Godfather Posted February 21, 2006 Report Share Posted February 21, 2006 Hi to all,My name is Alex,I'm Romanian and I am a student in third year on electronics(RTV).I have to make a project about Bootstrap circuit ,but since I haven't used it I don't know anything about it.I will sure learn about it on school but later on.So can you give me a general perspective on Bootstrap circuit?What does it do,on what it is used?Olso can you give me an electronic scheme?Thx you..>!! Quote Link to comment Share on other sites More sharing options...
audioguru Posted February 21, 2006 Report Share Posted February 21, 2006 Hi Alex,Welcome to our forum. ;DAre you talking about bootstrapping the collector load of a transistor so it is more linear, has more gain and has a wider voltage swing? Quote Link to comment Share on other sites More sharing options...
Godfather Posted February 22, 2006 Author Report Share Posted February 22, 2006 Yea,I want to find out ,please tell me how does it work?and if you have a scheme I would apreciate very much.. ;) Quote Link to comment Share on other sites More sharing options...
audioguru Posted February 22, 2006 Report Share Posted February 22, 2006 This link shows how bootstrapping reduces distortion by 10 times:http://www.dself.dsl.pipex.com/ampins/discrete/twoq.htmThe capacitor causes a constant current to flow during signal changes in the transistor's collector resistance. Constant current means the resistor has a higher impedance, so its voltage gain is higher allowing for more negative feedback that reduces distortion.The capacitor also allows the collector's voltage to rise above the supply voltage on its positive swings, for max output voltage swing from the circuit. Quote Link to comment Share on other sites More sharing options...
Godfather Posted February 24, 2006 Author Report Share Posted February 24, 2006 thx you,I apreciate this ;) Quote Link to comment Share on other sites More sharing options...
Godfather Posted April 5, 2006 Author Report Share Posted April 5, 2006 Okay...now from what I'v understand the amplifiers with high imputy resistance , the value of this resistance depends very much on the bias resistance Rb.But stability requires that Rb cannot be very high , therefore it is necessary to use the bootstrap circuit so that high value of input resistance can be obtain with Quote Link to comment Share on other sites More sharing options...
Godfather Posted April 5, 2006 Author Report Share Posted April 5, 2006 I'v put Rb 900 k Quote Link to comment Share on other sites More sharing options...
audioguru Posted April 5, 2006 Report Share Posted April 5, 2006 Okay...now from what I'v understand the amplifiers with high imput resistance , the value of this resistance depends very much on the bias resistance Rb. But stability requires that Rb cannot be very high , therefore it is necessary to use the bootstrap circuit so that high value of input resistance can be obtain with Quote Link to comment Share on other sites More sharing options...
Godfather Posted April 5, 2006 Author Report Share Posted April 5, 2006 Thx you audioguru...you really know a lot and you are very helpfull.Now I understand ...PS:The program you use to simulate circuits it's free ware?If yes ,can you send it to me? Quote Link to comment Share on other sites More sharing options...
SM2GXN Posted April 5, 2006 Report Share Posted April 5, 2006 Hi Godfather!You can download it directly from LT website, here's the link to the download page just click on LTSpice/SwitcherCAD III Quote Link to comment Share on other sites More sharing options...
Godfather Posted April 5, 2006 Author Report Share Posted April 5, 2006 Hi SM2GXN!The link is not working...I am using Opera. :'( Quote Link to comment Share on other sites More sharing options...
audioguru Posted April 5, 2006 Report Share Posted April 5, 2006 I got this link from Google:http://www.linear.com/company/software.jsp Quote Link to comment Share on other sites More sharing options...
Godfather Posted April 6, 2006 Author Report Share Posted April 6, 2006 Thx ...a lot of interesting programs there... :D Quote Link to comment Share on other sites More sharing options...
SM2GXN Posted April 6, 2006 Report Share Posted April 6, 2006 Sorry I forgot to place the link in my post, there's nothing wrong with your opera GodfatherThanks audioguru ;) Quote Link to comment Share on other sites More sharing options...
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