Solid-state noise sources are essential components in highly reliable mm-wave systems for life- or mission-critical applications such as self-driving car radars, airborne and satellite communication systems, space science instruments, and 6G to THz communications. Integrating a noise source, typically based on the avalanche effect of diode junctions, allows for testing of the architecture during production and operational lifetime. This paper presents a comparative study of three avalanche noise diodes integrated in different silicon technologies. The study is based on a solid experimental work that highlights the key points for a successful device design aimed at increasing the generated noise power, bandwidth, and operating frequency.