University of Twente Student Theses


ADC buffer with fast settling and lower power consumption

Yuetian, Zou (2016) ADC buffer with fast settling and lower power consumption.

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Abstract:An ADC input Buffer amplifier with load capacitor pre-charging technology is shown in this report. The amplifier has high slew rate (peak slew rate = 180 V/us) and consume less power compare to conventional implementation. The conventional negative feedback amplifier under certain fixed load conditions, has its slew rate limited by its GBW and/or static power consumption. The GBW / feedback stability / power consumption are correlated, in case the amplifier under certain fixed load conditions. Not one of these three parameter can be made much better, and at same time not affect to other two parameters. In an application such large slew rate and relatively lower signal frequency is employed, a much larger GBW is need to fulfill the slew rate requirements. Such problem can be solved by combining a fast but not very precise pre-charge amplifier and a slower and much more precise amplifier. The fast amplifier only active in the fast slew period, and the precision amplifier only is active in the tracking period. Both amplifiers can be built with low power consumption in this case. The speed of the designed fast amplifier is maximized by utilizing one–shot nonlinear feedback technology. The effective gain window only open when the input signal around the determine voltage, such structure make the fast amplifier could operating over the unstable region without having oscillation problem. The precision amplifier is operating to several MHz range which, stability will be a problem if more than 2 stages is apply in the feedback loop. This amplifier is optimized for highest open loop linearity, which enable use only 2 stages and minimum GBW to meet closed loop distortion requirements. The low GBW results a lower power consumption, as the precision amplifier occupies the most part of total system operating time. The low GBW also results a lower cutoff frequency for the output noise.
Item Type:Essay (Master)
Faculty:EEMCS: Electrical Engineering, Mathematics and Computer Science
Subject:53 electrotechnology
Programme:Electrical Engineering MSc (60353)
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