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A new method is discussed for the systematic synthesis, design, and performance optimization of single-ended varactor-based 2:1 parametric frequency dividers (PFDs) exhibiting an ultralow-power threshold ( ${P_{\mathrm{ th}}}$ ). For the first time, it is analytically shown that the ${P_{\mathrm{ th}}}$ -value exhibited by any PFD can be expressed as an explicit closed-form function of the different impedances forming its network. Such a unique and unexplored property permits reliance on linear models, during PFD design and performance optimization. The validity of our analytical model has been verified, in a commercial circuit simulator, through the time- and frequency-domain algorithms. To demonstrate the effectiveness of our new synthesis approach, we also report on a lumped prototype of a 200:100 MHz PFD, realized on a printed circuit board (PCB). Although inductors with quality factors lower than 50 were used, the PFD prototype exhibits a ${P_{\mathrm{ th}}}$ -value lower than −15 dBm. Such a ${P_{\mathrm{ th}}}$ -value is the lowest one ever reported for passive varactor-based PFDs operating in the same frequency range.

In this work, we report a new class of passive acoustic-based transponders (PATs), enabling both continuous and threshold temperature sensing, in a reduced form-factor. These PATs rely, for the first time, on the dynamical features exhibited by high-Q X-cut Lithium Niobate (LiNbO 3 ) acoustic resonators, connected to the output of solid-state parametric frequency dividers (PFDs). The unique dynamics of the PFD boost the temperature sensitivity of the acoustic resonator by orders of magnitude. A threshold input power of ~ −15 dBm triggers a sub-harmonic oscillation in the PFD which is proportional to the temperature variations. This unique feature makes any temperature data accessible, in real-time, needlessly of expensive transponder architectures.

We present the design and measured performance of a two-stage ~ 2.3 GHz diode-based parametric frequency selective limiter (pFSLs), built on a FR-4 printed-circuit-board (PCB) and showing record-low power threshold ( $P_{th}$ , equal to −10.8 dBm) and insertion-loss value (ILS.S, equal to 1.66 dB) for driving power levels (P in ) lower than P th . Thanks to its optimally engineered dynamics, the built pFSL can not only selectively attenuate undesired signals with power levels ranging from −10.8 dBm to 4 dBm, but it also provides a strong suppression level (IS> 19 dB) when driven by much higher P in values than P th , even approaching 28 dBm. The record performance demonstrated in this work proves, for the first time, that diode-based pFSLs are suitable to increase the resilience to electromagnetic interference (EMI) even of those wireless radios designed for low-power consumption and, consequently, characterized by a narrow dynamic range.

Massive deployments of wireless sensor nodes (WSNs) that continuously detect physical, biological or chemical parameters are needed to truly benefit from the unprecedented possibilities opened by the Internet-of-Things (IoT). Just recently, new sensors with higher sensitivities have been demonstrated by leveraging advanced on-chip designs and microfabrication processes. Yet, WSNs using such sensors require energy to transmit the sensed information. Consequently, they either contain batteries that need to be periodically replaced or energy harvesting circuits whose low efficiencies prevent a frequent and continuous sensing and impact the maximum range of communication. Here, we report a new chip-less and battery-less tag-based WSN that fundamentally breaks any previous paradigm. This WSN, formed by off-the-shelf lumped components on a printed substrate, can sense and transmit information without any need of supplied or harvested DC power, while enabling full-duplex transceiver designs for interrogating nodes rendering them immune to their own self-interference. Also, even though the reported WSN does not require any advanced and expensive manufacturing, its unique parametric dynamical behavior enables extraordinary sensitivities and dynamic ranges that can even surpass those achieved by on-chip sensors. The operation and performance of the first implementation of this new WSN are reported. This device operates in the Ultra-High-Frequency range and is capable to passively and continuously detect temperature changes remotely from an interrogating node.

This article describes the design methodology to achieve reflective diode-based parametric frequency selective limiters (pFSLs) with low power thresholds ($P_{th}$) and sub-dB insertion-loss values ($IL^{s.s}$) for driving power levels ($P_{in}$) lower than $P_{th}$. In addition, we present the measured performance of a reflective pFSL designed through the discussed methodology and assembled on a FR-4 printed circuit board (PCB). Thanks to its optimally engineered dynamics, the built pFSL can operate around $\sim$2.1 GHz while exhibiting record-low $P_{th}$ (-3.4 dBm) and $IL^{s.s}$ (0.94 dB) values. Furthermore, while the pFSL can selectively attenuate undesired signals with power ranging from -3.4 dBm to 13 dBm, it provides a strong suppression level (IS > 12.0 dB) even when driven by much higher $P_{in}$ values approaching 28 dBm. Such measured performance metrics demonstrate how the unique nonlinear dynamics of parametric-based FSLs can be leveraged through components and systems compatible with conventional chip-scale manufacturing processes in order to increase the resilience to electromagnetic interference (EMI), even of wireless radios designed for a low-power consumption and consequently characterized by a narrow dynamic range., Comment: 11 pages, 10 figures

In this work, we present a new passive and batteryless temperature (T ) sensor, leveraging the unique dynamics of a varactor-based parametric frequency divider (PFD) to boost, by orders of magnitude, the temperature sensitivity attained by commercial and low-cost temperature sensitive components. We show that by including a ceramic thermistor in a PFD circuit made of off-the-shelf low-cost lumped components, the minimum PFD input power (P th ) triggering a sub-harmonic oscillation starts to depend on T . Such unexplored feature makes the generated PFD output power, at half of the driving frequency, exhibit a record-high sensitivity with respect to T that largely surpasses the maximum one attainable by operating the same thermistor in conventional read-out circuits. In order to demonstrate this unreported special operational feature, we built a PFD prototype on a Printed-Circuit-Board (PCB), operating at an input frequency of 886MHz (i.e. an output frequency of 443MHz) and strategically including a commercial thermistor in its network. Despite the fact that no supplied DC power was used, the output power of the built system showed a record-high sensitivity (up to 2.5dB/°C), thus offering exciting opportunities to attain low-cost chip-less temperature sensors for a variety of applications, ranging from smart manufacturing to environmental and agriculture monitoring.

Recently, photonic crystals have emerged to contribute in building all-optical computers and optical communication systems. This is due to the urgent need for faster computers and mobiles with high speed processing of data and with higher data transmission rates. In this paper we review the operation of photonic crystal logic gates and depict the different design techniques that produce a wide range of structures realizing the logic functions. We investigate several techniques such as self-collimated beam, multi-mode interference, interference based defect method and nonlinear Kerr materials based gates. As a summary, we compare the various key features of each design and illustrate the advantages and disadvantages of each design technique.