Preface
Terahe rtz (THz) radiation (0.1 ∼ 30 THz) fills the gap between electronics and
photonics with unique spectroscopic and communication properties. A great
deal of attention has been paid to THz electronic a nd pho tonics recently due
to their moderate wavelengths to leverage adva ntages of both microwave and
optics, such as good bandwidth, spatial resolution, and penetration depth
with no harmful ioniza tion. However, the current optics-based THz systems
are bulky, expensive, lack portability, and have low detection capability by
electro-optic sampling techniques.
With the rapid scaling of CMOS technology, it has become feasible to
realize integrated circuits with the standard C MOS process in millimeter-
wave (mm-wave) and even the THz frequency region towar d low-cost, portable
and large-arrayed systems on a chip. However, it is still challenging to deal
with generation, amplification, transmission and detection of THz signals by
a single CMOS transistor due to the huge substrate and path propagation
loss as well as low device gain. Instead, one needs to figure out how to have
a coherent design of arrayed CMOS tra nsistors with high output power, high
gain, and high sensitivity. The main point here is how to manipulate the phase
of EM waves.
As s uch, this book shows that with the use o f metamaterials, one can
have coherent THz signal generation, amplification, transmission, and detec-
tion for arrayed CMOS transistors with significantly improved performance.
New metamaterial-based THz imaging and communication systems have been
demonstrated in CMOS as well.
For CMOS THz signal ge ne ration, the target is to improve the output
power and power efficiency with a wide frequency tuning range (FTR)
in a compact size. By coupling N oscillators in- phase, the coupled
oscillator network (CON) can effectively achieve an N times higher
output power but also N times less phase noise. The conventional
on-chip coupling network by a length of λ/2 or λ transmission-line
xxvii
xxviii Preface
(T-line) is too bulky and lossy with difficulty for the same purpose as
phase synchronization. Non-resonant-type metamaterials such as the
magnetic plasmon waveguide (MPW) with zero-phas e-shift property
can be applied to achieve an in-phase and low-loss coupling between
oscillator s with compact size , which enables the des ign of a THz signal
source with high power density and high efficiency.
For CMOS THz signal amplification, the target is to improve the out-
put power density and bandwidth. With the use of non-resonant-type
metamaterials, composite right-/left-handed (CRLH) T-line, a new 2D
distributed in-phase power-combining network c an be developed to
provide distributed amplification and power combining within a com-
pact area simultaneously. As such, one can achieve high output power,
high output power density and wide-band performance for a power
amplifier (PA).
For CMOS THz signal transmission, the target is to design wide-
band, high-gain on-chip antennas within a compact area. Substrate
integrated waveguides (SIW) have been recently explored for the de-
sign of high quality factor (Q) pa ssive devices from mm-wave to THz,
which enables an on-chip a ntenna design that can leverage the ad-
vantages of bo th planar T-line and non-planar waveguides with low
loss and wide-ba nd performance in a miniaturized cavity. Moreover, a
non-resonant-type metamaterial such as CRLH T-line with a nonlin-
ear phase-to-length relationship enables more co mpact antenna design
toward even higher gain and efficiency.
For CMOS THz signal detection, the target is to improve receiver sen-
sitivity within a compact size. The use of r esonant-type metamaterial,
transmission line (T-line) loaded with a split ring re sonator (TL-SRR)
or complementary split ring resonator (TL-CSRR), can significantly
improve both high-Q o scillation and oscillatory amplification within a
compact area. As such, one can achieve high sensitivity for a super-
regenerative rec eiver (SRX) with quench control. Moreover, with the
use of zer o-phase co upling, one can further improve s ensitivity.
Finally, with the proposed coherent component designs, both narrow and
wide-band THz transceivers can be demonstrated at 135 GHz and 280 GHz,
respectively. In summar y, the coher ent CMOS THz transceiver by metama -
terials is explore d in this book with significantly improved performance for
signal generation, transmission, and detection. For signal generation, non-
resonant-type metamaterials such as MPW ca n be applied for high-power
signal source designs; for signal amplification, non-resonant-type metamate-
rials such as CRLH T-line can be applied for high PAE and compact power
amplifier designs; for signal transmissio n, non-resonant-type metamaterials
such as CRLH T-line can be applied for high-gain antenna designs; for sig-
nal detection, resonant-type metamaterials such as DTL-SRR or DTL-CSRR
Preface xxix
can be applied in high-sensitivity receiver designs. The component designs are
supported by chip demonstrations with measurement results. The system per-
formance is also evaluated after CMOS-based system-on-chip integration. It
has shown great potential for metamaterial-based coherent designs for CMOS
THz electronics with wide a pplications in nex t- generation communication and
imaging systems.
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