针对在测距过程中超声波的能量损耗和回波信号微弱的问题,在分析问题产生的基础上,利用可变增益放大器AD8338设计了超声波自动增益控制(AGC)接收补偿电路,动态范围达到80 d B。实验结果表明:该自动增益补偿电路结构简单,不需要额外的控...针对在测距过程中超声波的能量损耗和回波信号微弱的问题,在分析问题产生的基础上,利用可变增益放大器AD8338设计了超声波自动增益控制(AGC)接收补偿电路,动态范围达到80 d B。实验结果表明:该自动增益补偿电路结构简单,不需要额外的控制器件,可以使不同距离的超声波回波信号维持在合适的幅度范围内,有效地解决了回波信号衰减等问题,提高测距精度。展开更多
A CMOS variable gain amplifier（VGA） that adopts a novel exponential gain approximation is presented.No additional exponential gain control circuit is required in the proposed VGA used in a direct conversion receiver...A CMOS variable gain amplifier（VGA） that adopts a novel exponential gain approximation is presented.No additional exponential gain control circuit is required in the proposed VGA used in a direct conversion receiver.A wide gain control voltage from 0.4 to 1.8 V and a high linearity performance are achieved.The three-stage VGA with automatic gain control（AGC） and DC offset cancellation（DCOC） is fabricated in a 0.18-μm CMOS technology and shows a linear gain range of more than 58-dB with a linearity error less than ±1 dB.The 3-dB bandwidth is over 8 MHz at all gain settings.The measured input-referred third intercept point（IIP3） of the proposed VGA varies from-18.1 to 13.5 dBm,and the measured noise figure varies from 27 to 65 dB at a frequency of 1 MHz.The dynamic range of the closed-loop AGC exceeds 56 dB,where the output signal-to-noise-and-distortion ratio（SNDR） reaches 20 dB.The whole circuit,occupying 0.3 mm^2 of chip area,dissipates less than 3.7 mA from a 1.8-V supply.展开更多
文摘针对在测距过程中超声波的能量损耗和回波信号微弱的问题,在分析问题产生的基础上,利用可变增益放大器AD8338设计了超声波自动增益控制(AGC)接收补偿电路,动态范围达到80 d B。实验结果表明:该自动增益补偿电路结构简单,不需要额外的控制器件,可以使不同距离的超声波回波信号维持在合适的幅度范围内,有效地解决了回波信号衰减等问题,提高测距精度。
文摘A CMOS variable gain amplifier（VGA） that adopts a novel exponential gain approximation is presented.No additional exponential gain control circuit is required in the proposed VGA used in a direct conversion receiver.A wide gain control voltage from 0.4 to 1.8 V and a high linearity performance are achieved.The three-stage VGA with automatic gain control（AGC） and DC offset cancellation（DCOC） is fabricated in a 0.18-μm CMOS technology and shows a linear gain range of more than 58-dB with a linearity error less than ±1 dB.The 3-dB bandwidth is over 8 MHz at all gain settings.The measured input-referred third intercept point（IIP3） of the proposed VGA varies from-18.1 to 13.5 dBm,and the measured noise figure varies from 27 to 65 dB at a frequency of 1 MHz.The dynamic range of the closed-loop AGC exceeds 56 dB,where the output signal-to-noise-and-distortion ratio（SNDR） reaches 20 dB.The whole circuit,occupying 0.3 mm^2 of chip area,dissipates less than 3.7 mA from a 1.8-V supply.
