- Push–pull output
A push–pull output is a type of
electronic circuitthat can drive either a positive or a negative current into a load. Push–pull outputs are present in TTL and CMOSdigital logic circuits and in some types of amplifier, and are usually realized as a complementary pair of transistors, one dissipating or "sinking" current from the load to ground or a negative power supply, and the other supplying or "sourcing" current to the load from a positive power supply. Because of the way these circuits are drawn schematically, with two transistors stacked vertically, they are sometimes called " totem pole" outputs. Vacuum tubes (valves) are not available in complementary types (as are pnp/npn transistors), so tube push-pull amplifiers are symmetric, with an output transformersupplying phase reversal. These amplifiers preceded solid-state versions, and are still in limited use by audiophiles..
transistoris switched on only when its complement is switched off. A disadvantage of simple push–pull outputs is that two or more of them cannot be connected together, because if one tried to pull while another tried to push, the transistors could be damaged. To avoid this restriction, some push–pull outputs have a third state in which both transistors are switched off. In this state, the output is said to be "floating" (or, to use a proprietary term, "tri-stated").
The alternative to a push–pull output is a single switch that connects the
loadeither to ground (called an open collectoror open drainoutput) or to the power supply (called an open-emitter or open-source output).
In analog push-pull amplifiers the two output devices (transistors, tubes, FETs) operate in
antiphase(i.e. 180° apart).
A push-pull amplifier produces less
distortionthan a single-ended one. This allows a class A or AB push-pull amplifier to have much less distortion for the same power than the same devices used in single-ended configuration. Class AB and class B dissipate much less power for the same output than class A; distortion can be kept low by large amounts of negative feedback.
Push–pull converterfor more details on implementation
* [http://www.aikenamps.com/SingleEnded.htm Push–pull vs. single-ended output] in analogue tube amplifiers
Wikimedia Foundation. 2010.
Look at other dictionaries:
Push–pull — can refer to several things or concepts: *Push pull train (a train capable of being operated by a driver at either end) *Push–pull strategy (in marketing and advertising) *Push–pull output (type of electronic circuit) *Push–pull converter (in… … Wikipedia
Push–pull converter — A push–pull converter is a type of DC to DC converter that uses a transformer to change the voltage of a DC power supply. The transformer s ratio is arbitrary but fixed; however, in many circuit implementations the duty cycle of the switching… … Wikipedia
push-pull — [poosh′pool′] adj. Electronics designating or of an amplifier circuit in which two tubes or transistors operate 180° out of phase with each other, usually producing a higher output of the desired wave and canceling undesired qualities, as hum … English World dictionary
Salida push-pull — Saltar a navegación, búsqueda Una salida push pull es un tipo de circuito electrónico que puede impulsar una corriente eléctrica positiva o negativa en una carga. Las salidas push pull están presentes en circuitos lógicos digitales TLL y CMOS y… … Wikipedia Español
Demand-pull inflation — Aggregate Demand increasing faster than production. Demand pull inflation is asserted to arise when aggregate demand in an economy outpaces aggregate supply. It involves inflation rising as real gross domestic product rises and unemployment falls … Wikipedia
Cost-push inflation — Aggregate supply – aggregate demand model illustration of aggregate supply (AS) shifting to AS and causing price level to increase while output shrinks Cost push inflation is a type of inflation caused by substantial increases in the cost of… … Wikipedia
Valve audio amplifier - technical — Circuitry and performance Characteristics of valves Valves are very high input impedance (near infinite in most circuits) and high output impedance devices. They are also high voltage / low current devices.While valves themselves are described… … Wikipedia
Electronic amplifier — A practical amplifier circuit An electronic amplifier is a device for increasing the power of a signal. It does this by taking energy from a power supply and controlling the output to match the input signal shape but with a larger amplitude. In… … Wikipedia
List of vacuum tubes — This is a list of vacuum tubes or thermionic valves. Before the advent of semiconductor devices, hundreds of tube types were used in consumer and industrial electronics; today only a few types are still used in specialized applications. Contents… … Wikipedia
Sziklai pair — transistor configuration In electronics, the Sziklai pair (also known as a compound transistor ) is a configuration of two bipolar transistors, similar to a Darlington pair. In contrast to the Darlington arrangement, the Sziklai pair has one… … Wikipedia