Interaction of Self-Sustained Pulses in Tunnel-Diode Oscillator Lattices

A one-dimensional lattice in tunnel-diode (TD) oscillators supports self-sustained solitary pulses resulting from the balance between gain and attenuation. By applying the reduction theory to the device’s model equation, it is found that two relatively distant pulses moving in the lattice are mutually affected by a repulsive interaction. This property can be efficiently utilized in equalizing pulse positions to achieve jitter elimination. In particular, when two pulses rotate in a small, closed lattice, they separate evenly at the asymptotic limit. As a result, the lattice loop can provide an efficient platform to obtain low-phase-noise multiphase oscillatory signals. In this work, the interaction between two self-sustained pulses in a TD-oscillator lattice is examined, and the properties of interpulse interaction are validated by conducting several measurements using a test breadboarded lattice.

Low-Phase-Noise Oscillator Using a High-QL Resonator with Split-Ring Structure and Open-Loaded T-Type Stub for a Tumor-Location-Tracking Sensor

Sensors in the medical field to detect specific tissues, such as radars, must provide accurate signals from frequency generators. In order to supply an accurate frequency signal, the oscillator must have a low phase noise. Therefore, the resonator used in the oscillator must provide a high QL. Therefore, in this paper, we have proposed a low-phase-noise X-band oscillator that used a resonator with a high value of QL as a sensor for tissue-locating applications. The resonator had a split-ring structure and consisted of an open-loaded, T-type stub with a high-QL; such high-QL levels were enabled by controlling the length of the open-circuit in the T-type stub. This led to the generation of only low-phase noise in the proposed oscillator. Experimental results showed that, at an operating frequency of 10.08 GHz, the output power was 18.66 dBm, the second harmonic suppression was −34.40 dBc, and the phase noise was −138.13 dBc/Hz at an offset of 100 kHz. This proposed oscillator can be used as a sensor to detect the location of tissues during laparoscopic surgery.

On-Chip Voltage-Controlled Oscillator Based on a Center-Tapped Switched Inductor Using GaN-on-SiC HEMT Technology

This study presents a voltage-controlled oscillator (VCO) in a cross-coupled pair configuration using a multi-tapped switched inductor with two switch-loaded transformers in 0.5 µm GaN technology. Two switch-loaded transformers are placed at the inner and outer portions of the multi-tapped inductor. All the switches are turned off to obtain the lowest sub-band. The outer transformer with three pairs of switches is turned on alternately to provide three sub-band modes. A pair of switches at the inner transformer provide a high-frequency band. Two switch-loaded transformers are turned on to provide the highest sub-band. Six modes are selected to provide a wide tuning range. The frequency tuning range (FTR) of the VCO is 27.8% from 3.81 GHz to 8.04 GHz with a varactor voltage from 13 V to 22 V. At a 1 MHz frequency offset from the carrier frequency of 4.27 GHz, the peak phase noise is −119.17 dBc/Hz. At a power supply of 12 V, the output power of the carrier at 4.27 GHz is 20.9 dBm. The figure of merit is −186.93 dB because the VCO exhibits a high output power, low phase noise, and wide FTR. To the best of the author’s knowledge, the FTR in VCOs made of GaN-based high electron mobility transistors is the widest reported thus far.