Story Behind the Story: National Semi's speedy ADC

Mike ODELL mo at
Wed May 9 18:57:25 CDT 2012

There is an intermediate National part with 14 or 16 bits  resolution but slower sampling.
It's designed for advanced cellular base stations and in fact has two converters
In the package to get I/Q out of the ADC stage.

At some point one has to ask the question about direct coverage vs 
putting a mixer stage ahead of the ADCs. With good synthesizers
like the SiLabs units, one might trade continuous bandwidth for
Dynamic range with block tuning if that can still get  sufficiently 
Wide slice-o-Hertz.

Wideband receiver, spectrum analyzer with TG, 2 or 4 port network analyzer,
Transceiver...... All of these start looking a lot like each other when an 8 channel
0-75MHz Digital receiver strip fits on a small card and an equally powerful
I/Q exciter does as well. Synth/mixer on another, etc etc. 

The new FPGAs with quad-core Arm A9 SoC with all the  peripherals
You want to run Linux with multiple gigE spigots, tightly coupled to the
FPGA fabric has  all kind of possibilities, ESP if you put the UI on
a fondleslab.

It's not just receivers that are going to be disrupted - the test equipment guys
Are going to have to step up too.

Now think about putting a fully-balanced power amp at the feed point of an antenna.
Nothing but power up on copper with waveforms up and down on glass fiber.
Very wideband balanced impedance transformer - it ain't an antenna tuner - it is
The output coupler. 

Radio deconstructed - as it happens. 

      - mo

Sent from my iPad so please excuse the jammy fingers.

On May 9, 2012, at 6:58 PM, Samudra Haque <samudra.haque at> wrote:

> Well, I was curious and went to to see if the chip could be purchased on a single qty basis. Found a $1260 development system instead with all that you need for developing high speed SDR: 
> That said, is N/S helpful to the ham radio community? Sometimes they send samples out to developers on application. But the key is getting to the product manager and accepting early revision of products. Also an NDA will probably have to be agreed to..
> Samudra N3RDX.
> On Tue, Aug 23, 2011 at 3:34 PM, Frank Gentges <metavox at> wrote:
> 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
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