08-01-2006 05:48 AM
08-02-2006 07:25 PM
One possibility I've thought of, which should be doable, is to build my own model/circuit piecemeal and then make it a subcircut. I'm pretty sure Multisim has a VCO, and then the phase detector could be duplicated from the real McCoy. Then, of course, the rest is a given.
But it'd be great if I coud find a model...
08-12-2006 01:45 PM
Well, I'm glad I didn't wait around...
Answer:
To model a phase locked loop in Multisim requires building the phase locked loop components on your own: the phase detector, the loop filter, and the VCO. For the VCO use the virtual voltage-controlled voltage source (VCVS). The loop filter is a given, just R and C and, perhaps, an op amp (a saturating one!). The phase detector schematic, at least the one I wanted (PD II), is available via Fairchild or a more esoteric one is available via Texas Instruments app notes.
However, via the TI app note for the 4046/7046HCT..., I found two equations and two unknowns for designing the loop filter after a few givens. So, rather than complete the Multisim simulation, I went to Excel, after manipulating the equations a little to get the two time constants I needed, and walla now I have a working PLL, and it worked beautifully the first time. Hence, maybe if I have tme, just for the heck of it, I'll (try to) simulate it. The hard part was the loop filter; I only wanted to simulate the PLL because I couldn't find good information on the loop filter design, but now I have it.
06-17-2007 11:51 AM
09-04-2007 03:59 PM
Great, thanks for sharing.
Gosh, I whish NI would go all the way with EWB as it is still needing improvements.
09-04-2007 06:53 PM
I would like to add something to this post that I think may be useful. I am going to post a circuit that I created using the Virtual PLL that no one, including myself, knew how to hook-up. I was examining Euler's Identity's circuit and tried to hook up the Virtual PLL based upon his connections. I came up with the following circuit. It seems to work, but I will let you all examine it and see if I am correct in my assumption.
If it is working properly, then all the credit for figuring this out should go to Euler's Identitiy because without his circuit I wouln't have been able to come up with my circuit.
Here it is:
09-04-2007 08:29 PM
09-05-2007 12:27 PM
09-05-2007 01:11 PM
The reason it doesn't seem to be working is that I had the scope on normal. If you put it to auto, then it should show an ouput signal. If you wouldn't mine trying that and let me know if works then I would greatly appreciate that.
You are probably right about it being analog. I tried a square wave and the signal was all distorted. Anyway, I tried and we have Euler's Circuit that we can use to create a component if we need to.
Thanks and Hava a Nice Day
12-06-2007 07:09 PM