Microstrip line - where to place the amplifier

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arefeidi

Joined: 06 Sep 2007
Posts: 80
Helped: 3

25 Jun 2009 11:03 Microstrip line - where to place the amplifier

Hi,

I've got the ouptut of a PLL (~1 GHz, 0dBm) and the input of a tranceiver chip, connected by about 7cm microstrip line. However, I need to amplify the PLL's output by about 12dB, what I'm going to realize with a MMIC amplifier.

What's the best point to place the amplifier:

a) right behind the PLL output -> to amplify a clean signal, without amplifying other signals radiating into my microstrip line

b) right before the transceiver input -> to transmit only a low power signal on the 7cm microstrip line = to minimize radiating from my microstrip line into other parts of the circuit?

Thanks for any help!

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kspalla

Joined: 19 Aug 2008
Posts: 848
Helped: 140

27 Jun 2009 9:04 Microstrip line - where to place the amplifier

Its tricky solution.
As long there is no interference either of the method is OK.
If interfering signal presents then you need to choose.

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radiohead

Joined: 13 May 2004
Posts: 412
Helped: 34
Location: Heart of Europe

27 Jun 2009 23:32 Re: Microstrip line - where to place the amplifier

In terms of gain both are similar. Both microstrip sections have similar length so also similar losses. I would prefer putting the amplifier close to the transceiver. If the line couples to other lines/structures at least it is 20 dB smaller, so the isolation to other parts of the circuit is increased.