The Designer's Guide Community Forum
https://designers-guide.org/forum/YaBB.pl Design >> Analog Design >> Switched Cap. filter https://designers-guide.org/forum/YaBB.pl?num=1127699684 Message started by atul on Sep 25th, 2005, 1:25pm |
Title: Switched Cap. filter Post by atul on Sep 25th, 2005, 1:25pm Hi, i am designing a switch capacitor filter which is used in GSM technology by using spectreRF available in Cadence 5.3 version first step i have learned how to do simulation of spectreRF. Second step i have designed a simple low pass passive filter and replaced the resistance by capacitance and 2 nmos driven by clock. problem i couldnot make clocks i used 2 vpulses sources having max and min. voltages are opposites to avoid overlapping. this is not proper can anyone please tell me how to design a clock for switched capa. filter or is it available in library of cadence. also i could not able to change the resistance value. please help me, VERY URGENT [flash=200,200][/flash] |
Title: Re: Switched Cap. filter Post by Paul on Sep 25th, 2005, 2:20pm Hi Atul atul wrote on Sep 25th, 2005, 1:25pm:
If you explain what doesn't work it would be easier to help. Maybe you can post the definitions of the sources from the netlist. You can use vpulse sources to generate your clocks, provided you define the parameters correctly. Quote:
What do you mean by this? Did you try to change the capacitor value/frequency? Paul |
Title: Re: Switched Cap. filter Post by atul on Sep 25th, 2005, 3:02pm thanks paul for reply. i could not do the complete simulation as it showed the errors, the error message: Internal error found in spectre during periodic steady state analysis `pss'. Please run `getSpectreFiles' or send the netlist, the spectre log file, the behavioral model files, and any other information that can help identify the problem to support@cadence.com. Assertion failed in file `devices.c' at line 4587. Assertion failed. i could not able to locate the devices.c or run the getSpectreFiles. my circuit is right, i mean it is very basic circuit to design a switched cap filter. i am not sure about the clock. i am using primlibRF library components About the resistor, i am using poly2RF resistor available in primlibRF library, i could not able to change the value i want 10 kilo ohm, i can't, it can change max. to 5 kilo ohm, so i am adding the 2 resistor in series. But this is very simple circuit, for large circuit it will be very difficult. paul one more thing do you know where i can get the schematic of switched capacitor filter which is implemented in cadence. again thanks for replied, |
Title: Re: Switched Cap. filter Post by Paul on Sep 25th, 2005, 3:18pm This makes things a little clearer. As I am not a regular user of SpectreRF, I'm not sure to be able to answer your questions. I guess SpectreRF would like to see a single source defining the sampling clock. Try using a VCVS for the second clock signal. For the resistors, I thought you were talking about the switched cap equivalent resistor. I cannot help on this one. Paul |
Title: Re: Switched Cap. filter Post by Ken Kundert on Sep 25th, 2005, 6:49pm This error message is reporting an "Internal Error", also known as a bug. The file devices.c is part of the source code of Spectre. You should report this problem to Cadence. Given your unfamiliarity with Spectre, perhaps the problem is due to the way you describe the sources or analysis. Perhaps you can post those sections of the netlist? -Ken |
The Designer's Guide Community Forum » Powered by YaBB 2.2.2! YaBB © 2000-2008. All Rights Reserved. |