EDN's 19th Annual Innovation Awards Finalists

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Category: ADCs and DACs
Finalist: ADC12EU050 12-bit, octal ADC (National Semiconductor)

Continuous-time sigma-delta (CTSD) high-speed ADCs (analog to digital converters) have been the focus of university and industry research since the early 1990s. National Semiconductor’s ADC12EU050 is the industry’s first high-speed CTSD ADC. Because of over-sampling in the sigma-delta modulator and digital filtering at the modulator output, a CTSD ADC offers inherent anti-aliasing filtering. The ADC12EU050 provides 72 dB of stop-band attenuation, which significantly reduces the required order of the filter preceding the ADC and may even render such an external filter unnecessary. A second advantage is an input that’s purely resistive.

The power consumption of the ADC12EU050 is 25% lower than pipeline ADC solutions. An internal PLL + VCO (phase-lock-loop plus voltage-controlled oscillator) used to multiply up the output-rate input clock to the internal over-sampling frequency also provides for phase noise cleaning of the external sampling clock, enabling the use of lower-cost, lower-performance clock solutions. In addition, the part features a very fast overload recovery circuit, which allows the ADC to recover within one clock cycle.