A device includes an amplifier having inverting and non-inverting inputs and an output. The device includes a capacitor coupled to a first node and to ground, a resistor coupled to the first node and the amplifier output, and a first switch coupled to the first node and a current sink, which is coupled to ground. The device includes AND gate having inputs and an output coupled to control terminal of first switch. The device includes a first comparator having non-inverting and inverting inputs and an output coupled to an AND gate input; a second comparator having a non-inverting input coupled to the amplifier output, an inverting input coupled to a transistor stack, and an output coupled to an AND gate input; and a second switch coupled to the transistor stack and to a current source, the second switch having a control terminal coupled to the first comparator output.

One aspect of this disclosure is a power amplifier system that includes a control interface, a power amplifier, a passive component, and a bias circuit. The power amplifier and the passive component can be on a first die. The bias circuit can be on a second die. The control interface can operate as a serial interface or as a general purpose input/output interface. The power amplifier can be controllable based at least partly on an output signal from the control interface. The bias circuit can generate a bias signal based at least partly on an indication of the electrical property of the passive component. Other embodiments of the system are provided along with related methods and components thereof.

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 circuit has an input and a two-wire output. The circuit is designed for use with HTPE transducers and comprised of four stages. The first stage is a charge amplifier based on operational amplifier, the second stage is a 1-pole passive low-pass filter, the third stage is an active 2-pole low-pass filter based on two JFETs, and the fourth stage is an emitter follower comprising two bipolar junction transistors connected to each other in Darlington configuration.

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.

A device includes an amplifier having inverting and non-inverting inputs and an output. The device includes a capacitor coupled to a first node and to ground, a resistor coupled to the first node and the amplifier output, and a first switch coupled to the first node and a current sink, which is coupled to ground. The device includes AND gate having inputs and an output coupled to control terminal of first switch. The device includes a first comparator having non-inverting and inverting inputs and an output coupled to an AND gate input; a second comparator having a non-inverting input coupled to the amplifier output, an inverting input coupled to a transistor stack, and an output coupled to an AND gate input; and a second switch coupled to the transistor stack and to a current source, the second switch having a control terminal coupled to the first comparator output.

A device includes an amplifier having inverting and non-inverting inputs and an output. The device includes a capacitor coupled to a first node and to ground, a resistor coupled to the first node and the amplifier output, and a first switch coupled to the first node and a current sink, which is coupled to ground. The device includes AND gate having inputs and an output coupled to control terminal of first switch. The device includes a first comparator having non-inverting and inverting inputs and an output coupled to an AND gate input; a second comparator having a non-inverting input coupled to the amplifier output, an inverting input coupled to a transistor stack, and an output coupled to an AND gate input; and a second switch coupled to the transistor stack and to a current source, the second switch having a control terminal coupled to the first comparator output.

To easily adjust a gain of an amplifier. An applied input signal is input to a gate terminal of a first transistor, and a current depending on the applied input signal flows through the first transistor. A load section is connected to a drain terminal of the first transistor. A gate terminal of a second transistor is connected to the load section, and a current depending on a change in a voltage of the drain terminal of the first transistor flows through the second transistor. A source terminal of the first transistor and a drain terminal of the second transistor are connected in common to a first resistance, and the current from the first transistor and the current from the second transistor flow through the first resistance. A third transistor supplies a current approximately equal to the current of the second transistor. The current supplied by the third transistor is output from an output end.

A circuit has an input and a two-wire output. The circuit is designed for use with HTPE transducers and comprised of four stages. The first stage is a charge amplifier based on operational amplifier, the second stage is a 1-pole passive low-pass filter, the third stage is an active 2-pole low-pass filter based on two JFETs, and the fourth stage is an emitter follower comprising two bipolar junction transistors connected to each other in Darlington configuration.

A rail-to-rail potentiostat may require an offset current in order to support a bidirectional work electrode current at a work electrode. This offset current may improve measurements of the work electrode current made a dual-slope analog-to-digital converter, especially when the work electrode current is small, but can also lead to inaccuracies (e.g., due to a temperature coefficient) if it is not properly calibrated. Accordingly, bidirectional potentiostat is disclosed that can be configured in a normal configuration for measurement of a work electrode current or a calibration configuration for measurement (i.e., calibration) of an offset current. The reconfigurability allows calibrations to be taken as needed, on a schedule, or as specified by a user. The reconfigurability can also allow for maintaining a work electrode voltage and a work electrode current during calibration so that an electrochemical experiment using a cell coupled to the bidirectional potentiostat is unaffected by the calibration.