術語表 Glossary — 800V HVDC 功率半導體

跨課程共用術語表。英文技術名詞為主，中文說明輔助。
Terms used across all lessons. English technical terms with Chinese explanations. Grouped by concept cluster — return here whenever a word is unclear.

Power Architecture

HVDC High Voltage DC: Power distribution using high-voltage direct current rather than AC. In data centers: 48V (Stage 1, now), 380V (Stage 2), 800V (Stage 3). Higher voltage = lower current = less cable loss. No natural zero crossing unlike AC, which makes protection components more valuable.
Rack Bus Voltage: The voltage level that runs along the shared power rail inside a server rack. Stage 1 target is 48V DC. Traditional: 12V. This is the level at which 台達電 and 光寶科 operate (rack power systems).
VRM Voltage Regulator Module: Board-level converter that takes rack bus voltage (48V or 12V) and steps it down to the precise low voltage that CPU/GPU cores need (0.8V–1.8V). This is where 茂達 and 富鼎 operate.
Power Phases: In a multiphase VRM, multiple power conversion stages run in parallel to reduce ripple and handle high current. As GPU power grows (H100 700W → Rubin >1500W), the number of phases per board increases → more Gate Drivers, MOSFETs, and inductors per board.
BBU Battery Backup Unit: Rack-level power backup for uptime. Relevant to 台達電 and 光寶科 as part of their system integration offering for AI data centers.
PFC Power Factor Correction: Circuit stage at the PSU input that makes the current waveform match the voltage waveform, improving efficiency. Uses Superjunction MOSFETs. Where 朋程 and 杰力 operate.

Power Semiconductor Devices

MOSFET Metal-Oxide-Semiconductor Field-Effect Transistor: The fundamental power switching device. Turns current on and off at high frequency. Comes in many flavors: low-voltage (<100V, used in VRM), high-voltage (200–900V, used in PSU main stage), Superjunction (optimized for high-voltage efficiency). Taiwan suppliers: 朋程, 杰力, 富鼎, 尼克森.
Superjunction MOSFET: A high-voltage MOSFET variant with significantly lower on-resistance (R_DS(on)) for better efficiency. Used in PSU main power stages. Western IDMs (Infineon, ON Semi) are de-prioritizing standard versions — IDM transfer opportunity for Taiwan.
IGBT Insulated-Gate Bipolar Transistor: Power switching device for very high voltage/current (>600V). Used in industrial, EV inverters, large UPS. 強茂 makes these. Less directly relevant to AI server story but part of the IDM capacity picture.
SiC Silicon Carbide: Wide-bandgap semiconductor material. Handles higher voltages, higher temperatures, and switches faster than silicon. Primary material for Stage 3 800V HVDC. Western IDMs (Infineon, ON Semi) are racing into SiC — which is exactly why they're abandoning standard silicon products. 漢磊 is upstream in this space.
GaN Gallium Nitride: Wide-bandgap semiconductor. Ultra-high switching frequency; very compact. Used in fast chargers and starting to appear in data center PSUs. 杰力 has a GaN product line developing.
Rectifier Bridge: The front-end component that converts incoming AC power to DC. First stage in any PSU. Where 朋程 (8255) and 強茂 (2481) operate. Low-margin standard product being de-prioritized by IDMs.
Schottky Diode / FRED Fast Recovery Epitaxial Diode: Diode types used in switching power supplies. Very fast switching recovery time, important for efficiency. 強茂's product portfolio core.

Power ICs

Gate Driver IC: A control IC that amplifies the signal driving a MOSFET or IGBT gate, making it switch faster and more efficiently. 茂達 (6138) is the primary Taiwan Gate Driver company in this thesis.
PMIC Power Management IC: A single chip that manages multiple supply rails — Buck converters, LDOs, power paths. Handles voltage conversion and distribution across a motherboard. 茂達, 致新, 力智 are Taiwan PMICs. Core story: Rubin-gen GPU boards need more PMICs / more power rails.
DRMOS / DrMOS Driver + MOSFET integrated: A package that integrates the Gate Driver IC with the MOSFET (and sometimes the bootstrap diode) into one component. Used in CPU/GPU VRM. Simplifies board design and improves thermal performance. 茂達 is the key Taiwan DRMOS supplier — Q4 2025 +27.7% YoY is the first revenue signal. The more phases in a VRM, the more DRMOS units shipped.
DC-DC Controller: The control brains of a Buck or Boost converter — sets switching frequency, duty cycle, feedback control. 茂達 also makes these.

System Components

PSU Power Supply Unit: Converts AC mains input to the DC rails needed by a server. Typically a rack unit. 台達電 and 光寶科 make high-power AI server PSUs.
Power Shelf: A modular, hot-swap power supply unit in rack format, often delivering 110kW or more in AI rack configurations. 光寶科's 110kW Power Shelf for 800VDC racks was demonstrated at NVIDIA GTC 2026.
DC Relay / Contactor / SSCB: Electromechanical or solid-state devices that switch DC circuits for protection. Critical in HVDC: AC current has natural zero crossings (makes it easy to break), DC does not — so DC protection components are physically harder to design and more valuable. 松川精密 (7788) is the Taiwan play here.

Packaging

Leadframe 導線架: The metal framework stamped from copper alloy that sits inside a semiconductor package, connecting the die to the external pins and providing the primary thermal path. Every discrete power component and PMIC contains one. More power components shipped = more leadframes. Higher-spec copper alloy (厚銅, 高階銅合金) = higher ASP. 順德 (2351) and 長科 (6548) are the Taiwan leadframe plays.

Investment / Industry Terms

IDM Integrated Device Manufacturer: A company that designs AND manufactures its own chips. ON Semi, Infineon, TI, MPS are IDMs. They're shifting focus to SiC/GaN (55–65% gross margin) and away from standard MOSFETs and diodes (25–35% gross margin). This is the IDM transfer thesis: their abandoned standard product capacity flows to Taiwan fabless/IDM companies.
IDM Transfer Thesis: The investment idea that Western IDMs moving upmarket creates a standard-product overflow opportunity for Taiwan suppliers. Anchor signal: onsemi Q1 2026 YoY +4.7%, gross margin 38.5% (mix shift confirmed complete). Taiwan lag: typically 2–4 quarters.
ASP Average Selling Price: Key metric for the packaging theme. An AI/automotive-spec leadframe should command a higher ASP than a consumer-grade one. ASP rising alongside volume = "量價雙增" (quantity + price both rising) — the strongest financial signal.
法說法人說明會 — Earnings Call: Taiwan listed companies' investor conference call (quarterly). Key hunting ground for keywords that confirm thesis: "AI server", "HVDC", "800VDC", "DRMOS", "high-voltage MOSFET", "relay/contactor". Management saying these words = much stronger signal than analyst speculation.
月營收 Monthly Revenue: Taiwan listed companies report revenue monthly (by the 10th of the following month). YoY acceleration across consecutive months is the primary financial validation signal for this thesis.
Vera Rubin / Rubin Platform: NVIDIA's next-generation AI accelerator platform, ramp expected 2H 2026. GPU power consumption expected to exceed 1500W per GPU. This is the demand catalyst for the entire power chain upgrade thesis.