THz Power Generation Beyond Transistor Fmax

Dongha Shim, Seoul National University of Science and Technology (SNUST)
Eunyoung Seok, Texas Instruments
Daniel J. Arenas, University of North Florida
Dimitrios Koukis, University of Florida
David B. Tanner, University of Florida
K. O. Kenneth, The University of Texas at Dallas


This chapter describes the implementation of sub-terahertz oscillators using a multiple-push technique in digital CMOS technology. The application of sub-terahertz, especially in spectroscopy, is introduced along with emerging high-performance CMOS technology for sub-terahertz circuits. Basic operation principles and design considerations are discussed for the implementation of a push-push and quadruple-push oscillator. A 410-GHz push-push oscillator is demonstrated using in a 45-nm logic CMOS process.The second harmonic in the cross-coupled oscillator is combined at the push-push node, while the differential fundamental signals are canceled. A quasi-optical technique with high sensitivity and wide bandwidth is devised using an on-chip antenna and FTIR system to evaluate the performance of the oscillator. A 410-GHz push-push signal with the power level of -49. dBm (12.6. nW) is observed. A 553-GHz quadruple-push oscillator is also demonstrated in the same technology. A passive network constructively combines the fourth harmonic currents in the coupling transistors of the quadrature oscillator while other lower harmonics are canceled. Quasi-optical measurements showed that the circuit generates four harmonic signals at 553. GHz with a power level of 220. nW, while suppressing unwanted harmonic signals. The circuit consumes 64. mW from a 1.4-V supply. Those circuits would be readily integrated with various analog and digital circuits to implement practical and affordable sub-THz systems for security, healthcare, industrial, defense, and communication applications.