February 21, 2006 – Taiwanese foundry UMC has fabricated a push-push voltage-controlled oscillator (VCO) with an operating frequency of 192GHz using 0.13-micron process technologies, the highest operating frequency for any silicon-based circuit to date. The chip was developed by the Silicon Microwave Integrated Circuits and Systems Research Group (SIMICS) at the U. of Florida-Gainesville’s department of electrical and computer engineering. In June 2005 UMC produced a then-record 105GHz VCO based on the group’s design. VCOs are used in most RF and wireless systems, with other applications in remote sensing and imaging for chemical detection.
Oscillators are known for generating signals at normal operating frequencies and can be pushed to several orders of magnitude higher, but those signals are often too weak to be effective. In push-push VCOs, the core operating frequency is one half of the output frequency, with higher device gain, varactor, and capacitor Q factors, and lower transmission line loss — resulting in a stronger signal. The VCO provides output power of ~-20dBm and phase noise of ~-100dBc/Hz at 10MHz offset, while consuming 11mA from a 1.5V supply. This work has been supported by DARPA.
The Florida researchers also have a 140GHz VCO running in the lab, built with 90nm process technologies, which should be able to be turned into a push-push device to generate a ~280GHz signal, indicated professor Kenneth O. “Furthermore, if a 65nm process is used, we can probably reach 350-400GHz. Generating a THz signal in CMOS technology is not far off,” he stated.