Ultra‐stable, low‐noise two‐stage current source concept for electronics and laser applications

Abstract

This study presents a two‐stage current source concept which features low‐current noise, excellent drift and stability for higher operating currents. Generally, it is much easier to obtain higher stability and lower‐noise parameters for small operating currents rather than large ones. This fact was used within this concept, where a precise low‐current source (the second stage) corrects the fluctuations of high‐current one (the first stage). In details the theory of operation for setup, the noise‐sources analysis and measurement results are presented. For a maximum operating current equals 1 A, the current noise density of 126 nA/√Hz (at f = 1 kHz), long‐term stability of ±2.1 ppm and temperature coefficient equal 2.8 ppm/°C, were obtained, whereas the current noise below 1 nA/√Hz was obtained for lower operating currents. Presented circuit is inexpensive to construct, non‐thermally stabilised and very small size (1 × 1.2 in2). The obtained parameters are competitive to commercial current drivers designed for laser applications. The two‐stage current source has been successfully implemented in a fully integrated diode‐pumped solid‐state lasers.

Keywords

• ultra-stable low-noise two-stage current source concept
• laser applications
• electronics applications
• low-current noise
• noise-sources analysis
• current drivers