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[AMPS] 3rd order IMD driver/final

To: <amps@contesting.com>
Subject: [AMPS] 3rd order IMD driver/final
From: amps@txrx.demon.co.uk (Steve Thompson)
Date: Wed, 30 Sep 1998 18:08:50 +0100
In message <19980930104557.AAA9776@[209.239.238.83]>, Rich Measures
<measures@vc.net> writes
>
>>
>>If you have a transceiver with a 3rd transmitter IMD -25db below pep, and
>>the amplifiers third order imd is -40db, what is the final 3rd imd figure
>>for the combined transceiver and linear?
>>
>Pretty close to -25db
>
>>Secondly in the case ab2 grounded grid, when the driver contributes to feed
>>through power what is the final figure when the driver has a poorer IMD.
>
>the poorer source is still the prime determiner
>

If the drive is 10dB cleaner than the output stage, the worst case
effect is to make the output about 3dB worse than the output stage. If
the driver and output have the same IMD levels, the worst case is 6 dB
worse than either. The IMD levels add up in voltage, not power.

Steve

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