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Adam2008
Joined: 02 Jan 2008
Posts: 31
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 18 Aug 2008 20:17 How to realize the voltage reference? |
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Hi,
I am developing a charge pump PLL. If I am using the charge pump circuit in Razavi's book. how can I realize the two gate voltage of the current sources? Shall I use voltage reference?
Thank you.
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safwatonline
Joined: 19 Nov 2005
Posts: 1349
Helped: 164
Location: EGYPT
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| 18 Aug 2008 22:59 How to realize the voltage reference? |
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use a bias current generator
i.e. current is generated from bias cell then mirrored to the CP
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Adam2008
Joined: 02 Jan 2008
Posts: 31
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| 19 Aug 2008 14:23 Re: How to realize the voltage reference? |
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Thanks.
Could you give more detail about the bias current generator?
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jecyhale
Joined: 19 Feb 2008
Posts: 442
Helped: 46
Location: China
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| 21 Aug 2008 9:07 Re: How to realize the voltage reference? |
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| Adam2008 wrote: |
Hi,
I am developing a charge pump PLL. If I am using the charge pump circuit in Razavi's book. how can I realize the two gate voltage of the current sources? Shall I use voltage reference?
Thank you. |
NO, gate voltage is detemined by the Id of it. You should design current bisa. After you have a constant (some range) current, use current mirror as the current source.
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