Right, National was my "tutor" many years ago, long before the application note http://www.national.com/an/AN/AN-311.pdf was published. Look at it, it might give some hints.As you are no doubt aware, multiplication is a non-linear operation. The construction and use of non-linear circuits have numerous problems including the need to scale the output to prevent saturation.
The use of a logarithmic amplifier is straight forward, but the inverse operation of raising to a power has the problems of saturation and output scaling.
Check application notes from National Semiconductor for ideas on these beasties.
What frequency bandwidth, (or response time) do you need? If you need high speed (MHz for example) you will likely need an analog approach as discussed above. To avoid the difficult design work, you can buy an existing chip, but they are expensive.I am trying to design an voltage multipliers to calculate output voltage. output is a^b
Just about any old diode will work. Try a 1N914. The resistance value has to do with the end point of the input voltage. As the current through the resistor has to be matched by current through the diode, a reasonable resistance will keep the current below the output current limit of the op amp at the upper range of the input voltage.l want to know the model of diode and value of resistor
by Jake Hertz
by Aaron Carman
by Jake Hertz