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We obtained frequency increase in resonant-tunneling-diode (RTD) terahertz (THz) oscillators by thick antenna electrode. The THz oscillator was composed of an RTD and slot antenna. Because an oscillation at resonance frequency of the RTD and slot antenna occurs when the negative differential conductance of the RTD compensates for the loss of the antenna, a reduction in the conduction loss and inductance...
A report is presented on the dependence of oscillation frequency on antenna length in resonant-tunnelling-diode terahertz (THz) oscillators integrated with slot antennas. The upper limit of the oscillation frequency was maximised at an optimum antenna length. The highest oscillation frequency obtained in the experiment was 1.55 THz for a 16 μm-long antenna at room temperature.
Room-temperature fundamental oscillation of up to 1.31 THz was achieved in thin-well resonant tunneling diodes integrated with planar slot antennas. The output powers were ∼10 µW at 1.31 THz and around 30 nW in the 0.8–1.1 THz region. This high frequency oscillation with relatively high output power is attributed to a reduction in the intrinsic delay and an increase in the widths of current density...
We report on our recent results of terahertz oscillators with resonant tunneling diodes (RTDs) at room temperature. By a structure with high current density and small capacitance, a fundamental oscillation at 831 GHz was obtained in GaInAs/AlAs double-barrier RTDs integrated with slot antennas. A comparison with theoretical analysis shows a possibility of electron transition from the Γ to L bands...
Room-temperature THz oscillators using resonant tunneling diodes are shown. Structures for short transit time are fabricated toward 1 THz fundamental oscillation. Oscillators with offset slot antenna and array configuration are demonstrated for high power. Bias-dependent frequency, spectral linewidth, and direct modulation are also reported.
We demonstrated the operation of GaInAs/AlAs resonant tunneling diode (RTD) oscillators with high output power (100-200 μW) at frequencies of 430-460 GHz using an offset-fed slot antenna, in which the RTD was placed 45 μm from the center of a 100-μm-long antenna. The highest output power obtained in this study was 200 μW at 443 GHz for a single RTD with a peak current density of 18 mA/μm2. The output...
A fundamental oscillation up to 915 GHz was observed at room temperature in InGaAs/AlAs resonant tunneling diode integrated with planar slot antennas. By reducing the mesa area, parasitic capacitance of resonant tunneling diode was decreased. The output power was small (around a few tens nW) at present because of a small area (ap0.63 mum2) and a low available current density (ap3 mA/mum2) which is...
We report experimental and theoretical results on the increase in output power of resonant tunneling diode (RTD) oscillators in sub-terahertz (THz) range with an offset-fed slot antenna and high current density. Theoretical analysis shows that the oscillation frequency increases with an offset from the center of the slot antenna. Output power also increases with the offset up to the point of the best...
A fundamental oscillation of up to 831 GHz was observed at room temperature in GaInAs/AlAs resonant tunneling diodes integrated with planar slot antennas. The thickness of the collector spacer layer was optimized (20 nm) and the mesa area (<1 mum2) was reduced in order to reduce the resonant tunneling diode capacitance. Reduction in the negative differential conductance in the small mesa area was...
We observed coherent power combination in 3- and 6-element oscillator array using resonant tunneling diodes coupled through planar circuits in sub-THz range. InGaAs/AlAs resonant tunneling diode oscillators with slot antennas are arranged collinearly on the same InP wafer, and coupled with each other through a metal-insulator-metal stub structure. In 3-element array, a single peak at 293 GHz with...
We propose highly integrated array of resonant tunneling diode oscillators and observed coherent power combination in this structure. Two InGaAs/AlAs RTD oscillators with slot antennas on the same InP wafer are arranged collinearly, and coupled with each other through a 5-mum-long metal-insulator-metal stub structure. Although the individual oscillation frequencies were 329 GHz and 332 GHz, a single...
We propose resonant tunneling diode (RTD) oscillators with offset-fed slot antennas in THz and sub-THz range for high frequency and high output power oscillators at room temperature. We analyzed the dependence of the oscillation frequency and output power on RTD position along slot antenna using 3-dimensional electromagnetic-field simulation. The oscillation frequency and output power largely increase...
We propose THz oscillators using resonant tunneling diodes (RTDs) and slot antennas with stub-shaped reflectors. The stub-shaped reflectors are composed of metal-insulator-metal layer structure, and are put at the edges of slot antenna to obtain high reflection of electromagnetic field. Oscillation frequency and output power were analyzed theoretically including all the parasitic elements in RTD and...
The third harmonic oscillation around 1 THz at room temperature and its frequency change with bias voltage were observed in GaInAs/AlAs double-barrier resonant tunneling diodes integrated with slot antennas. The frequency changed from about 0.96 to 1.02 THz. Theoretical analysis using simple equivalent circuit was in reasonable agreement with the measurement
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