The present disclosure provides a protection circuit and a display panel. The protection circuit comprises: a power supply circuit for outputting a first voltage; an overvoltage protection circuit connected to the power supply circuit for feedback regulation of the first voltage, such that a first protection voltage outputted by the overvoltage protection circuit is maintained within a preset range; and an output regulator circuit connected to the overvoltage protection circuit for regulated output of a second protection voltage. Through the above embodiments, the present disclosure can always stabilize the outputted voltages within a preset range to achieve the purpose of providing a stable voltage for the display panel, thereby realizing accurate and rapid overvoltage protection of the display panel.

A feedback ammeter, which may be included in a source measure unit or a digital multi-meter, for example, including an operational amplifier having an input and an output and a feedback path electrically coupled between the output and the input of the operational amplifier. The feedback path includes a first non-linear device to allow the measurement of decades of current. The ammeter also includes an amplifier electrically coupled to the input of the operational amplifier and the output of the operational amplifier, a second non-linear device electrically coupled to an output of the amplifier, and a resistor electrically coupled between the second capacitor and the input of the operational amplifier. A constant resistance input impedance is established using the second non-linear device that can adjust the circuit gain.

An automatic gain control (AGC) transimpedance amplifier (TIA) uses a differential structure with feedback PIN diodes to adjust the loop gain of the amplifier automatically to maintain stability over a wide dynamic range when converting optical power using a photodiode to an electrical signal. A stable DC current derived from the photodiode current sets the voltage gain of the amplifier. The use of ultra-linear long carrier lifetime PIN diodes assures the transimpedance feedback resistance is linear. The AGC function adjusts the gain of the TIA to provide a linear stable differential transresistance controlled by the photodiode current; a linear stable AGC function using current supplied by the photodiode; an improvement of about 10 db of the transresistance dynamic range; and reduces the need for internal and external circuitry needed to provide the same function. The TIA is applicable to CATV optical systems which have very strict linearity requirements.

An apparatus for determining properties of an uncharacterized downhole fluid. The apparatus comprises an oscillation driver circuit comprising an amplifier having an output and an input, a feedback loop between the output and input of an amplifier or a logic gate, an electromechanical resonator disposed within the feedback loop such that a the resonator is driven by the oscillation driver circuit, wherein a resonant frequency of the resonator defines an oscillation frequency of the oscillator circuit, and a switch device for causing the oscillator circuit to stop driving the resonator, which thereby enables observation of a decay rate of the oscillation of the electromechanical resonator within the uncharacterized fluid. The electromechanical resonator is enclosed in a conductive layer to protect the resonator against capacitive effects of the downhole fluid.

An amplifier assembly (100) includes an amplifier (102) having an input terminal, an output terminal and a feedback terminal; a first feedback path connecting the output terminal to the feedback terminal; a second feedback path connecting the output terminal to the feedback terminal; a switch (124) positioned in the second feedback path, the switch (124) opening or closing in response to a voltage at the output terminal relative to a breakpoint, when the switch (124) is open, the amplifier assembly (100) has a first gain and when the switch (124) is closed, the amplifier assembly (100) has a second gain; and a thermally variable element (152) connected to the switch (124), the thermally variable element (152) configured to generate a compensation voltage to maintain the breakpoint in response to varying temperature of the switch (152).

A current detection circuit has a differential amplification circuit that outputs a differential output current dependent on a voltage difference between input terminals and first and second feedback circuits that output a detection current in response to the differential output current and form a feedback path to each input terminal of the differential amplification circuit. First and second MOS transistors that generate voltages dependent on respective source-drain voltages at a time when drain currents in a forward direction and a backward direction flow through an output MOS transistor are connected to respective input terminals of the differential amplification circuit.

A circuit for amplifying signals from a Micro Electro-Mechanical System (MEMS) capacitive sensor is provided. First and second input nodes receive a sensing signal applied differentially between the input nodes. A first amplifier stage and a second amplifier stage, respectively, produce a differential output signal between first and second output nodes. A common mode signal is detected at the output nodes. A voltage divider having an intermediate tap node is coupled between the first output node and the second output node. A feedback stage is coupled between the intermediate tap node of the voltage divider and the inputs of the first amplifier stage and the second amplifier stage, where the feedback line is sensitive to the common mode signal at the output nodes.

A pseudo-resistor structure, comprises: a first and a second PMOS transistor or PN diode configured as two-terminal devices, wherein the positive terminal of the first PMOS transistor or PN diode is connected to the positive terminal of the second PMOS transistor or PN diode, and wherein the negative terminal of the first PMOS transistor or PN diode is connected to an input (A) of the pseudo-resistor structure and wherein the negative terminal of the second PMOS transistor or PN diode is connected to an output (C) of the pseudo-resistor structure, and a dummy transistor or dummy diode connected to the input (A), wherein the dummy transistor or dummy diode is further connected to a bias voltage for compensating a leakage current through the first and the second PMOS transistors or PN diodes. A closed-loop operational amplifier circuit comprising the pseudo-resistor structure is provided. Also, a bio-potential sensor comprising the closed-loop operational amplifier circuit is provided.

A circuit for amplifying signals from a Micro Electro-Mechanical System (MEMS) capacitive sensor is provided. First and second input nodes receive a sensing signal applied differentially between the input nodes. A first amplifier stage and a second amplifier stage, respectively, produce a differential output signal between first and second output nodes. A common mode signal is detected at the output nodes. A voltage divider having an intermediate tap node is coupled between the first output node and the second output node. A feedback stage is coupled between the tap node of the voltage divider and the inputs of the first amplifier stage and the second amplifier stage, where the feedback line is sensitive to the common mode signal at the output nodes.

Control device for aerosol inhalation device, includes operational amplifier including output terminal configured to generate voltage according to voltage applied to load configured to heat aerosol source and having correlation between temperature and electrical resistance value, control unit including input terminal and configured to perform processing based on voltage applied to the input terminal, and voltage dividing circuit configured to electrically connect the output terminal of the operational amplifier and the input terminal of the control unit. Power supply voltage of the operational amplifier is higher than power supply voltage of the control unit, and equals voltage applied to aerosol generation circuit including the load, and one of inverting input terminal and noninverting input terminal of the operational amplifier is electrically connected to the aerosol generation circuit.