Fully integrated on-chip rectennas for K-band applications using a novel tunnelling diode

Abstract

Recent developments in the design of the epitaxial structure of an asymmetrical spacer layer tunnel (ASPAT) diode have included a quantum well next to the barrier. This leads to a substantially improved curvature coefficient due to a reduction in the leakage current, introducing yet further advantages over the standard ASPAT diode, which has temperature independence, zero bias operations, and a high dynamic range. This work has developed these diodes into a fully integrated miniature rectenna solution, which integrates an antenna, rectifier, and RC filter. This device targets an operating frequency of 26 GHz, where such a solution could see applications in wireless power transfer, energy harvesting, or signal detection. The current design uses a loop antenna, where the trace has been meandered to increase the electrical length whilst enabling the die size of the device to be reduced to 2x0.8 mm². This size, whilst at mm-scale, enables an efficient antenna to be designed with a simulated gain of 2 dBi. Integrated into this design is a general voltage doubler circuit, consisting of a series capacitor, a shunt diode, and a series diode, with this circuit followed by an RC filter, a shunt capacitor and a resistor, integrated on-chip. The design includes bond pads allowing the device to be packaged in standard QFN packages or onto PCBs for testing. Measurements confirmed that these devices can detect a K-band signal, with a peak reading of 55.2 mV detected at 23.5 GHz.