The present disclosure relates to a sensor circuit including a control circuit configured to control a constant first signal to a ratiometric second signal using a first amplifier adjustable by an actuating signal, and an adjustable second amplifier for a sensor signal, the gain of which is adjustable by the actuating signal.

In one implementation, a circuit can include a reference pin and an operational amplifier that can include an output pin, an inverting input pin and a non-inverting input pin. The inverting input pin can be electrically coupled to the output pin via a first impedance and to the reference pin via a second impedance. The non-inverting input pin can be electrically coupled to the reference pin via a third impedance and can be configured to receive a detection signal. The reference pin can be configured to receive a detection reference signal associated with the detection signal.

A signal measuring apparatus and method is provided. The signal measuring apparatus inputs a reduced voltage signal to an input end of an amplifier by resetting a voltage signal, which is acquired by applying a known current signal to a target object, using a common mode voltage at least once during one period of a current signal. The signal measuring apparatus acquires a digital signal corresponding to an object impedance change by converting an output of the amplifier.

A radiofrequency transmission/reception integrated circuit includes at least one radiofrequency signal amplifier (PA, LNA), the at least one amplifier being configured, in operational mode, so as to perform a function of amplifying a radiofrequency signal applied at input, wherein the amplifier is configured so as to perform an oscillator function in a self-test mode of the integrated circuit, to generate a radiofrequency signal on at least one of the input or the output of said amplifier. A self-test method for such an integrated circuit is also provided.

An electronic amplification-interface circuit includes a differential-current reading circuit having a first input terminal and a second input terminal. The differential-current reading circuit includes a continuous-time sigma-delta conversion circuit formed by an integrator-and-adder module generating an output signal that is coupled to an input of a multilevel-quantizer circuit configured to output a multilevel quantized signal. The integrator-and-adder module includes a differential current-integrator circuit configured to output a voltage proportional to an integral of a difference between currents received at the first and second input terminals. A digital-to-analog converter, driven by a respective reference current, receives and converts the multilevel quantized signal into a differential analog feedback signal. The integrator-and-adder module adds the differential analog feedback signal to the differential signal formed at the first and second input terminals.

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.

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.

The invention relates to a circuit containing a transimpedance amplifier for converting two input currents into two output voltages, having a first amplifier part containing a first input, to which a first input voltage is applied, and into which a first input current flows, and having a second amplifier part containing a second input, to which a second input voltage is applied and into which a second input current flows, wherein the first amplifier part and the second amplifier part are connected to a common supply voltage, the first amplifier part and the second amplifier part are connected to a common current source, the input of the first amplifier part and the input of the second amplifier part have a differing direct voltage, and the first amplifier part and the second amplifier part are designed such that an output voltage of the first amplifier part is proportional to the input current of the first amplifier part and an output voltage of the second amplifier part is proportional to an input current of the second amplifier part.

An electronic amplification-interface circuit includes a differential-current reading circuit having a first input terminal and a second input terminal. The differential-current reading circuit includes a continuous-time sigma-delta conversion circuit formed by an integrator-and-adder module generating an output signal that is coupled to an input of a multilevel-quantizer circuit configured to output a multilevel quantized signal. The integrator-and-adder module includes a differential current-integrator circuit configured to output a voltage proportional to an integral of a difference between currents received at the first and second input terminals. A digital-to-analog converter, driven by a respective reference current, receives and converts the multilevel quantized signal into a differential analog feedback signal. The integrator-and-adder module adds the differential analog feedback signal to the differential signal formed at the first and second input terminals.

A variable resistance element is connected between a first input terminal of a first amplifier and a second input terminal of a second amplifier, and has a resistance value between the first input terminal and the second input terminal that is varied according to an amplitude value of a first voltage signal or an amplitude value or a differential voltage signal. A variable current source is connected between the first input terminal and a ground, and controls a current value of a current flowing to the ground from the first input terminal according to a value of an offset of the differential voltage signal. A bias voltage having the same value as that of a bias voltage that is applied to the first input terminal is applied to the second input terminal.