Two-Stage CMOS Operational Amplifier

简体中文

This repository contains a complete course-design package for a two-stage CMOS operational amplifier in TSMC 0.18 um technology. It combines first-order analog design, transistor-level Spectre simulation, OCEAN measurements, and bilingual LaTeX reports.

Highlights

• Classical two-stage CMOS op-amp with Miller compensation.
• NMOS differential input pair with PMOS current-mirror active load.
• PMOS common-source second stage with NMOS current-source load.
• Spectre AC, DC, and transient simulation collateral.
• OCEAN measurement script for AC performance extraction.
• Chinese and English report sources and compiled PDFs.
• Independent parameter derivation and result summaries for cross-checking.

Target specifications

Specification	Target
Supply voltage	3.3 V
Open-loop gain	> 20,000 V/V
Gain-bandwidth product	>= 20 MHz
Slew rate	> 3 V/us
Input common-mode range	1.0–2.5 V
Phase margin	>= 60 deg
Output swing	0.5–2.5 V
Power dissipation	<= 2 mW
Load capacitance	5 pF

The detailed measurements and pass/fail summary are in outputs/course_spec_results.txt.

Circuit topology

NMOS differential pair → PMOS current-mirror load
                       → first-stage node
                       → Miller capacitor + nulling resistor
                       → PMOS common-source second stage
                       → single-ended output

The first stage converts the differential input into a high-gain single-ended signal. The second stage provides additional voltage gain and drives the load. Miller compensation establishes the dominant pole; the series resistor controls the compensation zero and helps improve phase-margin behavior.

Repository structure

Path	Description
report/main.tex	Chinese LaTeX report source
report/main_en.tex	English LaTeX report source
report/main.pdf	Chinese report PDF
report/main_en.pdf	English report PDF
report/figures/	Report figures and plots
outputs/course_spec_results.txt	Course-target measurement summary
outputs/independent_design_results.txt	Independent design result summary
outputs/independent_design_derivation.md	Independent parameter derivation
outputs/parameter_derivation_draft.md	Parameter-estimation draft
outputs/two_stage_opamp_full.scs	Full transistor-level Spectre netlist
outputs/two_stage_opamp_independent.scs	Independent design netlist
outputs/two_stage_opamp_ideal_param.scs	Parameterized simulation netlist
outputs/measure_opamp_ac.ocn	OCEAN AC measurement script

Verification flow

The reports and simulation collateral cover:

• DC operating points and bias behavior;
• AC open-loop gain, unity-gain bandwidth, and phase margin;
• transient slew rate, settling behavior, and output swing;
• power dissipation against the course limit.

Build the reports

XeLaTeX is required. From report/, compile each language twice to refresh the table of contents and cross-references:

cd report
latexmk -xelatex -interaction=nonstopmode -halt-on-error main.tex
latexmk -xelatex -interaction=nonstopmode -halt-on-error main_en.tex

The checked-in PDFs can be read without a LaTeX installation.

Reproduce simulations

The outputs/ directory contains Spectre netlists and OCEAN measurement collateral. Reproduction requires a compatible Cadence/Spectre installation and access to the relevant TSMC 0.18 um PDK, which are not included here. Results may vary with simulator version, model files, process corners, and analysis settings.

Scope and license

This is an educational analog IC design package, not a foundry sign-off database. No license file is currently included; add an appropriate license before redistribution.