some urgent problem of 4w hf RFID reader with TRF7970A

user4397992

Other Parts Discussed in Thread: TRF7970A

Hello

We are trying to make a 4W hf power RFID reader based on the design described on the application note from TI (See the attached file1488.appnote_trf796x_pwramp_4w.pdf). Basically I have followed the description and the schematic, used the same components etc. We can now read the tag ,but the read range is about 10cm (it is 40cm in the attached file ). The tag and antenna in the picture . they work well with the TRF7970A EVM modul ( the read range is about 20cm when 200mw mode was set ). I have changed the "Regulator & I/O control register" from 0x87 to 0xC7.

After a long investigation of the whole circuit we did not find any way out to overcome this problem. Please suggest me what to do.

over 8 years ago

0 Eddie LaCost over 8 years ago

TI__Mastermind 39710 points

Hello,

Have you offset the tuning of your antenna per section 4.3 of the app note? This prevents saturating the receiver. Also, what do your test point captures look like? Are they similar to the captures in the app note?

0 chia se over 8 years ago

Intellectual 260 points

Hi user4397992,

I take care the problem. Do you solve the it?

0 user4397992 over 8 years ago in reply to Eddie LaCost

Prodigy 65 points

Thanks for your fast answer!

The test point of Transmit circuit is similar to the captures in the app note. But TP11 Waveform just look like follow attached pic. And TP21 Waveform just look like follow attached pic. Is there a problem with the receiver circuit or antenna? Can you offer some reference about detials design of antenna ?

Best regard!

yuan

0 user4397992 over 8 years ago in reply to chia se

Prodigy 65 points

Hi chia,
I haven't solved the problem yet, Do you have any suggestions？The antenna was 30 by 40 cm antenna in the attached file above , But limited by our application, We can only use the above antenna. So do you have any suggestions about antenna of the 4w hf rfid reader.
thanks
Yuan

0 chia se over 8 years ago in reply to user4397992

Intellectual 260 points

Hi Yuan,

I tried the above circuit. But read distance is a few cm. I think the problem is at receiving circuit. It uses envelop detector. So, it's very sensitive with the noise such as power supply, environment, etc... In the addition, I also refer some long range reader such as Feig, they don't use the reader IC for demodulation. However, I hope you can solve the problem. (I'm not good at analog circuit!)

0 user4397992 over 8 years ago in reply to chia se

Prodigy 65 points

Hi chia!

Thanks for your Suggest. How did your antenna design？Is that according to that document ？ I also suspect that the receiving circuit has a problem. you know Feig HF reader .So can you offer some reference materials about Feig HF reader （ The best for reference circuits）.....

Thanks again

Yuan

0 chia se over 8 years ago in reply to user4397992

Intellectual 260 points

Hi Yuan,

My antenna is designed as HF Antenna Cookbook of TI. Regarding Feig reader, it dose not use IC reader. There are the guide documents (not schematic).

Chia

0 wenjiong feng over 7 years ago in reply to user4397992

Prodigy 20 points

Hi user4397992,
Finaly,did you solved the problem? And how to solve it?Now we also have the same problem.Thanks!

0 wenjiong feng over 7 years ago in reply to chia se

Prodigy 20 points

Hi chia se,
Now,we are trying the same circuit ,and also have the same problem as yours. Finaly,did you solved the problem? And how to solve it?
Thanks!

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some urgent problem of 4w hf RFID reader with TRF7970A