Operate AD633 on Single 12VDC Supply

Papabravo

Joined Feb 24, 2006
17,240
My reading of the datasheet is an unequivocal NO! On page 3, under power supply, it is ±8 volts to ±18 volts. No wiggle room for single supply operation: the device requires bipolar supply voltages. I cannot imagine what you might have done besides an accident to blow one of these chips up.
 

Thread Starter

Sir Kit

Joined Feb 29, 2012
85
Yes, I too noticed that on the datasheet. But some op amps that are similarly specified can be adapted to single supply.

Perhaps my question should have been ... what is the simplest way to power an AD633 when the main circuit is 12VDC single supply?

Failing that, does anyone know of any multiplier specifically designed for single supply. I have had no luck so far.
 

Papabravo

Joined Feb 24, 2006
17,240
Yes, I too noticed that on the datasheet. But some op amps that are similarly specified can be adapted to single supply.

Perhaps my question should have been ... what is the simplest way to power an AD633 when the main circuit is 12VDC single supply?

Failing that, does anyone know of any multiplier specifically designed for single supply. I have had no luck so far.
What can I say - this is not an opamp. It is in fact a 4-quadrant multiplier.
 

Thread Starter

Sir Kit

Joined Feb 29, 2012
85
Still looking for a practical solution for my project, can anyone please assist in answering the following question from my most recent post.

... what is the simplest way to power an AD633 when the main circuit is 12VDC single supply?
 

ronsimpson

Joined Oct 7, 2019
1,630
The AD633 will not work at 12V. It will work at 24V with a virtual ground, which needs to be some where near 1/2 supply.

I have used "digital pots" as a multiplier. or some DACs have both the +ref and the -ref brought out and make multipliers.
What are you trying to do?
 

crutschow

Joined Mar 14, 2008
28,158
what is the simplest way to power an AD633 when the main circuit is 12VDC single supply?
You might use a switched-capacitor negative voltage converter such as the LTC1044. to generate -12V from the +12V supply.
Not only will that generate the necessary negative supply voltage for the multiplier, but you then also don't have to worry about offsetting the input signal to some pseudo-ground level.
 

Thread Starter

Sir Kit

Joined Feb 29, 2012
85
I didn't recognize that part until I checked the datasheet and saw it is the "same" as the LMC7660. I had considered a converter but wanted to eliminate any simpler options first. I will use it to power the AD633 only, not the entire circuit, which I assume is what crutchow meant.
 

crutschow

Joined Mar 14, 2008
28,158
You could also use a 555 circuit to generate the minus voltage (LTspice simulation below):
I show it powering the AD633 (only thing power by the minus voltage as you surmised).
The voltage is not -12V but about -9.7V due to the diode losses and the 555 output being a volt or two less than the +12V supply, but that should have no significant effect on your circuit application.

1626070363606.png
 

Thread Starter

Sir Kit

Joined Feb 29, 2012
85
It appears from its data sheet that the LTC1044 is limited to 9V. Neither suitable it seems for my 12V rail. But I like the LM555 solution better. Thanks so much for the sim. I will keep it on file. Cheaper too and I have the parts here without ordering.

If I may ask, you wouldn't happen to know a low parts count substitute for the AD 633.
 

sparky 1

Joined Nov 3, 2018
607
The easiest way is to buy a DC-DC Boost Step up Converter
The AD633 uses about 30VDC 8.4mA which is 4.2mA plus and 4.2mA minus split supply +/- 15VDC
As a frequency doubler under 15 MHz the quality of the sine wave is very good but the output needs a buffer stage.
A sine wave input of 2Vp-p has an output of 400mVp-p so that a buffer with a gain of 5 will output 2Vp-p.
 
Last edited:

Thread Starter

Sir Kit

Joined Feb 29, 2012
85
Exactly what does the multiplier need to do (signal levels and max frequency)?
I am seeking to randomize individual sine waves. All are 2Vpp and below 100Hz. In other words, randomly modulate its frequency and/or phasing by a factor of about 5-10%. This is for general test purposes, so accuracy of the output is not a concern. The modulation signal is very low-pass-filtered white noise.

If there is a way to do this in built circuitry, or achieve a roughly similar effect, without a quad multiplier I would be very appreciative to know what that might be.
 
Last edited:

crutschow

Joined Mar 14, 2008
28,158
Below is the LTspice simulation of a 1-quadrant multiplier using a PWM technique (discussion here), which may work for you.
As shown it's good for a maximum of about 250Hz input signal frequency.



1626182595682.png
 

Thread Starter

Sir Kit

Joined Feb 29, 2012
85
That is a fascinating schematic crutshow.

You specify a 5V supply. Will it operate as drawn on 12V and with the same input amplitudes?

What is the amplitude and frequency of the saw tooth wave at U2 inverting input. I would substitute function generator output for this first just to explore the concept.

For some reason, I was unable to access any of the Electro-Tech thread you linked, even though I was logged in. "You do not have permission to view the full content of this resource."
 
Top