An operational amplifier having a broad bandwidth, very low power consumption and an externally variable bias current which adjusts the bias of various stages of the amplifier. The externally adjustable bias allows the adjustment of bias for various supply voltages and operating conditions and allows the operation of the amplifier on supply voltages as low as plus or minus one volt with a power dissipation as low as 60 microwatts. Active loads are used for each stage of the amplifier and the bro...

An operational amplifier comprises a differential amplifying circuit and an output circuit. The differential amplifying circuit comprises a pair of input transistors having control terminals connected to an inverting input terminal and a non-inverting input terminal, respectively. The output circuit is connected to the differential amplifying circuit for amplifying an output signal of the differential amplifying circuit and generating an amplified output from its output terminal. In this operati...

A current charged into or discharged from a phase-compensating capacitor C1 in an output circuit is controlled by a level shift circuit so that the current is kept constant for input signals inputted to the input terminals IN+ and IN- of a differential amplifier circuit, and also a current charged into or discharged from a phase-compensating capacitor C2 is controlled by the current correcting circuit so that the current become equal to a constant current controlled by the level shift circuit, n...

An operational amplifier provided with input and output stages comprises detecting means for detecting a differential voltage between a normal input signal terminal and an inverted input signal terminal of aforesaid input stage; and current varying means for varying a current for biasing an output stage buffer in response to an output signal produced from the detecting means. The output stage is driven by an output signal produced from the input stage by means of a single ended output; the detec...

An operational amplifier for producing an output signal representing the voltage differential between two input signals is powered by first, second and third power sources respectively having high, intermediate and low output voltage levels. A voltage buffer circuit, which is connected to the second power source, interconnects a constant current source, which is connected to the first power source, and an amplifier means, which is connected to the third power source, and separates the constant c...

An operational amplifier includes a pair of current mirror circuits and a buffer circuit commonly connected to outputs of the pair of current mirror circuits and a first current source. The first current source is electrically connected to the current mirror circuits so as to be controlled by operating currents of the current mirror circuits.

This invention discloses a high-slew-rate CMOS operational amplifier. This operational amplifier has a differential input stage formed by first and second transistors of the NMOS type connected together source-to-source and a first constant-current source. The first constant-current source is formed by an NMOS transistor coupled to the sources of the first and second transistors. The gates of third, fourth, and fifth transistors are respectively fed V.sub.in+, V.sub.in-, and the source voltage o...

An operational amplifier of the folded-cascode type with: push-pull output terminals; a differential-input transistors; a load impedance in the form of a cascode current source coupled to the differential-input, and a dynamic common-mode negative feedback. A current source transistor in the cascode current source is incorporated into the dynamic common-mode negative feedback.

The invention relates to an operational amplifier, particularly for signal amplification requiring high accuracy and extremely high speed which includes bandwidth, slew rate and settling time. A current feedback can be implemented with a low impedance inverting input for an increased high frequency performance. The operational amplifier according to the present invention has an input stage providing a pair of output signals, thus preserving a differential nature of the input signal of the operat...

An operational amplifier includes a first and second input JFETs having gate electrodes which are coupled to first and second input terminals respectively. A single ended output is taken from the drain of one of the JFETs and applied to an output gain stage including a Miller compensation capacitor. Circuitry is provided for producing a low impedance at the drain of the second JFET at high operating frequencies. This circuitry comprises an NPN transistor having an emitter coupled to ground, a ba...