Subharmonic injection‐locking and self‐oscillating mixing

Portable and wireless functional near-infrared spectroscopy is a growing field of research for real-time monitoring of brain functions. The most critical challenges in this field are the use of low-power and calibrated circuits. A novel transmitter architecture is proposed to overcome these barriers. This transmitter is low power, capable of being calibrated against process variation, and has a better phase noise and spurious-free dynamic range (SFDR) at the antenna. Besides that, the transmitter can be calibrated, which is not seen in similar research. In this transmitter, injection locking and frequency calibration lead to having an optimal and low-power circuit. The circuit is capable of transmitting data with BFSK and OOK modulations in the frequency band of the medical implant communication service (MICS). The transmitter is designed and simulated in a typical CMOS 0.18-μm technology with a 1-V power supply. The transmitter's power consumption is around 146 and 123 μW, equal to 5.92 nJ/bit and 246-630 pJ/bit for BFSK and OOK modulations, respectively. The signal's phase noise at the antenna is almost À109 dBc/Hz at 1-MHz frequency offset.

Section: Shilmentioning

confidence: 99%

Optimal sub‐harmonic injection‐locked MICS band transmitter for wireless CW‐fNIRS systems

Borjkhani

Setarehdan

Sheikhaei

2021

“…Injection locking is an efficient method to reduce phase noise of either oscillators 1 or frequency convertors 2,3 . When the seed signal comes from the original oscillator, rather than from an external source, the method is called self‐injection locking 4,5 .…”

Section: Introductionmentioning

confidence: 99%

Broadband reduction of phase noise in a spatially extended tunnel‐diode oscillator through multiple self‐injection locking

Narahara

2021

A self-injection locking scheme is proposed to reduce phase noise in a spatially extended oscillator that uses a tunnel-diode (TD) transmission line. When a linear transmission line is connected to each cell of the TD line, a part of the oscillating edge flows through the linear line. This wave on the linear line is reflected at its far end and flows back to the point of connection of the TD and linear transmission lines. By matching the time taken by the reflected wave on the linear transmission line to reach the point of connection with the time taken by the forward-moving oscillating edge to return to the point, the edge can be synchronized with the wave that flows back through each linear line. This multiple self-injection locking significantly reduces the phase noise of the oscillating edge. In this work, the technique of phase noise reduction is explained through numerical phase noise analysis using the perturbation projection vector of the system. Several experimental observations were made to validate the reduction of the phase noise in the oscillating edge traveling on the TD line.

“…After locking the frequencies of the local oscillation ( osc ) and the external signal ( inj ) are equal ( osc = inj ) while the phase difference between them is kept constant. The injection-locking/coupling technique is used for phase noise reduction [1], frequency division [2,3], or multiphase and hyperchaos generation [4][5][6][7]. The phenomenon is unwanted when injection through substrate or other environmental coupling results in an unintended lock.…”

Section: Introductionmentioning

confidence: 99%

A study of superharmonic injection locking in multiband frequency dividers

Plessas

2011

Self Cite

SUMMARYA superharmonic voltage-controlled injection-locked frequency divider, implemented using a modified Colpitts oscillator operating at 2.5, 5 and 10 GHz and a cross-coupled LC oscillator operating at 1.25, 2.5 and 5 GHz, is demonstrated. The proposed triple-band operation is achieved by employing a novel technique that uses pin-diodes and negative power supply. The discrete dividers, built with low noise hetero-junction FETs and high-frequency SiGe BJTs, are described theoretically while their functionality is proven experimentally. Additionally, a short phase noise analysis, which is missing in the literature, is given. Phase noise, frequency range of operation, and locking range measurement results are presented. Finally, post-layout simulation results of a 5 GHz fully differential injection-locked frequency divider, implemented in a 0.25 m SiGe process are provided.