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.

The present disclosure provides alternative solutions to the problem of providing a stable voltage reference to high speed ADCs that possess high sampling rates. In one example the high speed amplifier is replaced by a smaller, slower, lower power amplifier in combination with a relatively large capacitor connected to the same node as the amplifier output and the ADC reference input. The capacitor is charged substantially to the external reference voltage and hence keeps the reference input of the ADC almost at the external reference voltage between conversions, such that when conversion is about to occur and the external reference is switched in then very little charge is required from the external reference, and hence the reference signal quickly settles. An alternative arrangement is to replace the amplifier with a comparator that takes as one of its inputs the external reference signal, and as the other of its inputs the internal reference to the ADC, and makes use of a control circuit that adjusts the threshold of the comparator from bit-trial to bit-trial until the internal reference is brought up to substantially the same signal level as the external reference. When the external reference is then switched in to supply the ADC circuit it settles very quickly and draws very little power therefrom.

A dynamic differential amplifier includes: gain transistors to drive with differential input voltage levels; sample capacitors having first terminals to ramp from an initial voltage level to differential amplified voltage levels of the input voltage levels in response to the driven gain transistors; and adjustment circuits to adjust the amplified voltage levels in the direction of the initial voltage level by an offset voltage level. In some cases, second terminals of the sample capacitors are a common-mode node to maintain a common-mode voltage level midway between the ramping voltage levels of the first terminals. In some cases, the dynamic differential amplifier further includes a comparison circuit to compare the maintained common-mode voltage level to a threshold voltage level, wherein the first terminals of the sample capacitors stop ramping and the adjustment circuits adjust the amplified voltage levels in response to the compared common-mode voltage level reaching the threshold voltage level.

A controlled active resistance. The active resistance is implemented on an integrated circuit. In some embodiments, the active resistance includes a MOSFET. In alternate embodiments, the active resistance includes a MOSFET and a resistor. The control for the active resistance includes a reference resistor and an operational amplifier. The control for the active resistance further includes two current sources: i) a current source producing a current that is proportional to absolute temperature, and ii) another current source that is produced by a bandgap voltage reference. In one aspect, the active resistance generates an effective resistance that is proportional to thermal voltage. In another aspect, the active resistance generates an effective resistance that is proportional to inverse of the thermal voltage. In an alternate aspect, the current sources have various dependencies, and the active resistance generates an effective resistance that is proportional to those dependencies.

In embodiment, a measurement circuit forms a compensation signal that is representative of disturbances that are received while the measurement circuit is not receiving a signal to be measured, then the circuit removes the compensation signal from the measurement signal before measuring the value of the measurement signal.

An audio amplifier of a BTL (Bridged Tied Load) type, includes a first amplifier, a second amplifier, a first output pin connected to an output of the first amplifier, a second output pin connected to an output of the second amplifier, a first monitor pin, a second monitor pin, a current source connected to the first monitor pin and configured to be switched on and off, a switch interposed between the second monitor pin and a fixed voltage line, and a load state determination circuit configured to detect a state of a load based on a potential difference between the first monitor pin and the second monitor pin.

Technologies relating to RRAM-based crossbar array circuits and more specifically to reducing row switch resistance error of in crossbar array circuits are disclosed. An example apparatus includes: a first Op-amp including a first inverting Op-amp input, a first non-inverting Op-amp input, and a first Op-amp output; a row switch device including a row switch input and a row switch output; a crossbar array including a row wire, a column wire, and a cross-point device connected between the row wire and the column wire. The row switch input is connected to the first Op-amp output; the row switch output is connected to the first inverting Op-amp input; and the row switch output is connected to the row wire.

A programmable a fully-differential programmable gain amplifier for reducing distortion, switching transients and interference, and improving bandwidth. In one embodiment, the amplifier includes a programmable gain module, an amplifier coupled to the current mode outputs and a data latch circuit of the programmable gain module, the amplifier configured to apply common mode voltage to the data latch circuit, and a current-to-voltage converter. In one embodiment, the fully-differential programmable gain amplifier controls distortion and switching interference during amplification by sensing common mode signals to produce an error signal, and applying the resulting error signal to the programmable gain module for multiplying digital to analog conversion. Components of the fully-differential programmable gain amplifier provide compensation of distortion caused by nonlinearity of device switches and switch resistance, and can include a floating supply, galvanic isolation of control signals and a common mode voltage controller.

A clamp circuit can control a clamp transistor such that a change in a photodiode current detection voltage signal in an optical receiver circuit can control the clamp transistor to change state when a difference of a clamp voltage and the photodiode current detection voltage signal exceeds a threshold voltage of the clamp transistor. Using a feedback loop, the clamp circuit can accurately clamp a current when the photodiode current is larger than a detect current threshold.

A circuit arrangement comprises a first input node, a first output node, a sampling capacitor means and a first switching means being switchable between a first switching state and a second switching state. The first switching means is coupled to the sampling capacitor means, the first input node and the first output node in such a way that the sampling capacitor means is conductively connected to the first input node and disconnected from the first output node in the first switching state and the sampling capacitor means is disconnected from the first input node and conductively connected to the first output node in the second switching state. A first charge-storing element is coupled via a second switching means to the first input node in such a way that the charge-storing element is charged in the first switching state and discharged in the second switching state, thereby at least partly compensating current flow for charging the sampling capacitor means in the first switching state.