Frustration with Vendors!
in [FPGA]
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From: Nial Stewart on 27 Feb 2010 07:16 > I really have to say that paying for Hyperlynx once is a lot cheaper > than fixing board, after board, with bad SI. In fact one re-spin of > the pcb is about what the tool costs. Austin, You've posted this a few times. I've had a look at the Mentor web site for costs before but as usual they aren't mentioned. I don't want to contact them for pricing as it'll probably lead to being pestered by a rep. Does anyone know how much you'd pay for a one off license (US $ will do, although we probably pay the same in GBP as with most EDA tools)? Nial ---------------------------------------------------------- Nial Stewart Developments Ltd Tel: +44 131 516 8883 32/12 Hardengreen Business Park Fax: +44 131 663 8771 Dalkeith, Midlothian EH22 3NX www.nialstewartdevelopments.co.uk
From: Symon on 27 Feb 2010 08:59 On 2/26/2010 10:46 PM, -jg wrote: > > Why is there no simple Spice pathway to allow users do the 'sanity > check' stuff themselves ? > Because Spice models reveal more about the actual structure of the device than the vendors are prepared to give. The IBIS table based method keeps this proprietary information hidden. Syms.
From: Symon on 27 Feb 2010 09:13 On 2/27/2010 11:53 AM, Kolja Sulimma wrote: > > > If there are no transmission line effects involved there will be no > overshoot. Below, please find a LTSpice model with only lumped components that produces overshoots. > Clock lines should always be terminated. Not always. For example, if the rise time of the clock is longer than a sixth of the trace delay, you almost certainly don't need to worry about termination. If the trace delay is longer than the rise time, you almost certainly do need to worry about it. http://www.sigcon.com/Pubs/straight/termcraz.htm HTH., Syms. Model:- Version 4 SHEET 1 880 680 WIRE 176 48 96 48 WIRE 336 48 256 48 WIRE 96 96 96 48 WIRE 336 96 336 48 WIRE 96 208 96 176 WIRE 336 208 336 160 FLAG 96 208 0 FLAG 336 208 0 SYMBOL voltage 96 80 R0 WINDOW 3 -16 165 Left 0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V1 SYMATTR Value PULSE(0 1 0 1n 1n 9n 20n) SYMBOL ind 272 32 R90 WINDOW 0 5 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName L1 SYMATTR Value 1n SYMBOL cap 320 96 R0 SYMATTR InstName C1 SYMATTR Value 10p TEXT 62 266 Left 0 !.tran 100ns
From: Symon on 27 Feb 2010 09:20 On 2/27/2010 2:30 AM, rickman wrote: > > The problem started when we found the original setting produced a > rising edge so slow that it created multiple pulses on a clock line. > The board worked ok in the original chassis, but the new customer > design uses a faster FPGA to receive the clock and had failures. > I expect the actual failure was the newer FPGA occasionally saw the slow falling edge of the clock as a rising edge. It sounds like your clock frequency is low, why don't you just build a falling edge glitch filter in the new FPGA? Syms.
From: austin on 27 Feb 2010 14:27
Re: Spice I know that hspice has an interface to allow IBIS models to be declared, and used, with the spice netlist. I suspect, "real" spice tool vendors expect one to pay for this sort of feature, which is not part of the free UC Berkeley spice source code (on which all the free spice versions are 'based.') So, someone has to code the .model additions to the spice program to deal with the IBIS data files. Unless they are doing it for fun, they probably wish to get paid for their work: I would need some monetary motivaion now, as coding might have been 'fun' when I was 14 years old, but that was a long time ago. So, yes Hyperlynx ia not free, and neither is hspice. If everything used, free? I can not imagine that everyone out there is using free schematic, free pcb layout, etc. tools! Someone might be, but that must be the hobby type, or student (although students usually have free access to dozens of very powerful tools, if they would only ask their professor!). Anyone with a business can certainly justify paying for something useful, that would save them time (or money). I am a ham radio operator (AB6VU), and I do have my own collection of useful free stuff, but even I have purchased some of my hobby software when necessary (but, I will admit, I don't own any hobby software with more than a $100 price tag). Austin |