The invention relates to an operational amplifier (OA) particularly for signal amplification requiring wide bandwidth, high slew rate, and fast settling time. The OA contains two voltage followers rather than differential amplifier in the first stage. The OA has very low number of the components, especially resistors. The common base as the operation mode of the transistors is favored in order to achieve a very high and fastest possible signal amplification. The OA provides a pair of emitter fol...

An operational amplifier has a bias stage, a sampled differential stage, and a push-pull cascode stage. Unlike the conventional operational amplifier, the sampled differential stage is adopted in place of a differential stage has switches and capacitors. An input signal is transferred to the push-pull cascode stage through the capacitors in cooperation with the switches operated in response to clock signals phase-shifted by 180.degree., thereby applying optimal bias voltages to the push-pull cas...

An operational amplifier comprises an initial amplifier stage having a pair of inputs, and a second amplifier stage connected to an output of the initial stage. A phase compensating capacitive element is connected between an output terminal of the second stage and a virtual ground point, and a constant current source is connected to the virtual ground point and the output of the initial stage. A resistive element and a capacitive element are series-connected between the output of the initial sta...

An operational amplifier includes a differential amplifier portion for amplifying input signals and having an amplification path defined by plural series connected first switching devices extending between a supply and a ground, each of said first switching devices having a control input. The operational amplifier further includes an output portion for outputting signals amplified by the amplifier portion and having an output path defined by plural series connected switching devices extending be...

Both the distortion characteristic and the through rate characteristic of an operational amplifier are excellently retained over a wide range of a supply voltage. While an operating current of a differential circuit is controlled by a first current source circuit, an operating current of a level shift circuit is controlled by a second current source circuit. The first current source circuit controls the operating current to be substantially constant against a change of the supply voltage, so tha...

In an operational amplifier constituted by a differential stage which receives two input signals IN- and IN+ and outputs a signal NGP corresponding to the potential difference, a level shift stage which receives the signal NGP and outputs a level-shifted signal NGN, and an output stage which receives the signals NGP and NGN and outputs a signal OUT obtained by amplifying the potential difference between the two input signals, the level shift stage is formed from a DDA. Letting A1, A2, and A3 be ...

An operational amplifier includes an input stage, an output stage including first and second NPN output transistors and an intermediate stage including first and second emitter follower transistors. In this manner, a .beta..sup.3 current gain is achieved from the amplifier output to the output of the input stage to reduce output loading effects on the input stage. A first capacitor network is coupled between the amplifier output and the output of the input stage to frequency stabilize the amplif...

A differential amplifier stage is disclosed which utilizes opposed pairs of complementary transistors. The emitter electrodes of the complementary transistors of each pair are connected via matched resistors. A second matched pair of resistors are connected between the emitter electrodes of the input transistor of each complementary transistor pair. The interconnection of the second match pairs of resistors is connected to the base electrodes of the other transistors of each complementary transi...

The gain and phase characteristics of an operational amplifier are improved by adding a system zero to cancel a pole and thereby broadband the amplifier. This is accomplished by simultaneously driving the base terminals of the second stage gain transistor and preceding follower transistor and biasing the circuit such that the dynamic emitter resistance of the follower transistor is much greater than that of the gain transistor and/or by adding an additional emitter impedance.

An operational amplifier comprising a differential circuit, an output amplifier having an input terminal connected to the output terminal of the differential circuit, a phase compensating circuit, including an inverting amplifier having an input terminal connected to the output terminal of the differential circuit, and a phase compensating capacitor connected between the output terminal of the inverting amplifier and the output terminal of the differential circuit. The signal delay time of the i...