Difference between an ADC and an AFE

[migsantiago]

Hello

Recently, Microchip has been releasing new datasheets with new PICs and other ICs. There are some new analog-to-digital converters which feature Delta-Sigma architectures which reach resolutions up to 24 bits.

There are some PIC18 that include this new analog converters and are aimed to Energy measurements.

Code: [Select]

http://twitter.com/#!/MicrochipTech/status/25034688338
My question is, why are they calling these new analog converters "Analog Front End"? What makes them different to any Analog-To-Digital Converter (ADC) in the market? What's the difference between them?

http://bit.ly/bmqDQl

http://www.microchip.com/wwwproducts/Devices.aspx?dDocName=en544175

The only one I've spotted is that the so called AFE's are using an embedded PGA into the PIC... but that's all I got. There are so many 24bit ADCs out there that use normal SAR or Delta-Sigma architectures and are not called AFE.

[mikeselectricstuff]

I'd interpred AFE as meaning that there is hardware to help implement a software-based ADC, as opposed to a conventional ADC where all the work is done by hardware.

[hans]

This is analog frontend because it includes the full signal condition block on a chip die. You just put the differential signal from any sensor in it, and it amplifies the difference, filters it and proccesses it. If you'd do this manually, you need a extra couple of opamps and an A/D for better resolution. Yet though, if you do your best, you can easily beat the specs of this chip I think. Looking at the performance, it can do gains up to 32 times and gain 14.89 Effective resolution if you oversample 256x times (that's 4 bits extra due to that).

It's basically just an A/D with a bit of monolithic analog hardware in front of it. Saves board space and cost, if the performance figures fit your bill.

[Hypernova]

This is analog frontend because it includes the full signal condition block on a chip die. You just put the differential signal from any sensor in it, and it amplifies the difference, filters it and proccesses it. If you'd do this manually, you need a extra couple of opamps and an A/D for better resolution. Yet though, if you do your best, you can easily beat the specs of this chip I think. Looking at the performance, it can do gains up to 32 times and gain 14.89 Effective resolution if you oversample 256x times (that's 4 bits extra due to that).

It's basically just an A/D with a bit of monolithic analog hardware in front of it. Saves board space and cost, if the performance figures fit your bill.

The gain part isn't special, ATXMEGA's ADC has a preamp that does 64X and 200Ksps (official spec claims 2Msps). The Microchip one is special more from the opamp that sits in front of the delta-sigma which allows it to take high impedance signals and like you said the filtering.

[migsantiago]

Got it!

So an AFE is an ADC with all the signal acquisition and conditioning that a normal ADC doesn't have.

Thanks guys. 

[Zad]

On-die 24-bit ADCs? That has to be a triumph of marketing over engineering. Getting even 20 true bits is difficult on a standalone converter with good layout and components, so I can't see it making better than 14 or so. I guess they are doing it because they can and can shout about it in the advertising.

[migsantiago]

On-die 24-bit ADCs? That has to be a triumph of marketing over engineering. Getting even 20 true bits is difficult on a standalone converter with good layout and components, so I can't see it making better than 14 or so. I guess they are doing it because they can and can shout about it in the advertising.

They are selling a 4-layered demo board featuring the MCP3901.