Hi all
In a PLL contrlolled Rf amplifier front end how exactly the 1st RF stage frequency of the tuned circuit is contrlolled so it will be exactly the PLL freq+ IF frequncy ?
Thanks EC
- posted
15 years ago
FRONT END WITH PLL
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- posted
15 years ago
One method that gets used is lots of switched caps with varicap fine tuning. But all-band radios are inevitably a compromise.
The key thing is to be exceptionally linear and low-noise across a large dynamic range, so intermodulation doesn't become an issue before you hit those IF filters, or you get all kinds of spurious out-of-band response. The new DTV chipsets are amazing.
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- posted
15 years ago
The tuned circuit has a wide enough band width that a simple circuit with varactor diodes will be close enough.
The VCO tuning can also be a varactor diode. With care the voltage to frequency character of the two can be matched.
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- posted
15 years ago
frequency of the tuned circuit is contrlolled so it
Sounds interesting What are the specs, model numbers?
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- posted
15 years ago
That depends entirely (and exactly) on the radio designer. Tracking varactors, switched tuned circuits, wide-open front end -- they can all be used, and they each have their own advantages and disadvantages.
-- Tim Wescott Wescott Design Services http://www.wescottdesign.com Do you need to implement control loops in software? "Applied Control Theory for Embedded Systems" gives you just what it says. See details at http://www.wescottdesign.com/actfes/actfes.html
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- posted
15 years ago
Anadigics is one maker, look at their AIT-1010 and AIT-1021.
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- posted
15 years ago
look up "RF mixer.."
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- posted
15 years ago
Many tahnks EC
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