Avoid diodes

[Tiger555]

Hi,

I am looking for a chip that will avoid the diodes. I have a -1V always from the op amp. and when there is a pulse i will get 1v. What I want is avoid the -1V and make it 0 or GND and when pulse to 1V. So I used a Diode, but there is a drop!! So I am looking for a chip which can do this avoiding diode.

Circuit Simulator Applet

I read abt ULN 2001-4 Darlington Array, but in that I have to make another 1V and transistors to pull down to gnd..

any good chip??

Thanks in advance..

 

[Brevor]

You should be able to bias one input of the op-amp to cancel out the -1V.

 

[Tiger555]

Hi,
I have the similar for 8 diff circuits.. I.E this is only 1 circuit... i have 8 of the same.. then i need to take the sum... so a separator is needed... well.. something else??

 

[MrAl]

Hello,


If i understand you right you need a diode but cant afford the voltage drop. A while back a device made by Linear Tech came up in discussion which provides an IC chip that acts like a diode but doesnt have as much voltage drop. Maybe someone else here can remember the part number, or you can look it up on the Linear Tech site.

 

[Tiger555]

thanks... I am looking for something like that... I will give a search... the other thing i found is 
 UC3611 from Texas Ins, called Shottkey Array.. but that is a type of diode the drop is half the normal diode..

thanks..


 

[crutschow]

Use the op connected as a precision rectifier such as this (Figure 3). That way the diode drop is reduced by the open-loop gain of the op amp to essentially zero.