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Henry-cool
Joined: 21 Jul 2008
Posts: 27
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 22 Aug 2008 5:46 Power Amp Question(Skywork CX77144) |
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Dear all~!!
I have a quesion about CX77144(Power Amplifier Module for CDMA(887M~925MHz))
In case: Power setting => High Power
If RF input power is 5dBm, what is CX77144's output power?
Is still the output power 27dBm or the output power increase above 27dBm?
(Data sheet: High power setting => Output power: 18dBm to 27dBm)
If output power still increases, what is the maximun output power?
Thanks~!
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vfone
Joined: 10 Oct 2001
Posts: 1767
Helped: 232
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| 22 Aug 2008 7:24 Re: Power Amp Question(Skywork CX77144) |
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The gain of the PA is approximately 27dB (depends by mode).
The maximum linear output power is 27dBm (to meet CDMA specifications)
That means the maximum input power to meet the linearity spec is 0dBm.
At 5dBm the PA is in compression and it will fail the ACPR and EVM specifications.
This PA has two functions mode. Low Gain = 24dB with Pout=18dBm, and High Gain = 27.5 with Pout=27dBm, and the maximum input level shall be according the gain of each mode (-6dBm for Low Gain, and 0dBm for High Gain)
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Henry-cool
Joined: 21 Jul 2008
Posts: 27
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| 25 Aug 2008 1:49 Re: Power Amp Question(Skywork CX77144) |
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| vfone wrote: |
The gain of the PA is approximately 27dB (depends by mode).
The maximum linear output power is 27dBm (to meet CDMA specifications)
That means the maximum input power to meet the linearity spec is 0dBm.
At 5dBm the PA is in compression and it will fail the ACPR and EVM specifications.
This PA has two functions mode. Low Gain = 24dB with Pout=18dBm, and High Gain = 27.5 with Pout=27dBm, and the maximum input level shall be according the gain of each mode (-6dBm for Low Gain, and 0dBm for High Gain) |
Thank you for reply~!
But,
In data sheet, Maximum RF Input power is 7dBm.
If RF Input power is 7dBm, the power amp still can have good linearity that satisfy CDMA Spec?
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vfone
Joined: 10 Oct 2001
Posts: 1767
Helped: 232
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| 26 Aug 2008 9:05 Re: Power Amp Question(Skywork CX77144) |
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| No
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Henry-cool
Joined: 21 Jul 2008
Posts: 27
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| 28 Aug 2008 2:53 Re: Power Amp Question(Skywork CX77144) |
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Thanks~!!
Do you know the PA's P1dB(input-referred) in High Gain?
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vfone
Joined: 10 Oct 2001
Posts: 1767
Helped: 232
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| 28 Aug 2008 12:34 Re: Power Amp Question(Skywork CX77144) |
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| 28dBm
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Henry-cool
Joined: 21 Jul 2008
Posts: 27
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| 29 Aug 2008 3:47 Re: Power Amp Question(Skywork CX77144) |
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Thank you~!
I think 28dBm is Ouput-referred P1dB.
Do you know input-referred P1dB?
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vfone
Joined: 10 Oct 2001
Posts: 1767
Helped: 232
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| 29 Aug 2008 8:03 Re: Power Amp Question(Skywork CX77144) |
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| 28dBm minus PA_Gain
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kspalla
Joined: 19 Aug 2008
Posts: 201
Helped: 32
Location: Bangalore
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| 03 Dec 2008 12:38 Power Amp Question(Skywork CX77144) |
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Is RF maximum input power is specified in the absolute maximum ratings?
If so if you feed excess than this power then the device may breakdown.
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