An exemplary embodiment of the present invention relates to an electrical amplifier comprising a differential preamplifier having a first output port and a second output port; a first output unit connected to the first output port of the differential preamplifier and a second output unit connected to the second output port of the differential preamplifier, the first and second output units being electrically arranged in parallel relative to each other; and a positive feedback loop that couples the first and second output units and comprises a first capacitor and a second capacitor; wherein each of the first and second output units comprises an emitter-follower unit and a bias transistor that is connected in series with the emitter-follower unit of its output unit; wherein an emitter of the emitter-follower unit of the first output unit is connected to a base of the bias transistor of the second output unit through the first capacitor of the positive feedback loop; and wherein an emitter of the emitter-follower unit of the second output unit is connected to a base of the bias transistor of the first output unit through the second capacitor of the positive feedback loop.

An operational amplifier includes: a first amplifier stage, configured to generate first output voltages according to first input voltages; a second amplifier stage, configured to generate second output voltages according to the first output voltages; a second output stage circuit, configured to replicate an equivalent or a scaled-down version of the first output stage circuit; a first common-mode feedback circuit, configured to keep an output common-mode voltage of the second output stage circuit at a predetermined value; a logic loop circuit configured to, when the operational amplifier operates in a direct current calibration phase, adjust a difference between the first output voltages; a bias circuit, configured to generate a voltage close to a common mode voltage of the first output voltages produced after the operational amplifier is turned on, the voltage serving as a reference voltage of a second common-mode feedback circuit.

The operational amplifier disclosed includes an input stage configured to receive power from a floating supply in a low voltage range that can float according to the common mode voltage at the input. The floating supply facilitates the use of low voltage components that can improve the precision of the operational amplifier by lowering the offset voltage. The input stage includes a first gain stage including field effect transistors and a second gain stage using bipolar transistors. The gain stages can be implemented differently to accommodate different applications and fabrication capabilities.

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 amplifier may include a main signal path having a plurality of stages compensated by feedback elements, the plurality of stages comprising an output stage configured to receive electrical energy from a power supply and an auxiliary path independent of the main signal path and comprising an output stage compensation circuit configured to generate a compensation current proportional to noise present in the power supply and apply the compensation current to cancel a power supply-induced current present in at least one of the feedback elements.

A monolithically-integrated current-feedback instrumentation amplifier includes two differential pairs of transistors. A drain terminal of transistor is directly connected to a drain terminal of transistor and to a differential voltage amplifier, and is connected to a ground terminal by means of a first sink resistor. A drain terminal of transistor is directly connected to a drain terminal of transistor and to the differential voltage amplifier, and is connected to a ground terminal by means of a second sink resistor. An output terminal of the differential voltage amplifier is connected to a resistive voltage divider. Source terminals of the transistors are directly connected together and to a first bias current source without a degeneration resistor, and source terminals of the transistors are directly connected together and to a second bias current source without a degeneration resistor. A sensing system comprising a piezoresistive N&MEMS sensor and a monolithically-integrated differential readout circuit comprising the amplifier are also provided.

The present invention provides a circuit having a filter with an amplifier circuit for filtering and amplifying an input signal to generate an output signal, wherein a corner frequency of the filter is adjustable to control a settling time of the output signal.

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.

Techniques for monitoring a distortion signal of a power amplifier circuit, where the output of a distortion monitoring circuit includes little or no fundamental signal and closely represents the actual distortion of the amplifier circuit of a wired communications system. The power amplifier circuit can generate a distortion feedback signal that does not affect the power amplifier's output power capability, e.g., no inherent loss in the fundamental output of the amplifier. That is, using a distortion monitor circuit, the power amplifier circuit can resolve a distortion feedback signal from the intended output signal of the output power amplifier circuit.

An amplifier may include a main signal path having a plurality of stages compensated by feedback elements, the plurality of stages comprising an output stage configured to receive electrical energy from a power supply and an auxiliary path independent of the main signal path and comprising an output stage compensation circuit configured to generate a compensation current proportional to noise present in the power supply and apply the compensation current to cancel a power supply-induced current present in at least one of the feedback elements.