Dual Synthesizer for Dual Conversion Radio Design

[robismyname]

I'm considering using a National Semiconductor Dual Synthesizer for a dual conversion radio design . The part number is LMX2525. But I am not certain if this fits my application. The first IF section is 374MHz, second IF is 70MHz. Assuming that a PLL is absolutely necessary does this dual synthesizer fit the application? If it does then I ask what should be the frequency of my oscillator?

 

[kspalla]

May I Know the frequency of operation?

 

[yendori]

Not knowing your RF freq...

RF + 374MHz = LO1

374MHz +70MHz = LO2

Maybe try that first. Do a spur analysis.

 

[radiohead]

Why dual conversion? Seems like your frequency plan is perfectly suitable for single frequency conversion and this results in much less spurs