Power efficient multi-stage CMOS rectifier design for UHF RFID tags

Power efficiency of a UHF rectifier circuit, which is part of long-range IC-based passive RFID tags, has become a serious bottleneck in implementing power-hungry intelligent sensors. This paper presents an analytical approach for multi-stage rectifiers, which provides design tradeoffs as well as a set of design rules to improve power efficiency of the rectifier. As an example, three-stage rectifiers are designed with ST 90 nm CMOS technology for optimized performance at both 10 and 22 m distances. When compared with existing results at the same level of output power, the proposed rectifiers show a 3× better performance in power efficiency (73%) and 55% reduction in power-up threshold with longer operating range.     

A Modular Strategy for Control and Voltage Balancing of Cascaded H-Bridge Rectifiers

In this paper, a new strategy for voltage balancing of distinct dc buses in cascaded H-bridge rectifiers is presented. This method ensures that the dc bus capacitor voltages converge to the reference value, even when the loads attached to them are extracting different amounts of power. The proposed method can be used for an arbitrary number of series H-bridges, different voltage levels, and different power levels in unidirectional or bidirectional rectifiers. To reduce the current harmonics and distortion, the input current is programmed to be sinusoidal and in phase with the input voltage; however, it is possible to adjust the input power factor to control both the active and reactive powers. In the proposed approach, both the low frequency (stepped modulation) and high frequency [pulse-width modulation (PWM)] switching methods are utilized to improve the performance of the rectifier. Using theoretical analysis, the acceptable load power limits for a rectifier with N-H-bridge cells are derived. The validity of the proposed method is verified by simulation and experimental results.      

微波无线能量传输中S波段整流电路研究

本文通过对肖特基二极管等效电路模型的建立,分析了二极管的阻抗和微波整流电路的电压,并依据此模型设计了小功率微波整流电路。在此电路基础上,为了扩展电路的功率容量,提出了二极管阵列的思路并设计完成了中小功率以及大功率的微波整流电路。其中,基于单只二极管的微波整流电路最高效率为83．3％,基于二极管阵列的中小功率和大功率微波整流电路最高效率分别为69．4％和68％。三种电路实现10～43dBm的功率覆盖范围,提升了电路的实用价值。     

Design of an Auxiliary Converter for the Diode Rectifier and the Analysis of the Circulating Current

In variable-speed drives systems, diode rectifiers and thyristor rectifiers are often used as the front-end circuit for ac–dc conversion. The advantages of the conventional rectifier are its simplicity and high reliability. The drawbacks include the harmonic current distortion and the lack of re-generation capability. In recent years, industries adopt the transistor-based active front-end (AFE) technologies to accomplish high power factor operation and re-generation capability. However, the cost of AFE is much higher than the conventional diode/thyristor front-end. Besides, the AFE is often less reliable than the diode/thyristor front-end under utility transients. In this paper, an IGBT-based auxiliary converter (AXC) system is proposed. The AXC operates as a shunt active filter to compensate the harmonic current of the rectifier when the load consumes power. When the dc load re-generates, the AXC system can channel the re-generation energy back into the utility system. The combination of the diode rectifier and the AXC can accomplish unity power factor operation and re-generation, but it also causes circulating current between the AXC and the rectifier, which leads to higher operational losses and higher noise level. The mechanism of the circulating current is analyzed in this paper, and solutions are also presented. Computer simulation and field test results are presented to validate the performance of the proposed AXC system.      

A new phase-controlled parallel resonant converter

A phase-controlled resonant converter was obtained by connecting in parallel the AC loads of two identical parallel resonant inverters. A phase shift between the drive signals of the two inverters controls the amplitude of the output voltage of the new inverter. A voltage-driven rectifier is used as an AC load of the inverter, which results in a phase-controlled parallel resonant DC-DC converter. A frequency-domain analysis is performed for the steady-state operation of the inverter, and two types of voltage-driven rectifiers and design equations are derived. The converter can be operated at a constant switching frequency, which reduces EMI problems. It is found that for switching frequencies higher than the resonant frequency by a factor of 1.07, the load of each switching leg is inductive. The converter is capable of regulating the output voltage in the range of load resistance from full-load to no-load. Experimental results are presented for a prototype of the phase-controlled parallel resonant converter with a center-taped rectifier tested at an output power of 50 W and a switching frequency of 116 kHz     

Three-Phase Rectifier With Near Sinusoidal Input Currents and Capacitors Connected on the AC Side

An analysis of a three-phase low-harmonic diode rectifier equipped with inductors, capacitors connected on the ac side, and diodes is presented. Inductors and capacitors are used in conjunction with the three-phase diode bridge rectifier to improve the waveform of the currents drawn from the utility grid. The operation of the proposed converter is analyzed, and on this basis, design considerations are commented. The converter characteristics are determined as a function of the load current. Comparisons between the studied converter and other rectifiers (classical rectifiers with passive or active filters, three-phase rectifiers with near sinusoidal input currents and capacitors connected on the dc side, and three-phase low-harmonic rectifiers applying the third harmonic current injection) are also presented. Several possible applications of the two variants of the three-phase rectifiers with near sinusoidal input currents (with capacitors connected on the dc side or on the ac side) are mentioned. Analytically derived results are experimentally verified     

Module-type switching rectifier for cathodic protection of underground and maritime metallic structures

Cathodic protection is widely used to prevent corrosion of steel materials buried underground and in seawater. As a rectifier for cathodic protection, the conventional phase-controlled rectifiers with 50- or 60-Hz isolation transformers have been used so far in spite of such shortcomings as large volume, heavy weight, and poor power factor. In order to overcome such disadvantages, this paper proposes a new module-type switching rectifier for cathodic protection, which is composed of two parts, namely, ac/dc converter and module-type dc/dc converter. The ac/dc converter is a single-phase insulated gate bipolar transistor pulsewidth-modulation rectifier, thus resulting in almost unity power factor and controlled dc output voltage. The module-type dc/dc converter operates under zero-voltage switching/zero-current switching condition to permit high-frequency switching operation. It enables the use of a high-frequency transformer for electrical isolation, thus reducing volume and weight of the overall system and improving system efficiency. It is anticipated that the proposed rectifier techniques will apply to the similar technical areas such as multiple-module power supply systems and modular converter-fed dc motor drives.     

New single-switch three-phase high-power-factor rectifiers usingmultiresonant zero-current switching

A new family of single-switch three-phase high-power-factor rectifiers, which have continuous input and output currents, is introduced. By using a multiresonant scheme, the transistor operates with zero-current switching (ZCS), and the diodes operate with zero-voltage switching (ZVS). These multiresonant rectifiers with a single transistor are capable of drawing a higher quality input-current waveform at nearly unity power factor and lower stresses than quasi-resonant rectifiers. Buck-type converters are used for the power stage, and, hence, the output voltage is lower than the input voltage. Moreover, these rectifiers have a wide load range and low stresses on semiconductor devices. From the analysis, normalized characteristics of the rectifier are derived. The design and breadboard implementation of the rectifier delivering 147 V_dc at 6 kW from a 3φ 240-V _rms(LL) input is described. The total harmonic distortion (THD) of the line current is less than 5%, and the system efficiency is about 94% at the full load     

Piezoelectric micro-power generation interface circuits

New power conversion circuits to interface to a piezoelectric micro-power generator have been fabricated and tested. Circuit designs and measurement results are presented for a half-wave synchronous rectifier with voltage doubler, a full-wave synchronous rectifier and a passive full-wave rectifier circuit connected to the piezoelectric micro-power generator. The measured power efficiency of the synchronous rectifier and voltage doubler circuit fabricated in a 0.35-/spl mu/m CMOS process is 88% and the output power exceeds 2.5 /spl mu/W with a 100-k/spl Omega/, 100-nF load. The two full-wave rectifiers (passive and synchronous) were fabricated in a 0.25-/spl mu/m CMOS process. The measured peak power efficiency for the passive full-wave rectifier circuit is 66% with a 220-k/spl Omega/ load and supplies a peak output power of 16 /spl mu/W with a 68-k/spl Omega/ load. Although the active full-wave synchronous rectifier requires quiescent current for operation, it has a higher peak efficiency of 86% with an 82-k/spl Omega/ load, and also exhibits a higher peak power of 22 /spl mu/W with a 68-k/spl Omega/ load which is 37% higher than the passive full-wave rectifier.     

Active damping control of a high-power PWM current-source rectifier for line-current THD reduction

The use of active damping to reduce the total harmonic distortion (THD) of the line current for medium-voltage (2.3-7.2 kV) high-power pulsewidth-modulation (PWM) current-source rectifiers is investigated. The rectifier requires an LC filter connected at its input terminals, which constitutes an LC resonant mode. The lightly damped LC filter is prone to series and parallel resonances when tuned to a system harmonic either from the utility or from the PWM rectifier. These issues are traditionally addressed at the design stage by properly choosing the filter resonant frequency. This approach may result in a limited performance since the LC resonant frequency is a function of the power system impedance, which usually varies with power system operating conditions. In this paper, an active damping control method is proposed for the reduction in line current THD of high-power current-source rectifiers operating at a switching frequency of only 540 Hz. Two types of LC resonances are investigated: the parallel resonance excited by harmonic currents drawn by the rectifier and the series resonance caused by harmonic pollution in the source voltage. It is demonstrated through simulation and experiments that the proposed active damping control can effectively reduce the line-current THD caused by both parallel and series resonances.     

A digitally controlled switch mode power supply based on matrix converter

High power telecommunication power supply systems consist of a three-phase switch mode rectifier followed by a dc/dc converter to supply loads at -48 V dc. These rectifiers draw significant harmonic currents from the utility, resulting in poor input power factor with high total harmonic distortion (THD). In this paper, a digitally controlled three-phase switch mode power supply based on a matrix converter is proposed for telecommunication applications. In the proposed approach, the matrix converter directly converts the low frequency (50/60Hz, three-phase) input to a high frequency (10/20kHz, one-phase) ac output without a dc-link. The output of the matrix converter is then processed via a high frequency isolation transformer to produce -48V dc. Digital control of the system ensures that the output voltage is regulated and the input currents are of high quality under varying load conditions. Due to the absence of dc-link electrolytic capacitors, power density of the proposed rectifier is expected to be higher. Analysis, design example and experimental results are presented from a three-phase 208-V, 1.5-kW laboratory prototype converter.     

A RF to DC Voltage Conversion Model for Multi-Stage Rectifiers in UHF RFID Transponders

This paper presents a RF to DC conversion model for multi-stage rectifiers in UHF RFID transponders. An equation relating the RF power available from the antenna to the DC output voltage produced by a multi-stage rectifier is presented. The proposed model includes effects of the nonlinear forward voltage drop in diodes and impedance matching conditions of the antenna to rectifier interface. Fundamental frequency impedance approximation is used to analyze the resistance of rectifying diodes; parasitic resistive loss components are also included in the analysis of rectifier input resistance. The closed form equation shows insights into design parameter tradeoffs, such as power available from the antenna, antenna radiation resistance, the number of diodes, DC load current, parasitic resistive loss components, diode and capacitor sizes, and frequency of operation. Therefore, it enables the optimization of rectifier parameters for impedance matching with a low-cost printed antenna and shunt tuning inductor, in order to improve the RF to DC conversion efficiency and the operational distance of UHF RFID transponders. Three diode doublers and three multistage rectifiers were fabricated in a 130 nm CMOS process with custom no-mask added Schottky diodes. Measurements of the test IC are in good agreement with the proposed model.      

An Integrated Power-Efficient Active Rectifier With Offset-Controlled High Speed Comparators for Inductively Powered Applications

We present an active full-wave rectifier with offset-controlled high speed comparators in standard CMOS that provides high power conversion efficiency (PCE) in high frequency (HF) range for inductively powered devices. This rectifier provides much lower dropout voltage and far better PCE compared to the passive on-chip or off-chip rectifiers. The built-in offset-control functions in the comparators compensate for both turn-on and turn-off delays in the main rectifying switches, thus maximizing the forward current delivered to the load and minimizing the back current to improve the PCE. We have fabricated this active rectifier in a 0.5-μm 3M2P standard CMOS process, occupying 0.18 mm(2) of chip area. With 3.8 V peak ac input at 13.56 MHz, the rectifier provides 3.12 V dc output to a 500 Ω load, resulting in the PCE of 80.2%, which is the highest measured at this frequency. In addition, overvoltage protection (OVP) as safety measure and built-in back telemetry capabilities have been incorporated in our design using detuning and load shift keying (LSK) techniques, respectively, and tested.     

Dynamic and steady state analysis of a three phase buck rectifier

Current source rectifiers among other alternatives, offer several advantages over line commutated rectifiers. Advantages include displacement power factor control and reduced line current harmonic distortion. This paper analyzes the current source rectifier (CSR) in transient and steady state, the models are developed in a synchronous reference frame. The load behavior is characterized for two load conditions, resistive load or, in general, increasing current for increasing voltage, and constant output power, decreasing output current for increasing voltage. Constant power operation can occur for a converter system supplying a pulse width modulation (PWM) inverter with high dynamics. Several static converter characteristics such as power factor, real and reactive power are analyzed for both types of load. Transient characteristics are analyzed for both types of load by exact small-signal model with full set of equations     

High static gain single-phase PFC based on a hybrid boost converter

In this paper, a single-phase unity power factor rectifier, based on a hybrid boost converter, resulting from the integration of a conventional dc–dc boost converter and a switched-capacitor voltage doubler is proposed, analysed, designed and tested. The high-power rectifier is controlled by two feedback loops with the same control strategy employed in the conventional boost-based rectifier. The main feature of the proposed rectifier is its ability to output a dc voltage larger than the double of the peak value of the input line voltage, while subjecting the power switches to half of the dc-link voltage, which contributes to reducing the cost and increasing the efficiency. Experimental data were obtained from a laboratory prototype with an input voltage of 220 Vrms, line frequency of 60 Hz, output voltage of 800 Vdc, load power of 1000 W and switching frequency of 50 kHz. The efficiency of the prototype, measured in the laboratory, was 96.5% for full load and 97% for half load.     

Dynamic control of a fixed pattern rectifier

A three-phase, sinusoidal, active rectifier is presented, based on the classical inverter topology. The switches are governed by a fixed pulse width modulation (PWM) pattern, and the control strategy is extremely simplified as compared with many active rectifiers. General equations describing the steady-state operation of fixed pattern rectifiers are given. A dynamic model of the simplified control rectifier is presented, based on the nonlinear equations describing the system. Based on the analytical model, the classical PI-controller yields poor dynamic results, especially at low load conditions. However, the dynamic performance of the prototype is much better, due to the effects of commutation dead time of the rectifier switches. It is shown that a small modification to the classical PI-controller yields a remarkable increase in amplitude and phase margin, without slowing down the response. The obtained dynamics show a clear improvement over the classical PI-controller and are adequate for most applications     

Analysis and Design Strategy of UHF Micro-Power CMOS Rectifiers for Micro-Sensor and RFID Applications

Design strategy and efficiency optimization of ultrahigh-frequency (UHF) micro-power rectifiers using diode-connected MOS transistors with very low threshold voltage is presented. The analysis takes into account the conduction angle, leakage current, and body effect in deriving the output voltage. Appropriate approximations allow analytical expressions for the output voltage, power consumption, and efficiency to be derived. A design procedure to maximize efficiency is presented. A superposition method is proposed to optimize the performance of multiple-output rectifiers. Constant-power scaling and area-efficient design are discussed. Using a 0.18-mum CMOS process with zero-threshold transistors, 900-MHz rectifiers with different conversion ratios were designed, and extensive HSPICE simulations show good agreement with the analysis. A 24-stage triple-output rectifier was designed and fabricated, and measurement results verified the validity of the analysis     

A dual-input extended-dynamic-PCE rectifier for dedicated far-field RF energy harvesting systems

This paper presents a dual-input extended-dynamic-range, high-PCE rectifier for dedicated far-field RF energy harvesting systems. Two identical input RF energy supply source are applied into two individual rectifier. The rectifier with the highest PCE is selected to deliver dc power to a single-load element. A logic control circuit senses P_in from the rectified dc voltage and toggles between the rectifiers by generating two control voltage to attain high-PCE across P_in. Simulated in a 65nm CMOS process, the proposed system achieves an extended DR of 26 dB for an output load, R_L?=?100 kΩ. Furthermore, a peak PCE of 54.85% and 47.87% was achieved for R_L?=?100 kΩ and R_L?=?150 kΩ, respectively. The sensitivity for an output voltage of 1 V with R_L?=?100 kΩ is -20.6 dBm.

     

一种低关断功耗的地端关断整流器

基于TSMC 180 nm CMOS工艺,设计了一种采用负压关断的地端关断整流器。将关断时的控制电平从0降到负值,降低了使能管的亚阈值电流。将使能管的工作状态从亚阈值区变为截止区,进一步降低了关断功耗。仿真结果表明,当整流器使能时,该负压地端关断整流器的导通性能与传统地端关断整流器几乎相当。当整流器关断且输入电压幅值为1 V时,关断功耗为-24.0 dBm @953 MHz,与传统地端关断整流器相比,下降了7.5 dBm;与传统短路关断整流器相比,降低了23 dBm,功率转换效率提高了1.9 %。该地端关断整流器能满足射频能量收集系统中整流器低功耗待机的要求。     

Analysis of the Instantaneous Power Flow for Three-Phase PWM Boost Rectifier Under Unbalanced Supply Voltage Conditions

This paper proposes the analysis of the instantaneous power flow of three-phase pulse-width modulation (PWM) boost rectifier under unbalanced supply voltage conditions. An analytical expression for the instantaneous output power has been derived, which provides the link between the output dc link voltage and the instantaneous output power. A direct relationship between the dc link voltage ripples and the second harmonic component in the instantaneous output power has been established. Based on the input and output instantaneous power analytical expressions provided, the presence of the odd order harmonic components in the ac line currents can be explained. A simple cascaded PI control scheme has been developed for the dc output voltage control. The controller ensures that the dc link voltage is maintained constant and the supply side power factor is kept close to unity under the unbalanced supply voltage operating conditions. Simulation and experimental test results are provided on a 1.6-kVA laboratory-based PWM rectifier to validate the proposed analysis and control scheme.