Frequency Compensation Method Research Articles

基于频率补偿的窄脉冲量子级联激光器快速驱动技术

The line width of pulsed quantum cascade lasers(QCL) increases with the device heating up during the driving pulse, so QCL drivers need to generate ultra-short current pulse. Generally, pulses of 5 ns to 15 ns durations can reach the Fourier transform limit. However, due to the existence of parasitic parameters, narrow pulses will lead to overshoot or oscillation. Therefore, the current commercial QCL drivers can not meet this requirement. To obtain narrower line width of QCLs, a frequency compensation method based on conventional pulse constant current circuit was proposed in this work to eliminate overshoot and oscillation. And a stable pulse laser driving circuit was also designed which can output 0-2 A pulse current, with 8.4-200 ns pulse width, 4 ns rising time, and 1% overshoot. Function test was carried out with a QCL with 4.6m center wavelength made from Institute of Semiconductor of Chinese Academy of Sciences, and a Fourier transform infrared spectroscopy. The laser line width decreased almost linearly from 0.35 cm-1 to 0.12 cm-1, when the driving pulse width decreased from 100 ns to 10 ns. Experimental results show that the driver is able to output stable narrow pulses, which is suitable for narrow line width driving of QCLs and their applications.

A Location Method Using Sensor Arrays for Continuous Gas Leakage in Integrally Stiffened Plates Based on the Acoustic Characteristics of the Stiffener.

This paper proposes a continuous leakage location method based on the ultrasonic array sensor, which is specific to continuous gas leakage in a pressure container with an integral stiffener. This method collects the ultrasonic signals generated from the leakage hole through the piezoelectric ultrasonic sensor array, and analyzes the space-time correlation of every collected signal in the array. Meanwhile, it combines with the method of frequency compensation and superposition in time domain (SITD), based on the acoustic characteristics of the stiffener, to obtain a high-accuracy location result on the stiffener wall. According to the experimental results, the method successfully solves the orientation problem concerning continuous ultrasonic signals generated from leakage sources, and acquires high accuracy location information on the leakage source using a combination of multiple sets of orienting results. The mean value of location absolute error is 13.51 mm on the one-square-meter plate with an integral stiffener (4 mm width; 20 mm height; 197 mm spacing), and the maximum location absolute error is generally within a ±25 mm interval.

Compensating for Tissue Changes in an Ultrasonic Power Link for Implanted Medical Devices.

Ultrasonic power transfer using piezoelectric devices is a promising wireless power transfer technology for biomedical implants. However, for sub-dermal implants where the separation between the transmitter and receiver is on the order of several acoustic wavelengths, the ultrasonic power transfer efficiency (PTE) is highly sensitive to the distance between the transmitter and receiver. This sensitivity can cause large swings in efficiency and presents a serious limitation on battery life and overall performance. A practical ultrasonic transcutaneous energy transfer (UTET) system design must accommodate different implant depths and unpredictable acoustic changes caused by tissue growth, hydration, ambient temperature, and movement. This paper describes a method used to compensate for acoustic separation distance by varying the transmit (Tx) frequency in a UTET system. In a benchtop UTET system we experimentally show that without compensation, power transfer efficiency can range from 9% to 25% as a 5 mm porcine tissue sample is manipulated to simulate in situ implant conditions. Using an active frequency compensation method, we show that the power transfer efficiency can be kept uniformly high, ranging from 20% to 27%. The frequency compensation strategy we propose is low-power, non-invasive, and uses only transmit-side measurements, making it suitable for active implanted medical device applications.

Study of Bandwidth Expansion Based on Electrochemical Vibration Sensor

A vibration sensor based on electrochemical principle can be widely used in the field of seismology. For its instinctive bandwidth is limited, compensation by circuit is essential to expand the bandwidth. This article presents a method of frequency compensation by circuit based on the original amplitude-frequency characteristic of the electrochemical vibration sensor. The bandwidth is broadened obviously from 2s-10Hz to 25s-20Hz. The noise performance of the final output compared to the CME6011 is also presented.

Low-voltage process-insensitive frequency compensation method for two-stage OTA with enhanced DC gain

A proposed low-voltage pseudo-cascode frequency compensation technique to improve the phase-margin of the two-stage OTA in weak-inversion region is introduced. Furthermore, a enhanced composite-transistor technique to increase the DC gain of the two-stage OTA in weak-inversion region is also presented in this paper. Both the proposed techniques achieve enhanced performance without requiring any additional power dissipation. To compare the performance advantages of the proposed techniques, two two-stage OTAs were designed in a UMC 0.18μm CMOS process. Simulation results show that the DC gain of the two-stage OTA with enhanced composite-transistor is increased by a factor of 17dB, the unity-gain bandwidth of the OTA with the proposed pseudo-cascode compensation technique improved 18%, the phase-margin of the OTA is increased by 33%, and it is maintained over a factor of 300 (from 5 to 1500nA) scaling in its bias current.

DCCII based frequency compensation method for three stage amplifiers

A new frequency compensation scheme using a second generation differential current conveyor (DCCII) for three-stage amplifiers is proposed. By adding a DCCII as a feedback path from output of the second and the third stage to the output of the first stage, feed-forward path and the right-half plane zero will be removed subsequently, which significantly improves phase margin and gain-bandwidth product. Calculations are derived for two states. First state, a DCCII and two miller capacitors form the feedback paths and in the second state, two nulling resistors will be set series with miller capacitors. Analyses show that in both states, stability can be perfectly ensured.To demonstrate advantages of this technique over the traditional RNMC architecture, a three-stage amplifier is designed and simulated employing the proposed technique in a standard 0.18μm CMOS process. Simulation results show that, with the same load capacitance, the new amplifier achieved 85° and 9.63MHz as phase margin and gain-bandwidth product, respectively. The proposed amplifier dissipates only 0.31mW of power with a 1.8V supply.

A Compensation Technique for Two-Stage Differential OTAs

In this brief, a frequency compensation method for operational transconductance amplifiers is proposed, which poses no power overhead compared to Miller compensation, while improving the 3-dB bandwidth, the unity gain frequency, and the slew rate. The technique employees positive feedback to introduce an extra left half plane zero to cancel a pole. The phase margin shows good robustness against process and temperature variations. The proposed technique poses no design constraints on the transconductance or capacitor values, which makes it attractive for low-power applications with low area overhead.

Passive frequency compensation for high gain‐bandwidth and high slew‐rate two‐stage OTA

A passive frequency compensation method is presented for the first time, which can be applied to two/multi-stage operational transconductance amplifier (OTA) designs, to achieve high gain-bandwidth (GBW) and high slew-rate with no increase in the overall power consumption. A nulling resistor with series compensating capacitor is applied in the first stage and extends the GBW by introducing a left-hand-plane (LHP) zero. This design is implemented in a 0.18 μm CMOS process and the measured results show a GBW of 100 MHz and average SR of 60 V/μs with a power consumption of 1.7 mW. A high figure of merit (FoM) of 94.7 GHz pF V/μs/mA is achieved.

A Compact, Low-Power 40-GBit/s Modulator Driver With 6-V Differential Output Swing in 0.25-$\mu$m SiGe BiCMOS

This paper presents a high-speed, low-power modulator driver featuring a novel modified breakdown voltage doubler (BVD) topology. Further speed enhancement and reduction of power consumption is achieved by multiple frequency compensation methods. An optimization method combining small and large-signal analyses is presented. The driver was fabricated in a 0.25-μm SiGe BiCMOS technology with <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> of up to 180 GHz. It features 13-dB differential gain, a small-signal bandwidth of 33.7 GHz and delivers a single-ended output swing of 3 Vpp (6 Vpp differential) at 40 GBit/s into a 50-Ω load consuming only 1.35 W of DC power.

Holed MEM Resonators for High Accuracy Frequency Trimming

After consistently progress in Micro-Electro-Mechanical (MEM) resonators, Silicon oscillators are finally being commercialized for time and frequency control applications not requiring huge frequency accuracy. Indeed, they offer size reduction, potentially low cost and CMOS integration. However, frequency shift because of manufacturing mismatch is still one of the challenges to address high frequency accuracy applications. We propose a new frequency compensation method consisting in filling compensation holes smartly localized onto microresonators. This method enables to decrease the frequency dispersion over a full wafer of only few ppm, regarding to deviation of 1000ppm.

Compensation of high-frequency components of wind load by wind tunnel testing

To analyze the wind-induced response of structures, wind tunnel tests are often carried out to determine the wind loads on structures. However, due to the influence of similarity requirements in wind tunnel tests, the resulting data from the model test still needs to be translated by similarity rules for predicting the real loads on prototype structures. During this process, an inevitable result is that the high-frequency components of fluctuating wind loads get lost, which leads to some unexpected errors in the subsequent wind-induced response analysis. To solve this problem, a frequency compensation method is put forward. The purpose of this method is to reconstruct the high-frequency part of fluctuating wind loads based on experimental data and some basic principles of the aerodynamics of bluff bodies. The causes and effects of the frequency compensation problem are discussed first, then a practical method of frequency compensation is proposed by combining the fluctuating wind energy spectrum theory and the Proper Orthogonal Decomposition technique. Based on this method, the wind-induced response of a single-layer reticulated shell is analyzed to show the validity and necessity of this method.

Joint Carrier Frequency Offset Estimation and Compensation for Downlink Group-Orthogonal Multicarrier CDMA

A carrier frequency offset (CFO) estimation and compensation method is proposal for downlink group-orthogonal multicarrier code-division multiple-access (GO-MC-CDMA) system. The proposed algorithm has taken into consideration both the inherent orthogonality among subcarriers of different groups of GO-MC-CDMA system and the characteristics of Fast Fourier Transform (FFT) demodulation are taken into consideration. The CFO estimation is achieved by searching the value which minimizes the cost function constructed in terms of performing FFT on the interfering signals. Simulation results show that the estimated value of CFO is very close to the real value for the downlink GO-MC-CDMA system. In addition, it is shown that the bit error rate (BER) performance is improved significantly by CFO compensation.

Charge Amplifier With an Enhanced Frequency Response for SPM-Based Data Storage

Storage systems based on scanning probe microscopy incorporate an array of thermopiezoelectric cantilevers that require charge amplifiers with a wide frequency response but low power consumption. We use an improved frequency compensation method to enhance the in-band frequency response without requiring any additional power. Measurements show that the prototype chip draws the same 68 A at 1.8 V as an unmodified design but has a closed-loop frequency response that is ten times greater. The chip was fabricated in a 0.18-m standard CMOS process, and the charge amplifier core occupies 0.042 mm2.

A controllable resistor and its applications in pole-zero tracking frequency compensation methods for LDOs

This paper presents a controllable resistor, which is formed by a MOS-resistor working in the deep triangle region and an auxiliary circuit. The auxiliary circuit can generate the gate-source voltage which is proportional to the output current of an low dropout regulator for the MOS-resistor. Thus, the equivalent output resistance of the MOS-resistor is inversely proportional to the output current, which is a suitable feature for pole-zero tracking frequency compensation methods. By switching the type of the MOS-resistor and current direction through the auxiliary circuit, the controllable resistor can be suitable for different applications. Three pole-zero tracking frequency compensation methods based on a single Miller capacitor with nulling resistor, unit-gain compensation cell and pseudo-ESR (equivalent serial resistor of load capacitor) power stage have been realized by this controllable resistor. Their advantages and limitations are discussed and verified by simulation results.

A Highly Integrated Power Management IC for Advanced Mobile Applications

Wireless communication now has the speed and power to converge seamlessly with other consumer and business electronics. However, battery technology has not kept pace with advancement in circuit technology. As a result, design of power management is becoming a more complex problem for this new generation of wireless devices with converged voice, data, and multimedia. In this paper, a highly integrated power management IC (PMIC) is presented which enables mobile devices that are more cost effective, thinner and more compact with better power efficiency. The overall architecture and system level design considerations are described. The design details of two key building blocks - low-dropout linear regulator (LDO) and switch-mode DC-DC converter - are also discussed, including a novel frequency compensation method for LDO.

Time-Variant Doppler Frequency Estimation and Compensation for Mobile OFDM Systems

In mobile OFDM communication systems, Doppler spread leads to the loss of orthogonality between the sub-carriers, limiting the achievable throughput of the moving transceivers. In this paper, the effect of Doppler spread in Rayleigh fading channels is investigated, and a method of time-variant Doppler frequency estimation and compensation is proposed for mobile OFDM systems. Computer simulation results are included to support our development.

A new method of frequency compensation for bipolar Wilson current mirror

This paper proposes a new method of frequency compensation for a bipolar Wilson current mirror. The mirror is, first, modified: a resistor is inserted into the collector circuit of the diode-connected transistor, and another resistor of equal value is added into the emitter circuit of the same transistor. A compensation capacitor is connected between the collector and base of the feedback transistor. It is shown that the modification produces a pole-zero pair in the current-source transfer function. The split between pole and zero is reduced when the resistor value increases. This results in a wider bandwidth of the mirror transfer function and a faster step-transient response. These improvements are paid for in a small degradation of noise performance.

A technique of measuring relative sound velocity changes using a frequency variable type ultrasonic correlation system

A technique for measuring relative sound velocity changes using a frequency variable type ultrasonic correlation system in which introducing a frequency multiplication method is described. The experiment with water as a standard liquid sample was demonstrated to examine the performance of the system. Experimental results showed that the frequency compensation method together with the frequency multiplication method was useful to enhance the resolution of sound velocity change. With this system, a maximum resolution of sound velocity change better than 2 ppm has been attained.

Slew-induced distortion of single-amplifier active filters using the gain-sensitivity product concept

The Volterra-Wiener series is used to obtain an analytical formula for slew-induced distortion (SID) in single-amplifier active filters. It is shown that the relative change of the transfer function caused by SID depends on the parameters of the operational amplifier (OA) and on the method of frequency compensation applied to it. This change also depends on the transfer function to be realized, on the amplitude of the input signal and on the gain-sensitivity product (GSP). It is shown that reducing the GSP also reduces the SID. The corresponding relationship was verified experimentally.

Amplifier characteristics at low frequencies, with particular reference to a new method of frequency compensation of single stages

The paper deals with frequency characteristics of tetrode, pentode and triode amplifiers as determined by the impedances of the electrode supply circuits and interstage coupling circuits. Methods of complete compensation of the frequency characteristics due to these circuits are developed for single stages or single coupling circuits. These cases are of particular interest in the output stages of television receivers where the d.c. component of the signal is required.