The Experts below are selected from a list of 6 Experts worldwide ranked by ideXlab platform
William C. Rempfer - One of the best experts on this subject based on the ideXlab platform.
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The care and feeding of high performance ADCs: get all the bits you paid for
Analog Circuit Design, 2011Co-Authors: William C. RempferAbstract:A new generation of Analog-to-digital converters (ADCs) currently appearing on the scene brings higher performance and lower cost to new markets. At the same time, the new converters achieve better dynamic performance with high frequency input signals. This means that more system designers are facing the challenge of using high performance ADCs. This chapter discusses some of the problems designers encounter, such as how to recognize their symptoms and how to avoid them. For example, providing a clean Analog input signal to an ADC does not always guarantee a clean digital output signal. This is because an ADC has not just one input, but many. Ground pins, supply pins, and reference pins also act as “inputs” and must be given special care to prevent noise and unwanted signals from corrupting the ADC output. Grounding, bypassing of the supplies and the reference and driving the Analog and clock inputs are the major weapons in this battle against corruption. This chapter also focuses on the particular case of the LTC1410, a 1.25 Msps, 12-bit ADC. This provides an example that can be modified for the particular high performance converter used. All bypass caps, reference caps, and Ground connections for the ADC should be tied to the Analog Ground Plane. Tie them as close together as possible to reduce the sensitivity to currents that may flow in the Ground Plane. The input signal circuitry, filter caps, and op amp bypass caps (not shown) should also be Grounded to the Ground Plane near the ADC.
Stuart R. Ball - One of the best experts on this subject based on the ideXlab platform.
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9 – High-Precision Applications
Analog Interfacing to Embedded Microprocessor Systems, 2004Co-Authors: Stuart R. BallAbstract:This chapter focuses on high-precision applications that require more than 10 bits of accuracy. A requirement for high precision usually stems from one of two places: a need to measure very small values, or a need to measure a wide dynamic range. In an ideal opamp, the output will be zero any time both inputs are at the same voltage. In a real opamp, the internal transistors are not precisely matched and may not be at exactly the same temperature. Opamp designs usually assume that the current flowing into the opamp inputs is zero because the input impedance is infinite. A real opamp has some current flowing into the inputs because the impedance is finite. A single-point connection minimizes the amount of digital current that can flow in the Analog Ground Plane. When determining the worst-case range of values in an Analog circuit, one can use the specified extreme limits of the parts to guarantee a good design. One can estimate the percentage of circuits that will be out of tolerance by taking into account the tolerance ranges and distributions of all the parts in that specific circuit.
