Author Topic: Problems with circuit(shift an differential signal)  (Read 1128 times)

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Offline baksuzTopic starter

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Problems with circuit(shift an differential signal)
« on: May 14, 2019, 11:33:11 am »
Hiii guys,

I am trying to shift an differential signal, up to get for example from -2.5 , 2.5 to 0,5 .
I have found on Level Shifting Signals With Differential Amplifiers Texas Instruments
http://www.ti.com/lit/an/sboa038a/sboa038a.pdf (schematics of circuit is in attachment)

The problem is I have bought all part, but I cant make it work , and the problem is that I have just one power supply( I think that is a problem), I will attacht schematics of my circuit and hope so someone will help me.


Have nice day :D
 

Offline David Hess

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Re: Problems with circuit(shift an differential signal)
« Reply #1 on: May 15, 2019, 03:44:20 am »
First you will have to define the problem because that circuit will not shift a differential signal.  Do you actually mean differential signal?

If so, do you mean shift the differential or common mode value?

Leveling shifting a single ended signal just requires a summing amplifier although often this is done with an instrumentation amplifier as shown in your example.
 

Offline akowalczyk

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Re: Problems with circuit(shift an differential signal)
« Reply #2 on: May 15, 2019, 07:18:24 am »
Hi!

Can you clarify what U3 is? That will help determine what type of signal output it will have. Looks like some sort of encoder or resolver

If it's a resolver, I think your summing circuit is correct, but you might need both terminals of the device hooked up

Hope this helps!
1. Always read the datasheet
2. Never trust the datasheet
 

Offline pwlps

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Re: Problems with circuit(shift an differential signal)
« Reply #3 on: May 15, 2019, 09:34:13 am »
The problem is I have bought all part, but I cant make it work , and the problem is that I have just one power supply( I think that is a problem), I will attacht schematics of my circuit and hope so someone will help me.

Yes, quoting from the datasheet:
POWER SUPPLY
Voltage Range  : Min ±5  Max ±15

But in the document you cite they suggest :
Quote
For precision level shifting in low voltage applications, the INA213 is an alternative to the INA105. The INA213 operates from a single 2.7-V to 26-V power supply that makes it suitable for lower voltage systems with single supplies.
 

Online Zero999

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Re: Problems with circuit(shift an differential signal)
« Reply #4 on: May 15, 2019, 10:02:48 am »
I take it you want to convert a differential -2.5V to +2.5V signal to single ended 0 to +5V?

All you need to do is bias the reference pin of the INA105 at 2.5V, which could be done with an op-amp and potential divider, assuming you have an accurate enough 5V power supply available.

Note that the INA105, needs a bipolar power supply: at least +10V and -5V is recommended. It won't work off a single 5V power supply.
 


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