Can Opamps Square Input Signals?

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Discussion Overview

The discussion revolves around the capability of operational amplifiers (opamps) to square input signals. Participants explore whether opamps can produce an output that is the square of the input voltage, as well as alternative methods for achieving this function.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions if opamps can output the square of an input voltage, providing examples of input-output pairs (2 volts to 4 volts, 5 volts to 25 volts).
  • Another participant suggests that to obtain squares and square roots, a four quadrant multiplier like the MC 1494 is necessary, and mentions an analog solution using the square law characteristics of diodes or FETs, noting the complexity of setup.
  • A request for clarification on using diodes for squaring and square rooting is made, with a specific interest in techniques that would yield an output of n*n for an input of n volts.
  • A reference to a circuit from an external source is provided, discussing the use of transistors in a transdiode configuration for improved performance over standard diodes.
  • A repeated inquiry about the feasibility of squaring with opamps is made, alongside a question about the possibility of using an ADC, microcontroller, and DAC instead of solely relying on opamps.

Areas of Agreement / Disagreement

Participants do not reach a consensus on whether opamps can directly square input signals, and multiple competing views regarding the methods to achieve squaring remain present.

Contextual Notes

Some participants mention specific components and configurations that may be necessary for squaring functions, but the discussion does not resolve the limitations or assumptions associated with these methods.

Who May Find This Useful

Individuals interested in analog electronics, particularly those exploring the capabilities and limitations of operational amplifiers and alternative methods for signal processing.

XuFyaN
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can opamp work this way ??

can opamp work this way ..?

when i input 2volts the output is 4volts , when i input 5 volts the output is 25 volts

in simple words can opamp takes the square of input signals ??

is it possible ? i know how it work as differentiator, integrator, Summing amp but what about squaring ?
 
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To obtain squares and square roots you need a four quadrant multiplier, such as the MC 1494.

There is an analog solution using the square law characteritic of diodes or FETs but they are tricky to set up.
 


can you please help about using diodes for squaring and square rooting ? what technique we use for squaring ?

like if we Apply n volts the output must b n*n
or simply sum of n times ,
like if we apply 5 volts the output must be 5+5+5+5+5
 


Review the circuit in

http://www.analog.com/library/analogDialogue/bestof/pdf/19_1.pdf

The transistors are working in essentially the transdiode configuration, because they give superior diode lograrithmic performance than real diodes. Look at the equations Eq (1) thru (6). The (kT/q) log function is the ideal diode I-V response.

Bob S
 


XuFyaN said:
can opamp work this way ..?

when i input 2volts the output is 4volts , when i input 5 volts the output is 25 volts

in simple words can opamp takes the square of input signals ??

is it possible ? i know how it work as differentiator, integrator, Summing amp but what about squaring ?

Are you constrained to using opamps? Can you use an ADC + Microcontroller + DAC instead?
 

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