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A '''buffer''', is a basic [[logic gate]] that passes its input, unchanged, to its output. Its behavior is the opposite of a [[NOT gate]]. The main purpose of a buffer is to regenerate the input, usually using a strong high and a strong low. A buffer has one input and one output; its output always equals its input. Buffers are also used to increase the propagation delay of circuits by driving the large capacitive loads.
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! A !! Q
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== Description ==
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{{expand section}}
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A buffer is a very basic active device that generates an output identical to its input. In most technologies, a buffer is made of two [[inverter]]s back-to-back. One of the many purposes for a buffer is to regenerate weak output from [[non-restoring logic]].
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A '''buffer''', is a basic [[logic gate]] that passes its input, unchanged, to its output. It's behavior is the opposite of a [[NOT gate]]. The main purpose of a buffer is to regenerate the input, usually using a strong high and a strong low. A buffer has one input and one output; its input always equals its input. Buffers are also used to increase the propagation delay of circuits by driving the large capacitive loads.
 
  
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== Standard symbol ==
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==Design==
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Buffers are typically drown on schematics using one of the three standard symbols:
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{{empty section}}
  
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== Symbolic representation ==
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Buffers are typically drawn on schematics using one of a standard symbol. Below are three of the commonly found standard symbols.
 
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! ANSI !! IEC !! DIN
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! ANSI !! IEC !! DIN !! British
 
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| [[File:Buffer gate ansi.svg]] || [[File:Buffer gate iec.svg]] || [[File:Buffer gate din.svg]]
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| [[File:buffer gate (ansi).svg|100px]] || [[File:buffer gate (iec).svg|100px]] || [[File:buffer gate (din).svg|100px]] || [[File:buffer gate (british).svg|100px]]
 
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== CMOS Implementation ==
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==Implementations==
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A buffer can be implemented in variety of of technologies.
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=== CMOS ===
 
A CMOS buffer gate with one input and one output can be realized as simply two [[inverter]]s back to back - built out of just 4 gates.
 
A CMOS buffer gate with one input and one output can be realized as simply two [[inverter]]s back to back - built out of just 4 gates.
  
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[[File:Buffer gate cmos.png|200px]]
 
[[File:Buffer gate cmos.png|200px]]
 
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== Discrete chips ==
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== Discrete Chips ==
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Various buffers/drivers exist chips as well for both [[7400 series]] and [[4000 series]].
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=== [[7400 series]] chips ===
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{{empty section}}
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=== [[4000 series]] chips ===
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-CD4050 NonInverting 6 Channel (THE Jellybean go-to part for many people. This is often used as a 5 volt to 3.3 volt, voltage level shifter in hobby electronics for displays and sensors)
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-CD4049 Inverting version of the CD4050.
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-HEF40244 NonInverting 8 channel with 2 independently selected (4 channels each) tristate enable lines. This IC also has the advantage of inputs and outputs on opposing sides of the chip pin for pin.
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The 7407 is a TTL chip with 14 pins. Two pins are used for V<sub>DD</sub> and GND, the other 12 pins are used for the 6 independent buffers. The 4050 is a CMOS Hex Buffer with 16 pins. Two pins are used for V<sub>DD</sub> and GND, 12 pins are used for the 6 independent buffers. Pins 13 and 16 are not connected. Both chips implement the expression Q<sub>N</sub> = A<sub>N</sub>
 
The 7407 is a TTL chip with 14 pins. Two pins are used for V<sub>DD</sub> and GND, the other 12 pins are used for the 6 independent buffers. The 4050 is a CMOS Hex Buffer with 16 pins. Two pins are used for V<sub>DD</sub> and GND, 12 pins are used for the 6 independent buffers. Pins 13 and 16 are not connected. Both chips implement the expression Q<sub>N</sub> = A<sub>N</sub>
  

Latest revision as of 15:15, 11 August 2018

Buffer Gate
ANSI Symbol
buffer gate (ansi).svg
Functional
buffer gate functional.gif
Truth Table
Inputs Outputs
A Q
0 0
1 1
Other Gates
Buffer TriBuffer NOT
AND OR XOR
NAND NOR XNOR
Trans AOI OAI
MAJ INH IMPLY
NIMPLY
Other Components
Plexers
MUX DEMUX Encoder
Decoder Pri-Encoder
ALU
Adder Subtractor Multiplier
Divider Shifter Rotator
MAC Comparator Negator
Memory
D latch D flip-flop SR latch
JK flip-flop T flip-flop Register
Register file SRAM Counter
ROM CAM DRAM
I/O
Shift register SIPO PISO
ADC DAC

A buffer, is a basic logic gate that passes its input, unchanged, to its output. Its behavior is the opposite of a NOT gate. The main purpose of a buffer is to regenerate the input, usually using a strong high and a strong low. A buffer has one input and one output; its output always equals its input. Buffers are also used to increase the propagation delay of circuits by driving the large capacitive loads.

Description[edit]

New text document.svg This section requires expansion; you can help adding the missing info.

A buffer is a very basic active device that generates an output identical to its input. In most technologies, a buffer is made of two inverters back-to-back. One of the many purposes for a buffer is to regenerate weak output from non-restoring logic.

Design[edit]

New text document.svg This section is empty; you can help add the missing info by editing this page.

Symbolic representation[edit]

Buffers are typically drawn on schematics using one of a standard symbol. Below are three of the commonly found standard symbols.

ANSI IEC DIN British
buffer gate (ansi).svg buffer gate (iec).svg buffer gate (din).svg buffer gate (british).svg

Implementations[edit]

A buffer can be implemented in variety of of technologies.

CMOS[edit]

A CMOS buffer gate with one input and one output can be realized as simply two inverters back to back - built out of just 4 gates.

The table on the right shows the states of the four transistors with the various inputs of A.

Buffer Gate by Transistor
A Q1 Q2 Q3 Q4 Q
0 1 0 0 1 0
1 0 1 1 0 1

Buffer gate cmos.png

Discrete Chips[edit]

Various buffers/drivers exist chips as well for both 7400 series and 4000 series.

7400 series chips[edit]

New text document.svg This section is empty; you can help add the missing info by editing this page.

4000 series chips[edit]

-CD4050 NonInverting 6 Channel (THE Jellybean go-to part for many people. This is often used as a 5 volt to 3.3 volt, voltage level shifter in hobby electronics for displays and sensors)

-CD4049 Inverting version of the CD4050.

-HEF40244 NonInverting 8 channel with 2 independently selected (4 channels each) tristate enable lines. This IC also has the advantage of inputs and outputs on opposing sides of the chip pin for pin.


The 7407 is a TTL chip with 14 pins. Two pins are used for VDD and GND, the other 12 pins are used for the 6 independent buffers. The 4050 is a CMOS Hex Buffer with 16 pins. Two pins are used for VDD and GND, 12 pins are used for the 6 independent buffers. Pins 13 and 16 are not connected. Both chips implement the expression QN = AN

  • 7407 Hex Buffer/Driver

  • 4050 CMOS Hex Buffer/Driver

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