THz Using CMOS Approach

This chapter strives to give a complete picture of designing THz systems in CMOS technologies. First, it motivates the usage of such technologies as a necessary step toward the high-volume production of the THz systems. Second, it states the CMOS design challenges when operating at such high frequencies, mainly lack of power gain, low supply voltage, and increased loss of passive structures. Then, it gives a survey of commonly used techniques to address those challenges, both in the transmitter and the receiver case. To illustrate the potential of the presented design approaches, four CMOS chip examples are described. In the transmitter case, a 670 GHz 4 × 2 oscillator-radiator array and a 420 GHz multiplier-based transmitter, both implemented in a 40 nm CMOS technology, are presented. In the receiver case, a 28 nm CMOS 605 GHz harmonic injection-locked receiver and a 40 nm CMOS 420 GHz superheterodyne IQ receiver are depicted. Although targeting different applications and operating with different principles, those chips use some common, standard design techniques that can be identified as the foundation for most THz CMOS designs. The chapter is concluded with a description of a 420 GHz phase-imaging system, consisting of 420 GHz transmitter and receiver CMOS chips. Finally, the phase-imaging results obtained by using the designed system are demonstrated as illustrations of the potential of the THz system.