The modern integrated circuit (IC) manufacturing process has exposed chip designers to hardware Trojans which threaten circuits bound for critical applications. This paper details the implementation and analysis of a novel ring oscillator network technique for Trojan detection in an application specific integrated circuit (ASIC). The ring oscillator network serves as a power supply monitor by detecting fluctuations in characteristic frequencies due to malicious modifications (i.e. hardware Trojans) in the circuit under authentication. The ring oscillator network was implemented and fabricated in 40 IBM 90nm ASICs with controlled hardware Trojans. This work analyzes the impact of Trojans with varied partial activity, area, and location on the proposed ring oscillator structure and demonstrates that stealthy Trojans can be efficiently detected with this technique even while obfuscated by process variations, background noise, and environment noise.