3 months ago
- The author prefers real data for circuit illustrations in their book, avoiding fake or retraced diagrams.
- Measuring V-I plots for semiconductors is challenging due to tiny currents, sudden spikes causing device failure, and temperature-related drift.
- Using a benchtop multimeter and pulsed power helps measure microamps/microvolts and reduce heating effects; cooling with non-conductive liquid like mineral oil is recommended.
- Computer interfacing via SCPI protocol over RS-232, USB, or Ethernet automates measurements, but the author's power supply lacked remote control, leading to purchasing a source measure unit (SMU).
- The Rohde & Schwarz NGU401 SMU, bought second-hand cheaply, supports FastLog mode for high-speed data streaming, though USB caused issues, so Ethernet was used instead.
- A C program captures diode V-I curves using FastLog, averaging data for accuracy across current ranges from microamps to amperes.
- Real plots reveal deviations from idealized exponential models in diodes due to resistive effects, and transistor behavior shows constant-current traits and nuanced breakdown voltages.
- To measure beyond the SMU's 20V limit, a series power supply and pulsed VGS signals were used to prevent transistor damage from heating.