A THz Detector Chip with Printed Circular Cavity as Package and Enhancement of Antenna Gain

A terahertz (THz) detector chip with a low-cost printed circular cavity package is proposed in this article. The chip consists of a differentially fed antenna and a Schottky diode at its terminal. The passive structure of the Schottky diode is modeled into the antenna. To improve its performance, the detectenna (detector + antenna) chip is designed so that it can be mounted on the upper side of a Duroid substrate with a metal strip ring surrounding the chip. The ring is connected to the ground plane on the bottom of the substrate by vias to form a circular cavity. With the so-called circular cavity package, the radiation pattern of the antenna on the chip is not only converted from omnidirectional to unidirectional, but also with its surface wave well suppressed, the directivity of the antenna can increase, and hence improve its sensitivity. With this cavity, the isolation between adjacent elements can also be improved if it is used to build an array. The measured results show that a gain enhancement of 5.4-7.7 dB can be achieved within the operating bandwidth. The maximum sensitivity is 563 V/(W/mm²) and the minimum noise equivalent power density (NEPD) is 1.2(pW/mm²)/(Hz)^1/2 at 216 GHz.