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Q&A Differential current signal to single-ended voltage conversion

I’m looking for circuits which convert differential current signal into single ended voltage. If found two topologies in application notes, and though of one more [obvious] topology myself. How d...

0 answers · posted 2d ago by misk94555‭ · edited 2d ago by misk94555‭

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#2: Post edited by

misk94555‭ · 2025-01-19T18:58:07Z (2 days ago)

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I’m looking for circuits which convert differential current signal into single ended voltage. If found two topologies in application notes, and though of one more [obvious] topology myself. How do they compare?
The app notes where I found these circuits are about converting a differential current DAC output to single ended voltage.
The 1st topology runs the DAC currents through resistors. The resulting voltages are converted to single-ended by running them through a voltage diff op-amp.
![schematic snippet](https://electrical.codidact.com/uploads/41pmmgibj8l6968zwod1ymdvdc9t)
The 2nd topology converts the DAC currents to voltage using transimpedance amplifiers (TIA). The voltages are converted to single-ended by running them through a voltage diff op-amp.
![schematic snippet](https://electrical.codidact.com/uploads/vluzyh0944a1towgcahgfs28cj33)
The 3rd topology converts one side of the differential pair using a TIA. The other side goes through a resistor to ground, and the resulting offset provides an offset for the TIA. It seems fairly obvious, but I haven’t seen it in app notes. I wonder why it didn’t make it into app notes.
![schematic snippet](https://electrical.codidact.com/uploads/wjplyqk89ffccoqfjcbmkkkk8ksg)
<h3>Context</h3>
While these circuits came from a current output DAC app notes, my application doesn’t have a current output DAC.
My question originates from [this answer](https://electrical.codidact.com/posts/293080) which mentions external noise pickup. My differential current signal will pick up mains AC, and AM stations. Mains AC frequencies fall in the band of my signal. My proposed solution is to create the second inverse summing node, inject the inverse of each of the additive signal into it, subtract the differential summing nodes at the end.
DAC outputs shouldn’t pick up a lot of interference (no counting DC offsets), if the current to voltage conversion happen on the same board. (Is it common to run differential current outputs from a DAC through a cable, and convert to voltage on the other end of the cable?)
<h3>Referenced app notes</h3>
https://www.ti.com/lit/an/sbaa333a/sbaa333a.pdf
https://www.analog.com/media/en/training-seminars/tutorials/MT-019.pdf

I’m looking for circuits which convert differential current signal into single ended voltage. If found two topologies in application notes, and though of one more [obvious] topology myself. How do they compare?
The app notes where I found these circuits are about converting a differential current DAC output to single ended voltage.
The 1st topology runs the DAC currents through resistors. The resulting voltages are converted to single-ended by running them through a voltage diff op-amp.
![schematic snippet](https://electrical.codidact.com/uploads/41pmmgibj8l6968zwod1ymdvdc9t)
The 2nd topology converts the DAC currents to voltage using transimpedance amplifiers (TIA). The voltages are converted to single-ended by running them through a voltage diff op-amp.
![schematic snippet](https://electrical.codidact.com/uploads/vluzyh0944a1towgcahgfs28cj33)
The 3rd topology converts one side of the differential pair using a TIA. The other side goes through a resistor to ground, and the resulting offset provides an offset for the TIA. It seems fairly obvious, but I haven’t seen it in app notes. I wonder why it didn’t make it into app notes.
![schematic snippet](https://electrical.codidact.com/uploads/wjplyqk89ffccoqfjcbmkkkk8ksg)
<h3>Context</h3>
While these circuits came from a current output DAC app notes, my application doesn’t have a current output DAC.
My question originates from [this answer](https://electrical.codidact.com/posts/293080) which mentions external noise pickup. The summing node will pick up mains AC, and AM stations. Mains AC frequencies fall in the band of my signal. My proposed solution is to create the second inverse summing node, inject the inverse of each of the additive signal into it, subtract the differential summing nodes at the end.
DAC outputs shouldn’t pick up a lot of interference (no counting DC offsets), if the current to voltage conversion happen on the same board. (Is it common to run differential current outputs from a DAC through a cable, and convert to voltage on the other end of the cable?)
<h3>Referenced app notes</h3>
https://www.ti.com/lit/an/sbaa333a/sbaa333a.pdf
https://www.analog.com/media/en/training-seminars/tutorials/MT-019.pdf

#1: Initial revision by

misk94555‭ · 2025-01-19T18:50:43Z (2 days ago)

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Differential current signal to single-ended voltage conversion

The app notes where I found these circuits are about converting a differential current DAC output to single ended voltage.

The 1st topology runs the DAC currents through resistors. The resulting voltages are converted to single-ended by running them through a voltage diff op-amp.

![schematic snippet](https://electrical.codidact.com/uploads/41pmmgibj8l6968zwod1ymdvdc9t)

The 2nd topology converts the DAC currents to voltage using transimpedance amplifiers (TIA). The voltages are converted to single-ended by running them through a voltage diff op-amp.

![schematic snippet](https://electrical.codidact.com/uploads/vluzyh0944a1towgcahgfs28cj33)

The 3rd topology converts one side of the differential pair using a TIA. The other side goes through a resistor to ground, and the resulting offset provides an offset for the TIA. It seems fairly obvious, but I haven’t seen it in app notes. I wonder why it didn’t make it into app notes.

![schematic snippet](https://electrical.codidact.com/uploads/wjplyqk89ffccoqfjcbmkkkk8ksg)

<h3>Context</h3>
While these circuits came from a current output DAC app notes, my application doesn’t have a current output DAC.

My question originates from [this answer](https://electrical.codidact.com/posts/293080) which mentions external noise pickup. My differential current signal will pick up mains AC, and AM stations. Mains AC frequencies fall in the band of my signal. My proposed solution is to create the second inverse summing node, inject the inverse of each of the additive signal into it, subtract the differential summing nodes at the end.

DAC outputs shouldn’t pick up a lot of interference (no counting DC offsets), if the current to voltage conversion happen on the same board. (Is it common to run differential current outputs from a DAC through a cable, and convert to voltage on the other end of the cable?)

<h3>Referenced app notes</h3>

https://www.ti.com/lit/an/sbaa333a/sbaa333a.pdf
https://www.analog.com/media/en/training-seminars/tutorials/MT-019.pdf

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