Attenuator Circuit Research Articles

Integrated photonics cascaded attenuation circuit towards single-photon detector calibration

Integrated photonics platforms are a key driver for advancing scalable photonics technologies. To rigorously characterize and calibrate on-chip integrated photodetectors for ultra-sensitive applications such as quantum sensing and photonic computing, a low-power calibration source down to single-photon levels is required. To date, such sources still largely rely on off-chip bulk or fiber optic setups to accurately attenuate a laser beam referenced to a sub-mW-level primary standard. Here, we demonstrate an on-chip integrated attenuation solution where a mW-level beam is coupled to a silicon nitride photonics circuit, and is attenuated by a series of cascaded directional couplers (DCs). With an integrated silicon photodetector, we measured an attenuation at 685 nm wavelength of up to 16.61 dB with an expanded uncertainty of 0.24 dB for one DC stage. With appropriate scattering mitigation, we infer from our results that a total attenuation of 149.5 dB (expanded uncertainty of 0.5 dB) can be obtained with 9 stages of cascaded DCs, thus allowing single-photon power levels to be obtained directly on-chip from a moderate-power laser source.

Research on the key technology of high-precision waveform synchronization identification and measurement.

High-precision waveform identification and measurement are effective for waveform detection and evaluation in signal processing. The accuracy of waveform identification, precision of measurement, and speed of response are important indicators of waveform measurement instruments. To detect the waveform accurately, a hold and attenuation circuit divided into two is designed, and the STM32F4 microcontroller is used to accurately capture and perform spectrum analysis using a high-precision analog-to-digital converter based on fast Fourier transform technology to identify key parameters, such as waveform type, frequency, peak-to-peak value, and duty cycle. To improve the recognition accuracy and response speed, technical solutions, such as high-frequency sampling and over-zero detection, are used to improve the system efficiency. Algorithm simulation, circuit simulation, and physical testing show that the high-precision waveform synchronization recognition circuit and algorithm can accurately recognize various essential waveforms in the voltage and frequency ranges of 50 mV ≤ VPP ≤ 10 V and 1 Hz ≤ f ≤ 50 kHz, respectively, and simultaneously measure important parameters, such as frequency, peak-to-peak value, and duty cycle with an accuracy within ±1%. Intelligent linkage, no intermediate parameter setting, and a response speed of approximately 0.3 s make it suitable for such applications as fast and high-precision waveform intelligent detection and display. The method is highly integrated, simple to operate, cost-effective, and practical.

Design and Performance Evaluation of a Directional Telescopic Microphone for Enhanced Environmental Sound Capture

A directional telescopic microphone is composed of two parts. One is the pick-up circuit made up of 34 different length aluminum tubes to respond in a specific frequency. The use of a sensitive FET mic is to pick up a sound from a direction. The signal from the FET mic will be feed to the microphone preamplifier in order to amplify the signal. The Equalization and Attenuation circuit is responsible for the balancing and boosting the low and high frequency. The pick-up signal can be easily recordedto a device through the recording unit or can be heard through the speaker, driven by a power amplifier in order to set up the signal. The main purpose of the gadget is to be used in an environmental study. This can pick up sound that was not normally heard by human ear in a specify distance.

Real-Time Control of Active Catheter Signals for Better Visual Profiling During Cardiovascular Interventions Under MRI Guidance

In MR-guided interventional procedures, RF coils can be attached to the instruments to provide a positive MR signal for device tracking. The signal from these coils can vary strongly over the procedure and mask the surrounding anatomy. The purpose of this study is to introduce and demonstrate a low-cost, vendor- and device-independent interface circuit that allows the interventionalist to adjust the active device signal intensity. In this work a variable attenuator circuit was constructed to control the tip signal of an active coronary artery catheter in real-time from within the MR scanner room. Performance of the attenuator circuit and the active catheter was characterized on the test bench, in a phantom model, and in vivo. The system was used in a pig model at 3T during the introduction of the catheter into the left coronary artery. The circuit could attenuate the amplitude of the tracking coil signal by up to 20 dB. Without attenuation, the tracking coil signal intensity was masking anatomical details of the coronary ostium making it impossible to reliably introduce the catheter into the artery. After interactive adjustment, which was performed in a few seconds by the interventionalist, the improved visualization of the vascular anatomy enabled a rapid insertion of the catheter into the coronary ostium. The vendor-independent variable attenuator provides real-time control of the catheter signal without interrupting the image acquisition. Even though most MRI systems can control the individual signal levels from coils by software, the attenuator hardware is advantageous as it can be integrated into any MR-system, and it provides a direct interface for the interventionalist at the magnet.

Syn-STELLAR: An EM/Power SCA-Resilient AES-256 With Synthesis-Friendly Signature Attenuation

Mathematically secure cryptographic algorithms leak meaningful side-channel information in the form of correlated power and electromagnetic (EM) signals, leading to physical side-channel analysis (SCA) attacks. Circuit-level countermeasures against power/EM SCA include a current equalizer, IVR, non-linear LDOs, enhancing protection up to 10M traces, and current-domain signature attenuation (CDSA), and randomized NL-LDO cascaded with arithmetic countermeasures achieved protection up to >1B. This work embraces the concept of analog CDSA but makes it easily scalable over technology nodes with digital-friendly current sources, digital control loop, and digital bleed path to increase the MTD from 10M to 250M (25x improvement, using a single digital countermeasure). Ring oscillator (RO) used as the bleed path to bypass encryption-dependent leakage acts as local negative feedback (LNFB). Besides, based on RO oscillation frequency, AES node voltage can be tuned at startup, PVT, or frequency variation. Thus, RO acts as integrated LNFB and global feedback for the digital signature attenuation circuit (DSAC). Another circuit technique, namely, the time-varying transfer function (TVTF), removes the requirement of dc bias in the current-domain equalizer (best switch capacitor-based countermeasure till date) to make it digital and utilizes switch cap-based circuit for time-domain obfuscation to achieve enhanced security. This work, namely, Syn-STELLAR: SYNthesis-friendly Signature aTtenuation Embedded crypto with Low-Level metAl Routing, combines both DSAC and TVTF techniques to achieve an MTD>1.25B for both EM and power SCA, which is 25% higher than the existing state of the art. The 65-nm CMOS test chip contains unprotected and both the protected (DSAC and DSAC-TVTF) parallel AES-256 implementation. This implementation is the first synthesis-friendly countermeasure, which converges two analog-type strong protections (signature attenuation and switched cap current equalizer) in a digital-friendly solution and achieves >1.25B MTD with power and area overheads comparable to previous circuit-level countermeasures.

Control system of electric traction drive of electric vehicle

The growth rate of electric transport production is increasing every year, so the issues of its improvement and development are relevant. The developmentof a traction electric drive control system that would meet all the requirements, it is the aim of the article. There is a strong weakening of the field, providing a quick change in torque. The results of the created electric drive system are obtained with simulation in the MATLAB. The control system provides the engine in traction mode, recovery mode, reverse, and also allows you to develop high torque at low speeds. The result is a trapezoidal velocity diagram and an almost rectangular moment diagram. When operating at higher speeds up to 400 rad/s, the system works stably. At higher speeds, moment fluctuations appear and dynamics deteriorates. Fluctuations in flux linkage are observed at a speed of more than 700 rad/s. The modeling also showed that the system maintains a constant voltage in the field weakening mode. The development of the control system in order to increase the torque at low speeds is possible due to the introduction of the controller of the balances of the real current of the machine and the current calculated in the engine model. The introduction of a dynamic field attenuation circuit serves to provide high torque when it is not possible to further increase the voltage of the motor stator.

Development of Alternating Current (AC) Line Monitoring Device for Power System Management

This work presents a study of the effect of imbalance between the supply of and demand of power from the National grid on electrical appliances. In the study, an alternating current (ac) line monitoring device was developed using arduino microcontroller to carry out the investigation. The device is a single system capable of measuring both the main frequency and nominal voltage of electricity supply. The device consists of seven major components: 12 V step-down transformer, half-wave rectifier, attenuator, wave-shaping circuit, arduino microcontroller, Liquid crystal display and micro SD card. The heart of the device is the arduino microcontroller that reads the period of the pulses from the shaping circuit and the output voltage from the scale resistor connected to the attenuator circuit in order to measure the levels frequency and voltage of the ac main source. By graphically compared the reading of the voltage obtained by the ac monitoring device with that of the standard Mastech voltmeter, it was shown that the device has a good correlation with the standard voltmeter with a deviation of ±0.21%, and this has proven that the device is capable of measuring ac voltage accurately. From the frequency test level results, it was found that the frequency measured by the device closely related to the frequency measured by the standard frequency meter. This shows that the device satisfied the requirement of the overall design. Hence, it can be used in the laboratory for demonstration and research purposes as well as in power plant industries.
 Keywords: Mains frequency, nominal voltage, half-wave rectifier, attenuator, wave-shaping circuit, Arduino microcontroller

Implementation of time-window based analog self-interference cancellation for full-duplex radios

Multi-tap delay line circuits are widely used to model the analog self-interference multipath channel in full-duplex wireless communication systems. However, the complexity of these circuits is a considerable problem. To overcome this issue, this paper investigates a simple dual-channel analog self-interference cancellation circuit. Instead of modeling the multi-tap for multipath reflections, the key sight is that the light-of-sight self-interference is estimated by designing a dual-channel with the fixed delay and tunable attenuator circuit. Feasibility of only canceling the light-of-sight self-interference is explored first. Then, according to the distance of transceiver antennas, delays of the dual-channel are calculated which acts as a time-window to let the light-of-sight self-interference pass. Additionally, due to the error caused by the non-light-of-sight self-interference, attenuators of the dual-channel are designed be tuned adaptively based on the minimum residual mean square error. Finally, the experimental results show that the proposed method can provide up to 50 dB cancellation over different transmission signal bandwidths.

The Design and Verification of an Active SAMSR Ultrasonic Guided Wave Monitoring System with Ultra-Low Crosstalk.

Due to long propagation distance and high sensitivity to a variety of damages, ultrasonic guided wave technologies have been widely applied in the damage detection or health monitoring of pipe networks and large plate-like structures. However, there are two important problems to be solved when applying this technology; namely, the large scanning time required for monitoring large-scaled structures and the serious crosstalk between the actuation and receiving signals, especially when monitoring hot-spot regions. Therefore, this study mainly designed key parts, such as the matrix switcher and attenuation circuit. The single-actuation and multiple-simultaneous-reception (SAMSR) mechanism based on an analog switching matrix and a low noise charge amplifier circuit was designed and integrated with the SPI control bus to shorten the scanning time. Moreover, a two-stage attenuation circuit with an interlocking isolation structure is presented to effectively isolate the receiving signals from the actuation signals to obtain ultra-low crosstalk even under a high voltage actuation source. In this study, the designed matrix switcher and other components were integrated into the developed ultrasonic guided wave monitoring system. Several experiments were conducted on a stiffened composite structure to illustrate the effectivity of the developed SAMSR ultrasonic guided wave system by comparing the signals collected with those from a commercial ultrasonic guided wave system.

Design of Green Building Energy Consumption Data Acquisition System Based on Biological Nano Sensors

The traditional energy consumption data acquisition system for green building has low accuracy. Based on biological nano-sensors, the energy consumption data acquisition system for green building is optimized. The original chip of the data acquisition sensor of AD9280 chip is adopted, the sampling circuit of energy data is designed according to the construction of attenuation circuit, and the rs-485 communication interface electricity meter is connected with the data collector reflecting the building energy consumption to complete the system hardware design. The function of the data collector was analyzed and the collection program was designed. The energy consumption data analysis method was designed after the serial port code was converted to complete the software design of the energy consumption data collection system for green buildings. It is found that the designed system solves the problem of "data missing zero" and can effectively eliminate the fault of communication lines. Moreover, when the data volume is 800 bits, the time of the energy consumption data acquisition system is only 2.5 s, which is significantly lower than the other two collection methods, and the collection efficiency is high.

Research on Test Method of Communication Interface Converter Based on Simulated Field Conditions

This paper used the wind pressure, sealed water circulation system, wireless attenuator and interface state analog circuit to establishes simulated field operation condition of “Multi-meter unification”. A test method of communication interface converters and concentrator for “Multi-meter unification” is proposed based on the experimental environment, which including function test, interface performance test and compatibility test, and to ensure the stable operation of the field communication interface converter and concentrator.

Mitigation of DC Current Injection in Transformer-Less Grid-Connected Inverters Using a Voltage Filtering DC Extraction Approach

Transformer-less grid-connected PV inverters are an attractive technology choice due to their high-efficiency performance and relatively small volume. However, in the absence of galvanic isolation, dc current can potentially flow into the grid and adversely affect the grid performance. In addition, as the sinusoidal ac output is significantly larger than the dc injection component, accurate dc current sensing at the inverter output remains a technical challenge. As a result, this paper proposes a two-stage dc voltage detection technique that employs an isolated RC attenuation circuit and a software dc-component filtering algorithm. The principle of the proposed technique can be applied in many switch-mode power converter topologies. The simple and cost-effective combination facilitates dc component extraction within the accuracy of 1 mV; moreover, this can be further used as digital dc feedback for active current control purposes. Experimental results from a laboratory prototype demonstrate the high performance of the proposed dc extraction and suppression approach.

Design and Analysis of a Low Loss, Wideband Digital Step Attenuator With Minimized Amplitude and Phase Variations

A compact, low loss, wideband digital step attenuator (DSA) is presented. The proposed DSA utilizes amplitude/phase-compensated T-type attenuator cells, in which the locations of poles and zeros are manipulated for minimizing variations in attenuation and phase. In addition, the reduced T-type attenuator cells that eliminate series switch transistors are used to achieve low insertion loss (IL). These techniques provide wideband (dc-20 GHz) operation for the DSA, with significantly decreased attenuation/phase errors and reduced IL. The DSA was implemented in a 130-nm silicon-germanium (SiGe) BiCMOS platform. The full attenuator circuit has binary-coded 6-bit digital control inputs with a least significant bit of 0.5-dB attenuation. It has a root-mean-square (rms) attenuation error of 0.37 dB and an rms phase error of 4°, both at 20 GHz. The IL and the input 1-dB compression point at 10 GHz are 4 dB and 10 dBm, respectively. The active core layout area is 0.14 mm2 (1.0 mm $\times $ 0.14 mm).

Design of Digital to Analog Converters with Arbitrary Radix

There are DAC structures available in the literature for radix r = 2, 3, and 4; but how they are arrived at is missing. No general structure is available for any radix r. The aim of the paper is, therefore, to fulfil these gaps. To start with, the design relations are derived for the simplest possible attenuator circuit when connected to a voltage source V and a series resistance R, such that the complete circuit offers the Thevenin resistance R. Spread relations for this attenuator are derived. An example when 3 such attenuators with different attenuation constants are connected in cascade is given. Interestingly, the two attenuators with attenuation factors 1/2 and 1/3 have the same spread of 2. A generalized attenuator is then obtained when N number of identical attenuators are connected in cascade. This is modified to derive a digital to analog converter for any radix r.

Frequency adaptive driver for ultrasonic vibrators with motional current feedback

A driving circuit of frequency adapting for an ultrasonic vibrator with motional current feedback has been presented in this paper. Via a voltage-controlled oscillator (VCO) and a digital/analog converter (DAC), the driving signal would be magnified by a linear power amplifier to actuate the vibrator. Since the vibrating velocities or displacements at the surface end of a vibrator could be predicted through the measurement of motional current, the motional current passing through the vibrator was detected by a current transformer (CT) type sensor as feedback to monitor the optimal level of output power. The calculation for phase difference and the tuning strategy for driving frequency were implemented by a microcontroller integrated with an A/D converter and a voltage comparator as well as the signal attenuation and level tuning circuit. The experiment demonstrates that the temperature effect corresponding to frequencies is at 9.75 Hz/°C shifting and the external loading reflected to frequencies is about 8.3 Hz/gm offset. The proposed circuit has the great performance in rejecting the disturbances from external loading and thermal effect.

Design of Automatic Level Control for Microwave Signal Source

The performance of the automatic level control（ALC） system determines the stability of the microwave signal source output power, accuracy and linear flatness in each frequency range, directly determining the signal generator power characteristic indicators. This paper gives an implementation of a high-performance feed-forward ALC circuit, the negative feedback loop consists of the power detector circuit, logarithmic amplifier, the integral hold circuit, attenuator driving circuit, PIN attenuation circuit and so on.

Research on Portable Virtual Oscilloscope Based on USB Bus

A designed method of portable virtual oscilloscope with USB interface is proposed in this paper. The programmable gain amplifier (attenuator) circuit is used to adjust the different range of inputting signal to the A/D converter's. The A/D convert is realized by using ADS830E, which is a chip with maxim 60MHz sample rate and 8-bit data width. CY7C68013A, one chip of EZ-USB FX2 series, is used to achieve the data transfer to computer in block mode. The FPGA is programmed as an external host controller to control the gain amplification and attenuation circuit, and provide the sample clock for high-speed A/D converter ADS830E, and send the data to the Slave-FIFO. Application software is designed with VC++ platform to calculate and display the received data graphically.

Research on Portable Virtual Oscilloscope Based on USB Bus

A designed method of portable virtual oscilloscope with USB interface is proposed in this paper. The programmable gain amplifier (attenuator) circuit is used to adjust the different range of inputting signal to the A/D converter's. The A/D convert is realized by using ADS830E, which is a chip with maxim 60MHz sample rate and 8-bit data width. CY7C68013A, one chip of EZ-USB FX2 series, is used to achieve the data transfer to computer in block mode. The FPGA is programmed as an external host controller to control the gain amplification and attenuation circuit, and provide the sample clock for high-speed A/D converter ADS830E, and send the data to the Slave-FIFO. Application software is designed with VC++ platform to calculate and display the received data graphically.

A small-area inductorless configurable wideband LNA with high dynamic range

This paper presents a two-stage fully differential inductorless wideband low noise amplifier (LNA) with high dynamic range, using a switchable capacitive attenuation circuit, selectable-input impedance-matching topology, and bypassable amplifier. The proposed LNA is fabricated in a double-oxide 65nm/0.2μm minimum channel length CMOS technology and achieves a bandwidth from 500MHz to 2.5GHz, a voltage gain range of 30.6dB, a minimum noise figure of 4.1dB, and a maximum IIP3 of 22.8dBm. The LNA dissipates between 28.8 and 39.5mW and occupies an area of 0.041mm2.

High-Directivity Enhancement With Passive and Active Bypass Circuit Techniques for GaAs MMIC Microstrip Directional Couplers

This paper describes monolithic microwave integrated circuit microstrip directional couplers based on a new directivity enhancement technique. This technique utilizes a bypass circuit-a phase shifter and an attenuator-placed between the coupling and isolation ports to cancel out backward wave leakage to the coupling port, thereby enhancing directivity of the couplers. The bypass circuit can be implemented with a simple passive LCR circuit or an active heterojunction bipolar transistor (HBT) phase-inversion attenuation circuit. Edge-coupled-type microstrip spiral couplers using the passive and active bypass circuits were fabricated in a GaAs HBT process. Measurements are as follows. The coupler with the passive LCR bypass circuit delivers a -21-dB coupling factor and a 0.14-dB insertion loss (IL) at 2.6 GHz while keeping enhanced directivity of more than 30 dB with a 23.1% relative bandwidth. This corresponds to more than 21-dB improvement of directivity at the same frequency, compared to the coupler without the bypass circuit. For the coupler with the active attenuator, a peak directivity of 46 dB and more than 30-dB directivity with a 120% relative bandwidth are achieved while a -21-dB coupling factor and a 0.13-dB IL are delivered at 2 GHz. Additional measurements of HBT power detectors integrated with the couplers show that the couplers with passive and active bypass circuits can suppress detection errors of less than ±0.20 and ±0.10 dB, respectively, under 4:1 voltage standing-wave ratio load mismatching conditions, thus proving the effectiveness of the bypass techniques.