multiplication using analogLib components

[rover8898]

Hello all,

I feel quite daft for having to ask this:

I am working with Cadence's analog artist environment + Virtuoso
schematic editor. I want to multiply 2 voltages (for testbench
purposes). I can not seem to find a way to do this using the vccs,
cccs dependant sources. Is there a way a simple way to do this ?

(I want to use the product of the voltages to control a vccs in order
to emulate a current path)

Any help will be appreciated.
-Roger

 

[gert1999]

On 16 dec, 21:41, rover8898 <rover8...@gmail.com> wrote:

Hello all,

I feel quite daft for having to ask this:

I am working with Cadence's analog artist environment + Virtuoso
schematic editor. I want to multiply 2 voltages (for testbench
purposes). I can not seem to find a way to do this using the vccs,
cccs dependant sources. Is there a way a simple way to do this ?

(I want to use the product of the voltages to control a vccs in order
to emulate a current path)

Any help will be appreciated.
-Roger

Hi

This used to be done with analog multipliers eg AD633. It is a basic
IC that simply calculates the multiplication of 2 voltages
The problem is that those IC's have become very hard to get as in
modern solutions this kind of problem is solved digital

Several years ago I got the same problem in a design and was very
lucky to get a free sample.
I think it might be possible to build the circuit with operational
amplifiers with a special construction of multiple feedback to get the
same result

I hope this might help

Gert

 

[Bob Masta]

On Sat, 20 Dec 2008 08:23:57 -0800 (PST), gert1999
<ggddbb@gmail.com> wrote:

On 16 dec, 21:41, rover8898 <rover8...@gmail.com> wrote:
Hello all,

I feel quite daft for having to ask this:

I am working with Cadence's analog artist environment + Virtuoso
schematic editor. I want to multiply 2 voltages (for testbench
purposes). I can not seem to find a way to do this using the vccs,
cccs dependant sources. Is there a way a simple way to do this ?

(I want to use the product of the voltages to control a vccs in order
to emulate a current path)

Any help will be appreciated.
-Roger

Hi

This used to be done with analog multipliers eg AD633. It is a basic
IC that simply calculates the multiplication of 2 voltages
The problem is that those IC's have become very hard to get as in
modern solutions this kind of problem is solved digital

Several years ago I got the same problem in a design and was very
lucky to get a free sample.
I think it might be possible to build the circuit with operational
amplifiers with a special construction of multiple feedback to get the
same result

I can't help you with simulation, but I can tell
you that there is no way to build a multiplier
with ordinary op-amps alone as the active
elements. Analog multipliers are typically
special nonlinear circuits that look sorta like
two differential pairs stacked together. They
usually need a lot of supporting Rs to set biases
and offsets. The RC4200 is one example.

You can use an Operational Transconductance
Amplifier like the CA3080 to make a simple
2-quadrant multiplier.

You can also use log amps, even homebrew versions
using diode nolinearities if you don't need great
accuracy.

For low frequencies, a common multiplier method is
to use one input to control a pulse width
modulator which chops the other input, then
average the result.

Probably a few methods I missed, but the take-home
message is that analog multiplication is
non-trivial in the real world.

Best regards,


Bob Masta

DAQARTA v4.51
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Sound Level Meter
FREE Signal Generator
Science with your sound card!

 

[Andrew Holme]

"Bob Masta" <N0Spam@daqarta.com> wrote in message
news:494e511a.1122928@news.sysmatrix.net...

On Sat, 20 Dec 2008 08:23:57 -0800 (PST), gert1999
ggddbb@gmail.com> wrote:

On 16 dec, 21:41, rover8898 <rover8...@gmail.com> wrote:
Hello all,

I feel quite daft for having to ask this:

I am working with Cadence's analog artist environment + Virtuoso
schematic editor. I want to multiply 2 voltages (for testbench
purposes). I can not seem to find a way to do this using the vccs,
cccs dependant sources. Is there a way a simple way to do this ?

(I want to use the product of the voltages to control a vccs in order
to emulate a current path)

Replying to Bob's post because I don't see gmail posts:

Can't comment on Analog Artist; but in LTSpice I use the "arbitrary
behavioral voltage source" e.g.

SYMATTR InstName B1
SYMATTR Value V=V(carrier)*V(env)