Hybrid handles highest CCD performance

Edited by the Electronicstalk editorial team May 2, 2003

The ADCDS-1405 is a functionally complete, top of the line image digitiser made for direct connection to the highest performing CCDs.

Developed in partnership with users in the CCD-based, electronic-imaging industry, Datel's new ADCDS-1405 is a functionally complete, top of the line image digitiser made for direct connection to the highest performing CCDs (charge couple devices).

Among other functions, the ADCDS-1405 contains a user-configurable input amplifier, a critically important correlated double sampling (CDS) function, and a high-speed (5MHz), high-resolution (14bit) A/D convertor in its single 40-pin TDIP package.

The ADCDS-1405 uses modern high-density SMT assembly techniques to combine a variety of mixed-signal ICs and passives in a single assembly.

Exploiting the best performance characteristics of multiple process technologies, the unit far surpasses the overall performance of any single-chip solution.

Optimised parameters include: 14bit resolution; 5Mpixel/s sampling rate; 50-145mV RMS noise; 73dB minimum signal/noise ratio; 16,384 to 1 dynamic range; and 0.9LSB maximum differential nonlinearity.

Because the ADCDS-1405 is a complete assembly, users need not concern themselves with noise-sensitive layout issues involving signal/return paths, analogue/digital ground currents, decoupling/filter elements etc.

Additionally, users can vary the bandwidth of the 1405's input stage to tradeoff noise against sampling rate.

The 145mV RMS noise specified at 5Mpixel/s can be reduced to an incredible 50mV (approximately a third of an LSB) at lower conversion rates.

The ADCDS-1405 requires only two, externally generated timing signals: a reference-hold pulse to initiate the all-important CDS operation, and a start-convert signal to trigger each conversion.

Correlated double sampling is an operation unique to CCDs.

It is essentially an analogue subtraction function that eliminates the effects of residual charge, charge injection, and noise on the CCD's output floating capacitor.

CDS is critical to applications seeking the highest achievable dynamic range and signal to noise ratio.

The functionally complete ADCDS-1405 also includes a user-configurable input stage, gain and offset adjustments, a precision reference circuit, an out-of-range indicator and all the internal timing circuits referred to above.

Applications for the ADCDS-1405 include scientific imaging (such as spectroscopy), studio-grade electronic cameras, electro-photometry, astronomy, medical diagnostic imaging, infrared imaging for military or commercial environments, high quality graphic scanning and photo-CD image capture.

The ADCDS-1405 consumes a mere 700mW from +5 and +12V supplies.

It is housed in a small 40-pin TDIP and is available for operation over either commercial or military temperature ranges.