autir Posted September 28, 2005 Report Share Posted September 28, 2005 What are the differences between an operational and a differential amplifier? Quote Link to comment Share on other sites More sharing options...
audioguru Posted September 28, 2005 Report Share Posted September 28, 2005 Hi Autir,An opamp is a building block with extremely high voltage gain and differential inputs.A differential amplifier is a circuit using a single opamp or 3 of them, with the inputs properly biased and with negative feedback for a certain defined voltage gain.Some differential amplifier circuits are already made as an IC and are called Intrumentation Amplifiers. Some even have differential outputs. ;D Quote Link to comment Share on other sites More sharing options...
autir Posted September 28, 2005 Author Report Share Posted September 28, 2005 So, as a rule, I buy Op.Amp ICs? And I decide whether I will use these ICs as Op.Amps or create with them a diff.amp. circuit? Quote Link to comment Share on other sites More sharing options...
audioguru Posted September 28, 2005 Report Share Posted September 28, 2005 There are only a few applications for differential amplifiers. A balanced input for a dynamic microphone's preamp would use a differential amp if you didn't want to use a transformer.Ordinary opamp circuits usually have only one input. Quote Link to comment Share on other sites More sharing options...
prateeksikka Posted October 8, 2005 Report Share Posted October 8, 2005 hi audioguru!we generally call opamps as linear ICs .Do u know why is it so? Quote Link to comment Share on other sites More sharing options...
audioguru Posted October 8, 2005 Report Share Posted October 8, 2005 Opamps usually operate with a linear input and output. They aren't used in switching circuits very much.Because opamps have such a lot of voltage gain, with negative feedback their non-linearity is extremely low. Therefore they are linear amplifiers. Quote Link to comment Share on other sites More sharing options...
prateeksikka Posted October 8, 2005 Report Share Posted October 8, 2005 Are the simple FETs and BJTs which we use non linear amplifiers?By linear do you mean Y=m*X kind of relation?or in otherwords gain independent of input?i think u are right gain of a single transistor amplifier depends on i/p level. Quote Link to comment Share on other sites More sharing options...
audioguru Posted October 8, 2005 Report Share Posted October 8, 2005 Individual FETs and BJTs have non-linearity. An opamp is much better. Quote Link to comment Share on other sites More sharing options...
Guest Alun Posted October 9, 2005 Report Share Posted October 9, 2005 And op-amp isn't always that much better it's just negitive feedback makes it better. Quote Link to comment Share on other sites More sharing options...
audioguru Posted October 9, 2005 Report Share Posted October 9, 2005 Well, a single transistor amplifer needs a lot of negative feedback to make it linear, then it doesn't have any voltage gain. An opamp amplifier has both.A two and three transistors amplifier is much better but approaches becoming an opamp.http://www.dself.dsl.pipex.com/ampins/discrete/cfp.htmhttp://www.dself.dsl.pipex.com/ampins/discrete/singleq.htmhttp://www.dself.dsl.pipex.com/ampins/discrete/twoq.htmhttp://www.dself.dsl.pipex.com/ampins/discrete/discrop.htm Quote Link to comment Share on other sites More sharing options...
prateeksikka Posted October 9, 2005 Report Share Posted October 9, 2005 Any other ICs which are called linear Ics along with op amps? Quote Link to comment Share on other sites More sharing options...
audioguru Posted October 9, 2005 Report Share Posted October 9, 2005 Any other ICs which are called linear Ics along with op amps?Lots of ICs like linear voltage regulators and radio ICs. The timing section of a 555 timer IC operates linearly.Many circuits use Cmos digital inverters DC-biased so that they are linear amplifiers. Quote Link to comment Share on other sites More sharing options...
prateeksikka Posted October 17, 2005 Report Share Posted October 17, 2005 I had a misconception that it is their manufacturing process which makes tham called so i.e linear ICs. It is because that they operate linearly.thanx buddies! Quote Link to comment Share on other sites More sharing options...
Guest Alun Posted October 17, 2005 Report Share Posted October 17, 2005 It's the design that makes it linear of analogue, you can use an op-amp as a digital comparator, and you can just as easily use a 4011 as an analogue amplifier. IC's are called analogue or digital because it's how they are normally used. You can also use a BJT as a digital switch or an analogue amplifier. Quote Link to comment Share on other sites More sharing options...
prateeksikka Posted October 21, 2005 Report Share Posted October 21, 2005 hi alun!i guess digital - analog and linear -non linear are two different clasifications.as far as i know opamps are always linear. Quote Link to comment Share on other sites More sharing options...
Guest Alun Posted October 21, 2005 Report Share Posted October 21, 2005 They aren't if you're using them as comparators. Quote Link to comment Share on other sites More sharing options...
prateeksikka Posted October 22, 2005 Report Share Posted October 22, 2005 Then why do you think we call them as linear ICs. I mean any vendor would say 741 linear IC unlike any other IC. Quote Link to comment Share on other sites More sharing options...
Guest Alun Posted October 22, 2005 Report Share Posted October 22, 2005 That's because it's designed to be used as a linear IC. Quote Link to comment Share on other sites More sharing options...
prateeksikka Posted October 23, 2005 Report Share Posted October 23, 2005 by using the word linear here,do you mean a linear operation like i/o slope is constant?like constant increase in o/p leads to constant increase in o/p? Quote Link to comment Share on other sites More sharing options...
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