ΣΔ ADC 2nd order w. displays

863

06:02:31

I previously published a ΣΔ ADC circuit
https://everycircuit.com/circuit/4549196269223936,
but at that time i got the principal wrong. This time though, I'm quit confident, that I got it right.

The relays are obviously not part of the real thing, but they were necessary to get the simulation started.

Please note, that it takes a couple of samples after start or change of the input, before the result is accurate. And when i say accurate, I mean within a couple of decimals ;) 

One sample is a full count to 50 on the most left displays, at which point the result is loaded to the displays to the most right. The middle displays show the sum of 1s in the bit stream. This counting is actually how it is done in reality at incredible speed.


My other designs:
RF Up and Down Mixing
http://everycircuit.com/circuit/6321309163454464
DC Motor Rev. Sliding Mode Controller
http://everycircuit.com/circuit/5398415189213184
DC Motor Revolution Detector
http://everycircuit.com/circuit/6753368923176960
Amplitude Modulation and Demodulation
http://everycircuit.com/circuit/5510207106187264
Boost SMPS Unlimited Voltage Build Up
http://everycircuit.com/circuit/6448454909034496
High Power Charge Pump w. Mosfets
http://everycircuit.com/circuit/5016778832084992
Transformerless 230 Vac to 10 Vdc
http://everycircuit.com/circuit/4981362800197632
Motor Revolution Controller
http://everycircuit.com/circuit/6424781689978880
Motor Current Sliding Mode Controller
http://everycircuit.com/circuit/5502940846751744
300W Class D Amplifier w. Mosfet output
http://everycircuit.com/circuit/5452375043342336
Three Phase Star Δ Safe Relay Wiring
http://everycircuit.com/circuit/4748634531037184
Accidental 555 High Voltage Generator LOL
http://everycircuit.com/circuit/5057154477457408

published 2 years ago

592azy2circuitdude

2 years ago

Very interesting. I don't know too much about Delta Sigma ADCs, but I created a circuit that may use the same principle. Check it out if you'd like. https://everycircuit.com/circuit/6172260362354688

Roaldchr

2 years ago

Thanks for stopping by and for the comment :) I checked out your curcuit, and i think it works the same way as my first attempt of a delta sigma adc design, which I mention in the description, and which I think turned out not to a delta sigma converter at all. Yours looks a lot nicer though. As i see it, your circuit, and mine the first, basically measures how long it takes to charge a specific capacity, where the delta sigma continuously compares a DAC value of the output bit stream to the analog value and adds 1 or 0 based on the comparison.

592azy2circuitdude

2 years ago

Thanks for the helpful info. I'll need to learn more about it. Thank you for taking the time to check out my circuit.

Roaldchr

2 years ago

Thank you too.

gabidegabidegab

1 year ago

The most of the difficulty with SD-DAC is in the decimator filter architecture (which is a series of differents filters (comb, half-band, ...) and design which can take a lot of place if it's not programmed in a processor.

Roaldchr

1 year ago

Thanks for the comment. I dont work with this, but I think it depends on who's asked. In the digital part, at least noise is no longer a hughe concern. I bet that the analog engineers would tend to say, that the analog part is the most difficult because of that, even though the digital part may take up a lot of space. And I just want to mention, that even this very simple design implements a low pass filter in that it sums up the number of '1's during a specific period of time, which would be the first of many dig. filters in a real adc. See this for more https://www.analog.com/en/resources/technical-articles/sigmadelta-adcs-tutorial.html

Roaldchr

1 year ago

(I know, in here (the simulation) a lot of circuitry is hidden in some of the components such as counters etc.)

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