Abstract: Generation of Terahertz range (300 GHz to 3 THz) frequencies is increasingly important for communication, imaging and spectroscopic systems, including concealed object detection. Apparatus and methods describe generating multiple phase signals which are phase-locked at a fundamental frequency, which are then interleaved into an output which is a multiple of the fundamental frequency. By way of example phase generators comprise cross-coupling transistors (e.g., NMOS) and twist coupling transistors (NMOS) for generating a desired number of phase-locked output phases. A rectifying interleaver comprising a transconductance stage and Class B amplifiers provides superimposition of the phases into an output signal. The invention allows frequency output to exceed the maximum frequency of oscillation of a given device technology, such as CMOS in which a 324 GHz VCO in 90 nm digital CMOS with 4 GHz tuning was realized.

Abstract: Generation of Terahertz range (300 GHz to 3 THz) frequencies is increasingly important for communication, imaging and spectroscopic systems, including concealed object detection. Apparatus and methods describe generating multiple phase signals which are phase-locked at a fundamental frequency, which are then interleaved into an output which is a multiple of the fundamental frequency. By way of example phase generators comprise cross-coupling transistors (e.g., NMOS) and twist coupling transistors (NMOS) for generating a desired number of phase-locked output phases. A rectifying interleaver comprising a transconductance stage and Class B amplifiers provides superimposition of the phases into an output signal. The invention allows frequency output to exceed the maximum frequency of oscillation of a given device technology, such as CMOS in which a 324 GHz VCO in 90 nm digital CMOS with 4 GHz tuning was realized.