Chapter 2
CMOS Metamaterial
Devices
2.1 Introduction
Metamaterial was first demonstrated by [54] with the use of split ring res-
onator (SRR) and metallic wire, among which SRR and metallic wire show
the properties of negative permeability (µ) and negative permittivity (ε) at
the resonance frequency, respectively. Metamaterial is not a traditionally de-
fined materia l. It comprises many periodic or non-periodic unit cells. By giving
different structure and property to these unit cells, the whole array of unit
cells, which is the metamaterial, would show some prope rties that do not nat-
urally exist. A more clear definition can be found in Figure 2.1 [55], where
both x and y axes correspond to the material relative permittivity (ε
r
) and
permeability (µ
r
), respectively. Most natural materials lie on the horizontal
line in the 1s t quadrant (ε
r
> 0, µ
r
> 0) with a relative permittivity larger
than 1 and a nearly unity relative permeability. But with metamaterial, by
giving different design for unit cells, theoretically we can construc t a material
located in any of the regions of Figure 2.1 that enables many interesting appli-
cations. According to the transmission and reflection pr operty, metama terial
can be categorized into two types: non-resonant-type and resonant-type.
Metamaterial in the 1st and 3rd quadrants are transmission-types, where
EM wave is able to propagates inside. The EM wave that propagates in the
1st quadrant (ε
r
> 0 , µ
r
> 0 ) has a positive phase velo city, which is a linear
function of frequency. But when metamaterial appears in the 3rd quadra nt
(ε
r
< 0, µ
r
< 0), it is called left-handed material. Left-handed material has a
non-linear negative phase velocity, which means when the energy propagates
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