifier to a positive input of the first amplifier. The system can include a chopper clock circuit configured to output a variable duty cycle chopper clock signal. The system can include a common mode loop circuit including a second amplifier and chopper switches. The common mode loop circuit can be configured as a local feedback loop for the first amplifier. The chopper switches can be configured to receive the chopper clock signal and control current flow into the positive and negative inputs.

A power amplifier includes a signal input unit to which an input signal is applied, an output stage that is electrically isolated from the signal input unit, where the output stage is configured to amplify an output signal of the signal input unit based on a power supply voltage from a floating power supply, a reference potential switch that is inserted between a reference node of the power supply voltage generated by the floating power supply and a reference potential line, and a feedback circuit configured to amplify a differential voltage between an output node of the output stage and the reference node, and feed the resultant voltage back to the signal input unit.

In one form, a signal generator system such as a power amplifier system includes an amplification stage, a lowpass filter, and a controller. The amplification stage includes a first amplifier having an input for receiving an input signal, a control input for receiving a first control signal, and an output. The lowpass filter has a first input coupled to the output of the first amplifier, and an output. The controller has a first input coupled to the output of the lowpass filter, and a first output coupled to the control input of the first amplifier, wherein the controller varies the first control signal to reduce a difference between the output of the lowpass filter and a first target voltage level.

Systems and methods are provided for amplifying multiple input signals to generate multiple output signals. An example system includes a first channel, a second channel, and a third channel. The first channel is configured to receive one or more first input signals, process information associated with the one or more first input signals and a first ramp signal, and generate one or more first output signals. The second channel is configured to receive one or more second input signals, process information associated with the one or more second input signals and a second ramp signal, and generate one or more second output signals. The first ramp signal corresponds to a first phase. The second ramp signal corresponds to a second phase. The first phase and the second phase are different.

Power amplifiers having reduced loss. In some embodiments, a power amplification system can include a plurality of power amplifiers, with each power amplifier being configured to receive and amplify a signal in a frequency band. The power amplification system can further include an output filter coupled to each of the power amplifiers by a separate output path such that the power amplification system is substantially free of a band selection switch between the plurality of power amplifiers and their corresponding output filters. Each power amplifier can be further configured to operate with a high-voltage supply to provide an impedance similar to an impedance of the corresponding output filter.

The present disclosure provides a gradient amplifier driver stage circuit, a gradient amplifier system and a control method thereof. The gradient amplifier driver stage circuit includes: a gradient coil and a plurality of gradient driver modules electrically cascaded with each other and forming an output end, the output end being electrically connected to the gradient coil, wherein each gradient driver module includes a pre-stage power supply and a bridge amplifier connected in parallel, output voltage of the pre-stage power supplies of the plurality of gradient driver modules are the same, and each gradient driver module is configured to provide an inductive voltage drop and a resistive voltage drop on the gradient coil.

One example includes a device that is comprised of a pre-power amplifier, a power amplifier, a signal path, and a dynamic bias circuit. The pre-power amplifier amplifies an input signal and outputs a first amplified signal. The power amplifier receives the first amplified signal and amplifies the first amplified signal based on a dynamic bias signal to produce a second amplified signal at an output thereof. The signal path is coupled between an output of the pre-power amplifier and an input of the power amplifier. The dynamic bias circuit monitors the first amplified signal, generates the dynamic bias signal, and outputs the dynamic bias into the signal path.