Xignal Announces Breakthrough Analog-to-Digital Conversion Technology That Delivers High Speed, Very Low Power Consumption and Simplified System Design.

MUNICH, Germany -- Xignal Technologies AG today announced a breakthrough in analog-to-digital converter (ADC) technology. Utilizing proprietary architectural advances in continuous time delta sigma (CTDS) conversion, Xignal's innovative architecture enables the design of high resolution (12-bits and above) ADCs that convert at up to several hundred megahertz effective sampling rates on a power budget less than half that of existing pipeline solutions. Moreover, the breakthrough is accomplished in mainstream 130 nm CMOS technology that is available from a wide variety of foundries. This facilitates a high degree of functional integration including an on-chip, low-jitter, precision clock that eliminates the need for external timing circuits.

Xignal's CTDS technology will produce the world's lowest power ADCs, by far. The technology enables alias-free Nyquist sampling, which means that anti-aliasing filters are not needed, so system cost is reduced. ADCs based on the technology will have easy-to-drive differential inputs, eliminating a costly input differential amplifier and further reducing external component count. The integrated precision sampling clock also cuts design complexity. Crucially, the technology scales with the CMOS process roadmap, making it future-proof.

Xignal has already demonstrated the CTDS technology in the laboratory and is preparing first commercial products to be released in the coming months.

Industry's lowest power ADC technology - bar none

Power consumption is reduced because continuous time design methods are inherently lower power than discrete time. The latter use sampled discrete time circuits that have to slew continuously on each sample clock edge to track and hold the input signal. This requires very high speed, power-hungry circuits. Moving to a continuous time sampling system, where the input signal is integrated over the full sample period, eliminates the sample and hold amplifier (SHA) to give a significant reduction in power consumption. This is best demonstrated by calculating the conversion power efficiency figure of merit (FOM) recognised by the IEEE as an objective comparison method to assess individual merits of ADC architectures. Xignal's ADC returns better than 0. 5 pJ/conv (picojoules/conversion) compared to greater than 1 pJ/conv for best-in-class pipeline designs.

No anti-alias filter

The CTDS architecture does not generate the aliased errors in the frequency-domain found with pipelined architectures. Neither external anti-aliasing filters, nor power-hungry over-sampling techniques (used to reduce external filter complexity) are required to eliminate aliased errors in the sampled base-band. This significantly reduces both system cost and power consumption, and enables CTDS operation up to the Nyquist limit, without compromising performance.

Easy to drive inputs

The input stage equivalent circuit of Xignal's CTDS ADC is a simple resistive load rather than the complex capacitive impedance used in contemporary switched-capacitor systems. This not only eliminates the need for discrete differential drivers but also means that signal path components, such as low-noise amplifiers and programmable gain amplifiers can be integrated on-chip to achieve further reductions in system size and cost.

Integrated precision sampling clock

In high dynamic range systems, errors in the sample clock can lead to decibels (dBs) of lost dynamic performance (SNR). Xignal solves this problem by exploiting its LC-PLL expertise. Products using CTDS technology will include a low jitter, on-chip LC-PLL, which may either be supplied by a low cost crystal or a medium-performance external clock, removing any further clock design effort.

Future proof technology

A further important advantage of Xignal's breakthrough is scalability with shrinking process geometry. Today Xignal is designing CTDS ADCs on 0.13 micron CMOS and has demonstrated 12-bit resolution sampling at 40 MSPS on a 1.2 V supply. In future, process scaling will yield further performance (speed and power) improvements and cost reductions over time - something that pipeline ADCs are already struggling to do.

"ADCs based on CTDS technology will appeal to designers of low power systems who demand high dynamic range at high sample rates and are challenged by space. Next generation portable ultrasound is an excellent example where CTDS will be of high value." stated Mark Holdaway, Xignal's Marketing Director. "Also, by exploiting a mixed signal implementation, Xignal gains a versatile and flexible technology platform able to target a broad range of ADC resolutions and sample rates."

More information about the technology is available at http://www.xignal.com/ctds.

About Xignal Technologies AG

Xignal Technologies AG is a privately held company that develops and markets mixed-signal ICs that enable new system architectures through significant improvements in performance and in power consumption. Xignal's strategy is to develop multi-market products that are of value to many customers across a wide spectrum of applications. We are currently engaging with leading customers in the medical, automotive, consumer and communications segments. Xignal has world-class expertise in analog-to-digital converters and silicon timing products. The company is headquartered in Munich, Germany and has a US office in Silicon Valley, CA. Xignal products are sold either directly or through a global network of independent sales representatives and distributors.

Additional information is available at www.xignal.com.