Adjustable shunt regulator based control systems

Adjustable shunt regulators known as TL431 are extensively used to build the control systems in switched-mode converter applications. The resulting control system is typically a two-loop system, where one loop defines the low frequency behavior, and the other loop the higher frequency behavior, respectively. The shunt regulator is regarded to possess characteristics similar to an operational amplifier, even if it is basically a transconductance amplifier having current as an output signal instead of voltage as well as positive feedback instead of negative feedback. The small-signal response of a shunt regulator shows that it may be modeled as a voltage-controlled current source with a small transconductance gain and an equivalent capacitor as output impedance, which may be extracted from the open-loop frequency response by inspection. The variance in the parameters may be high depending on the manufacture, and operating point, i.e., cathode current, which is normally chosen to be close to 1 mA due to the specifications. The analysis shows, however, that the cathode current should be at least 5 mA for stable equivalent circuit parameters. If low cathode current is used, the control system may not be better than a Zener diode replacing the shunt regulator.     

All-metal high-isolation series and series/shunt MEMS switches

This paper presents a novel all-metal series switch with several different pull-down electrode geometries. The switch results in an up-state capacitance of 5-9 fF and an isolation of -25 to -30 d8 at 10 GHz. The fabrication process is completely compatible with the standard capacitive (or dc-contact) shunt switch, A dc-30 GHz series/shunt switch is also presented with an isolation of -60 dB at 5 GHz and -42 dB at 10 GHz. This is the highest isolation switch available to-date. The performance is limited by radiation in the CPW lines and not by the series/shunt switch characteristics. The application areas are in high-isolation switches for basestations and satellite systems     

A dual-loop shunt regulator using current-sensing feedback techniques

The dual-loop shunt regulator using current-sensing feedback techniques is proposed in this paper. This architecture adopts a voltage and current loops to increase the transient response of the proposed shunt regulator. The maximum output current of the proposed shunt regulator is 180 mA at a 1.8 V output. Moreover the architecture of the proposed shunt regulator can suppress the stray effect which is from power supply. The prototype of the proposed shunt regulator is fabricated by the Taiwan Semiconductor Manufacturing Corporation (TSMC) 0.35-μm CMOS 2P4M process. The active area is only 579×355 μm².     

一种平均电流控制型开关调节系统的建模

文中对BUCK型DC_DC变换器进行了系统建模。为了得到包含平均电流调节开关控制方式的双环控制系统的简化模型,提出了一种电流环闭环传递函数的近似函数,并分别对电流控制器,电流补偿网络和功率级进行了建模,采用Mathcad进行仿真,得到系统相位裕度达到54°的结果。     

A monolithic high-power series voltage regulator

A complete series voltage regulator circuit capable of delivering /SUP 1///SUB 2/ ampere of current has been built on a single 63/spl times/66-mil die using the conventional all- diffused processing technology. Improved performance has been achieved by using an internal low-power voltage regulator to supply the desired dc output voltage reference directly to a second main regulator. This permits the dc and ac characteristics of the regulator to be separately optimized with the result that excellent transient characteristics are realized simultaneously with low drift and excellent regulation.     

A new current-mode fast-transient-response shunt regulator using CMOS technology

The demand for current-mode fast-transient-response shunt regulator is increasing for the growth of portable electronics, such as cellular phones, PDA, laptops, etc. A new current-mode fast-transient-response shunt regulator is presented in this paper. The proposed shunt regulator used a single Miller compensation capacitor to increase stability. The current-mode shunt regulator helps the transient response to be faster than the voltage-mode low-dropout regulator (LDO) and the power noise (bounce noise) is smaller than one. The proposed current-mode shunt regulator has been fabricated with TSMC 0.35 μm 2P4M CMOS technology. The experimental results show the transient-response time is only 400 ns within 0.5% error and the maximum output voltage dip is only 70 mV for full loading current variation. Moreover, the line and load regulations are 26 μV/mA and 8 ppm/mA, respectively. The dropout current is 1.0741 mA for loading current 150 mA. The active chip area is 226 μm × 310 μm.     

Modeling of capacitor impedance in switching converters

Switched capacitor (SC) converters are gaining acceptance as alternatives to traditional, inductor-based switching power converters. Proper design of SC converters requires an understanding of all loss sources and their impacts on circuit operation. In the present work, an equivalent resistance method is developed for analysis, and equivalent resistance formulae are presented for various modes of operation. Quasiresonant converters are explored and compared to standard SC converters. Comparisons to inductor-based switching power converters are made. A number of capacitor technologies are evaluated and compared for applications to both SC converters and inductor-based converters. The resulting model can be used to accurately predict and optimize converter performance in the design phase.     

Predictive transient-following control of shunt and series activepower filters

A novel technique is presented for generation of a contemporary estimate of the fundamental component of the distorted input current or voltage to an uncontrolled three-phase bridge rectifier with a DC link smoothing filter. This allows for accurate calculation of cancellation references for series and shunt active power filters (APF) operating under steady-state and transient conditions. Improved transient performance allows for reduction of the power rating and control system bandwidth of an APF. An artificial neural network (ANN) predictor has been used to directly calculate the mean dq-axis input to the rectifier without filtering. This is a critical stage in separating harmonic distortion from fundamental current or voltage. The technique is developed using simulation data for both series and shunt APFs and validated with experimental results. The predictive harmonic identifier shows good steady-state performance and excellent transient performance that far exceeds that of a conventional identifier using time-domain or frequency-domain filtering     

Electrothermal compact macromodel of monolithic switching voltage regulator MC34063A

In this paper a new electrothermal compact macromodel of the monolithic switching voltage regulator MC34063A for SPICE is proposed. This macromodel, valid for the transient analysis, is composed of two essential parts: the electrical model consisting of the most important fundamental blocks as: the oscillator, the comparator, the RS flip-flop, the output stage as well as the lumped thermal model. The correctness of the macromodel is verified experimentally. The values of the macromodel parameters are determined from the measurements and the catalogue data. Some of the calculated characteristics are compared with the measuring results.     

Van der Graaf's equivalent circuits for series and shunt modulators

It is shown that the equivalent circuits used by van der Graaf, while giving perfectly correct results for the problems to which he applied them, lack general validity, even within the conditions assumed by him. In particular they appear to demonstrate that it is possible to obtain a constant input resistance (i.e. constant with respect to time) in a series or shunt modulator, whereas clearly such a result is impossible in reality. An alternative system of equivalent circuits is shown to avoid the difficulty. An explanation is given.     

A switching regulator and lightning protector for a subscriber line interface circuit

Two monolithic ICs, a switching regulator and a crowbar protector circuit fabricated in a 90-V complementary bipolar technology are described. These devices enhance the performance of a basic subscriber-line interface circuit (SLIC) by extending the range to the customer so that 20-mA DC feed current can be supplied to a 2800-/spl Omega/ loop without the need for a -72-V office battery. The power dissipation of the entire SLIC subsystem is at most 1.5 W for any length of subscriber loop. All circuitry is robustly protected from foreign 60-Hz and lightning voltages.     

Integrated mixed signal control IC for 500-kHz switching frequency buck regulator

The main purpose for this work is to study the challenges of designing a digital buck regulator using pipelined analog to digital converter (ADC). Although pipelined ADC can achieve high sampling speed, it will introduce additional phase lag to the buck circuit. Along with the latency brought by processing time of additional digital circuits, as well as the time delay associated with the switching frequency, the closed loop will be unstable; moreover, raw ADC outputs have low signal-to-noise ratio, which usually need back-end calibration. In order to compensate these phase lag and make control loop unconditional stable, as well as boost up signal-to-noise ratio of the ADC block with cost-efficient design, a finite impulse response filter followed by digital proportional-integral-derivative blocks were designed. All these digital function blocks were optimised with processing speed. In the system simulation, it can be found that this controller achieved output regulation within 10% of nominal 5 V output voltage under 1 A/µs load transient condition; moreover, with the soft-start method, there is no turn-on overshooting. The die size of this controller is controlled within 3 mm² by using 180 nm CMOS technology.     

High-isolation CPW MEMS shunt switches. 1. Modeling

This paper, the first of two parts, presents an electromagnetic model for membrane microelectromechanical systems (MEMS) shunt switches for microwave/millimeter-wave applications. The up-state capacitance can be accurately modeled using three-dimensional static solvers, and full-wave solvers are used to predict the current distribution and inductance of the switch. The loss in the up-state position is equivalent to the coplanar waveguide line loss and is 0.01-0.02 dB at 10-30 GHz for a 2-μm-thick Au MEMS shunt switch. It is seen that the capacitance, inductance, and series resistance can be accurately extracted from DC-40 GHz S-parameter measurements. It is also shown that dramatic increase in the down-state isolation (20⁺ dB) can be achieved with the choice of the correct LC series resonant frequency of the switch. In part 2 of this paper, the equivalent capacitor-inductor-resistor model is used in the design of tuned high isolation switches at 10 and 30 GHz     

Influence of DC conversion ratio over small-signal performances ofbuck-boost programmable switching regulator

The influence of DC conversion ratio on the dynamic characteristics of a PWM buck-boost programmable regulator using current-injected control (CIC) and the capability of the control scheme to improve performance of the regulator are investigated. The analysis is performed by applying the small-signal model of the regulator to a number of steady-state operating points. The comparison between small-signal characteristics obtained for the same operating points and for different system open-loop gains (SOLGs) is used to evaluate the capability of CIC to improve the performance of the regulator. The analysis shows that considerable improvements can be expected only for frequencies below unity SOLG cross-over frequency and for small DC conversion ratios     

Control of the switching transients of IGBT series strings byhigh-performance drive units

In the field of power electronics, the use of series-connected insulated gate devices, such as insulated gate bipolar transistors or power MOSFETs, is interesting in order to obtain fast and efficient power switches in medium-range power converters. In this kind of application, the control of the voltage sharing across the series strings of devices is an important aspect to be considered. The proposed technique allows obtaining safe commutations of the switches by simple and effective control circuits acting on the gate side of the power devices. In particular, the gate drive units are arranged in order to ensure good performance during the switching transients, while preventing overvoltage peaks on the devices. Both the design criteria and analysis of the control circuit are developed. Several experimental tests are reported in order to demonstrate the validity and correctness of the proposed approach     

Effect of series resistance on the switching time of a tunnel diode

A simple technique to reduce the switching time of a tunnel diode is discussed. The theoretical analysis using analytical expressions for the t.d, static characteristic is also given. It is found that mere addition of a resistance which is less than the negative resistance of the t.d. decreases the transient, time of the t.d. without introducing any complexity in the circuit behaviour and adjustments     

基于MAX8515并联稳压器的Li+电池充电器应用

由于Li+电池充电器的充电过程会持续一个小时甚至更长的时间,利用实际负载(即电池)对充电器进行测试将非常耗时。文中介绍了一种简单的Li+电池仿真方法,与采用实际电池进行测试相比,这种方法能够更加方便地测试Li+电池充电器。     

Modeling the optical switching of MESFET's considering the externaland internal photovoltaic effects

One of the aspects of the merging of microwave and optical technologies is the use of optical signals to switch electronic circuits in general and microwave circuits in particular (including MMIC). During the last decade, the feasibility of optical switching of MMIC's has been demonstrated. This paper presents a novel model for the optical switching of the MESFET, which is the building block of MMIC's. The model predicts the optical switching performance as a function of the optical signal parameters, the bias level, and the device physics and geometry. The results and conclusions from the theory are verified by measurements. The new model can serve as a design tool for designing an optimal MESFET for optical switching purposes     

Modeling and simulation of core switching noise for ASICs

This paper presents simulation and analysis of core switching noise for a CMOS ASIC test vehicle. The test vehicle consists of a ceramic ball grid array (CBGA) package on a printed circuit board (PCB). The entire test vehicle has been modeled by accounting for all the plane resonances using the cavity resonator method. The models included both the on-chip and off-chip decoupling capacitors. Using both time domain and frequency domain simulations, the role of plane resonances on power supply noise for fast current edge rates has been discussed. The models have been constructed to amplify certain parts of the test vehicle during simulations