BUFFER AMPLIFIER


An electronic circuits whose primary function is to connect a high-impedance source to a low-impedance load without significant attenuation or distortion of the signal. Hence, the output voltage of a buffer replicates the input voltage without loading the source. Buffers are generally applied in analog systems to minimize loss of signal strength due to excessive loading of output nodes (illus. a).

Buffer

Buffer

Two kinds of circuits are frequently used: the operational-amplifier-based buffer and the transistor follower.
In other words, a buffer amplifier, is an electronic amplifier that is designed to have an amplifier gain of one (1). Buffers are used in Impedance matching, the benefit of which is to maximize energy transfer between circuits or systems. There are two main types of buffer circuits, Voltage buffers and Current buffers. The purposes of each is to isolate the mentioned characteristic to avoid loading the input circuit or source from the output stage.

Another name by which buffer amplifiers are known as is a voltage follower. The name is given because of the characteristic of the amplifier to output a signal of the same amplitude as the input
Voltage buffer
A voltage buffer amplifier is used to transfer a voltage from a first circuit, having a high output impedance level, to a second circuit with a low input impedance level. The interposed buffer amplifier prevents the second circuit from loading the first circuit and interfering with its desired operation.
A buffer is a unity-gain amplifier that has an extremely high input resistance and an extremely low output resistance, it is also called as Voltage follower. This means that the buffer can be modeled as a voltage controlled voltage source that has a gain of one.
In the ideal voltage buffer properties are:
Input resistance should be infinite and the output resistance zero (impedance of an ideal voltage source is zero).
Perfect linearity, regardless of signal amplitudes;
Instant output response, regardless of the speed of the input signal.

current ampli
Current buffer
Current buffer is a circuit that is used to transfer current from a low input impedance circuit to a circuit having high input impedance. The current buffer circuit connected in between the two circuits prevents the second circuit from loading the first circuit.
The features of an ideal current buffer are:
Infinite input impedance
Zero output impedance
Perfect linearity, regardless of signal amplitudes.
Instant output response, regardless of the speed of the input signal.
Current follower
A current buffer with unity gain (B=1) is called a unity gain current buffer or current follower. Here the output current just tracks or follows the input current. A current buffer can be realized using transistor (BJT or MOSFET).

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This article was written by Jalaja Kh

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