A potentiostat circuit for controlling a work electrode voltage and for measuring a work electrode current is disclosed. The disclosed potentiostat circuit implementations have a topology and include elements to provide a plurality of benefits. The plurality of benefits includes an enlarged range of controllable work electrode voltages and bidirectional work electrode current measurements, high immunity from temperatures variations and process mismatch. The disclosed potentiostat circuit implementations can be used in applications requiring accuracy, low power consumption, and small size. The applications can include portable and/or multichannel electrochemical applications.

A method includes receiving, by a regulating circuit, a battery feedback parameter and producing, by an operational transconductance amplifier, a first output current at an output terminal based on the battery feedback parameter and a battery current regulation voltage. The method also includes producing, by a current source, a second current at the output terminal based on the battery feedback parameter and a reference voltage.

A method includes receiving, by a regulating circuit, a battery feedback parameter and producing, by an operational transconductance amplifier, a first output current at an output terminal based on the battery feedback parameter and a battery current regulation voltage. The method also includes producing, by a current source, a second current at the output terminal based on the battery feedback parameter and a reference voltage.

An input circuit includes an input stage having an input node and a direct-current (DC) amplifier coupled to the input node. The input circuit also includes an alternating-current (AC) amplifier coupled to an output node of the DC amplifier. The input circuit also includes a capacitor coupled between the input node and the output node of the DC amplifier. The input circuit also includes a voltage divider coupled to the DC amplifier and the AC amplifier. The voltage divider includes first resistor associated with the DC amplifier and a second resistor associated with the AC amplifier, where the first resistor is larger than the second resistor.

A starting circuit capable of further reducing an influence of a variation in the threshold voltage of a transistor is proposed. The starting circuit includes an N-type first MOS transistor whose threshold voltage is near 0 V, a resistor interposed between a source terminal of the first MOS transistor and a ground, and a control circuit controlling a gate voltage of the first MOS transistor. An amount of first current transmitted to a device to be driven and starting the device is controlled according to the control of the gate voltage.

An amplifier applied to TIA is provided to suppress the noise caused by a current source. An amplifier constituting a transimpedance amplifier includes an inductor element inserted between a current source connected to an input terminal of an amplification stage and a power source voltage line. The current source includes a first transistor in which a base terminal is connected to a current control bias and a collector terminal is connected to the input terminal. The inductor element is inserted between the emitter terminal of the first transistor and the power source voltage line.

An amplifier applied to TIA is provided to suppress the noise caused by a current source. An amplifier constituting a transimpedance amplifier includes an inductor element inserted between a current source connected to an input terminal of an amplification stage and a power source voltage line. The current source includes a first transistor in which a base terminal is connected to a current control bias and a collector terminal is connected to the input terminal. The inductor element is inserted between the emitter terminal of the first transistor and the power source voltage line.

In certain aspects, an apparatus includes a transformer including an input inductor and an output inductor, wherein the input inductor is magnetically coupled to the output inductor. The apparatus also includes a transconductance driver configured to drive the input inductor based on an input signal. The apparatus further includes a feedback circuit configured to detect an output voltage swing at the output inductor, generate a regulated voltage at the input inductor, and control the regulated voltage based on the detected output voltage swing.

Concurrent electrostatic discharge and surge protection clamps in power amplifiers. In some embodiments, a semiconductor die can include a semiconductor substrate and an integrated circuit implemented on the semiconductor substrate. The integrated circuit can include a power amplifier and a controller. The semiconductor die can further include a clamp circuit implemented on the semiconductor substrate and configured to provide electrostatic discharge protection and surge protection for at least some of the integrated circuit.

One aspect of this disclosure is a power amplifier module that includes a power amplifier on a substrate and a semiconductor resistor on the substrate. The power amplifier includes a bipolar transistor having a collector, a base, and an emitter. The collector has a doping concentration of at least 310.sup.16 cm.sup.3 at an interface with the base. The collector also has at least a first grading in which doping concentration increases away from the base. The semiconductor resistor includes a resistive layer that that includes the same material as a layer of the bipolar transistor. Other embodiments of the module are provided along with related methods and components thereof.