Differential to Single Ended

[hebu]

convert differential op amp

In integrated circuit, we utilize differential ckt to overcome the common mode
noise, but I need to make the differential signal into single ended fomat, how
I cancel the common mode noise?
Any ckt schematic?

 

[ze_dib]

differential ckt

Hi,

What do you mean by ckt ?

Usually, you convert differential to single endded signal by using an op-amp in non inverter mode. The positive input of the Op-Amp is connected by a avoltge divider.

When the two resistors of the Amplifier and the two resistors of the voltage divider are equal, you do a conversion, without amplification, and you have the Op-Amp rejection ratio for common mode perturbations.

Hope I helped

Ze_DIB

 

[estradasphere]

Hi,

There two possibilities that are known to me. The first one is that you use a balun at your output. Since there is a phase difference of 180° between each path of your balun, the common-mode, such as noise or local oscillator signal in a double-balanced mixer is cancelled. Your differential signals become at the output of your balun in-phase.

The second possibility is to use a current mirror just like in op-amps (please razavi's gray-meyer's book). In this configuration, since the phase difference between gate and drain is 180°, the common-mode is again cancelled, whereas your differential signals become in-phase.

hope this helps

 

[pit]

Hello!

What do you mean with ckt?

And how is the relation between common noise and your signal?

If you have a balanced signal with common mode noise you can use either a transformer or an op amp (differential amplifier) to turn the signal into a single ended signal. With a differential opamp circuit you can cancel the common mode noise.

May you could explain your circuit in more details so we can help you better?


Greetings

 

[hebu]

Thanks, ze_dib
A substractor like you told me can do this.

For pit,
how can you control the output dc voltage if you just use
the OTA like ckt?

Thanks,

 

[pit]

Hello!

What do you mean with "ckt"?

Greetings

 

[hebu]

ckt=circuit ^_^

 

[power-twq]

as long as he input stage is differential,

then the input common mode noise will besupressed.

then the following stage can output single ended signal.

best regards

In integrated circuit, we utilize differential ckt to overcome the common mode
noise, but I need to make the differential signal into single ended fomat, how
I cancel the common mode noise?
Any ckt schematic?