Resonant Tunneling Diode Terahertz Sources With up to 1 mW Output Power in theJ-Band

Abstract

Terahertz (THz) oscillators based on resonant tunneling diodes (RTDs) have relatively low output power, tens to hundreds of microwatts. The conventional designs employ submicron sized RTDs to reduce the device self-capacitance and, as a result, realise higher oscillation frequencies. However, reducing the RTD device size leads to lower output power. In this paper we present RTD oscillators which can employ one or two RTD devices of relatively large size, 9-25 µm 2 , for high power and, at the same time, can oscillate at THz frequencies. This is achieved through low resonating inductances realized by microstrip or coplanar waveguide (CPW) transmission line short stubs with low characteristic impedances (Z0), which have lower inductance values per unit length and so compensate the increase of the selfcapacitance of large area RTD devices. Thus, fabrication using only photolithography is possible. It is also shown that device sizing, which is limited only by bias stability considerations, does not limit device bandwidth. Further, we report a new way to estimate the RTD oscillator output power with frequency. A series of oscillators with oscillation frequencies in the 245-309 GHz range and output powers from 0.1-1 mW have been demonstrated showing the feasibility of the proposed approach. Index Terms-Resonant tunnelling diode (RTD), terahertz (THz) sources, photolithography.

Roadmap of Terahertz Imaging 2021

“…This is a consequence of the sub-micron size of the RTDs arising from the need for a low device capacitance as a price for the high operation frequency. Recently, incorporation of RTDs in transmission lines has allowed for a larger diode footprints and a higher output power, reaching 1 mW at 260 GHz [124]. Another approach for power enhancement is the use of power combining arrays [122].…”

Terahertz band: Lighting up next-generation wireless communications

“…After- RTD oscillators possesses quantities of strengths, such as compact and low power consumption. Furthermore, the output signal of the RTDs is easily modulated via a bias voltage [31]. These features are suitable for THz wireless communication.…”

Long‐range millimetre wave wireless links enabled by travelling wave tubes and resonant tunnelling diodes

“…where ∆I and ∆V are the peak-to-valley current and voltage differences, respectively. State of the art RTD based transmitters include 2 mW, 15 Gbps at W-band using on-off keying (OOK) and amplitude shift keying (ASK) [15] and 1 mW with 110 GHz modulation bandwidth at 260 GHz [16,17]. The fastest reported wireless data rates using RTD based transmitters include 34 Gbps at 500 GHz using single channel and 56 Gbps using dual channel links [18 -20].…”

“…The cut‐off frequency f max is given by where C n is the RTD self‐capacitance, G n is the absolute value of maximum negative differential conductance and R S is the contact resistance, and the maximum power is estimated by where Δ I and Δ V are the peak‐to‐valley current and voltage differences, respectively. State‐of‐the‐art RTD‐based transmitters include 2 mW, 15 Gb/s at W‐band using on–off keying and amplitude shift keying [15] and 1 mW with 110 GHz modulation bandwidth at 260 GHz [16, 17]. The fastest reported wireless data rates using RTD‐based transmitters include 34 Gb/s at 500 GHz using single‐channel link and 56 Gb/s using dual‐channel link [18–20].…”