6
\$\begingroup\$

I have a problem: I've got five tiny CMOS image sensors (2mm x 2mm), each in a small space (about 10mm x 15mm). They take a clock signal in, and output an analog signal, requiring an 8MSPS ADC each. Somehow I need to get the image data into a PC. This is difficult because of the tight space constraints.

Ideally, I'd like to locally sample the data with a DSP, and video-encode it, at which point, it will be relatively easy to get into the PC via an EtherCAT bus which is close by.

The problem is, how on earth can I get 8MSPS into a tiny DSP in a tiny space? I know there are some pretty small DSPs, but: Are there any tiny DSPs with 8MSPS ADCs? Are there any tiny 8MSPS ADCs?

I have looked hard, but I cannot find any. Sad

Many thanks

Hugo Elias

\$\endgroup\$
  • 1
    \$\begingroup\$ Please provide details: Are you looking for one processor to handle all five inputs, or a separate processor for each? How much processing do you need to do to the data? What ADC resolution do you need? \$\endgroup\$ – Windell Oskay Aug 17 '10 at 22:32
  • \$\begingroup\$ Aren't there dedicated ICs made specifically to interface with it? You can't choose different sensors? \$\endgroup\$ – endolith Aug 17 '10 at 23:25
4
\$\begingroup\$

How about using a dedicated video processor in combination with a small microcontroller? (You might be able to fit a tiny double-sided PCB in there?)

A device like the vsp2582 takes in 12-bit resolution samples at up to 36 MHz and outputs a 12-bit parallel bus. Tiny at 6.3 mm square.

The AD9945 is similar, but 40 MHz and only 5 mm square. (Both TI and AD have other models as well.)

I'm sure that you can find any number of small microcontrollers that can read 12 input pins at high speed and process them as you see fit.

\$\endgroup\$
  • \$\begingroup\$ Thanks, those are some good chips, and may well be the ones to solve the problem. Answer accepted! \$\endgroup\$ – Rocketmagnet Sep 13 '11 at 21:52
2
\$\begingroup\$

Hearing "tiny" and "adc", I'd think of Linear first. You might want to look through their stuff.

\$\endgroup\$
1
\$\begingroup\$

How about TI's C2000 microcontrollers.

80ns sample rate 12.5 MSPS. 1cm^2 BGA package.

\$\endgroup\$
  • \$\begingroup\$ Getting close! It's a nice part, but at 10x10mm, it leaves almost no room for other components and wire termination, especially considering the number of vias required for a 179 pin BGA. \$\endgroup\$ – Rocketmagnet Aug 17 '10 at 21:49
1
\$\begingroup\$

your not going to fit that sensor and a DSP in that amount of space no matter what you do, even if you fit the IC's in that space you've not considered any of the required external circuitry. decoupling caps probably taking the most space, as well as a clock source, regulators, any analog preprocessing needed before ADC conversion.

Better options:

Transmit the analog signal carefully to an external processing location, as close as possible and with care to maintain signal quality. I recommend converting the analog signal to differential for transmitting.

Identify a CMOS sensor with digital output (on board ADC) and again transmit to a nearby processing location.

Your processing location needs to convert to some format to get it to a PC, not to mention the interface circuitry needed for etherCAT or whatever you wish to transmit over.

\$\endgroup\$
  • \$\begingroup\$ That's my backup plan if it turns out to be impossible to integrate all this into the available space. EtherCAT node is a couple of inches away. \$\endgroup\$ – Rocketmagnet Aug 18 '10 at 0:31

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.