In order to reduce the fluctuation of LIBS detection spectrum of liquid sample,the full-spectrum sum method and the internal standardization method is adopted,using an equal-RSD normalization algorithm to calibrate th...In order to reduce the fluctuation of LIBS detection spectrum of liquid sample,the full-spectrum sum method and the internal standardization method is adopted,using an equal-RSD normalization algorithm to calibrate the detection spectrum.Experiment result shows that the full-spectrum sum method reduced the RSD of parallel samples of Cd and Cr to 9.4% and 11.06% from 28.32% and 31.93% respectively,yielded better overall calibration than the singleelement internal standardization approach,thereby suggesting that the former method is convenient and effective for online calibration of LIBS for detection of aqueous heavy metals.展开更多
A low power 10-bit 250-k sample per second （KSPS） cyclic analog to digital converter （ADC） is presented. The ADC＇s offset errors are successfully cancelled out through the proper choice of a capacitor switching s...A low power 10-bit 250-k sample per second （KSPS） cyclic analog to digital converter （ADC） is presented. The ADC＇s offset errors are successfully cancelled out through the proper choice of a capacitor switching sequence. The improved redundant signed digit algorithm used in the ADC can tolerate high levels of the comparator＇s offset errors and switched capacitor mismatch errors. With this structure, it has the advantages of simple circuit configuration, small chip area and low power dissipation. The cyclic ADC manufactured with the Chartered 0.35 μm 2P4M process shows a 58.5 dB signal to noise and distortion ratio and a 9.4 bit effective number of bits at a 250 KSPS sample rate. It dissipates 0.72 mW with a 3.3 V power supply and occupies dimensions of 0.42 × 0.68 mm2.展开更多
文摘In order to reduce the fluctuation of LIBS detection spectrum of liquid sample,the full-spectrum sum method and the internal standardization method is adopted,using an equal-RSD normalization algorithm to calibrate the detection spectrum.Experiment result shows that the full-spectrum sum method reduced the RSD of parallel samples of Cd and Cr to 9.4% and 11.06% from 28.32% and 31.93% respectively,yielded better overall calibration than the singleelement internal standardization approach,thereby suggesting that the former method is convenient and effective for online calibration of LIBS for detection of aqueous heavy metals.
基金Project supposed by the Science and Technology Program of Tianjin,China(No.08ZCKFGX00200)
文摘A low power 10-bit 250-k sample per second （KSPS） cyclic analog to digital converter （ADC） is presented. The ADC＇s offset errors are successfully cancelled out through the proper choice of a capacitor switching sequence. The improved redundant signed digit algorithm used in the ADC can tolerate high levels of the comparator＇s offset errors and switched capacitor mismatch errors. With this structure, it has the advantages of simple circuit configuration, small chip area and low power dissipation. The cyclic ADC manufactured with the Chartered 0.35 μm 2P4M process shows a 58.5 dB signal to noise and distortion ratio and a 9.4 bit effective number of bits at a 250 KSPS sample rate. It dissipates 0.72 mW with a 3.3 V power supply and occupies dimensions of 0.42 × 0.68 mm2.
