Being a single ended or differential for opamp depends on type of device or just wiring ? I mean whether the opamp is same but our wiring makes it single ended or differential ? or opamp type makes it single ended or differential ? for example if I wire - of an opamp to ground it will be single ended if I don't it will be differential. Is it like that ?

Thanks in advance.

 

hi alex,
Look thru this OPA collection PDF.
E

 

Hi Eric,
Thanks for respond. The document seems to be very useful but since I am a new automation engineer(not being good at electronic) I think I couldn't find the answer of question above.
Just the respond to question above will help me understand wiring of analog inputs.
Regards,

 

hi alex,
If only one input of a OPA has 'active' signal applied I would call Single.
Where both inputs have 'active' signal inputs it can be called a Difference or Differential amplifier.
Often a DC signal is applied to one of the 'single type' inputs, in order to apply a DC offset voltage on its output.

Look at this link.
https://www.electronics-tutorials.ws/opamp/opamp_5.html

E

 

You can also have an opamp with differential output like AD8138. The input can then be configured either as single ended or differential.

 

Differential input or differential output?
As @kubeek has pointed out, there are opamps that are available with differential outputs.

By definition, operational amplifiers have differential inputs, i.e. they amplify the voltage difference between the two inputs.
You can fix the voltage reference of either input to turn it into a single ended input amplifier.

 

Being a single ended or differential for opamp depends on type of device or just wiring ? I mean whether the opamp is same but our wiring makes it single ended or differential ? or opamp type makes it single ended or differential ? for example if I wire - of an opamp to ground it will be single ended if I don't it will be differential. Is it like that ?

I think the key to ending your confusion is to make a distinction between opamps and opamp circuits.

Opamps themselves have inputs that are inherently differential; that is, the opamp's output responds to the voltage difference between its two inputs. However, their gain factor (e.g., the ratio of output voltage change to input differential voltage change) is extremely high, anywhere from a couple thousand to hundreds of millions, varies wildly with temperature, and is different from one unit to the next.

Opamp application circuits seek to use the opamp's high open-loop gain along with feedback through discrete components to create a controlled input-output relationship which is determined by the feedback components rather than the characteristics of the opamp. And the opamp application circuit can be arranged to function in either single-ended or differential fashion, as desired.

 

I think the key to ending your confusion is to make a distinction between opamps and opamp circuits.

Opamps themselves have inputs that are inherently differential; that is, the opamp's output responds to the voltage difference between its two inputs. However, their gain factor (e.g., the ratio of output voltage change to input differential voltage change) is extremely high, anywhere from a couple thousand to hundreds of millions, varies wildly with temperature, and is different from one unit to the next.

Opamp application circuits seek to use the opamp's high open-loop gain along with feedback through discrete components to create a controlled input-output relationship which is determined by the feedback components rather than the characteristics of the opamp. And the opamp application circuit can be arranged to function in either single-ended or differential fashion, as desired.

Thanks for respond. As I understand from your respond. There is just one type of opamp ( I mean no distinction as single ended or differential) and my circuit makes it single ended or differential ?

 

I have a question about wiring analog input and measuring method.

It seems to me;

• 2 and 3 wire current analog input wiring is single ended measuring and is going to an amplifier in module that is single ended.
  
  
• 4 wire current analog input wiring is differential measuring and is going to an amplifier in module that is differential.
  
  
• Voltage input wiring is also same with 4 wire current which is differential.
  

My thinking is right or I am missing something ?

Thanks in advance.

 

Thanks for respond. As I understand from your respond. There is just one type of opamp ( I mean no distinction as single ended or differential) and my circuit makes it single ended or differential ?

Yup. Except, as @kubeek and @MrChips pointed out, there are a few opamps that have differential outputs as well.

 

My thinking is right or I am missing something ?

No, you're trying too hard to classify things based on strict rules. Just look at each circuit on a case-by-case basis, and understand what it does.

 

Some help -

https://www.analog.com/en/analog-dialogue/articles/deeper-look-into-difference-amplifiers.html


Regards, Dana.