An ion detection current conversion circuit includes a conversion amplifier coupled with a conversion resistor assembly for converting an ion detection current produced by an ion detector into an ion detection voltage, the conversion resistor assembly comprising a resistor having a high resistance and a capacitive compensation element, and a compensation voltage circuit for deriving a compensation voltage from the ion detection voltage and feeding the compensation voltage to the capacitive compensation element, the compensation voltage circuit comprising a variable resistor for adjusting the compensation voltage.

The amplifier load current cancellation in a current integrator comprises applying an input current to an operational transconductance amplifier provided with an integration capacitor for current integration, leading an output current of the operational transconductance amplifier through a sensing resistor, thus producing a voltage drop over the sensing resistor, generating a cancellation current dependent on the voltage drop over the sensing resistor, and injecting the cancellation current to the output current, before or after the output current passes the sensing resistor, thus eliminating a dependence of the output current on the input current.

Embodiments of a device and method are disclosed. In an embodiment, a current sensing circuit includes first and second integrated resistors on a semiconductor die, a controllable current source configured to provide a reference current, and a current determination circuit. A resistance value of the second integrated resistor is a factor n larger than a resistance value of the first integrated resistor. A current drawn by a target circuit is configured to flow through the first integrated resistor, and the reference current is configured to flow through the second integrated resistor. The current determination circuit is configured to determine a value of the current drawn by the target circuit based on the value of the reference current when a first voltage at a terminal of the first integrated resistor is approximately equal to a second voltage at a terminal of the second integrated resistor.

Techniques for generating a power tracking supply voltage for a circuit (e.g., a power amplifier) are disclosed. The circuit may process multiple transmit signals being sent simultaneously on multiple carriers at different frequencies. In one exemplary design, an apparatus includes a power tracker and a power supply generator. The power tracker determines a power tracking signal based on inphase (I) and quadrature (Q) components of a plurality of transmit signals being sent simultaneously. The power supply generator generates a power supply voltage based on the power tracking signal. The apparatus may further include a power amplifier (PA) that amplifies a modulated radio frequency (RF) signal based on the power supply voltage and provides an output RF signal.

A system may include a Class-D stage comprising a first high-side switch coupled between a supply voltage and a first output terminal of the Class-D stage, a second high-side switch coupled between the supply voltage and a second output terminal of the Class-D stage, a first low-side switch coupled between a ground voltage and the first output terminal, and a second low-side switch coupled between the ground voltage and the second output terminal. The system may also include current sensing circuitry comprising a sense resistor, such that an output current through a load coupled between the first output terminal and the second output terminal causes a first sense voltage proportional to the output current across the sense resistor. The system may additionally include a modulator for generating a differential pulse-width modulation driving signal to the first high-side switch, the second high-side switch, the first low-side switch, and the second low-side switch and pilot tone injection circuitry configured to inject a periodic pilot tone into the differential pulse-width modulation driving signal at a pilot tone frequency.

Herein disclosed in some embodiments is a fault detector for power amplifiers of a communication system. The fault detector can detect a portion of the power amplifiers that are in fault condition and can prevent or limit current flow to the power amplifiers in fault condition while allowing the rest of the power amplifiers to operate normally. The fault detector can further indicate which power amplifiers are in fault condition and/or the cause for the power amplifiers to be in fault condition. Based on the indication, a controller can direct communications away from the power amplifiers in fault condition and/or perform operations to correct the fault condition.

Examples provide methods and apparatus for controlling a DC bias current in an RF amplifier. In one example where the RF amplifier is implemented on an amplifier die, a reference voltage is produced across a reference resistor implemented on the amplifier die, the DC bias current is measured, and a current controller, which is implemented on a controller die that is separate from the amplifier die, operates a feedback loop using the reference voltage to control a level of the DC bias current.

A switching amplifier comprises a controller, configured to receive an input signal and a reference signal, and to generate a control signal according to the input signal and the reference signal; a pulse-width modulation (PWM) modulator, coupled to the controller, configured to generate a PWM signal according to the input signal and the control signal; a power management unit, coupled to the controller, configured to receive a power supply and the control signal, and to provide an adaptive supply voltage according to the power supply and the control signal; and a switching power stage, coupled to the power management unit and the PWM modulator, configured to generate an output signal according to the PWM signal and the adaptive supply voltage.

Circuits for protecting devices, such as gallium nitride (GaN) devices, and operating methods thereof are described. The circuits monitor a magnitude of the current in a device and reduce the magnitude of the current and/or shut down the device responsive to the magnitude of the current exceeding a threshold. These circuits safeguard devices from damaging operating conditions to prolong the operating life of the protected devices.

An ion detection current conversion circuit includes a conversion amplifier coupled with a conversion resistor assembly for converting an ion detection current produced by an ion detector into an ion detection voltage, the conversion resistor assembly comprising a resistor having a high resistance and a capacitive compensation element, and a compensation voltage circuit for deriving a compensation voltage from the ion detection voltage and feeding the compensation voltage to the capacitive compensation element, the compensation voltage circuit comprising a variable resistor for adjusting the compensation voltage.