Chapter 12
CMOS THz Imaging
12.1 Introduction
High performance THz imaging systems can be constructed by the proposed
on-chip metamaterial-based signal sources, receivers and antennas in the pre-
vious s ections. As illustra ted in Figure 12.1, A high power THz signal firstly
generated by MPW-based zero-phase CON and then radiated by the CRLH
T-line-based on-chip LWA. After penetrating through the sample under test,
the resulting THz signal is received by a hig h sensitivity super-regenerative
receivers by TL-SRR/TL -CSRR-based quench-controlled os cillators. With the
proposed transmitter and receiver designs, both narrow-band and wide-ba nd
THz imaging systems can be demonstra ted at 135 GHz and 280 GHz, respec-
tively.
In this chapter, firstly, a narrow-band tr ansmission type THz image r is
demonstrated at 135 GHz w ith various pharmacy and security applicatio ns.
To further enhance a wide-band CMOS THz imaging system at 280 GHz with
high sensitivity, and high spectrum resolution, a heterodyne receiver architec-
ture is required [260]. As s hown in Figure 12.2, a high-sensitivity CMOS wide-
band transmission-type THz imager is also demonstrated by integrating the
circular polarized substrate integrated waveguide (SIW) antenna introduced
in Sec. 8.3 with a heterodyne receiver, which consists of a down-conversion
mixer and a power gain amplifier (PGA). The down-conversion mixer with
single-ga te topology can achieve 80-GHz bandwidth with a conversion gain
of -19 dB. The thre e-stage PGA achieves 150-MHz bandwidth for the detec-
tion resolution. The entire imager is measured with -2-dBi conversion ga in
over 42-GHz bandwidth, -54.4-dBm sensitivity at 100-MHz detection resolu-
tion bandwidth, 6.6-mW power cons umption and 0.99-mm
2
chip area with
high-contrast images measured.
261
262 Design of CMOS Millimeter-Wave and Terahertz Integrated Circuits
Figure 1 2.1: Metamaterial-based THz imaging system.
Figure 12.2: THz image system with heterodyne receiver for high
spectrum resolu tion detection and circular-polarized antenna for the
tolerance of depolarization effect.
In addition, a reflection-based THz imager is a lso required for in-vivo skin
cancer dia gnosis. Compared to the transmissive imaging system, the reflective
type has a highe r requirement for transmitter power, receiver sensitivity and
the control of path of incident and reflected signal. As such, a reflective CMOS
THz imaging system is also proposed based on simulation results in this work
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