This may sound very naive and impractical question, and most likely the answer is negative, but still: is there any more or less simple (simpler than ADC/DAC) analog component or circuit, which makes modulo operation on the value of voltage, given Vref?

For example, if Vref = 1V and input V = 11.56V, then the device will produce 0.56V. Similarly, with Vref=2V, the same input will give 1.56V. Of course, Vinput must be from some sensible range.

If such a thing exists, then it can be used to make a new(?) type of ADC.

UPDATE: I am aware, that modulo function (applied to time) is just a sawtooth http://en.wikipedia.org/wiki/Sawtooth_wave , so there may be some solution involving linearly turning voltage to time period, then reading the sawtooth value.


Such circuits are already part of many existing ADCs, so if your main goal is just to make a new type of ADC, you might be disappointed.

For an example, see this Analog Devices article about the architecture of a folding ADC. On page 2, it shows a single stage resulting in a 1-bit digitization and a residue voltage, which is the same as the modulo of the voltage. It is only modulo \$V_{ref}/2\$, but by cascading \$n\$ stages you can get the residue modulo \$V_{ref}/2^n\$. The schematic from the article:

single stage

  • \$\begingroup\$ This is exactly what I was looking for. Funny, that more than half a century ago this method was unusual: B. D. Smith, "An Unusual Electronic Analog-Digital Conversion Method," IRE Transactions on Instrumentation, June 1956, pp. 155-160. \$\endgroup\$ – Roman Susi Jul 31 '13 at 12:34

This is exactly what the low bits of a A/D provide. For example, if you have a 12 bit A/D with a 5 V reference, then the low 8 bits of the result will give you the input voltage modulo 313 mV.

You say you want something simpler than a A/D, but that means you apparently don't know how simple these things are. Everything else I can imagine would either require some sort of partial A/D conversion inside, or have a bunch of level shifters and comparators and the like. A A/D is a single-chip solution that gets you what you want directly. Much of the time a A/D will be even simpler because it is built into a microcontroller you are using for other reasons anyway. The added complexity is wiring the analog signal input a particular pin and a little firmware.

  • \$\begingroup\$ Thank you. This is a valid answer too, but the idea was to do it in analog domain. I can even imagine, that it's cheaper to chain ADC and DAC, than to implement an ADC stage. \$\endgroup\$ – Roman Susi Jul 31 '13 at 12:40

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.