MOS Differential and Power Amplifier Design in LTspice

Two-stage course project covering the design of MOS differential amplifiers and a feedback-stabilized MOS/BJT power amplifier. The repository preserves the editable LTspice schematics, reports, and curated figures while excluding reproducible simulator output files.

Important

All numerical values are schematic-level simulation results. Process corners, mismatch/Monte Carlo analysis, PCB parasitics, fabricated hardware, and laboratory measurements are not included.

Project stages

Phase 1 — Differential amplifier

• NMOS differential pair with a resistive load
• PMOS active-load replacement
• Current-mirror biasing
• Gain, CMRR, output resistance, power, and source-degeneration trade-offs

The four incremental designs are stored in Part1/ through Part4/.

Phase 2 — Power amplifier

• High-gain MOS differential input stage
• Complementary BJT Class-B output stage
• Negative feedback for closed-loop gain control and crossover-distortion reduction
• Output-swing, ICMR, THD, and quiescent-power analysis while driving a $100,\Omega$ load

Reported simulation results

Metric	Reported result
Closed-loop gain	approximately 2 V/V
Output swing	approximately 16.5 V p-p
THD near maximum reported swing	approximately 0.04%
Quiescent power	approximately 54 mW
Load	$100,\Omega$

Repository structure

.
├── Part1/ ... Part4/                  # Phase-1 LTspice schematics and figures
├── Phase2/
│   ├── Sim/Pre/                       # Preliminary power-stage studies
│   ├── Sim/Design/                    # Final integrated design
│   ├── Sim/output/                    # Output-stage study
│   ├── Fig/                           # Report figures
│   └── ElectronicsII_Project_Phase2.pdf
├── ElectronicsII_Project_Phase1.pdf
└── README.md

Reproduce the simulations

1. Install LTspice.
2. Clone this repository.
3. Open the desired .asc file from Part1/–Part4/ or Phase2/Sim/.
4. Run the configured operating-point, transient, AC, or FFT analysis.

The transistor models required by the designs are embedded in the schematic directives. LTspice regenerates .raw, .log, and .fft files locally; they are intentionally excluded from version control.

Course context

• Course: Electronics II
• Institution: Sharif University of Technology
• Author: Moein Yousefinia
• Term: Spring 2025

No open-source license is granted by this repository unless a license file is added explicitly.