Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [r2r]

An R-2R Ladder is a simple and inexpensive way to perform digital-to-analog conversion, using repetitive arrangements of precision resistor networks in a ladder-like configuration.

29 questions
17
votes
5 answers

Why can't this LM324 op amp reproduce a signal above a certain frequency?

There seems to be no shortage of circuits like this that attempt to use an R2R as a DAC and an op. amp. as an output buffer. These make sense to me so I decided to try and construct one. I constructed a slightly simpler circuit simulate this…
Eric Urban
  • 1,249
  • 12
  • 28
11
votes
2 answers

Reason for brief spike in op amp output when crossing 0V?

Does anyone recognize this spike in the output of an op amp when the signal crosses 0V? It spikes up when crossing up and down when crossing down. In one of the EEVBlog videos, Dave pointed to something exactly like this on the oscilloscope and said…
Willis Blackburn
  • 1,217
  • 1
  • 13
  • 24
8
votes
1 answer

How Significant is VGA Impedance Matching?

I've seen a multitude of different resistor DAC solutions for a VGA signal, however they almost always have an impedance of >200 ohms per color, e.g. when I've been lead to believe that we want to match the 75 ohm input impedance of the VGA…
Connor Spangler
  • 259
  • 1
  • 10
7
votes
4 answers

Counteracting Sound Card AC Coupling for Reading Digital Data

Disclaimer: I am new to EE. Everything I have learned so far I have taught myself from reading online and posting questions like this while working on this project. I apologize if I do a poor job of explaining my problem as I probably lack to the…
Mike
  • 231
  • 1
  • 4
4
votes
0 answers

How to control DAC white noise at increasing sample rates?

A lot of background, the question is at the end: I have made some simulations and experimental tests with the goal of achieving lowest possible noise floor using DACs with a sample rate of at least 200 kHz (BW ~ 100 kHz). Specifically I want to…
tobalt
  • 18,646
  • 16
  • 73
4
votes
2 answers

Is this how a R-2R DAC for VGA should work?

I'm trying to wrap my head around if this is how a R-2R DAC should work. I say should for two reasons: (1) because I think I understand the theory behind the resistor ladder of subsequent voltage-dividing, and (2) because I analysed the schematic of…
Hugo Sereno Ferreira
  • 554
  • 1
  • 3
  • 20
4
votes
3 answers

Output impedance of the current output DAC

As known there are two types DAC using R-2R ladder. One is voltage output and another is current output. The voltage output type has a constant output impedance which equal to R. The current output type has a input code dependent output impedance.…
diverger
  • 5,828
  • 5
  • 43
  • 79
4
votes
1 answer

Arduino audio output via R-2R DAC - biasing output for piezo speaker

I followed a tutorial on 8-bic DACs using an R-2R resistor ladder. I am outputting a sine-wave using data from 0 to 255 on pins 0-7. This goes through the pins into the R-2R DAC producing an analogue signal. Now I would like to convert this signal…
Kingsley
  • 143
  • 4
3
votes
1 answer

Reading Flow Meters from Mic Port

I am attempting to read two hall-effect flow meters through the audio-in (mic) port of an Android device. I want to be able to read both flow meters independently. The audio-in port is a standard headset port so it only has one channel for the…
Mike
  • 231
  • 1
  • 4
3
votes
1 answer

Weird samples from SAR ADC

I am playing around with some SAR (Successive Approximation) A/D-converters. I have made a test circuit where I have a 16-bit DAC from Texas Instruments (R2R-based) and an 16-bit SAR ADC from Analog Devices. Using a micro controller and some SPI…
pvh1987
  • 325
  • 2
  • 11
2
votes
2 answers

Why is my basic DAC incorrect?

I tried to make a basic R2R digital to analog converter in a simulator. Even with all bits set, I get an output of 4.98V rather than the 5V I would expect. I expected 5V since so many online resources say things like the output "ranging from 0 to…
user260321
  • 29
  • 7
2
votes
1 answer

How do you output whole number voltages (1-4V) from an Arduino/5V source using only digital pins and passive components?

I would like to output whole number voltages 0V,1V,2V,3V and 4V from two digital pins on an arduino/5V source. A simple r2r ladder doesn't seem like it would work because it would split its definition across the whole 0-5V range. Is there a way to…
Garrett Dreyfus
  • 21
  • 2
2
votes
2 answers

R-2R ladder D/A converter with mutilple non-zero inputs

PROBLEM: So I am not used to r-2r ladders where 3 out of 4 inputs are 0V. Here both A and B are 5V, so I don't know how to approach this problem. This is what i get when i simplify the ladder: I think there is a virtual short at the terminal…
NeedHelp2015
  • 21
  • 1
2
votes
2 answers

Converting Pulses to Analog Input for Mic

A continuation of this question. I am attempting to read two flow meters through the mic port of a phone/tablet. The flow meters' pulse pins toggle between +0V and +5V as their pinwheels rotate. I use an R-2R to combine the pulses from the flow…
Mike
  • 231
  • 1
  • 4
1
vote
3 answers

Using a "non-audio" oriented DAC IC as an audio DAC

I'm starting a project that consists of a simple embedded 16-bit PCM audio player, where no actual DSP takes place, only plays PCM and outputs something you can then amplify. I am currently searching for my DAC IC, and I'm hesitating between these…
DashNode
  • 75
  • 4
1
2