ECE 3150: Introduction to Microelectronics
Professor El-Ghazaly taught the mid-level undergraduate microelectronics course and revamped the laboratory assignments and exercises to make the course more engaging. In these updated labs, students get to apply their knowledge to construct hands-on prototypes of useful systems that are based on the topics discussed in class, including current mirroring and amplification, transistor-level logic gates, and differential amplification with high common-mode rejection, among others.
Lab 1: Decrypting the Message (Demodulation)
In this updated version of the lab, students must build a circuit to decrypt a hidden message from an audio file. The encrypted message that students receive is a recorded voice message (the human voice ranges from 20 Hz – 20 kHz) that is amplitude modulated with a 1 MHz carrier signal.
Students build a demodulation circuit and pass the audio signal through.
Finally, students listen to the demodulated signal to hear the decrypted message. In the video below, first, the original message can be heard. Then, the demodulation circuit is connected and the decrypted message can be heard.
Lab 2: Treasure Box (Current Amplification and Mirroring)
Students begin by measuring the impedance of the solenoid and selecting the rail voltage needed as well as the bias current required to source to the bases of the transistors and activate the solenoid plunger.
If all goes well, the treasure box opens and they can enjoy the treat hidden inside!
Lab 3: Logic Lights (Transistor Logic Gates)
In this lab, students build and characterize a CMOS inverter. The updated version of this lab, expands the topic to transistor-level digital logic gates, more generally. Student not only characterize the CMOS inverter but also build it with LED indicators and DPDT switches as logic inputs. After verifying its operation on a breadboard, students solder the inverter and later get to keep it!
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Lastly, students decode a mystery logic gate. If the DPDT button is up, the logic input represents a digital high (digital 1). If the button for the switch is down, the input is a digital low. Sample mystery logic gates are shown below.
Lab 4: Audio Filtering (Differential Amplification and Common Mode Rejection)
In this lab, students build a differential amplifier and test its differential gain, common mode gain, and common mode rejection ratio (CMRR). The updated version of this lab takes the lesson one step further to illustrate the impact of a high CMRR by asking the students to filter out the common mode music from an audio file that has an underlying differential mode voice message. The stereo audio file is prepared with music on both left and right audio tracks (in other words in mono mode) and the voice message on only stereo left. To prepare for the lab, the students need:
| Stereo Sound Input | Stereo Sound Output |
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| Concept of Audio Differential Amplification and Common Mode Rejection |
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By connecting their differential amplifier to the speakers and playing the audio files, students can immediately understand the role of common mode rejection. The effectiveness of the differential amplifier can literally be heard!
| WITHOUT Differential Amplifier | WITH Differential Amplifier |
Lab 5: Square Wave Fidelity (Intrinsic vs. Extrinsic Bandwidth)
