The disclosure provides a slew rate enhancement apparatus that is connected to an operational amplifier that receives an input signal and generates an output signal according to the input signal for driving a pixel. The slew rate enhancement apparatus comprises a signal edge detector, a comparator, an adjustment unit. The signal edge detector is coupled to the operational amplifier and configured to detect a signal edge and outputting a difference signal corresponding to a difference between the input and output signals. The comparator is coupled to the signal edge detector to receive the difference signal and configured to generate a control signal according to the difference signal. The adjustment unit is coupled to the comparator to receive the control signal, and configured to couple a compensation signal generated by a current source to the operational amplifier according to the control signal to enhance a slew rate of the operation amplifier.

An operational amplifier integrated circuit includes a differential pair of transistors having a first input, a second input. A bias current generator applies a bias current to an output of the differential pair of transistors. A control loop generates a control voltage arising from a difference in potentials between the first input and the second input. An additional current that is added to the bias current is generated in response to the control voltage.

A differential input stage of a circuit includes a first transistor, a second transistor, a third transistor, and a fourth transistor. Drains of the first and third transistors couple together at a first node, and drains of the second and fourth transistors couple together at a second node. A first slew boost circuit includes a fifth transistor and a first current mirror. A gate of the fifth transistor couples to the second node. A source of the fifth transistor couples to the first node. The first current mirror couples to the fifth transistor and to the second node. A second slew boost circuit includes a sixth transistor and a second current mirror. A gate of the sixth transistor couples to the first node. A source of the sixth transistor couples to the second node. The second current mirror couples to the sixth transistor and to the first node.

An operational amplifier includes a single-stage amplifier and a current controller. The single-stage amplifier receives an input signal, and amplifies the input signal to generate an output signal, wherein the single-stage amplifier includes a voltage controlled current source circuit that operates in response to a bias voltage input. The current controller receives the input signal, and generates the bias voltage input according to the input signal.

An amplifier circuit can be configured to receive a differential input signal having a common mode component that can extend to at least one power supply rail for the amplifier circuit. The amplifier circuit can include an input stage, such as having a first differential transistor pair, and the input stage can receive the differential input signal and in response conduct a differential first current to a cascode output stage. The cascode output stage can include or use a cascode control signal that is adjusted in response to the differential input signal. The cascode control signal can be independent of a transconductance of the first differential transistor pair. In an example, the amplifier circuit includes a slew boost circuit configured to source or sink current at an output of the amplifier based on a magnitude and polarity of the differential input signal.

A differential input stage of a circuit includes a first transistor, a second transistor, a third transistor, and a fourth transistor. Drains of the first and third transistors couple together at a first node, and drains of the second and fourth transistors couple together at a second node. A first slew boost circuit includes a fifth transistor and a first current mirror. A gate of the fifth transistor couples to the second node. A source of the fifth transistor couples to the first node. The first current mirror couples to the fifth transistor and to the second node. A second slew boost circuit includes a sixth transistor and a second current mirror. A gate of the sixth transistor couples to the first node. A source of the sixth transistor couples to the second node. The second current mirror couples to the sixth transistor and to the first node.

A voltage follower circuit according to an embodiment includes first and second paths, the first path includes a first nMOS transistor and a first pMOS transistor, the second path includes a second nMOS transistor and a second pMOS transistor, an input voltage is supplied to the gate of the first nMOS transistor, an output voltage is supplied to the gate of the second nMOS transistor, a voltage lower than the output voltage is supplied to the gate of the first pMOS transistor, and a voltage lower than the input voltage is supplied to the gate of the second pMOS transistor.

A slew rate adjusting circuit includes an adjustment transistor configured to provide an adjustment current into an output port of an arithmetic amplifier, a first transistor connected between a power line of the arithmetic amplifier and the adjustment transistor, and a second transistor connected between the first transistor and an output node of the output port, wherein the adjustment transistor is turned on by the second transistor in response to a difference between an input voltage and an output voltage being equal to or greater than a reference voltage, and the adjustment current is provided to the output port in response to the adjustment transistor being turned on.

A transmitter circuit includes a slew rate control circuit, a hysteresis circuit, a logic control circuit, and an amplifier circuit. The slew rate control circuit controls a slew rate of an input signal to generate a first output signal. The hysteresis circuit generates a first control signal according to the first output signal. The logic control circuit generates a second control signal and a third control signal according to the input signal and the first control signal. The amplifier circuit generates a second output signal according to the first output signal, the second output signal, the second control signal, and the third control signal.

Transimpedance amplifiers with feedforward current are provided herein. In certain embodiments, an amplifier system includes a transimpedance amplifier that amplifies an input current received at an input to generate an output voltage at an output. The amplifier system further includes a controllable current source that is coupled to the output of the transimpedance amplifier, and operable to provide a feedforward current that changes in relation to the input current of the transimpedance amplifier. By providing a feedforward current in this manner, gain and speed performance of the transimpedance amplifier is enhanced.