topic Re: I/Q sampling with LPC4370 in LPC Microcontrollers

I/Q sampling with LPC4370

juanhidalgo — Thu, 16 Mar 2017 11:59:49 GMT

Hello,

I'd like to know if it's possible to interface an I/Q demodulator, like for example the LTC5586, directly to the ADC inputs of the LPC4370 to send the samples through the USB port.

Best regards,

Juan

Re: I/Q sampling with LPC4370

kerryzhou — Fri, 17 Mar 2017 07:30:21 GMT

Hi Juan Hidalgo,

LPC4370 have the 12 bit high speed analog and the USB module.

Whether it can used to interface the I/Q demodulator, you still need to check whether the ADC sample rate and the measurement range meet the demand.

From the datasheet you can find:

Please whether check 80Msample/s and the 0-1.2V can meet your I/Q demodulator demand.

If it has no problem, you can use it, after you get the ADC data, you can send the data through the USB.

Wish it helps you.

Have a great day,
Kerry

-----------------------------------------------------------------------------------------------------------------------
Note: If this post answers your question, please click the Correct Answer button. Thank you!
-----------------------------------------------------------------------------------------------------------------------

Re: I/Q sampling with LPC4370

juanhidalgo — Fri, 17 Mar 2017 08:36:17 GMT

Hello Kerry,

Thanks for your answer,

I was interested in using the ADCHS but the demodulator has 2 differential outputs I and Q, and I'm a little bit confused.

How I understand the datasheet (but I'm not sure at this point), we can use only one differential input using the ADCHS_NEG for the Negative differential input and any ADCHS_X for the positive input.

So I think it could be done in two ways:

1. Using an external switch to alternate the sampling of the two differential signals.

2. Using two baluns to change the differential signals to single-ended.

I'm not sure if what I'm saying is correct, so what do you think?

Good day,

Juan

Re: I/Q sampling with LPC4370

kerryzhou — Mon, 20 Mar 2017 07:01:30 GMT

Hi Juan Hidalgo,

As you know, LPC4370 ADCHS just have one differential input channel or 6 signal-sided input channels.

So, I think you can change the differential signals to single-ended, and make sure the measurement range is in 0 to 1.2V, this may keep the synchronization.

Wish it helps you!

Have a great day,
Kerry

Re: I/Q sampling with LPC4370

juanhidalgo — Mon, 20 Mar 2017 07:11:22 GMT

Hello Kerry Zhou,

Thanks for your answer, I also think that it is the better way to do it, possibly with a differential amplifier.

Best regards,

Juan

Re: I/Q sampling with LPC4370

kerryzhou — Tue, 21 Mar 2017 09:36:43 GMT

Hi Juan Hidalog,

You are welcome!

If your problem is solved, please help to mark the correct answer, thank you!

Have a great day,
Kerry