# Design of a Wideband Antenna for Wireless Network-On-Chip in Multimedia Applications
## 2 Design of the On-Chip High-Bandwidth Antenna  
For the antenna operating frequency, the spectrum range of mm-waves (literally 30 GHz-300 GHz; in this work, restricted to 50 GHz-100 GHz) has been selected. As it has been demonstrated in Ref. [57; 58; 59; 60; 61; 62; 63; 64; 65; 66; 67], transceivers operating at such high frequencies can be designed using low-cost and low-power CMOS technologies. Above 50 GHz, the wavelength amounts to a few millimeters. This aspect is useful to reduce the size of the transceiver and of the antenna with respect to other designs operating at frequencies in the X Band (10 GHz) or below (at sub-GHz frequencies), see as an example Ref. [39; 68; 69; 70; 71]. In literature, a widely used mm-wave frequency range is the spectrum around 60 GHz. Indeed, this spectrum range is already used in high bandwidth communications due to the availability of a large unlicensed spectrum from 57 GHz to 66 GHz. Industrial alliances such as WiGiG or Wireless HD already use the 60 GHz spectrum. It is worth noting that cm-range communications in WiNoC applications do not suffer from licensing issues since they are spatially limited and self-contained. Therefore, for WiNoC applications, a large spectrum can be addressed, from 50 GHz to 100 GHz in this work. Indeed, new CMOS SOI (Silicon on Insulator) technologies, characterized by a transition frequency Ft of 300 GHz, or higher, allow operating up to 100 GHz. To meet this high bandwidth value, a wide band antenna design is proposed in this paper. To this aim, a bow-tie antenna topology, see Figure 1, is proposed. In classic antenna design, such as the zig-zag antenna proposed for WiNoC in [31; 37], the size of the antenna depends on the wavelength. Therefore, a conventional antenna is frequency-specific. Instead, the proposed bow-tie antenna is specified by angles and hence the bow-tie antenna is inherently a wideband antenna. With respect to an ideal bow-tie design, the antenna in Figure 1 has the following innovations:  
- custom circuitry for antenna-driver matching  
- rounded corners to reduce charge accumulation phenomena  
Figure 1 shows the layout of the antenna with reference to implementation in a 65 nm SOI CMOS technology. Table 1 shows the values of the design parameters of the bow-tie antenna (L1, L2, L3, W1, W2, W3 and angle \(\alpha\) in Figure 1) and of the length and width (L4 and W4 in Figure 1) of the Co-planar Stripline (CPS), which connects the bow-tie antenna to the single-ended port of the transceiver (antenna feed in Figure 1). It is to be noted that the bow-tie antenna is characterized by both horizontal and vertical symmetry, and hence the values of the parameters in Table 1 are valid for both the right and left parts, and for both the top and bottom parts of the bow-tie antenna. Table 1 also shows the area of the rectangle that includes the proposed antenna. The SOI technology has been selected for this work, since it has been proven to be well suited for on-chip antenna integration and for mm-waves operations, see [57; 60; 61]. Indeed, due to the presence of a high resistive substrate in the SOI technology, it is possible to separate the integrated RF (Radio Frequency) part from the noise coupling due to other circuits (e.g., switching noise of the digital circuits). Moreover, in CMOS SOI technology, passive components can be designed with a higher good-quality factor than in bulk CMOS. In the proposed on-chip realization, a conductive copper layer with a thickness of about 1 \(\upmu\)m is printed on a multi-layer substrate that includes: \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Parameter** & **L1** & **L2** & **L3** & **L4** & **W1** & **W2** & **W3** & **W4** & \(\alpha\) \\ \hline Value & 350 \(\upmu\)m & 50 \(\upmu\)m & 350 \(\upmu\)m & 637 \(\upmu\)m & 60 \(\upmu\)m & 330 \(\upmu\)m & 275 \(\upmu\)m & 20 \(\upmu\)m & 25\({}^{\circ}\) \\ \hline Area of the rectangle & & & & & & & & & \\ including the antenna & & & & & & & & & \\ \hline \hline \end{tabular}
\end{table}