A unity gain buffer provides an ON state in which the input signal is coupled to the output terminal and an OFF state in which the input signal is isolated from the output terminal. Multiple unity gain buffers may share the same load to form a voltage-mode maximum follower or a multiplexer.

An integrated circuit and method for providing a variable gain amplifier are disclosed. One embodiment of the a variable gain amplifier comprises at least one load, a cascode circuit coupled to the load, a folded-gilbert stage, coupled to the cascode circuit, the folded-gilbert stage comprising a main differential pair of transistors and an internal pair of transistors, and a digital to analog converter, coupled to the folded-gilbert stage, for steering currents between the main differential pair of transistors and the internal pair of transistors to change a gain of the variable gain amplifier.

A semiconductor circuit includes a differential amplifier having a first positive terminal, a second positive terminal, a first negative terminal, a second negative terminal, and an output terminal. The output voltage is at a level that corresponds to a voltage level obtained by subtracting a voltage of the first negative terminal and the second negative terminal from a voltage sum of the first positive terminal and the second positive terminal. A first diode has a first anode connected to one of the first positive or the first negative terminal. A second diode has a second anode connected to the other of the first negative and first positive terminal. A predetermined reference voltage is applied to the second positive terminal. And a voltage corresponding to the output voltage of the differential amplifier is fed back to the second negative terminal.

A current-bootstrap comparator includes a receiving unit, a first current generation unit and a second current generation unit. The receiving unit receives a load voltage signal, a low threshold voltage and a high threshold voltage. The first current generation unit generates a first current. The second current generation unit generates a second current having a magnitude substantially same as a magnitude of the first current and a direction reverse to the first current. The first current and the second current are supplied to a next-stage circuit as a source current and a corresponding sink current, respectively, when the level of the load voltage signal is higher than the high threshold voltage or lower than the low threshold voltage. The magnitudes of the first current and the second current substantially equal zero when the level of the load voltage signal is between the high threshold voltage and the low threshold voltage.

The disclosure provides an amplifier. The amplifier includes a first transistor that receives a first input. A second transistor receives a second input. A plurality of impedance networks is coupled between the first transistor and the second transistor. At least one impedance network of the plurality of impedance networks includes a first impedance path and a second impedance path. The first impedance path is activated during single ended operation, and the second impedance path is activated during differential operation.

A driver for a piezo actuator includes a transconductance amplifier to produce an output current, a slew rate-controlled amplifier, and a logic gate. The logic gate receives a first control signal to cause the transconductance amplifier to transition to a high impedance mode, receive a compare signal indicative of the amplitude of the output current produced by the transconductance amplifier being less than a threshold, and generate a second control signal to the transconductance amplifier responsive to the first control signal indicating the high impedance mode for the transconductance amplifier and the compare signal indicative of the output current being less than the threshold. A voltage is provided to the slew rate-controlled amplifier upon assertion of the first control signal, wherein the voltage causes the slew rate controlled amplifier to generate a voltage to the transconductance amplifier that causes the transconductance amplifier's output to fall below the threshold.

A driver for a piezo actuator includes a transconductance amplifier to produce an output current, a slew rate-controlled amplifier, and a logic gate. The logic gate receives a first control signal to cause the transconductance amplifier to transition to a high impedance mode, receive a compare signal indicative of the amplitude of the output current produced by the transconductance amplifier being less than a threshold, and generate a second control signal to the transconductance amplifier responsive to the first control signal indicating the high impedance mode for the transconductance amplifier and the compare signal indicative of the output current being less than the threshold. A voltage is provided to the slew rate-controlled amplifier upon assertion of the first control signal, wherein the voltage causes the slew rate controlled amplifier to generate a voltage to the transconductance amplifier that causes the transconductance amplifier's output to fall below the threshold.

Disclosed are an operational amplifier and a method for reducing an offset voltage of the operational amplifier, which control an auxiliary circuit to generate a first auxiliary current and a second auxiliary current by adjusting the resistance of a resistance regulator, thereby adjusting a first current and a second current outputted from an input-stage circuit and further adjusting the offset voltage of the operational amplifier. Therefore, the operational amplifier and the method for reducing the offset voltage of the operational amplifier use the resistors to adjust the offset voltage so as to reduce the Least Significant Bit (LSB) distribution, thereby enhancing the accuracy of the offset voltage.

A programmable gain amplifier includes an active load module, a first differential pair, a second differential pair and a power source module. The first and second differential pairs are electrically connected to the active load module. The power source module is electrically connected to the first current source end of the first differential pair and the second current source end of the second differential pair. The power source module supplies a first current to the first differential pair through the first current source end. The power source module supplies a second current to the second differential pair through the second current source end. The power source module adjusts the potential of the first current, the potential of the second current, or both.

A sensing system with an AC feedback to the non-signal and non-biased terminal of the transducer. An impedance element, such as two anti-parallel diodes, are provided at the amplifier input, and the amplifier gain is negative and has a size sufficient to ensure that the input on the one terminal does not exceed the forward voltage of the diode.