Designing for Picoamps: Modern Applications of Linear Systems’ Low Leakage Diodes

JC - Linear Systems
Sep 15
2 min read

Precision Protection for Precision Circuits

In modern high-impedance analog systems, every picoamp counts. When your front end is measuring nanoamps—or even picoamps—microamp-level diode leakage can swamp the signal, distort measurements, and silently undermine performance.

That’s why designers turn to Linear Systems’ PAD and DPAD Series Low Leakage Diodes—purpose-built to deliver ultra-low reverse leakage, low junction capacitance, and exceptional thermal stability.

Why Low Leakage Matters

Standard silicon diodes can leak nanoamps to microamps, which becomes significant in sensor and measurement circuits. Linear Systems’ PAD and DPAD Series diodes achieve reverse leakage in the picoamp range, even across temperature extremes, helping engineers maintain accuracy and repeatability.

Key benefits:

⚡ Ultra-low reverse leakage → preserves accuracy in high-impedance circuits
📉 Low junction capacitance → maintains bandwidth and reduces distortion
♨️ Thermally stable → consistent performance over temperature
🛡️ Fast recovery → protects sensitive nodes without adding error

The Product Families

PAD Series – Single Low Leakage Diodes

Industry-leading reverse leakage in the picoamp range
Ideal for guarding, clamping, or protecting single high-impedance nodes
Common part numbers: PAD1, PAD2, PAD5

DPAD Series – Dual Matched Low Leakage Diodes

Two matched low-leakage diodes on the same die
Excellent thermal tracking and symmetry
Ideal for differential sensor front ends, precision measurement bridges, and long-term stability
Common part numbers: DPAD1, DPAD2, DPAD5

Where They’re Used Today

Precision Measurement & Test Equipment

Guard diodes and clamps in electrometers, picoammeters, and high-impedance voltage dividers
Leakage-sensitive front ends in source-measure units (SMUs) and photodiode amplifiers

Sensor Interfaces

Protecting ADC and amplifier inputs in spectroscopy, photometry, and bio-sensing systems
Limiting charge injection in capacitive or charge-redistribution sensors

Low-Noise Analog & RF Systems

Bias stabilization and protection in ultra-low-noise audio preamps, RF front ends, and oscillators
Diode clamps in high-impedance nodes to prevent overvoltage without adding leakage

Industrial & Aerospace Systems

Monitoring high-resistance networks (e.g., insulation monitors) where leakage corrupts readings
Long-duration missions where diode stability over decades is crucial

Summary

Leakage currents that were once negligible are now design-limiters. Linear Systems’ PAD and DPAD Series Low Leakage Diodes give engineers the picoamp-level assurance they need to build stable, accurate analog systems in today’s high-impedance designs.