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[参考译文] AFE7950EVM:内部 AGC 模式下的 LNA 增益配置

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Other Parts Discussed in Thread: AFE7950
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。

https://e2e.ti.com/support/rf-microwave-group/rf-microwave/f/rf-microwave-forum/1410829/afe7950evm-lna-gain-configuration-in-internal-agc-mode

器件型号:AFE7950EVM
Thread 中讨论的其他器件:AFE7950

工具与软件:

您好!

我已成功配置 AFE7950的数字步进衰减器(DSA)和自动增益控制(AGC)、以将 ADC 输入调节到指定阈值范围内。 当应用超过此阈值的射频信号时、AFE7950会使该信号衰减、以将其保持在所需的范围内。 对于低于阈值的信号、系统传递输入信号而不会衰减。

但是、我还想放大低于阈值的低功耗信号。 因此、为此、我已经配置了低噪声放大器(LNA)和自动级别控制(ALC)以及 DSA 和 AGC。 但这对我来说是无效的。

因此、是否可以使用 AFE7950通过调整这些设置来放大低功耗输入信号? 如果是、则需要执行哪些配置步骤来实现这一点?

我还附加了我为此设置所设置的 Latte 配置。

for i in range(4):
	# Internal AGC mode
	### RXA/B config
	sysParams.agcParams[i].agcMode = 1 				# Internal AGC mode
	sysParams.agcParams[i].rfdeten = 0 				# RF analog detector is enabled.
	sysParams.agcParams[i].atken = [0,1,1] 			# attack peak detector is enabled with big step. # big step, small step, pow det
	sysParams.agcParams[i].decayen = [0,1,1] 		# decay power detector is enabled. # big step, small step, pow det
	
	sysParams.agcParams[i].atkthreshold = [-25,-27,-28] 		# Applied threshold of attack detector # big step=-8, small step=-10, pow det
	sysParams.agcParams[i].decaythreshold = [-28,-26,-26] 	# Applied threshold of decay detector # big step=-22, small step=-20, pow det
	
	sysParams.agcParams[i].atkwinlength = [160,170] 		# Attack detector Time Constant in absolute time in ns. Max is 40ms
	sysParams.agcParams[i].decaywinlength = 87380 			# Decay detector Time Constant in absolute time in ns. Max is 40ms
	sysParams.agcParams[i].atkNumHitsAbs = [8,8]			# Absolute Number of times signal crosses threshold.
	sysParams.agcParams[i].decayNumHitsAbs = [8,8]			# Absolute Number of times signal crosses threshold.
	
	sysParams.agcParams[i].custRfMode = 1 					# Use RF analog detector as very big step attack in internal AGC.
	sysParams.agcParams[i].atksize = [4,2]					# Whenever detector triggers the DSA change 0.5dB* value
	sysParams.agcParams[i].decaysize = [4,2] 				# Whenever detector triggers the DSA change 0.5dB* value
	sysParams.agcParams[i].minDsaAttn = 0 					# Minimum DSA attenuation used by AGC, 0.5dB* value
	sysParams.agcParams[i].maxDsaAttn = 50 # 60 # 23		# Maximal DSA attenuation used by AGC, 0.5dB* value
	sysParams.agcParams[i].totalGainRange = 50 # 57 # 50	# Total gain range used by ALC for gain compensation
	
	sysParams.agcParams[i].rfdetnumhits = 8 				# Absolute Number of times signal crosses threshold.
	sysParams.agcParams[i].rfdetstepsize = 8 				# Whenever RF detector triggers the DSA change 0.5dB* value, i.e.25 dB.
	
	## External LNA control
	sysParams.agcParams[i].lnaEn = True 					# Enternal RXA LNA control
	sysParams.agcParams[i].extLnaTempModel = 0				# Use a temperature model for the lna gain
	sysParams.agcParams[i].singleDualBandMode = 0 			# RXA is single band
	sysParams.agcParams[i].lnagain0 = 40 					# The gain of external RXA LNA for AGC to compensate, the resolution is 0.03125 dB 864 or 27.0?
	sysParams.agcParams[i].lnaphase0 = 0 					# The phase of external RXA LNA for AGC to compensate in Band0
	sysParams.agcParams[i].lnaGainMargin = 4 				# hysteresis value when to turn on lna
	sysParams.agcParams[i].blank_time_extcomp = 255 		# number of clocks of FadcRx/8 max 65535

for i in range(4):
	# ALC and floating point mode
	sysParams.agcParams[i].alcEn = 1 						# RXA ALC enabled
	sysParams.agcParams[i].alcMode = 3						# RXA coarsefineIQ mode 3
	sysParams.agcParams[i].stepSize = 3						# Step Size of 3
# 	sysParams.agcParams[i].fltPtMode = 1 					# RXA Always send MSB of mantissa in floating point mode
# 	sysParams.agcParams[i].fltPtFmt = 2 					# RXA 4 bit exponent, 11 bit mantissa and 1 bit sign

  • 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。

    尊敬的 Numeer:

     

    也许这里有一个误解。 AFE7950没有内部 LNA。 LNA 旁路和控制是用于控制外部 LNA 的 GPIO 功能。

     

    例如、如果系统在其中一个 RX 通道前面有一个外部 LNA、而信号将变得过高。 AFE 可以使用其中一个 LNA 旁路输出来禁用 LNA 上的增益。

     

    让我们知道这是否会清除一切。

     

    此致!

     

    Camilo