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.

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We report on high efficiency, high power and low phase noise resonant tunneling diode (RTD) oscillators operating at around 30 GHz. By employing a bias stabilization network which does not draw any direct current (DC), the oscillators exhibit over a 10-fold improvement in the DC-to-RF conversion efficiency (of up to 14.7%) compared to conventional designs (0.9%). The oscillators provide a high maximum output power of around 2 dBm, and low phase noise of-100 dBc/Hz and-113 dBc/Hz at 100 kHz and 1 MHz offset frequencies, respectively. The proposed approach will be invaluable for realizing very high efficiency, low phase noise and high-power millimeter-wave (mmwave) and terahertz (THz) RTD-based sources.

The paper reports on a 15 Gbps wireless link that employs a high power resonant tunneling diode (RTD) oscillator as a transmitter. The fundamental carrier frequency is 84 GHz and the maximum output power is 2 mW without any power amplifier. The reported performance is over a 50 cm link, with simple amplitude shift keying (ASK) modulation utilized. The 15 Gbps data link shows correctable bit error rate (BER) of 4.1×10-3 , while lower data rates of 10 Gbps and 5 Gbps shows BER of 3.6×10-4 and 1.0×10-6 , respectively. These results demonstrate that the RTD transmitter is a promising candidate for the next generation low cost, compact, ultra-high data rates wireless communication systems. Index Terms-resonant tunneling diode, wireless communication systems, amplitude shift keying, oscillator, high power transmitter.

This paper presents a novel, on-wafer de-embedding technique for the accurate small-signal equivalent circuit modelling of resonant tunneling diodes (RTDs). The approach is applicable to stabilised RTDs, and so enables the modelling of the negative differential resistance (NDR) region of the device's current-voltage (I-V) characteristics. Further, a novel quasianalytical procedure to determine all the equivalent circuit elements from the de-embedded S-parameter data is developed. Extraction results for a 10 x 10 µm 2 stabilised, low-current density RTD at different bias points show excellent fits between modelled and measured S-parameters up to 110 GHz.Index Terms-Bias oscillations, experimental modelling, parameter extraction, Resonant tunneling diode (RTD), smallsignal equivalent circuit. Lisbon. His current research interests include applications of resonant tunneling diodes and resonant tunneling diode based optoelectronic devices, and neural-inspired photonic circuits.