Gain Enhancement of Millimeter-Wave on-Chip Antenna through an Additively Manufactured Functional Package

Antenna-on-chip (AoC) presents an excellent solution for applications requiring higher integration levels and lower cost, however, its radiation performance is poor due to the inherent lossy Si substrate in conventional complementary metal– oxide–semiconductor (CMOS) processes. It is well known that every chip requires a package to protect it from the environment, however this package does not provide any functionality, despite adding to the cost and required space. In this paper, we propose a functional package which has been designed to enhance the gain of the AoC. A 71 GHz coplanar waveguide (CPW) fed on-chip monopole antenna, driven by a voltage-controlled oscillator (VCO) and frequency doubler, was realized in standard 0.18 μm CMOS technology. As a first step to enhance its gain, the AoC was designed on top of an Artificial Magnetic Conductor (AMC) surface. Further gain enhancement was achieved by transforming the chip package into a combination of a superstrate layer and a Fresnel lens, qualifying this as a System-on-Package (SoP). The package has been realized through additive manufacturing to maintain the low-cost aspect. Overall, the measured gain of the packaged AoC is 6.8 dBi, which has been enhanced by ~20 dBs as compared to the unpackaged antenna without an AMC layer.