Equation 8 can be used to analyze the smallest detectable distance by considering noise from components upstream and downstream from the amplifier. The components upstream from the amplifier include environment noise, transducer noise, noise from any current limiting resistors, and noise the amplifier itself. Downstream components include the ADC quantization noise and filter calculations errors.
Here are three different scenarios that illustrate distance detection.
Figure 2: Effect of increasing the gain does not produce a change in the smallest possible threshold value or largest measurable distance.
Figure 2 shows that the effect of increasing the amplifier gain really depends on the relative noise magnitudes of the components both upstream and downstream from the amplifier. If noise from upstream components dominates the overall noise, then increasing the gain will not help detect objects at farther distances.
Datasheet for the PGA450-Q1
About the author:
Arun Tej Vemuri
is a systems architect with the Mixed-Signal Automotive group at Texas Instruments
where he is responsible for product definition of automotive sensor signal conditioners. Arun received his Ph.D. in Electrical Engineering from the University of Cincinnati, his MS in Systems Science from IISc Bangalore, India, and BSEE in Electrical Engineering from IIT Roorkee, India. Arun can be reached at email@example.com
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