[参考译文] AFE7950EVM：主 DAC 时钟杂散强于预期

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Other Parts Discussed in Thread: AFE7950EVM

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https://e2e.ti.com/support/rf-microwave-group/rf-microwave/f/rf-microwave-forum/1128041/afe7950evm-main-dac-clock-spur-stronger-than-expected

器件型号：AFE7950EVM

您好！

我将 AFE7950EVM PCB 修订版 A DC135与 Latte 结合使用。

该电路板已使用粘贴的自动化和启动文件进行配置、如下所示。

DAC 时钟为8844Msps、我已将其配置为产生2GHz 音调。

频谱分析仪输出位于下图中。时钟杂散在标记 3上可见、标记上的音调也可见 1。

DAC 在 f3-f1 = 6.8G (标记 2)和 f1+f3 = 10.8G (标记 4)时生成二阶互调乘积。

根据数据表、杂散远高于预期。

我是否有任何可能出错的地方？请提供任何帮助。

此致

Khusro Saleem

频谱分析仪输出

AFE79xx/自动化/script.py

#setupParams.skipFpga = 1
mainWindow.clearSession()

## Note : below base_directory needs to be modified per user's environment. 
base_directory = "C:\\Users\\User\\Documents\\Texas Instruments\\Latte\\projects\\AFE79xx\\"

'''************INITIALIZATION**********************'''
mainWindow.runFile(base_directory + r"bringup\setup.py")
mainWindow.runFile(base_directory + r"bringup\devInit.py")

'''************RUN BASICBRINGUP.PY**********************'''
mainWindow.runFile(base_directory + r"bringup\script11.py")

AFE79xx/bringup/script.py

'''
Validation :  AFE79xx Library Version 
				v1.67, v1.74
Case			RX					TX						   FB						CLK					Notes
----	-----------------	  -----------------			-----------------			-----------			------------
1		245.76Msps, 24410     491.52Msps, 44210			491.52Msps, 22210			FADC=2949.12M       DAC in interleaved mode
		SerDes=9830.4Mbps     SerDes=9830.4Mbps			SerDes=9830.4Mbps			FDAC=8847.36M
		NCO=3500M		      NCO=3500M			        NCO=3500M                   REF=491.52M
		
2		245.76Msps, 24410     491.52Msps, 44210			491.52Msps, 22210			FADC=2949.12M       DAC in straight mode
		SerDes=9830.4Mbps     SerDes=9830.4Mbps			SerDes=9830.4Mbps			FDAC=8847.36M
		NCO=3500M		      NCO=3500M			        NCO=3500M                   REF=491.52M
		
3		122.88Msps, 14810     245.76Msps, 24410			245.76Msps, 24410			FADC=2949.12M       DAC in straight mode
		SerDes=9830.4Mbps     SerDes=9830.4Mbps			SerDes=9830.4Mbps			FDAC=8847.36M
		NCO=3500M		      NCO=3500M			        NCO=3500M                   REF=491.52M

4		122.88Msps, 14810     245.76Msps, 24410			245.76Msps, 24410			FADC=2949.12M       DAC in interleave mode
		SerDes=9830.4Mbps     SerDes=9830.4Mbps			SerDes=9830.4Mbps			FDAC=8847.36M
		NCO=3500M		      NCO=3500M			        NCO=3500M                   REF=491.52M

5		245.76Msps, 24410     245.76Msps, 24410			245.76Msps, 24410			FADC=2949.12M       DAC in straight mode.
		SerDes=9830.4Mbps     SerDes=9830.4Mbps			SerDes=9830.4Mbps			FDAC=8847.36M       AFE79xx set up in repeater mode.
		NCO=3500M		      NCO=3500M			        NCO=3500M                   REF=491.52M         No FPGA/ASIC necessary.

6		245.76Msps, 24410     491.52Msps, 44210			491.52Msps, 22210			FADC=2949.12M       DAC in straight mode
		SerDes=9830.4Mbps     SerDes=9830.4Mbps			SerDes=9830.4Mbps			FDAC=5898.24M
		NCO=750M		      NCO=750M			        NCO=750M                    REF=491.52M
		
'''
setupParams.skipFpga 				= 1
sysParams							= AFE.systemParams
setupParams.fpgaRefClk 				= 245.76	
AFE.systemStatus.loadTrims			= 1

sysParams.FRef                    	= 491.52
sysParams.FadcRx                  	= 2949.12
sysParams.FadcFb				  	= 2949.12
sysParams.Fdac                    	= 2949.12*3

sysParams.enableDacInterleavedMode	= False 					#DAC interleave mode to save power consumption. Fs/2 - Fin spur occurs

sysParams.modeTdd 					= 0		
										# 0- Single TDD Pin for all Channels
										# 1- Separate Control for 2T/2R/1F
										# 2- Separate Control for 1T/1R/1F	
										
sysParams.topLevelSystemMode		= 'StaticTDDMode'
sysParams.RRFMode 					= 0   #4T4R2F FDD mode
sysParams.jesdSystemMode			= [1,1]
										#SystemMode 0:	2R1F-FDD						; rx1-rx2-fb-fb
										#SystemMode 1:	1R1F-FDD						; rx1-rx1-fb-fb
										#SystemMode 2:	2R-FDD							; rx1-rx1-rx2-rx2
										#SystemMode 3:	1R								; rx1-rx1-rx1-rx1
										#SystemMode 4:	1F								; fb-fb-fb-fb
										#SystemMode 5:	1R1F-TDD						; rx1/fb-rx1/fb-rx1/fb-rx1/fb
										#SystemMode 8:	1R1F-TDD 1R-FDD	(FB-2Lanes)(RX1 RX2 interchanged)		; rx2/fb-rx2/fb-rx1-rx1
										

sysParams.jesdLoopbackEn			= 0 	#Make it 1 to Enable the JESDTX to JESDRX internal loopback
sysParams.LMFSHdRx                	= ['24410', '24410', '24410', '24410']	
										# The 2nd and 4th are valid only for jesdSystemMode values in (2,6,7,8). For other modes, select 4 converter modes for 1st and 3rd.
sysParams.LMFSHdFb                	= ["24410","24410"]
sysParams.LMFSHdTx                	= ["24410","24410","24410","24410"]

sysParams.jesdTxProtocol            = [0,0]
sysParams.jesdRxProtocol            = [0,0]
sysParams.serdesFirmware			= True 		# If you want to lead any firmware, please speify the path here. Otherwise it will not write any firmware
sysParams.jesdTxLaneMux				= [0,1,2,3,4,5,6,7]
												# Enter which lanes you want in each location. 
												# Note that across 2T Mux is not possible in 0.5.
												# For example, if you want to exchange the first two lines of each 2T, this should be [[1,0,2,3],[5,4,6,7]]
sysParams.jesdRxLaneMux				= [0,1,2,3,4,5,6,7]	
												# Enter which lanes you want in each location.
												# Note that across 2R Mux is not possible in 0.5.
												# For example, if you want to exchange the first two lines of each 2R, this should be [[1,0,2,3],[5,4,6,7]]
												
sysParams.jesdRxRbd					= [4, 4]

sysParams.rxJesdTxScr				= [True,True,True,True]
sysParams.fbJesdTxScr				= [True,True]
sysParams.jesdRxScr					= [True,True,True,True]

sysParams.rxJesdTxK					= [16,16,16,16]
sysParams.fbJesdTxK					= [16,16,16,16]
sysParams.jesdRxK					= [16,16,16,16]

sysParams.ncoFreqMode 				= "1KHz"
	
sysParams.txNco0					= 	[[1000,0],		#Band0, Band1 for TxA for NCO0
										[2000,0],        #Band0, Band1 for TxB for NCO0
										[3500,0],        #Band0, Band1 for TxC for NCO0
										[3500,0]]        #Band0, Band1 for TxD for NCO0

sysParams.rxNco0					= 	[[3500,2600],		#Band0, Band1 for RxA for NCO0
										[3500,2600],        #Band0, Band1 for RxB for NCO0
										[3500,2600],        #Band0, Band1 for RxC for NCO0
										[3500,2600]]        #Band0, Band1 for RxD for NCO0

sysParams.fbNco0					= 	[3500,3500]			#FBA, FBC for NCO0
sysParams.fbNco1					= 	[3500,3500]			#FBA, FBC for NCO1
sysParams.fbNco2					= 	[3500,3500]			#FBA, FBC for NCO2
sysParams.fbNco3					= 	[3500,3500]			#FBA, FBC for NCO3



sysParams.numBandsRx				= [0]*4					# 0 for single, 1 for dual
sysParams.numBandsFb				= [0,0]				
sysParams.numBandsTx				= [0]*4


sysParams.ddcFactorRx             	= [12,12,12,12]
sysParams.ddcFactorFb             	= [12,12]
sysParams.ducFactorTx             	= [36,36,36,36]

AFE.systemStatus.loadTrims			=1

## The following parameters sets up the LMK04828 clocking schemes
lmkParams.pllEn						=	True  #False
lmkParams.inputClk					=	1474.56  #737.28
lmkParams.lmkFrefClk				=	True

## The following parameters sets up the register and macro dumps
logDumpInst.setFileName(ASTERIX_DIR+DEVICES_DIR+r"\Afe79xxPg1.txt")
logDumpInst.logFormat				= 0x01
logDumpInst.rewriteFile				= 1
logDumpInst.rewriteFileFormat4		= 1
device.optimizeWrites				= 0
device.rawWriteLogEn				= 1

## The following parameters sets up the SYNCIN and SYNCOUT to interface with the TSW14J57
sysParams.jesdABLvdsSync			= 1
sysParams.jesdCDLvdsSync			= 1
sysParams.rxJesdTxSyncMux			= [0,0,0,0]
sysParams.fbJesdTxSyncMux			= [0,0]
sysParams.jesdRxSyncMux				= [0,0,0,0]		#[0,0,1,1]
sysParams.syncLoopBack				= False


#sysParams.defaultTxDsa = [0,0,0,0]
#sysParams.txEnable = [False, True, False, False]
#sysParams.rxEnable = [False, False, False, False]
#sysParams.fbEnable = [False, False]


# ## The following parameters sets up the AGC
# sysParams.agcParams[0].agcMode = 1 ##internal AGC
# sysParams.agcParams[0].gpioRstEnable = 0 ##disable GPIO based reset to AGC detector 
# sysParams.agcParams[0].atken = [0, 1, 0] ##enable big and small step attack
# sysParams.agcParams[0].decayen = [0,1,0] ##enable big and small step decay
# sysParams.agcParams[0].atksize = [2,1,0] ## bigs step = 2dB, small step = 1dB
# sysParams.agcParams[0].decaysize = [2,1,0] ##big step = 2dB, small step = 1dB
# sysParams.agcParams[0].atkthreshold = [-1, -2, -14] ##attack threshold
# sysParams.agcParams[0].decaythreshold = [-14, -6, -20] ##decay threshold
# sysParams.agcParams[0].atkwinlength = [170, 170] ## detector time constant expressed inn absolute time in ns. 
# sysParams.agcParams[0].decaywinlength = 87380 ##detector time constant expressed in absolute time in ns. All detectors use the same value for decay time constant
# sysParams.agcParams[0].atkNumHitsAbs = [8,8] ##absolute number of times signal crosses threshold. These crossing are with respect to the FADC/8 clock
# sysParams.agcParams[0].decayNumHitsAbs = [100,100] ##absolute number of times signal crosses threshold. These crossing are with respect to the FADC/8 clock
# sysParams.agcParams[0].minDsaAttn = 0 ##minimum DSA attenuation used by AGC
# sysParams.agcParams[0].maxDsaAttn = 22 ##maximum DSA attenuation used by AGC
# sysParams.agcParams[0].totalGainRange = 22 ##total gain range used by ALC for gain compensation
# sysParams.agcParams[0].minAttnAlc = 0 ##minimum attenuation used by ALC for compensation when useMinAttnAgc = 0
# sysParams.agcParams[0].useMinAttnAgc = 1 ##enable ALC to use minimum attenuation from AGC for which compensation is required.
# sysParams.agcParams[0].alcEn = 1
# sysParams.agcParams[0].alcMode = 0 ##floating point DGC
# sysParams.agcParams[0].fltPtMode = 0 ##if exponent > 0, dont send MSB
# sysParams.agcParams[0].fltPtFmt = 1 ##3 bit exponent


## The following parameters sets up the GPIOs
sysParams.gpioMapping={
		'H8': 'ADC_SYNC0',
		'H7': 'ADC_SYNC1',
		'N8': 'ADC_SYNC2',
		'N7': 'ADC_SYNC3',
		'H9': 'DAC_SYNC0',
		'G9': 'DAC_SYNC1',
		'N9': 'DAC_SYNC2',
		'P9': 'DAC_SYNC3',
		'P14': 'GLOBAL_PDN',
		'K14': 'FBABTDD',
		'R6': 'FBCDTDD',
		'H15': ['TXATDD','TXBTDD'],
		'V5': ['TXCTDD','TXDTDD'],
		'E7': ['RXATDD','RXBTDD'],
		'R15': ['RXCTDD','RXDTDD']}
        
device.delay_time = 0
## Initiates LMK04828 and AFE79xx Bring-up
AFE.deviceBringup()

AFE.TOP.overrideTdd(15,3,15)
#AFE.adcDacSync()
#AFE.LMK.lmkSysrefEn(1)
#AFE.LMK.lmkSysrefEn(0)
#AFE.JESD.SUBCHIP.toggleSync()

for i in [0,1]:
	for j in [0,1]:
		AFE.JESD.DACJESD[i].dacJesdConstantTestPatternValue(1,j,0,16384,0) # enable, channelNum, bandNum, Ival, Qval

3 年多前

0 admin 3 年多前

TI__Guru**** 2477065 points

请注意，本文内容源自机器翻译，可能存在语法或其它翻译错误，仅供参考。如需获取准确内容，请参阅链接中的英语原文或自行翻译。

Khusro、

我们将对此进行研究。

此致、

Jim

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[参考译文] AFE7950EVM：主 DAC 时钟杂散强于预期