How to config DPD on AD9375?

Donot post duplicate threads. Will be followed here:

https://ez.analog.com/microcontroller-no-os-drivers/f/q-a/164495/how-to-config-dpd-on-ad9375

HI srimoyi,

I have mistake once post this question in to that forum, then I received this answer:

"Moving to No-Os forum for comments on the DPD configuration"

Because I don't know delete that question, I have post again in this forum.

Thanks

Yes the PAR of the signal needs to be between 7.5dB and 8.5dB for best DPD performance.

Hi Vinod,

I have a question.

have i must calibration DPD again  use MYKONOS_runInitCals and MYKONOS_enableTrackingCals every change frequency or only calibration DPD once at Initialize and change any frequency without DPD calibration again?

Thanks

Please refer "RF PLL FREQUENCY CHANGE PROCEDURE" in UG 992.

It is recommended to run init cal each time you change frequency if that is a possibility.

Also on clipped waveform generation, you can use the DPD GUI. connect to board ,select waveform and required PAR and you can save waveform from GUI.

For your DPD testing you can use same.

Thanks Vinod,

But why in frequency 4.6G above. although dpdErrorStatus  return 0, spectrum had configure DPD is not different from no have DPD ?

Thanks

What is the raw ACLR (without DPD) of PA for same power at frequencies 4,5 G, 4.6G  and  4.8G ?

Hi Vinod

ACLR without DPD:

4.6G: -30dbc for right adj channel, -35dbc for left adj channel

4.5G: -29dbc for right adj channel, -33dbc for left adj channel

4.8: -36dbc for right adj channel, -37dbc for left adj channel

Here are image of 3 above frequency. Thanks

What is your target output power,?

Above measurements are done at different power and hence the variation in ACLR is more.For comparison you need to make measurements at same output power. You can keep Tx1 as primary (center) so that you can read ACLR directly.

4.5 -28.54 dBm
4.6 - -26.84 dBm
4.8 - 25.4 dBm

Bandwidth is 22MHz , IS the waveform custom?

The ACLR is not symmetric, The right and left adjacent are having upto 5 dB variation.You may need to correct that for better DPD performnce.

Hi Vinod

My system run custom waveform with bandwidth 21.4Mhz. And now different frequency, output power may be not the same. My target output power is 30dbm. Above system has output power with attenuation 30dbm. 

You say: "The ACLR is not symmetric, The right and left adjacent are having upto 5 dB variation.You may need to correct that for better DPD performence". So what is the maximum different  variation between right and left adjacent that AD9375 can still DPD? 

I don't have a exact value for symmetry , Its recommended to be within +/- 1 dB.

For different power levels the linearity of PA will be different and different ACLR and DPD correction is as well dependent on that. So I guess what you see is expected.

Mykonos DPD is good for LDMOS PA's where the memory effects are less. For GAN PA's electron trapping adds to short term memory effects and it becomes difficult for DPD to correct.

Thanks Vinod, PVALAVAN

Thanks for your information.

I have implement DPD successful follow your instruction.

But there is one problem about consume current. My system have limit consume current is 3A.

When my system run with output power 30dbm, consume current is 1.2A. Once DPD, consume current suddenly increase 2.2A in 0.2 seconds then return 1.2A after that.

But once my system run at higher power  33dbm, consume current is 1.4A, Once DPD, consume current suddenly increase over 3A. Over current occur and my system be turn off.

Can you explain this phenomenon and give me solution.

Thanks

Thanks Vinod, PVALAVAN

Thanks for your information.

I have implement DPD successful follow your instruction.

But there is one problem about consume current. My system have limit consume current is 3A.

When my system run with output power 30dbm, consume current is 1.2A. Once DPD, consume current suddenly increase 2.2A in 0.2 seconds then return 1.2A after that.

But once my system run at higher power  33dbm, consume current is 1.4A, Once DPD, consume current suddenly increase over 3A. Over current occur and my system be turn off.

Can you explain this phenomenon and give me solution.

Thanks

When you say Enable DPD , What function is called ? What is the sequence.? 

Peak current going high, you can try adding some bulk capacitor to PA drain bias , Say 220 UF. 

Can you share a wide band span spectrum plot of PA output with DPD enabled., Is the output unstable?

Hi Vinod

With output power 30dbm, with DPD enable, spectrum plot stable.

Here is sequence once change frequency and calib DPD:

mykonosErr_t		mykError;


#if DPD_ENABLE

	/*************************************************************************/
	/*****            Enable DPD calibrations                            *****/
	/*************************************************************************/
	uint8_t				errorFlag = 0;
	uint8_t				errorCode = 0;
	uint32_t			initCalsCompleted;

	uint32_t initCalMask = TX_BB_FILTER | ADC_TUNER | TIA_3DB_CORNER | DC_OFFSET |
										  TX_ATTENUATION_DELAY | RX_GAIN_DELAY | FLASH_CAL |
										  PATH_DELAY | TX_LO_LEAKAGE_INTERNAL | TX_QEC_INIT |
										  LOOPBACK_RX_LO_DELAY | LOOPBACK_RX_RX_QEC_INIT |
										  RX_LO_DELAY | RX_QEC_INIT ;

	uint32_t trackingCalMask = TRACK_ORX1_QEC | TRACK_ORX2_QEC | TRACK_RX1_QEC |
							 TRACK_RX2_QEC | TRACK_TX1_QEC | TRACK_TX2_QEC | TRACK_TX1_LOL | TRACK_TX2_LOL;

	uint32_t initCalMaskDpd = initCalMask | DPD_INIT | CLGC_INIT | VSWR_INIT;


#endif
	if ((mykError = MYKONOS_radioOff(&mykDevice)) != MYKONOS_ERR_OK)
	{
		/*** < Info: errorString will contain log error string in order to debug why radioOn failed > ***/
		//errorString = getMykonosErrorMessage(mykError);
		puts(getMykonosErrorMessage(mykError));

	}

	if ((mykError = MYKONOS_setRfPllFrequency(&mykDevice, TX_PLL, u64TxFrq)) != MYKONOS_ERR_OK) {
		return MYKONOS_ERR_FAILED;
	}

#if DPD_ENABLE

	// Make sure PA is ON
	if((mykError = MYKONOS_abortInitCals(&mykDevice, &initCalsCompleted)) != MYKONOS_ERR_OK)
	{
		/*** < Info: errorString will contain log error string in order to debug why failed > ***/
		//errorString = getMykonosErrorMessage(mykError);
		puts("abortInitCals failed");
		fflush(stdout);
		puts(getMykonosErrorMessage(mykError));
	}

	xil_printf("\r\n Mykonos ARM Initialization Calibrations for DPD");

	if ((mykError = MYKONOS_runInitCals(&mykDevice, (initCalMaskDpd & ~TX_LO_LEAKAGE_EXTERNAL))) != MYKONOS_ERR_OK)
	{
		/*** < Info: errorString will contain log error string in order to debug why failed > ***/
		//errorString = getMykonosErrorMessage(mykError);
		puts("MYKONOS_runInitCals");
		fflush(stdout);
		puts(getMykonosErrorMessage(mykError));

	}

	if ((mykError = MYKONOS_waitInitCals(&mykDevice, 60000, &errorFlag, &errorCode)) != MYKONOS_ERR_OK)
	{
		/*** < Info: errorString will contain log error string in order to debug why failed > ***/
		//errorString = getMykonosErrorMessage(mykError);
		puts("MYKONOS_waitInitCals");
		fflush(stdout);
		puts(getMykonosErrorMessage(mykError));
	 }

	if ((mykError = MYKONOS_getEnabledTrackingCals(&mykDevice, &trackingCalMask)) != MYKONOS_ERR_OK)
	{
		/*** < Info: errorString will contain log error string in order to debug why failed > ***/
		//errorString = getMykonosErrorMessage(mykError);
		puts("MYKONOS_getEnabledTrackingCals");
		fflush(stdout);
		puts(getMykonosErrorMessage(mykError));

	}

	trackingCalMask |= TRACK_TX1_DPD | TRACK_TX2_DPD | TRACK_TX1_CLGC | TRACK_TX2_CLGC | TRACK_TX1_VSWR | TRACK_TX2_VSWR;

	if ((mykError = MYKONOS_enableTrackingCals(&mykDevice, trackingCalMask)) != MYKONOS_ERR_OK)
	{
		/*** < Info: errorString will contain log error string in order to debug why enableTrackingCals failed > ***/
		//errorString = getMykonosErrorMessage(mykError);
		puts(getMykonosErrorMessage(mykError));

	}

#endif

	MYKONOS_radioOn(&mykDevice);

	return MYKONOS_ERR_OK;

What is the max current you are seeing when you are running init cals other than DPD?

Please refer to the max current requirement for Mykonos chip from the datasheet, section "CURRENT AND POWER CONSUMPTION SPECIFICATIONS", table 2.