В® DDC101 101 DDC 20-BIT ANALOG-TO-DIGITAL CONVERTER
FEATURES APPLICATIONS в—Џ MONOLITHIC CHARGE INPUT ADC в—Џ DIRECT PHOTOSENSOR DIGITIZATION в—Џ DIGITAL FILTER NOISE REDUCTION:
0.9ppm, rms в—Џ PRECISION INSTRUMENTATION
в—Џ INFRARED PYROMETRY в—Џ DIGITAL ERROR CORRECTION: CDS в—Џ PRECISION PROCESS CONTROL
в—Џ CT SCANNER DAS
в—Џ CHEMICAL ANALYZERS в—Џ CONVERSION RATE: Up to 15kHz
в—Џ USER FRIENDLY EVALUATION FIXTURE DESCRIPTION
The DDC101 is a precision, wide dynamic range, charge
digitizing A/D converter with 20-bit resolution. Low
level current output devices, such as photosensors, can be
directly connected to its input. The most stringent accuracy requirements of many unipolar output sensor applications occur at low signal levels. To meet this requirement, Burr-Brown developed the adaptive delta modulation architecture of the DDC101 to provide linearly
improving noise and linearity errors as the input signal
level decreases. The DDC101 combines the functions of
current-to-voltage conversion, integration, input programmable gain amplification, A/D conversion, and digital
filtering to produce precision, wide dynamic range results. The input signal can be a low level current connected directly into the unit or a voltage connected
through a user selected resistor. Although the DDC101 is
optimized for unipolar signals, it can also accurately
digitize bipolar input signals. The patented delta modula-tion topology combines charge integration and digitization functions. Oversampling and digital filtering reduce
system noise dramatically. Correlated Double Sampling
(CDS) captures and eliminates steady state and conversion cycle dependent offset and switching errors that are
not eliminated with conventional analog circuits.
The DDC101 block diagram is shown below. During
conversion, the input signal is collected on the internal …
