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wccheng
Joined: 16 May 2004
Posts: 197
Helped: 1
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 19 Aug 2008 15:43 QVCO sim. fund=4GHz, it give the fund=2GHz. so strange!! |
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Dear all,
I simulate the QVCO using spectreRF. I have set the fundamental frequency = 4GHz. Actually, this circuit should operate at 4GHz. After simulating, it give the fundamental frequenyc is 2GHz (-80dB). The 2nd harmonic is 4GHz (the one I wanted). It gives -3dB. Actually, what is my problem? Why it will give out a strange frequency to me?
thanks
wccheng
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khouly
Joined: 20 Oct 2003
Posts: 2468
Helped: 341
Location: EGYPT
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| 19 Aug 2008 16:42 QVCO sim. fund=4GHz, it give the fund=2GHz. so strange!! |
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i think u need to increase the sampling frequency of ur simulation.
khouly
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BigBoss
Joined: 17 Nov 2001
Posts: 928
Helped: 47
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| 19 Aug 2008 17:36 QVCO sim. fund=4GHz, it give the fund=2GHz. so strange!! |
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| Increase the estimated osc frequency.This should be as close as possible to wanted one..
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wccheng
Joined: 16 May 2004
Posts: 197
Helped: 1
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| 20 Aug 2008 1:27 QVCO sim. fund=4GHz, it give the fund=2GHz. so strange!! |
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| How could I increase the sampling rate of the simulation setting?
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BigBoss
Joined: 17 Nov 2001
Posts: 928
Helped: 47
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| 20 Aug 2008 10:36 Re: QVCO sim. fund=4GHz, it give the fund=2GHz. so strange! |
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Look at this ...
 [/code]
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wccheng
Joined: 16 May 2004
Posts: 197
Helped: 1
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| 21 Aug 2008 8:32 QVCO sim. fund=4GHz, it give the fund=2GHz. so strange!! |
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| However, my predicted osc freq is around 4GHz. If I set this is too high, willi it cause problem?
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jecyhale
Joined: 19 Feb 2008
Posts: 442
Helped: 46
Location: China
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| 21 Aug 2008 8:52 Re: QVCO sim. fund=4GHz, it give the fund=2GHz. so strange! |
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| wccheng wrote: |
Dear all,
I simulate the QVCO using spectreRF. I have set the fundamental frequency = 4GHz. Actually, this circuit should operate at 4GHz. After simulating, it give the fundamental frequenyc is 2GHz (-80dB). The 2nd harmonic is 4GHz (the one I wanted). It gives -3dB. Actually, what is my problem? Why it will give out a strange frequency to me?
thanks
wccheng |
Do you design a prescaler (divider by 2) follow the VCO?
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wccheng
Joined: 16 May 2004
Posts: 197
Helped: 1
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| 22 Aug 2008 1:04 QVCO sim. fund=4GHz, it give the fund=2GHz. so strange!! |
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| surely NO.
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