A dynamically stabilizable amplifier drives an output current into an RLC load. A driver stage generates the output current, and a control circuit compares a current level of the amplifier output with a threshold and selectively enables a stabilizing resistor (to selectively shunt the load or dampen in series with the load, depending on RLC load type) at the driver stage output based on the comparison so that the amplifier is stable across a range of the output current level. The control circuit disables the resistor when the output current is above the highest threshold and enables it when below. The control circuit may control the resistor to have one of multiple resistance values based on a comparison with multiple thresholds. The output current level may be determined by replicating the output current level or by an input current level that sets the output current level independent of the load.

A method for generating digital, high resolution pulse width modulation (PWM) signals and a digital feedback correction method suited to the method of generation of the digital, high resolution PWM signals intended for using in feed forward systems, feedback systems and combined feed forward system and feedback system are provided.

A radio-frequency (RF) amplifier having a direct response to an arbitrary signal source to output one or more electrosurgical waveforms within an energy activation request, is disclosed. The RF amplifier includes a phase compensator coupled to an RF arbitrary source, the phase compensator configured to generate a reference signal as a function of an arbitrary RF signal from the RF arbitrary source and a phase control signal; at least one error correction amplifier coupled to the phase compensator, the at least one error correction amplifier configured to output a control signal at least as a function of the reference signal; and at least one power component coupled to the at least one error correction amplifier and to a high voltage power source configured to supply high voltage direct current thereto, the at least one power component configured to operate in response to the control signal to generate at least one component of the at least one electrosurgical waveform.

This application relates to circuitry for monitoring for instability of an amplifier. The amplifier (100) has a first signal path between an amplifier input (IN.sub.N) and an amplifier output (V.sub.OUT) and a feedback path from the output to form a feedback loop with at least part of the first signal path. A comparator (212) has a first input configured to receive a first signal (IN.sub.N) derived from a first amplifier node which is part of said feedback loop and a second input configured to receive a second signal (IN.sub.P) derived from a second amplifier node which varies with the signal at the amplifier input but does not form part of said feedback loop. The comparator is configured to compare the first signal to the second signal and generate a comparison signal (COMP), wherein in the event of amplifier instability the comparison signal comprises a characteristic indicative of amplifier instability.

This application relates to circuitry for monitoring for instability of an amplifier. The amplifier (100) has a first signal path between an amplifier input (IN.sub.N) and an amplifier output (V.sub.OUT) and a feedback path from the output to form a feedback loop with at least part of the first signal path. A comparator (212) has a first input configured to receive a first signal (IN.sub.N) derived from a first amplifier node which is part of said feedback loop and a second input configured to receive a second signal (IN.sub.P) derived from a second amplifier node which varies with the signal at the amplifier input but does not form part of said feedback loop. The comparator is configured to compare the first signal to the second signal and generate a comparison signal (COMP), wherein in the event of amplifier instability the comparison signal comprises a characteristic indicative of amplifier instability.

Aspects disclosed herein eliminate audible disturbances that may occur when an audio amplifier is activated and deactivated. A feedback circuit is used to maintain a closed loop when transistors of a power output stage are activate or deactivated, thereby enabling the charge to build or dissipate without causing an audible disturbance. Further, in certain implementations, the power output stage may remain in an enable state for a period of time after deactivation of the audio amplifier regardless of whether an audio input signal is received enabling dissipation of charge without causing an audible disturbance.

An envelope tracking (ET) radio frequency (RF) front-end circuit receives a single tracking signal (e.g., Vramp) from a baseband transceiver and generates a plurality of control signals (Vcc). The control signals are created by a multiple control signal generator circuit based on a calculated load estimate for each relevant power amplifier. The load estimate may be calculated from a sensed current and voltage. By providing control signals optimized for loads presented to the power amplifiers, the overall efficiency of the transmitter is improved.

This application relates to circuitry for monitoring for instability of an amplifier. The amplifier (100) has a first signal path between an amplifier input (IN.sub.N) and an amplifier output (V.sub.OUT) and a feedback path from the output to form a feedback loop with at least part of the first signal path. A comparator (212) has a first input configured to receive a first signal (IN.sub.N) derived from a first amplifier node which is part of said feedback loop and a second input configured to receive a second signal (IN.sub.P) derived from a second amplifier node which varies with the signal at the amplifier input but does not form part of said feedback loop. The comparator is configured to compare the first signal to the second signal and generate a comparison signal (COMP), wherein in the event of amplifier instability the comparison signal comprises a characteristic indicative of amplifier instability.

A signal processor and method. The signal processor includes a signal current path. The signal processor includes a transconductor. The transconductor has an input operable to receive an input voltage of the signal processor. The transconductor also has an output operable to output a current based on the input voltage. The signal processor also includes a processing stage coupled to the output of the transconductor to receive and process the current outputted by the transconductor. The signal processor further includes a current replicator operable to generate a replica current proportional to the current outputted by the transconductor. The signal processor also includes a comparator operable to compare an output of the current replicator with a reference. The signal processor further includes a current limiter operable to limit the current outputted by the transconductor based on the comparison of the output of the current replicator with the reference.

An amplifier circuit with in-band gain degradation compensation is shown. The amplifier circuit has an input-stage amplifier, at least one intermediate-stage amplifier, and an output-stage amplifier cascaded between an input port and an output port of the amplifier circuit. A compensation capacitor is coupled between the output port of the amplifier circuit and an output port of the input-stage amplifier. A high-order damping circuit is coupled to an output port of the intermediate-stage amplifier.