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.

A neural-signal amplifier includes an amplifier, a switched-capacitor circuit-input unit, a switched-capacitor feedback-circuit unit, and a switched-capacitor circuit-output unit. Each of the switched-capacitor circuit-input unit, the switched-capacitor feedback-circuit unit, and the switched-capacitor circuit-output unit includes a plurality of differential switches, a plurality of common mode switches, and a plurality of capacitors. By controlling the switches to turn on or performing the switched-capacitor operation, the neural-signal amplifier is controlled to suppress the DC drift and reconstruct the DC input of the common-mode power supply.

Various embodiments of the present technology comprise a method and apparatus for a dual mode operational amplifier. According to various embodiments, the operational amplifier functions as both a fully-differential amplifier and a single-ended amplifier. The operational amplifier may comprise additional transistors that function as switches, which can be selectively operated according to a desired mode.

A bandgap reference circuit includes a circuit for high-order temperature curvature compensation; and a circuit for low output impedance and current drive capability, wherein an output voltage of the bandgap reference circuit can be independently adjusted to be either above or below a silicon bandgap voltage without impacting temperature curvature.

A positive-side power supply terminal (1-1a) of a differential amplifier (1-1) is connected to a positive-side power supply line (L1). A negative-side power supply terminal (1-2b) of a differential amplifier (1-2) is connected to a negative-side power supply line (L2). A negative-side power supply terminal (1-1b) of the differential amplifier (1-1) and a positive-side power supply terminal (1-2a) of the differential amplifier (1-2) are connected to each other. A final-stage amplifier (2) is connected between the positive-side power supply line (L1) and the negative-side power supply line (L2).

A circuit for implementing an operational transconductance amplifier (OTA) based on telescopic topology, wherein cascode transistors of the operational transconductance amplifier (OTA) are self-biased without using additional biasing circuitry, which not only reduces power consumption but also achieves high gain without extra current, and each cascode stage of the OTA has a pair of transistors so that the swing of the output differential signals of the OTA can be completely symmetrical so as to benefit second-order harmonic rejection, CMRR and PSRR.

Apparatus and methods for frequency compensation of amplifiers are provided herein. In certain embodiments, an amplifier includes an input transistor (which can be part of a differential input pair) electrically connected to a first node, a folded cascode transistor electrically connected between the first node and a second node, a current source electrically connected to a third node, a current source transistor electrically connected between the third node and the first node, a first output transistor having an input (for example, a gate) electrically connected to the second node and an output (for example, a drain) electrically connected to a fourth node, and a frequency compensation capacitor electrically connected between the fourth node and the third node.

An integrated circuit (IC) includes first, second, third, and fourth transistors, first and second current source devices, and a trim circuit. The first transistor has a first control input and a first current terminal. The second transistor has a second control input and a second current terminal. The third transistor had a third control input and third and fourth current terminals. The fourth transistor has a fourth control input and fifth and sixth current terminals. The first current source is coupled between a first power supply node and the third current terminal. The second current source is coupled between the first supply node and the fifth current terminal. The trim circuit is coupled between the fourth current terminal and a second power supply node, and is coupled between the sixth current terminal and the second power supply node. The trim circuit includes a resistive digital-to-analog converter (RDAC) circuit.

Described herein is an apparatus and system of a low-impedance reference voltage generator. The apparatus comprises: a voltage-control loop including a first transistor to provide an output voltage; and a current-control loop to sense current through the first transistor, relative to a reference current. The node having the output voltage is a low-impedance node.

A bandgap reference circuit includes a circuit for high-order temperature curvature compensation; and a circuit for low output impedance and current drive capability, wherein an output voltage of the bandgap reference circuit can be independently adjusted to be either above or below a silicon bandgap voltage without impacting temperature curvature.