Noise of a Self-Sustaining Avalanche Discharge in Silicon: Studies at Microwave Frequencies

Abstract

The studies of avalanche noise reported by Haitz are extended to frequencies up to and above the avalanche frequency ωa. It is found that the open-circuit spectral voltage density is flat within ±5% from less than 100 Hz up to frequencies approaching ωa. Near ωa the open-circuit spectral voltage density increases with frequency, goes through a maximum at ωa and then decreases rapidly. The spectral power density is similarly flat but fails to exhibit an expected maximum at ωa. For ω≫ωa the spectral power density decreases with ω−4. The experimental results are in good agreement with Hines' theory of avalanche noise for ω≪ωa and ω≫ωa. The discrepancies observed near ωa are thought to be caused by an oversimplification in Hines' theory which neglects internal diode losses. Compared with conventional noise sources such as temperature-limited diodes or gas discharge tubes, avalanche diodes have several advantages: larger noise output, larger bandwidth, lower 1/f noise, low power consumption, small size, and low weight.