Fwd: Story Behind the Story: National Semi's speedy ADC

[Frank Gentges]

tacoistas,

I saw the announcement of the National Semi high speed A/D and had to 
wonder if it was for real or just a marketing department fishing trip to 
see if it would sell if they made it.

Since then, it looks like it is for real and got the Electronic Products 
award for Product of the Year.  I fell I must put most of my skepticism 
aside.  This A/D can change receiver design and will introduce a bunch 
of new design challenges as so many bits have to be processed so fast as 
more bits will be coming into the process.  It may be that a really fast 
FPGA may be a required part to eat the high speed data stream.

Frank K0BRA

Hearst Electronic Products | Story behind the Story

	
	August 2011 	No-nonsense tools for the busy EE 		

	
Each year, the editors at Electronic Products choose the Product of the
Year awards, representing what they believe to be the most outstanding
products introduced during the last year. In the article below - part of
our Story Behind the Story series - we go beyond the specs to uncover
how these innovative products came to be.

	National Semi's speedy ADC 	
		
	DC enables fundamental architecture changes in a variety of applications

The 12-bit ADC12D1800 A/D converter from National Semiconductor offers a
sampling speed of 3.6 Gsamples/s, which at the time of introduction (May
22, 2010) was said to be 3.6 times faster than the closest competitor.
That is what made it a Product of the Year winner for our publication.
However, there was more to it.

National had two main goals for the product. The first was to maintain
and extend National's leadership in gigasamples per second (GSPS)
analog-to-digital converters (ADCs) by releasing the industry's fastest
12-bit ADC by a factor of several times. The second was to enable
fundamental architecture changes in a variety of applications by
enabling truly wideband software-defined radios (SDRs), thereby
introducing the GSPS ADCs to many new markets.

A wideband SDR approach allows systems that process multiple channels to
be greatly simplified by collapsing all channels into a single signal
path. The approach also allows systems that process
very-high-input-frequency signals with multiple frequency conversion
stages to be simplified by sampling at RF or much higher IF. Although
National already offered a large portfolio of GSPS ADCs, the ADC12D1800
was the first GSPS ADC to provide sufficient dynamic performance to
allow the deployment of such wideband SDRs in applications including
military, communications, industrial, and consumer.

The ADC12D1800 High-Speed Signal Path team was presented with the
Electronic Products (EP) Product of the Year trophy. Pictured from left
to right: Product Marketing Engineer Scott Kulchycki, EP Magazine editor
Jim Harrison, Product Engineer Andrew Glenny, Engineering Program
Manager Carlos Hinojosa, Marketing Director Jon Baldwin, Applications
Engineers Jim Brinkhurst and Marjorie Plisch, Product Engineer Ryan
Hashimoto and Test Development Engineer Linton Park.

Overcoming challenges
The biggest technical challenge was achieving the conversion speed of
dual 1.8 GSPS (or single 3.6 GSPS) for a 12-bit ADC in 180-nm CMOS. This
challenge was addressed by using a rigorous methodology, simulating the
database at the top level over process, voltage, and temperature
corners, with layout parasitics included to expose any weakness in the
high-speed paths.

Another challenge of the ADC12D1800 and all of National's GSPS ADCs is
that they are complex systems, requiring significant resources and
long-term commitment for successful release. The ADC12D1800 is the
newest and highest-performance product in National's family of GSPS
ADCs; the product is the latest result of many years of investment and
focus by the GSPS ADC development team and by National Semiconductor
management.

Christina Nickolas

Learn more about National Semiconductor
<http://elecp-media.com/portal/wts/cemcfMaFuu6baPes2g4s3Ba9qymDgb> 	



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