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university:courses:electronics:electronics-lab-14 [15 Sep 2013 15:30] – created Doug Mercer | university:courses:electronics:electronics-lab-14 [15 Nov 2017 08:05] – Trecia Agoylo | ||
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=====Background: | =====Background: | ||
- | We will exploit the simple CMOS inverter logic gate as a pair of switches. The digital I/O signals of the Analog Discovery | + | We will exploit the simple CMOS inverter logic gate as a pair of switches. The digital I/O signals of the ADALM2000 |
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=====Materials: | =====Materials: | ||
- | + | ADALM2000 Active Learning Module\\ | |
- | Analog Discovery Lab hardware\\ | + | |
Solder-less breadboard\\ | Solder-less breadboard\\ | ||
Jumper wires\\ | Jumper wires\\ | ||
- | 9 - 20KΩ Resistors\\ | + | 9 - 20 KΩ Resistors\\ |
- | 9 - 10KΩ Resistors\\ | + | 9 - 10 KΩ Resistors\\ |
1 - OP27 amplifier | 1 - OP27 amplifier | ||
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Connect the 8 digital outputs designated by the blue boxes, and the scope channel and AWG output designated by the green boxes to the resistor ladder circuit as shown. Remember to connect power to the op amp supply pins. | Connect the 8 digital outputs designated by the blue boxes, and the scope channel and AWG output designated by the green boxes to the resistor ladder circuit as shown. Remember to connect power to the op amp supply pins. | ||
- | =====Hardware | + | =====Hardware |
- | With both R< | + | {{ : |
- | Start the Waveforms software. Open up the Digital Patterns screen. Add a bus signal. Select DIO 0 - 7 and click on the right green arrow to add signals | + | <WRAP centeralign > Figure 3 R-2R Resistor Ladder Circuit Breadboard Connections </ |
+ | |||
+ | =====Proceduce: | ||
+ | With both R< | ||
+ | Start the Scopy software. Open up the Pattern Generator screen. Select and group DIO 0 - 7. Now edit the parameters. Set pattern to Binary counter. The output should be PP (for push-pull) and set the frequency for 256 KHz. You should see something that looks like the screen below shown in figure | ||
{{ : | {{ : | ||
- | <WRAP centeralign > Figure | + | <WRAP centeralign > Figure |
- | Open the Scope screen, turn channel | + | Open the Scope screen, turn channel |
{{ : | {{ : | ||
- | <WRAP centeralign > Figure | + | <WRAP centeralign > Figure |
Change the digital pattern. Try the Random pattern and open the FFT window on the scope. You can also load custom patterns by making a plain text csv file with a column of numbers ranging from 0 to 255 (for the 8 bit wide bus). Load your custom pattern and see what happens. | Change the digital pattern. Try the Random pattern and open the FFT window on the scope. You can also load custom patterns by making a plain text csv file with a column of numbers ranging from 0 to 255 (for the 8 bit wide bus). Load your custom pattern and see what happens. | ||
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2. How much current will flow through this resistor network when input D6 is connected to 3.3 volts and D7 to ground? | 2. How much current will flow through this resistor network when input D6 is connected to 3.3 volts and D7 to ground? | ||
- | 1. Discuss which DAC topology had better linearity, and why you would (or would not) expect this to be the case. | + | 3. Discuss which DAC topology had better linearity, and why you would (or would not) expect this to be the case. |
- | 2. How would you expect these DACs to perform for high frequency inputs? For better high frequency components, would you want smaller or larger resistor values? Discuss the relative merits of choosing large or small resistors for the DAC. | + | 4. How would you expect these DACs to perform for high frequency inputs? For better high frequency components, would you want smaller or larger resistor values? Discuss the relative merits of choosing large or small resistors for the DAC. |
- | 3. One of the effects of reducing the size of the resistors is that the parasitic switch resistances could start to become significant relative to the resistors. What would the output levels be for a 3-bit Binary-Weighted Resistor DAC where the switch resistance in figure 1 was 0.25R? | + | 5. One of the effects of reducing the size of the resistors is that the parasitic switch resistances could start to become significant relative to the resistors. What would the output levels be for a 3-bit Binary-Weighted Resistor DAC where the switch resistance in figure 1 was 0.25R? |
- | If you were going to design a 16-bit DAC for audio purposes (for a mp3 player output), how would the resistor tolerances affect the errors in the output for an R-2R ladder DAC? | + | 6. If you were going to design a 16-bit DAC for audio purposes (for a mp3 player output), how would the resistor tolerances affect the errors in the output for an R-2R ladder DAC? |
====For further reading: | ====For further reading: |