A maximum current detection circuit with multiple input current ports and a maximum current port generates, on the maximum current port, a maximum current corresponding to the largest input current on one of the input current ports. The maximum current detection circuit includes multiple current mirror circuits, each controlled by one of the input currents. Each of the current mirror circuits includes outputs, each coupled to a respective one of the input current ports and the maximum current port. The current mirror circuit controlled by the largest input current becomes the dominant source for the input currents on each of the input current ports and also drives the maximum current on the maximum current port. The input currents may be single-ended or differential signals. The input currents may be respectively delayed signals of a windowing circuit in an envelope tracking circuit controlling a power amplifier of a wireless device.

In one embodiment, stable and controlled circuit element biasing is provided in a circuit comprising a voltage source operable to output a first voltage, a reference voltage source operable to output a reference voltage, a circuit element biased, during operation, by the first voltage at a first end and by a second voltage at a second end, a voltage controller coupled to the second end of the circuit element, wherein the voltage controller is operable to adjust the second voltage based on a gain output, a gain controller operable to receive the reference voltage as a first input and the second voltage as a second input, wherein the gain controller is operable to generate, at an output of the gain controller, the gain output based on the second voltage and the reference voltage, and a feedback loop that extends from the output of the gain controller, through the voltage controller, and to the second input.

A peak detector for a power amplifier is provided that includes a threshold voltage detector configured to pulse a detection current in response to an amplified output signal from the amplifier exceeding a peak threshold. A plurality of such peak detectors may be integrated with a corresponding plurality of power amplifiers in a transmitter. Should any peak detector assert an alarm signal or more than a threshold number of alarm signals during a given period, a controller reduces a gain for the plurality of power amplifiers.

An amplifier circuit according to an embodiment includes a first circuit, a second circuit, and a third circuit. The first circuit includes a first transistor connected between an input node through which an input current flows and a reference potential node. The first transistor has a gate electrode connected to the input node. The second circuit includes a low-pass filter circuit and a second transistor connected in parallel to the first transistor between the input node and the reference potential node. The second transistor has a gate electrode connected to the gate electrode of the first transistor via the low-pass filter circuit. The third circuit includes a third transistor connected between an output node through which an output current flows and the reference potential node, the third circuit having a gate electrode connected to the gate electrode of the first transistor.

An overcurrent protection circuit includes: a first transistor and a second transistor configured to form an amplifier input stage that receives input of a detection signal according to a monitoring target current; and a third transistor configured to form an amplifier output stage that generates a current output signal according to a difference between the detection signal and a reference signal and causes the current output signal to be negatively fed back to the amplifier input stage, wherein the monitoring target current is limited based on the current output signal output from the third transistor.

A balanced differential transimpedance amplifier with a single-ended input operational over a wide variation in the dynamic range of input signals. A threshold circuit is employed to either or a combination of (1) generate a varying decision threshold to ensure a proper slicing over a wide range of input current signal levels; and (2) generate a bias current and voltage applied to an input of a transimpedance stage to cancel out a dependence of the transimpedance stage voltage input on input current signal levels.

A current mirror circuit that amplifies a reference current generated by a current source at a first magnification to supply a mirror current to a load circuit. The current mirror circuit includes a first transistor and a second transistor that share a power supply, and a drain potential mirror unit that amplifies the reference current at a second magnification to generate a first current, that amplifies a generated first current at a third magnification to generate a second current, and that supplies a predetermined potential determined based on the second current to a drain of the second transistor. The mirror current is supplied from the second transistor to the load circuit based on a potential of a gate of the first transistor determined based on the reference current.

An embodiment voltage-current converter circuit comprises a first amplifier and a second amplifier having homologous first input nodes configured to receive a voltage signal therebetween as well as homologous second input nodes having a resistor coupled therebetween. First and second current mirror circuits are provided comprising first input transistors having their control terminal coupled to the output nodes of the amplifiers. First and second current sensing circuitry having first and second current output nodes are coupled to the current mirror output nodes of the current mirror circuits and configured to provide therebetween a current which is a function of the voltage signal between the homologous first input nodes of the amplifier.

An optical sensor and a method having a high linearity digital controlling mechanism are provided. An optoelectronic component converts a light energy into a photocurrent. Then, the photocurrent flows to a current mirror and is amplified by a gain to form a charging current by the current mirror to charge a capacitor. A comparator compares a voltage of the capacitor with a reference voltage multiple times to generate a comparison signal. A counter determines a digital value capturing range according to the gain, and counts bit values that fall within the digital value capturing range from the comparison signal to output a counted signal. A noise cancellation processor reduces the digital value capturing range according to the gain, and removes one or more of the bit values that do not fall within the digital value capturing range from the counted signal to output a sensed signal.

Disclosed is an operation amplification circuit and an over-current protection method therefor. The operation amplification circuit comprises: a control unit, configured to generate an output control signal according to an input signal and an output signal; an output unit, configured to generate an output current under control of the output control signal, wherein the output unit comprises an output capacitor which is charged or discharged by the output current to generate the output signal; an over-current protection unit, obtaining a temperature control current according to an operating temperature of the operation amplification circuit, wherein when the operating temperature is greater than or equal to a predetermined temperature, the temperature control current is positively correlated with the operating temperature, and the over-current protection unit adjusts the output control signal according to the temperature control current to limit the output current.