Properties of Basic amplifier - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 10th November 2002, 09:24 AM   #1
Edo is offline Edo
diyAudio Member
 
Join Date: Oct 2002
Location: Australia
Send a message via ICQ to Edo
Default Properties of Basic amplifier

Does anyone know the basic properties of the following four op amp.

I know Current Amplifier has a

Low Input Impedance
High Output Impedance

but how about

Voltage Amplifier
Transconductance
Transresistance

Ed
__________________
Cheers
  Reply With Quote
Old 10th November 2002, 01:10 PM   #2
eLarson is offline eLarson  United States
diyAudio Member
 
eLarson's Avatar
 
Join Date: Aug 2002
Location: Gaithersburg, MD
voltage amplifier:
high input impedance
low output impedance
(drive with a voltage source, get voltage out)

transconductance amplifier:
high input impedance
high ouput impedance
(drive with a voltage source, get current source
out)

transimpedance amplifier
low input impedance
low output impedance
(drive with a current source, get voltage out)

Erik
  Reply With Quote
Old 11th November 2002, 01:14 AM   #3
Edo is offline Edo
diyAudio Member
 
Join Date: Oct 2002
Location: Australia
Send a message via ICQ to Edo
Default When do you use each cause

Hi Erik

The output impedance you're refering to is the overall circuit and not the op amp itself right.

so do you know under which case do we use what?? For example say erm you would have to make a voltage amp from an op amp with a high input impedance and a low output impedance that would give a gain of erm say 23. Which Feedback would you use in this case and why??

Ed
__________________
Cheers
  Reply With Quote
Old 11th November 2002, 06:24 PM   #4
diyAudio Member
 
traderbam's Avatar
 
Join Date: Jan 2002
Location: Earth
Lightbulb definitions

Reciprocals:
Resistance Conductance
Reactance Susceptance
Impedance Admittance

Ratios:
V/V voltage gain, no units
V/I resistance or impedance, ohms
I/V conductance or admittance, mhos or siemens
I/I current gain or beta, no units


A trans[ratio] amplifier converts ratio denominator (input) to the ratio numerator (output).

Input and output impedances are not defined by the type of amplifier, they can be anything. In general a current input will have lower Z than a voltage input and a current output will have higer Z than a voltage output.
  Reply With Quote
Old 11th November 2002, 09:42 PM   #5
eLarson is offline eLarson  United States
diyAudio Member
 
eLarson's Avatar
 
Join Date: Aug 2002
Location: Gaithersburg, MD
Default Re: When do you use each cause

Hi, Ed,

Quote:
Originally posted by Edo
Hi Erik

The output impedance you're refering to is the overall circuit and not the op amp itself right.
Yes, that is right. It is the influence of the feedback network that causes the impedance to change.

Quote:
so do you know under which case do we use what?? For example say erm you would have to make a voltage amp from an op amp with a high input impedance and a low output impedance that would give a gain of erm say 23. Which Feedback would you use in this case and why??

Ed
Here are the 4 basic feedback arrangements. Which one you would want to pick depends on what is feeding the circuit and what it needs to feed in return.

1. Series-shunt feedback (so called because it is in series with the input and shunts the output) will increase your input impedance and decrease your output impedance. This would be good for a voltage amplifier: voltage in, voltage out.

2. Shunt-shunt will decrease both your input and output impedances. This would make it a good transimpedance (transresistance) amplifier: current input, voltage output.

3. Shunt-series feedback would decrease the input impedance and increase the output impedance. This would make it a good current amplifier: current input, current output.

4. Series-series feedback would increase both the input impedance and the output impedance. This would make it a good transconductance amplifier: feed it with a voltage, and treat the ouput as a current source.

Hope that helps,
Erik Larson
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Kenwood Basic M1 Amplifier Rte 66 Dave Solid State 22 27th June 2012 01:10 AM
PCB Trace properties for PP tube amplifier ( 12AQ5, 6v6 etc) bbuz Tubes / Valves 8 8th July 2008 04:01 PM
Basic OPA134 amplifier amirmk Solid State 5 5th November 2004 09:56 PM
Basic amplifier questions jsd Solid State 2 23rd August 2004 10:19 AM
Basic Amplifier Question RobPhill33 Solid State 22 6th October 2002 11:22 AM


New To Site? Need Help?

All times are GMT. The time now is 01:29 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2