PSpice 9.1 Current Controlled Current Source (F)

[DaveLessnau]

This ought to be easy, so I'm embarrased. But, can anyone clear up how
to use a current-controlled current source (part "F") in PSpice 9.1?
To get it to measure the controlling current, I have to connect the two
measuring terminals with a resistor in between them. However, it then
looks like PSpice treats the path through the CCCS as a short-circuit.
So, I guess I have to attach a resistor someplace in that path. But,
what value resistor? The same as the one between the two connection
points? Or, do I have to come up with a combination of two parrallel
resistors with an equivalent resistance equal to the resistance
originally between the two connection points?

 

[Jim Thompson]

This ought to be easy, so I'm embarrased. But, can anyone clear up how
to use a current-controlled current source (part "F") in PSpice 9.1?
To get it to measure the controlling current, I have to connect the two
measuring terminals with a resistor in between them. However, it then
looks like PSpice treats the path through the CCCS as a short-circuit.
So, I guess I have to attach a resistor someplace in that path. But,
what value resistor? The same as the one between the two connection
points? Or, do I have to come up with a combination of two parrallel
resistors with an equivalent resistance equal to the resistance
originally between the two connection points?

No resistor needed in the sensing path... it's a zero-volt voltage
source.

The _output_ is a current source (selectable gain), but you need to
load it with something to avoid floating node issues.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

It's what you learn after you know it all that counts.

 

[Charlie Edmondson]

This ought to be easy, so I'm embarrased. But, can anyone clear up how
to use a current-controlled current source (part "F") in PSpice 9.1?
To get it to measure the controlling current, I have to connect the two
measuring terminals with a resistor in between them. However, it then
looks like PSpice treats the path through the CCCS as a short-circuit.
So, I guess I have to attach a resistor someplace in that path. But,
what value resistor? The same as the one between the two connection
points? Or, do I have to come up with a combination of two parrallel
resistors with an equivalent resistance equal to the resistance
originally between the two connection points?

Dave,
The inputs don't actually exist as a pin connection in 9.1, they are
just sense points. What you need the resistor for is two-fold. First,
it provides a second connection point, so you don't get an unconnected
pin warning. Second, if the other end is grounded, it provides a DC
path to ground to prevent floating nodes. Usually, a very high value
resistor prevents any loading effects.

Charlie