Wide Input Power Range Research Articles

Analysis and Design of a Reconfigurable Rectifier Circuit for Wireless Power Transfer

An efficient and reconfigurable rectifier circuit, with the capability of automatically switching from low-power to high-power operation mode, is presented in this paper. The new topology allows the rectifier to convert RF power to dc power efficiently over an extended input power range. The circuit consists of diodes as rectifying elements and of n-channel field effect transistor in a depletion mode acting as the automated switch. Without using an external dc source, the circuit directly uses the rectified output dc voltage to bias the transistor, allowing high conversion efficiency over a wide input power range. This results in a compact and self-contained circuit. A total of two prototypes optimized for near-field and far-field wireless power transfer systems are fabricated and the measured results show that the performance exceeds that of the conventional rectifier circuit, which can only stay efficient over a limited range of the input power. The proposed design can maintain more than 50% of conversion efficiency over more than 25-dB range of the input power, with peak efficiency of 88% and 80% for near-field and far-field rectifiers, respectively. A system-level validation also confirms the improvement of the proposed rectifier design.

An 18.9-dB Dynamic-Range Rectifier Based on Time-Domain Modeling and Quality Factor

This letter presents a design of 433-MHz rectifier for wireless power transmission (WPT) in medical implant devices (MIDs). By modeling microwave Schottky diode in the time domain, the dc voltage and the optimal input impedance can be obtained at the high input power range when the current waveform at each input power was determined and implemented. At the input terminal, a pair of shunt capacitors were connected with the series and shunt inductors to improve the quality ( $Q$ ) factor of matching network, which enhanced the rectifier efficiency in the wide input power range. By using lump elements in matching network, the 1.1 cm $\times0.4$ cm compact-size rectifier had the measured efficiency above 50.1% where the input power from −6.8 dBm (0.209 mW) to 12.1 dBm (16.22 mW) and thus, the dynamic range of 18.9 dB achieved. The peak efficiency was 64.4% at 5 dBm (3.16 mW).

A -20 to 30 dBm Input Power Range Wireless Power System With a MPPT-Based Reconfigurable 48% Efficient RF Energy Harvester and 82% Efficient A4WP Wireless Power Receiver With Open-Loop Delay Compensation

This paper presents a reconfigurable wide input power range radio frequency (RF) energy harvester (EH) with alliance for wireless power (A4WP) wireless power receiver (WPR). A reconfigurable RF-DC converter for RF EH and maximum power point tracking algorithm are proposed to maintain high efficiency over a wide input power range –20 to +20 dBm. The A4WP WPR is designed and merged with the EH to receive power higher than +20 dBm. In order to improve the power conversion efficiency (PCE), the delay between the ac input voltage and current is compensated by the proposed open-loop delay compensation method. The chip is implemented in 0.18 μm bipolar-CMOS-double-diffused metal-oxide-semiconductor process. The die area of the chip is 4.3 mm × 3.2 mm, including the pads. The proposed EH with WPR achieves a measured peak PCE of 48.19% with respect to the input power of 0 dBm at 900 MHz. It also has a peak PCE of 82.14% with respect to the input power of 30 dBm in an A4WP mode operation at 6.78 MHz.

Single- and Dual-Band RF Rectifiers with Extended Input Power Range Using Automatic Impedance Transforming

This paper presents an automatic impedance transforming technique to extend the radio frequency rectifier input power range with high conversion efficiency. The rectifier employs two branches of subrectifier, each achieving impedance matching at high and low input power ranges. Then, the two branches are connected by a $\lambda/4 $ T-junction power divider. With such configuration, the input impedance of the two subrectifiers are transformed automatically, allowing the impedance matching over a wide input power range. In this way, the injected power can be optimally delivered to the subrectifiers, achieving a high efficiency over this wide input power range. This scheme manages to eliminate the power detetor for branch selection and can be applied to both single- and dual-band rectifiers with a reduced design difficulty. For validation, a single-band rectifier working at 915 MHz and a dual-band rectifier at 915/2450 MHz are implemented. Design analysis on the single- and dual-band rectifiers is carried out. The measurement results show that 68% maximum efficiency is achieved for the single-band (915 MHz) rectifier, and the input power range for the efficiency >70% of the peak efficiency is from −5 to 31 dBm. Besides, the dual-band rectifier shows 66% and 58% peak efficiencies at 915 and 2450 MHz, respectively. The input power range is from −6 to 33 dBm for the efficiency >70% of its peak value at 915 MHz, while from 10 to 32 dBm at 2450 MHz. These indicate that the input power range with high efficiency is extended.

An Adaptable Interface Circuit With Multistage Energy Extraction for Low-Power Piezoelectric Energy Harvesting MEMS

This paper presents a self-powered interface circuit to extract energy from ambient vibrations for powering up microelectronic devices. The circuit interfaces a piezoelectric energy harvesting micro electro-mechanical systems (MEMS) device to scavenge acoustic energy. Synchronous electric charge extraction (SECE) technique is deployed through the implementation of a novel multistage energy extraction (MSEE) circuit in 180 nm HV CMOS technology to harvest and store energy. The circuit is optimized to operate with minimum power losses when input power is limited, and adapts well to operating conditions with higher input power. The highly accurate peak detector was validated for a wide piezoelectric frequency range from 20 Hz to 4 kHz. A charging efficiency of about 84% has been achieved for 4.75 V open-circuit piezoelectric voltage excited at 390 Hz input vibration under nominal input power range of 30–80 μW. Power optimizations enable the circuit to maintain a conversion efficiency of 47% at input power level as low as 3.12 μW. MSEE provides up to 15% efficiency improvement compared to traditional SECE, and maintains power efficiency as high as possible for a wide input power range.

A −40 dB EVM, 77 MHz Dual-Band Tunable Gain Sub-Sampling Receiver Front End in 65-nm CMOS

In this paper, the first dual-band sub-sampling receiver front end with sampling frequency optimization to meet the ultimate receiver error vector magnitude (EVM) of −40 dB over wide input power range of 19 dB is proposed. A systematic sub-sampling receiver chain EVM optimization with respect to major system-level impairments, such as noise folding, sampling frequency, IQ mismatches, phase noise of the sub-sampling clock, and unit capacitor value realizable at the decimation filter, is presented. The proposed dual-band sub-sampling receiver has a 26–41 dB continuously tunable gain for 2.4 GHz and 26–38.5 dB for the 5 GHz WLAN band. Continuously tunable gain ensures the ultimate receiver EVM performance over wider input power levels. In addition, the 5 GHz band is continuously tunable from 4.5 to 5.7 GHz. An active balun feedback low-noise amplifier followed by a sub-sampling down-conversion mixer is implemented to down-convert both WLAN bands to an intermediate frequency in the range from 445 to 538 MHz. Sub-sampling frequency optimization proposed in this paper down-converts both WLAN bands with the sampling frequency from 1.78 to 2.15 GHz to reach the target EVM. Additionally, a switched capacitor decimation filter running at 90 MHz is implemented to provide dual functionalities of down-conversion to baseband and band selection. A test-chip is implemented in a 1.2 V 65-nm CMOS technology. The proposed dual-band sub-sampling receiver occupies a total active area of 0.72 mm2 and has a total power dissipation of 55.6 mW. The overall receiver chain shows a noise figure of 11.5 dB at the highest gain and an IIP3 of −8 dBm at the lowest gain.

RF Energy Scavenging With a Wide-Range Input Power Level

Energy scavenging is a promising technique for micro-devices such as wireless sensor networks (WSNs). Radio frequency (RF) is considered a sustainable source that can be utilized and harvested due to its important features. The essential goal of this study was designing and investigating a wide input power range through a theoretical and simulation work for the 900 MHz frequency band with acceptable efficiency. In this work, we investigated both the low input power and the high input power range circuits; the two circuits were combined to achieve the goal of the wide input power range. L impedance matching elements were used to perform the desired matching between the power source and the circuit to reduce the reflected power resulted in enhanced RF-DC conversion efficiency. 60 % was the peak efficiency for the proposed design at 0 dBm with the output voltage of 16.56 V, and a generated current of 1.39 mA for the load of 12KΩ.

High-Efficient Rectifier With Extended Input Power Range Based on Self-Tuning Impedance Matching

In this letter, a microwave rectifier with a wide input power range is presented by proposing a self-tuning impedance matching (STIM). The STIM consists of a varactor reversely biased by the output voltage of the rectifier to compensate the variation of the input impedance caused by the input power, so that impedance matching is obtained over a wider input power range. For validation, the proposed rectifier at 2.4 GHz was designed and implemented. The experimental results show that the RF-dc power conversion efficiency maintains over 50% and 70% within the input power ranges of 2.5–25.5 dBm and 11–24.5 dBm, respectively. Compared with the counterpart without the STIM, an improvement of 7.2 dB in terms of the input power range when the reflection coefficient is less than −10 dB was successfully demonstrated.

A Simple Wireless Sensor Node System for Electricity Monitoring Applications: Design, Integration, and Testing with Different Piezoelectric Energy Harvesters.

Real time electricity monitoring is critical to enable intelligent and customized energy management for users in residential, educational, and commercial buildings. This paper presents the design, integration, and testing of a simple, self-contained, low-power, non-invasive system at low cost applicable for such purpose. The system is powered by piezoelectric energy harvesters (EHs) based on PZT and includes a microcontroller unit (MCU) and a central hub. Real-time information regarding the electricity consumption is measured and communicated by the system, which ultimately offers a dependable and promising solution as a wireless sensor node. The dynamic power management ensures the system to work with different types of PZT EHs at a wide range of input power. Thus, the system is robust against fluctuation of the current in the electricity grid and requires minimum adjustment if EH unit requires exchange or upgrade. Experimental results demonstrate that this unit is in a position to read and transmit 60 Hz alternating current (AC) sensor signals with a high accuracy no less than 91.4%. The system is able to achieve an operation duty cycle from <1 min up to 18 min when the current in an electric wire varies from 7.6 A to 30 A, depending on the characteristics of different EHs and intensity of current being monitored.

Two‐terminal InGaAs microwave amplifier

AbstractThe feasibility of using a 2‐terminal InGaAs planar Gunn structure as a microwave amplifier is proposed and verified. By achieving a pronounced negative differential resistance with a peak‐to‐valley current ratio of 1.20, our devices are able to amplify microwaves at a high gain of 17 dB. When compared with commonly used 3‐terminal transistor‐based microwave amplifiers, the proposed devices not only have a simple structure but also are capable of achieving high operating frequencies even with relatively large feature sizes. The device with a channel length of 4 μm has a positive gain up to about 77 GHz, and the 2‐μm device is able to amplify microwaves well beyond 110 GHz. Furthermore, the planar Gunn amplifier shows a good linearity over a wide input power range from −45 to about 0 dBm. A good operation stability has also been demonstrated despite having no substrate thinning and heat sink.

High-Efficiency Rectifier With Wide Input Power Range Based on Power Recycling

In this brief, a novel rectifier with power recycling based on a branch-line coupler is proposed to operate within a wide input power range. In the proposed topology, two output ports of the coupler are connected with two subrectifiers dealing with higher power level (main branches), while the isolation port is connected with the subrectifier dealing with lower power level (power recycling branch). By using the branch-line coupler, the power reflected from the two main branches can be efficiently transmitted to the power recycling branch. Consequently, the power can be reused and thus the RF-dc conversion efficiency can be improved. In this way, the rectifier can maintain high efficiency in a wide input power range. Theoretical analysis and performance comparison are carried out, which show that the proposed topology features recycling ability within a wide input power range. For validation, a rectifier working at 2.45 GHz is implemented and compared to other designs. The measured efficiency remains over 50% from 8.5 to 32.5 dBm, indicating that high efficiency can be obtained within wide input power range.

Linearization of CMOS Hot-Electron Injectors for Self-Powered Monitoring of Biomechanical Strain Variations

In our previous work we demonstrated that by eliminating regulation and rectification modules from the energy harvesting pathway, the minimum activation power of a piezoelectricity-driven hot-electron injector (p-HEI) can be reduced down to a few nanowatts. As a result the p-HEI device could be used for self-powered, in-vivo recording of biomechanical strain variations. However, for large magnitudes of input strain energy, the response of the modified p-HEI sensor was found to be quasi-linear with respect to the number of loading cycles, which made the calibration of the sensor difficult across a wide variety of biomedical applications. In this paper we propose a compensation circuit that is able to linearize the response of the p-HEI injector over a wide range of input power while maintaining a low activation threshold. The compensation circuit uses a combination of a storage capacitor and a non-linear resistor which produces a compressive input-output response required for linearization. Using prototypes fabricated in a 0.5-μm bulk CMOS process we validate the functionality of the injector and demonstrate that it can achieve a linear injection response for input power ranging from 5 nW to 1.5 μW.

A Four-Band Rectifier With Adaptive Power for Electromagnetic Energy Harvesting

This letter presents a novel adaptive power rectifier operating at four bands to harvest the electromagnetic energy in the low and wide-range power density conditions. The power range of the rectifier is extended by two operation modes controlled adaptively by a FET switch according to the input power level. A cross-shaped match stub connected by a stepped impedance microstrip line is designed to make the rectifier work at four bands. Two cascaded radial open stubs act as a dc-pass filter to block the fundamental frequency wave and the high order harmonics to further improve the RF-DC (radio frequency-direct current) efficiency, and to smooth the output dc power. When the input power level is −10dBm, the measured maximum RF-DC efficiencies are 47.8%, 33.5%, 49.7% and 36.2% at the frequencies of 0.89GHz, 1.27GHz, 2.02GHz and 2.38GHz, respectively. The efficiency is above 30% in every band when the input power is from −12dBm to 12dBm, which shows a wide input power range.

Differential Rectifier Using Resistance Compression Network for Improving Efficiency Over Extended Input Power Range

This paper presents a differential rectifier with high radio frequency (RF)-dc conversion efficiency over an extended input power range by using resistance compression network (RCN). The RCN is cascaded with a typical differential rectifier. It can reduce the variation range of rectifier input impedance, which changes with input power levels, and better impedance matching can be realized. Thus, the loss due to impedance mismatch is reduced, and high efficiency can be obtained in a wider input power range. First, the theoretical analysis of the RCN is carried out. Then, the detailed analysis of the rectifier input impedance and efficiency is derived in closed form. Based on the analytical results, a 915-MHz rectifier incorporating RCN is implemented. The measured results show that the RF-dc conversion efficiency keeps above 50% and 70% in the input power range 5.5–33.1 and 13.5–31.3 dBm, respectively. The maximum efficiency is 84.8%. Compared with the counterpart without RCN, the efficiency at lower input power levels is improved without degrading the peak efficiency.

A Highly Linear Low Noise Amplifier With Wide Range Derivative Superposition Method

This letter presents an L-band highly linear differential low noise amplifier (LNA) in a standard 90-nm CMOS process. A wide range derivative superposition technique is proposed to maximize the third-order intercept point (IP3), and at the same time, minimize the third-order intermodulation distortion (IMD3) over a wide input power range. The LNA chip achieves a measured OIP3 of $+33.7~{\rm dBm}$ and IMD3 of $-65~{\rm dBc}$ with $-15~{\rm dBm}$ input power. The measured peak gain and minimum noise figure are 15.4 dB and 1.36 dB at 1.27 GHz, respectively. The LNA chip consumes 40 mA from a 3.3-V supply.

Spectral Analysis Using a Dispersive Microwave Photonics Link Based on a Broadband Chirped Fiber Bragg Grating

We report on the use of a dispersive microwave photonics analog optical link for spectral analysis and wavelength measurement in optical fiber sensors. The system is built on the concept of wavelength to group-delay mapping, with a scale determined by the dispersion of the link. In our demonstration, the dispersive channel is a chirped fiber Bragg grating for dispersion compensation of 10 km of single-mode fiber and low third-order dispersion, with a reflection band in the range 1540–1560 nm. The spectral analysis is performed by a vector network analyzer with time-domain analysis software, as in incoherent optical Fourier-domain reflectometry. The spectrum is reproduced as the time-domain impulse response of the fiber-optics link, and the system operates over a wide range of input power and acquisition parameters. As a spectrometer, the system shows sensitivities up to −23.3 dBm, measured at the input of the link, resolutions up to 170 pm, and dynamic range up to 34 dB after windowing the radio frequency response. As a wavelength meter, picometer resolution is demonstrated for laser lines within a 40 pm range, and also an uncertainty of ±4 pm for Bragg wavelength shifts of FBG when the reflected power is −10 dBm.

Design and performance of 10-Gb/s L-band REAM-SOA for OLT Transmitter in next generation access networks

We present a 10-Gb/s L-band reflective electro-absorption modulator integrated with a semiconductor optical amplifier (REAM-SOA) having improved transmission performance at very low input power of seed light. To decrease the input power of seed light, the absorption characteristics of the REAM are adjusted to reduce the amplified spontaneous emission light returned into the SOA, suppressing the gain saturation effect of the SOA. At a considerably low input power of -16 dBm, the REAM-SOA exhibits a low transmission penalty of about 1.2 dB after 50-km SMF transmission. Over a wide input power range from -16 dBm to 5 dBm, a penalty of less than 1.6 dB is achieved at 50-km transmission.

System-On-Mud: Ultra-Low Power Oceanic Sensing Platform Powered by Small-Scale Benthic Microbial Fuel Cells

A self-sustainable sensing platform powered entirely by small-scale benthic microbial fuel cells (MFCs) for oceanic sensing applications is presented. An ultra-low power chip featuring an ARM Cortex-M0 processor, 3 kB of SRAM, and power management unit (PMU) is designed to consume 11 nW in sleep mode for perpetual sensing operation. The PMU includes a switched-capacitor DC/DC converter designed for efficient energy harvesting and step-down conversion for a wide range of input and output power. A small-scale MFC with 21.3 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> anode surface area was connected to the PMU to charge a thin-film battery of 1 mAh capacity. A 49.3-hour long-term experiment with 8-min sleep interval and 1-s wake-up time demonstrated the sustainability of system-on-mud concept. During sleep mode operation, the system charges the 4 V battery at 380 nA from the micro-MFC generating 5.4 μW of power, which allows up to 20 mA of active mode current with net energy neutrality.

Research of PFC Based on Boost Converter

Principles of traditional Boost PFC circuit are introduced. Based on average current control, a large signal model is obtained and turned into small signal model carrying constant load. And current regulator and voltage regulator are designed accordingly. Directing at strong non-linear characteristics of the circuit, this paper adopts double average method to analyze its low frequency stability. This converter can achieve high power factor in wide range of input and load power and simulation result shows that power factor is above 0.99.

Optical frequency comb based multi-band microwave frequency conversion for satellite applications

Based on optical frequency combs (OFC), we propose an efficient and flexible multi-band frequency conversion scheme for satellite repeater applications. The underlying principle is to mix dual coherent OFCs with one of which carrying the input signal. By optically channelizing the mixed OFCs, the converted signal in different bands can be obtained in different channels. Alternatively, the scheme can be configured to generate multi-band local oscillators (LO) for widely distribution. Moreover, the scheme realizes simultaneous inter- and intra-band frequency conversion just in a single structure and needs only three frequency-fixed microwave sources. We carry out a proof of concept experiment in which multiple LOs with 2 GHz, 10 GHz, 18 GHz, and 26 GHz are generated. A C-band signal of 6.1 GHz input to the proposed scheme is successfully converted to 4.1 GHz (C band), 3.9 GHz (C band) and 11.9 GHz (X band), etc. Compared with the back-to-back (B2B) case measured at 0 dBm input power, the proposed scheme shows a 9.3% error vector magnitude (EVM) degradation at each output channel. Furthermore, all channels satisfy the EVM limit in a very wide input power range.