Need front end amplifier for AD8302
I would like to get phase measurement with the AD8302 for Bluetooth (2.4ghz).
I've been told, because the AD8302 is not extremely sensitive, I may need a stage or two of amplifiers in the front end.
Do you have any example of such design? Suggested circuit? Or better, any already existing module?
Thx
Regards
Michel
The minimum input level of AD8302 is -60dBm, which should be enough for most applications.
The simplest amplifier can be done using a MMIC amplifier:
http://194.75.38.69/products/amplifiers_smt_gpw.shtml
OK Thank you.
Which one would you advise for Bluetooth applications ?
Thx
http://194.75.38.69/pdfs/ERA-3+.pdf
Hi
Thank you for your help.
This amplifier requires 12V as suggested on its reference design.
-Is there an alternative but with 3V input?
-should I put one or two ampfliers in cascade?
Thx
Michel
Most of the ERA series MMICs it will work fine at 3V if the bias resistor is adjusted properly (about 50 ohms for 3V operation...check for the required DC current in the datasheet).
Placing two amplifiers in cascade it will not help much in your case. One should be enough.
Thank you for the response.
In the meantime I also found the TI CC2592 sold as range extender for 2.4Ghz transceivers.
How does it compare to MMICs? in particular the ERA-3+?
thx
On receive side CC2592 is worse than most of ERA MMICs (lower gain and higher noise figure).
Thank you for your response. It makes sense
Last question: I want my device to work with Bluetooth frequencies only, I plan to use a SAW filter to select the frequency band. Do I have to put the SAW filter before or after the ERA MMIC? which configuration is the best:
1) antenna <=> SAW filter <=> ERA MMIC <=> AD8302
2) antenna <=> ERA MMIC <=> SAW filter <=> AD8302
Thank you
Regards,
Michel
The ERA series definitely isn't suitable for a 3V supply, since its nominal output bias voltage is 3.2V. Hard to recommend specific devices without any solid requirements from you.
Do you actually need transmit and receive operation on your phase detector? You may want to explain your application with a bit more detail.
What is the minimum voltage supply for the ERA series? 3.3v?
The application is about direction finding. I essentially need to receive in order to get phase and amp detection. Transmission may occur on a separate antenna
Device operating voltage of ERA-1 is about 3.3V (datasheet page 2).
Is not shown in the datasheet, but if use a 22 ohms bias resistor you get the recommended device operating current of the MMIC when is supplied at 3.3V.
https://www.minicircuits.com/pdfs/ERA-1+.pdf
The circuit works even without bias resistor, but to meet thermal requirements the bias resistor need to be at least 10 ohms, and the bias current not higher than the recommended one.
Thank you for the precision.
Finally, which configuration is the best?
1) antenna <=> SAW filter <=> ERA MMIC <=> AD8302
2) antenna <=> ERA MMIC <=> SAW filter <=> AD8302
Thank you
Regards,
Michel