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A digital volt meter (DVM) based on the pipeline analog to digital converter (ADC). Range is from 0 to 10V with an accuracy of 1V. This is set to read 10V
INSTRUCTIONS:
The voltage source in the top left is the unknown voltage to be measured. The 7-segment displays on the right show the result of the measured value.
DVM Series:
Ramp Type https://everycircuit.com/circuit/4592385207304192
Dual Slope Integrating Type DVM https://everycircuit.com/circuit/6675184624599040
Integrator Type (voltage to frequency) https://everycircuit.com/circuit/6172260362354688
Successive Approximation Type (hex) https://everycircuit.com/circuit/6044286526947328
Successive Approximation Type (decimal) https://everycircuit.com/circuit/5334865438048256
Ramp Type (negative volts) https://everycircuit.com/circuit/5763215168110592
Ramp Type (auto ranging) https://everycircuit.com/circuit/6110164975091712
Counter Type ADC https://everycircuit.com/circuit/4509930926899200
Tracking Type ADC https://everycircuit.com/circuit/6418942605918208
Tracking Type ADC Full Version https://everycircuit.com/circuit/4688147021299712
Flash Type ADC https://everycircuit.com/circuit/4806466994962432
Pipeline Type ADC 2 Bit Stages
https://everycircuit.com/circuit/6081127019970560
GENERAL:
A pipeline ADC works by subdividing the input voltage through multiple steps (called stages). Each stage will resolve the unknown voltage into a digital bit and pass the remainder (called residue) to the next stage. In this circuit, there are 4 stages, each resolving 1 bit of the input voltage. These bits are combined and encoded to a BCD representation and displayed.
The blue waveform is the input; and the green, orange, and red waveforms are the first, second, and third residues.
DETAILS:
Each stage consists of a simple flash ADC, a DAC, and a subtractor amplifier. The last stage only needs the ADC.
A one bit flash ADC is a simple opamp comparator. It is biased to set what voltage is considered 1 bit (in this case, at 8V). Here is where the input is resolved to one bit. The DAC converts this back to an analog voltage.
The difference between the input voltage and the DAC output is the quantization error (residue). This is found by the opamp subtractor.
The residue is amplified so that it doesn't continue to decrease as it goes through the stages. The residue is passed to the next stage, where the process will repeat.
As an example, let's follow a voltage down the pipeline. In this specific case, there is 10V input.
First stage: ADC, 10V ≥ 8V, so MSB = 1
DAC, 1 bit back to analog = 8V
The subtractor takes 10 - 8 = 2V
Amplifier Takes 2×2 = 4V
Residue = 4V
MSB = 1
Second: ADC, 4V is not ≥ 8V, so Bit = 0
DAC, 0 bit back to analog = 0V
The subtractor takes 4 - 0 = 4V
Amplifier Takes 2×4 = 8V residue
Residue = 8V
Bit = 0
Third: ADC, 8V ≥ 8V, so Bit = 1
DAC,1 bit back to analog = 8V
The subtractor takes 8 - 8 = 0V
Amplifier Takes 2×0 = 0V residue
Residue = 0V
Bit = 1
Fourth: ADC, 0 is not ≥ 8V, so LSB = 0
LSB = 0
1010 binary is 10 decimal, which is what is displayed.
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