What is the usage of source follower?

• May 10, 2006

• #1

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pyrite

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I am still confused on the purpose of souce follower?
When do I need to use it?

 

• May 10, 2006

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pfd001

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u can use it in the following conditions: level shift.
drive a low impedence load

 

• May 10, 2006

• #3

flatulent

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It also provdes isolation. Following an oscillator it makes the load have less effect on the oscillator frequency and amplitude.

 

• May 10, 2006

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avlsi

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U can use source follower for isolating i.e., in Common mode Feedback(see Chap 16. of Gray & Meyer).

This is all on voltage side. Instead it can be used as a current amplifier.

Common usage is voltage buffer(Av=1)

 

• May 10, 2006

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eldo

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Buffer. High input impedence and low output impedance.

 

• May 21, 2006

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jinxingsun

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The drawbacks of source follower are:nonlinearity due to the body effect,the bad driving ability and output swing,so the common usage is dc voltage shift

 

• May 22, 2006

• #7

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vbhupendra

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level shifting & impedance matching

 

• May 24, 2006

• #8

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dejunwang

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But watch out when driving a large load. Due to the complex pole, it might end up ringing. Check Ken Martin's book for explanations.

 

• Jun 8, 2006

• #9

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cliffj

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Level shit and buffer ( high impedance input and low impedance output)

 

• Jun 9, 2006

• #10

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tomhive

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pyrite said:

I am still confused on the purpose of souce follower?
When do I need to use it?

Click to expand...

Source follower is used 4 impedance matching....

 

• Jun 11, 2006

• #11

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wpchan05

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Source follower is fundamental as in current conveyors and current feedback opamps. Of course, a buffered voltage opamp also composes of source follower to drive low resistive loads.

 

• Jun 11, 2006

• #12

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wanily1983

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level shifting & impedance matching & improve current ability

 

• Jun 20, 2006

• #13

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Areky_qin

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enhance driving ablility.

 

• Jun 21, 2006

• #14

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tandr

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I think it will :
1 . It works as buffer for it's high input impendeace and low
output impendence , so it likes a real voltage source .
And so , the load effect of back end stage to the frond
stage is decreased
2. voltage shift .