Various embodiments of the present technology may provide methods and apparatus for an amplifier integrated circuit. The amplifier integrated circuit may provide a low gain bandwidth product to amplify at a higher speed and a high gain bandwidth product to amplify at a lower speed. The amplifier integrated circuit may achieve the low and high gain bandwidth product by generating a first current and a second current through a plurality of sets of series-connected transistors and operating a plurality of switches.

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 signal process circuit includes a signal modulation unit, a first resistor, a second resistor, a first discharge unit, a second discharge unit and a discharge detection unit. The signal modulation unit is used to modulate an input signal for generating a modulated signal. The first resistor is coupled between the signal modulation unit and an operation node. The second resistor is coupled between the operation node and the signal modulation unit. The first discharge unit is coupled to the signal modulation unit. The discharge unit is coupled to the signal modulation unit. The discharge detection unit is coupled to the first discharge unit, the operation node and the second discharge unit for detecting an output common voltage and control a discharge path accordingly.

A differential circuit is provided. The differential circuit comprises a plurality of electrodes comprising at least a middle electrode, wherein the middle electrode is directly adjacent to a first electrode and a second electrode of the plurality of electrodes; a plurality of amplifiers, coupled to the plurality of electrodes; and at least a buffer, coupled between the middle electrode and at least one amplifier of the plurality of amplifiers.

An amplifier includes a printed circuit board that includes an output terminal for outputting an electrical signal to an outside and a bias terminal for receiving a bias of the electrical signal from the outside, and an integrated circuit, a capacitor, an inductor, and a ferrite bead element mounted on the printed circuit board. The integrated circuit includes a driving circuit and an output end, and outputs the electrical signal generated by the driving circuit from the output end. The capacitor is connected between the output end and the output terminal. A series circuit includes the inductor and the ferrite bead element connected to each other in series, with the inductor connected to the output end, and the ferrite bead element connected to the bias terminal.

Isolators and methods for operating the same are described for opto-isolators with improved common mode transient immunity (CMTI). In some embodiments, a pair of photodetectors are provided in the opto-isolator and configured to generate photocurrents of opposite signs or directions in response to a light signal. Photocurrents from the pair of photodetectors are combined in a differential manner to represent data transmitted in a light signal, while common mode transient noise at the two photodetectors is attenuated or eliminated.

Neuromodulation systems in accordance with embodiments of the invention can use a feed-forward common-mode cancellation (CMC) path to attenuate common-mode (CM) artifacts appearing at a voltage input, thus allowing for the simultaneous recording of neural data and stimulation of neurons. In several embodiments of the invention, the feed-forward CMC path is utilized to attenuate the common-mode swings at V.sub.in,CM, which can restore the linear operation of the front-end for differential signals. In several embodiments, the neuromodulation system may utilize an anti-alias filter (AAF) that includes a duty-cycles resistor (DCR) switching at a first frequency f.sub.1, followed by a DCR switching at a second frequency f.sub.2. The AAF allows for a significantly reduced second frequency f.sub.2 that enables the multi-rate DCR to increase the maximum realizable resistance, which is dependent upon the frequency ratio f.sub.1/f.sub.2.

An analog-to-digital converter (10) comprises a first and a second sampling capacitor (24, 25), a first integrator (26), a first and a second input switch (31, 32) coupling a first input terminal (11) and a common mode terminal (39) to a first electrode of the first sampling capacitor (24), a third and a fourth input switch (33, 34) coupling a second input terminal (12) and the common mode terminal (39) to a first electrode of the second sampling capacitor (25), a fifth and a sixth input switch (35, 36) coupling a second electrode of the first sampling capacitor (24) to an amplifier common mode terminal (40) and the first integrator input (27), and a seventh and an eighth input switch (37, 38) coupling a second electrode of the second sampling capacitor (25) to the amplifier common mode terminal (40) and the second integrator input (28).

Methods, circuits, and apparatuses that provide Buffer Amplifier, containing Amplifiers and Buffer Drivers, one or more of the following: ultra low power Buffer Amplifier, capable of having high gain, low noise, high speed, near rail-to-rail input-output voltage span, high sink-source current drive capability for an external load, and able to operate at low power supply voltages. Methods, circuits, and apparatuses that provide regulated cascode (RGC) current mirrors (CM) capable of operating at low power supply and having wide input-output voltage spans.

Methods, circuits, and apparatuses that provide Buffer Amplifier, containing Amplifiers and Buffer Drivers, one or more of the following: ultra low power Buffer Amplifier, capable of having high gain, low noise, high speed, near rail-to-rail input-output voltage span, high sink-source current drive capability for an external load, and able to operate at low power supply voltages. Methods, circuits, and apparatuses that provide regulated cascode (RGC) current mirrors (CM) capable of operating at low power supply and having wide input-output voltage spans.