Designer’s Guide Community

‹ Previous topic | Next topic ›

Pages: 1

question on the "ddt" usage (Read 2789 times)

Patrick520

New Member

Offline

Posts: 4
Hong Kong

question on the "ddt" usage
Apr 03^rd, 2011, 8:12am

Hi!
I am new to verilogA.
I wanna describes an analog block which has a function of differentiating.
So, I describes a sentence as below:

"V(out)<+ ddt(V(in))"

But however, when using spectre to simulate it.
There is error like "V（t0,out）= 6.28 GV exceeds the blowup limit".

There is a case. When the input wave voltage changes very sharp, the differential result will be infinitely large.
So how to describe a bound for the differentiated value? How to set the limit?

Thanks in advance.

IP Logged

Sumit Adhikari Community Member Offline Posts: 44	Re: question on the "ddt" usage Reply #1 - Apr 3^rd, 2011, 12:38pm There are two questions : 1. How is the input signal in nature ? 2. What is that the output is driving ? Regards, Sumit
Back to top	IP Logged

boe Community Fellow Offline Posts: 615	Re: question on the "ddt" usage Reply #2 - Apr 4^th, 2011, 1:50am Patrick520, What do you want to do? Increase the blowup limit (for which simulator?) or change the value of the derivative? B O E
Back to top	IP Logged

Geoffrey_Coram Senior Fellow Offline Posts: 1999 Massachusetts, USA	Re: question on the "ddt" usage Reply #3 - Apr 4^th, 2011, 12:04pm Patrick520 wrote on Apr 3^rd, 2011, 8:12am: Hi! There is a case. When the input wave voltage changes very sharp, the differential result will be infinitely large. So how to describe a bound for the differentiated value? How to set the limit? Verilog-A provides the "slew" filter to do this, I believe.
Back to top	If at first you do succeed, STOP, raise your standards, and stop wasting your time. IP Logged

Pages: 1

‹ Previous topic | Next topic ›