[SOLVED] Convert Analog 0 to -3v pulse to +5 to -5

[niloc]

Hi everyone,

i have searched the forum and found several threads that discuss the opposite, ie +/- 5 to 0-5v etc but haven't found something for my particular problem.

I am just after some direction in solving a design for a video interface to an ADC.

The video pulse is 0 to -3v and I need to convert the pulse to +5v to -5v to give full resolution at the ADC.

I have considered having a two stage op amp design with a dc offset on a Voltage Follower at 1st stage and then a Non Inverting Second Stage with a little gain to give full voltage swing. However the amount of DC Offset required is quite high, so I thought I would ask for some ideas and feedback here.

Does anyone have any suggestions?

 

[kam1787]

I would have a level shifter [to shift to +-1.5V] then a non inverting gain of about 3.3

 

[erikl]

Or use the opAmp with 4 precision resistors and a -1.5V reference voltage:

The opAmp's supply voltages have to be larger than its max. output voltages, e.g. ±8 or ±10V .

 

[niloc]

Hey, thanks for the feedback, I slept on it and have found

https://www.analog.com/library/anal...hapter 6 Interfacing to Data Converters F.pdf

which combined with your suggestions has steered me in a better direction. :thumbsup: