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https://designers-guide.org/forum/YaBB.pl Design >> RF Design >> Help on Passive Bandpass Filter with Spectre https://designers-guide.org/forum/YaBB.pl?num=1105639859 Message started by alesi616 on Jan 13th, 2005, 10:10am |
Title: Help on Passive Bandpass Filter with Spectre Post by alesi616 on Jan 13th, 2005, 10:10am Hi all, I currently working on Passive RF Bandpass Filter for CDMA2000 standard. Below are the specs. Center Frequency = 1.9GHz Bandwidth = 200MHz topology = 2nd order Butterworth (with Q-enhanced resonator) 1) is it filter Gain response = Insertion Loss?? 2) with Cadence Spectre, I have to show the filter response with AC Gain& Phase plot or S21 (Insertion Loss) plot from S-parameter?? because i notice that both of the graphs won't be the same, which plot should I use for my filter's response?? really confuse about it.......need help..... How about the Phase response?? is it important for bandpass Filter?? 3) for Return Loss (S11), should it be more negative or less negative to better?? what are the values for my specs?? 4) for 1-dB Cpmpression Point and IIP3 plot, should it be bigger or smaller to better?? what are the values for my specs?? 5) how about the Noise Figure?? what are the suitable value for my circuit in 1.9GHz ranges and CDMA application?? Helps are needed....thanx!! |
Title: Re: Help on Passive Bandpass Filter with Spectre Post by sheldon on Jan 14th, 2005, 8:15am Greetings, Could you provide some additional information about the filter? Are you using a model from rfLib to model the filter? Are you using the Verilog-A laplace function to model the filter? Are you using s-parameter data, n-port, to model the filter? 1) 2) In general, s-parameter and ac analysis should not match. Ac analysis is peformed in the voltage domain and s-parameters calculated from the normalized power wave response (forgot the exact term) Circuit designers will probably find the ac characteristics easier to understand and RF designers will probably prefer s-parameters Since phase response is related to group delay, it is very important for filters. The "flatter" the group delay the less data is distorted going through the filter. 3) Less return loss is better. 4) Passive filters should have infinite IP3 and P1dB 5) Noise Figure is determined by insertion loss Best Regards, Sheldon |
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