Choosing crystal for RX circuit
时间:04-04
整理:3721RD
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I am designing a receiver circuit around a RF receiver chip. The app note in the datasheet specifies a crystal with a 20ppm tolerance. However, the best I can find on Digikey and Mouser is 30ppm. Will this part work ok or do I need to keep searching?
Thanks
Thanks
Depends on many parameters like
- receiver bandwidth
- utilized temperature range
- possible channel assignment in utilized RF band
YOu can't make an Xtal 20 ppm over a wide temperature range due to the 3rd order variations with different cuts.
You can get a 25ppm tolerance at room temp and a 25 ppm over a wide temp range and design a compensation and null offset circuit.
But no need now.
For about S2~4 now you can get a 0.5 to 10ppm TCXO which is temperature compensated at D-K
Use one of these. http://www.digikey.com/product-searc...0&pageSize=500
Of course if this just for room temp, a Varicap or trimcap can null any offset 50 ppm or whatever.