Receiver Amplifier Research Articles

Implementation of broadband optical receiver amplifier with low group delay variation

Considering the ever-increasing growth of data traffic in communication systems, optical receiver amplifiers are now emerging as a key feature of various optical receivers. This article presents a broadband optical receiver amplifier for high-speed and low latency communication systems. The proposed amplifier is based on the distributed amplifier configuration, and employs the negative group delay technique to reduce the group delay variation. The experimental results of the proposed amplifier show a 15 dB average gain, 3 dB noise figure, and 8 ps group delay variation at frequency ranging from DC to 40 GHz. To the best of our knowledge, the proposed distributed amplifier (DA) demonstrates the lowest group delay variation among the reported forward optical module distributed amplifiers (DAs) for high data rates applications.

Isolation Improvement in Reflectarray Antenna-Based FMCW Radar Systems.

This paper presents an optimization of reflectarray-based RF sensors for detecting UAV and human presence. Our previous human detection radar system adapted a center-fed reflectarray antenna to a commercially available radar system, successfully increasing the gains of the transmit (TX) and receive (RX) antennas by 21.18 dB and the range for detecting human targets 3.4 times. However, because the TX and RX antennas were placed in the focal point of the reflectarray, the TX signal reflected by the reflectarray was directly propagated into the RX antenna, causing desensitization or damage to the receiving circuit if high powers were used. To reduce this direct reflection, we propose a novel radar antenna configuration in which the TX and RX antennas are placed back-to-back with each other. In this configuration, the RX antenna does not directly face the reflectarray, thus direct path between the TX to RX through the reflectarray is removed. The results demonstrate that this approach achieves the optimum isolation level of 51.3 dB. With the reflectarray, the TX antenna gain increases to 30.6 dBi, but the RX antenna gain remains at 16 dBi since the RX antenna does not utilize the reflectarray. The TX and RX gain difference (14.6 dB) is a trade-off for good isolation and may be reduced by utilizing a high-gain receiver amplifier.

Acoustic communication through well-head for an untethered autonomous well logging tool

Untethered autonomous well logging tools have recently been introduced to oilfields. Once deployed into a well, the tools autonomously travel in the well to collect data and return to surface after the mission is completed. A service operator needs to travel to the well-site and open the well cap to check if the tool has returned. This increases the operational time and cost. This can be addressed by implementing a return detector and notifying the operator. Steel well-head construction leaves acoustics as the most viable option for such detection. We demonstrated a proof of concept of acoustic based simplex communication system through well-head. A pair of identical transducers were used as transmitter and receiver that operates at 155 kHz. Transmitter piezo was positioned at the center of a water filled steel wellhead with 7-inch diameter and 0.25-in. wall thickness, while the receiver was taped outside the wellhead with grease to increase acoustic coupling. Transmission loss was measured as -57 dB which was partially compensated by using a receiver amplifier stage with a gain of 1000. Next, the transmitter will be incorporated on a miniaturized untethered well logging tool.

Design and development of ultrasonic bipolar square-wave pulser for non-destructive testing of concrete structures.

This paper provides design and development details of the generation of bipolar High Voltage (HV) square wave pulses for the excitation of low frequency ultrasonic transducers. Such a circuit is required for the purpose of ultrasonic inspection of components, particularly where high energy is required to insonify the attenuative medium, such as concrete. A HV (±350 V) square wave pulse has been generated by an ultrafast complementary Metal Oxide Semiconductor Field-Effect Transistor (MOSFET) pair, which is driven by high speed MOSFET drivers. The generated bipolar square wave pulse has been utilized to energize a 108 kHz ultrasonic transducer to operate in the pulse-echo mode for the evaluation of a concrete test block. The receiver amplifier filters the received low-amplitude echo signals, which are reflected back from a discontinuity, and amplifies further for signal to noise ratio enhancement. The pulser board designed has been tested and evaluated for its functionality to measure ultrasonic velocity in the highly attenuative concrete medium up to a depth of 1 m. The measured value of acoustic velocity was compared with the value obtained from the commercially available ultrasonic pulse velocity instrument, and the values obtained are within ±5%.

On-time modelling using system response convolution for improved shallow resolution of the subsurface in airborne TEM

ABSTRACTWe describe a new approach for modelling airborne transient electromagnetic (TEM) data which combines the use of on- and off-time data for inversion. Specifically, the response is modelled using system response convolution both during and after transmitter ramp-down. High near-surface sensitivity can be achieved through a combination of fast transmitter ramp-down, broad receiver system bandwidth, efficient suppression or explanation of the primary field, and by combining the use of on-time gates with accurate knowledge of the system response. The system response can either be calculated based on the transfer function of the individual system components (i.e. receiver coil, amplifiers, low-pass filters and current waveform) or it can be measured at high altitude. The latter approach has the advantage of avoiding the specific modelling of individual system components. By comparing model parameter uncertainty when the on-time gates are included in the inversion versus when they are not, we show that a significant improvement in near-surface sensitivity is obtained. The method is used to invert both synthetic and field data. In the inversion of synthetic data, we see clear improvements in the determination of thin shallow layers, especially when they are resistive. This is confirmed by inversion of field data where we observe more pronounced structures with better definition of layer boundaries and layer resistivities.

Power-Efficient Spin-Torque Nano-Oscillator-Based Wireless Communication With CMOS High-Gain Low-Noise Transmitter and Receiver

A low-power spin-torque nano-oscillator (STNO)-based wireless communication is demonstrated with a 180 nm CMOS transmitter and receiver. The ON–OFF keying (OOK) modulation is employed to overcome the inherent drawbacks of the STNO, such as low output power and spectral purity, despite its advantages of a wide frequency tuning range and nano-scale dimensions. As the magnetic-tunnel-junction (MJT) STNO with an MgO barrier has a maximum oscillation power as small as −75 dBm at 3.39 GHz, a 68 dB high-gain amplification throughout the transmitter and receiver is needed for a 1 m wireless communication. A 36 dB high-gain amplifier with a 3.9 dB low noise figure is implemented for the OOK transmitter together with an external modulator. The receiver is composed of a 3.5 dB low-noise amplifier (LNA) with a high gain of 27 dB, gain-boosted envelope detector, and baseband amplifier. The transmitter and receiver amplifiers are implemented with a highly isolated ground between each stage in order to prevent oscillations even at the high gain. The communication system with the STNO achieves an 11.8 Mb/s wireless data transmission over 1 m, with a power consumption of 41.4 mW. The implemented transmitter and receiver occupy 2.34 and 4.08 mm2, including all of the pads, respectively. The proposed system achieves the highest data rate with the lowest power consumption compared to those of the previous state-of-the-art STNO-based wireless communication systems.

Вплив каналу синхронізації на завадостійкість цифрової системи передачі

The purpose of this article is to determine the optimal distribution of energy potential of information and synchronization channels with limitations for peak power for plesiochronous digital transmission systems (DTS) and quasi-optimal choice of potential distribution of synchronous DTS [1, 2], based on the noise immunity criterion. The goal is achieved by systematic physical and mathematical simulation of the synchronization process using the latest results of the theory of radio-electronic measurements [3, 4]. The optimization task is suitable for determining the optimum for the limitations of the peak power of the transmitter or the dynamic range of the first receiver amplifier, as well as in the case of general bandwidth constraints, especially in radio communication satellite systems. The noise immunity in the problem of quasi-optimal choice of energy potentials for synchronous systems with a separate channel of synchronization, depending on its potential and the content band, has the nature of saturation. Therefore, the principle of sufficiency and the optimal solution in the first approximation are used. The expression for measuring precision with automatic synchronization is similar for different types of phase meters or time shifting of the signal fronts. The optimum noise immunity of the transmission system is sensitive to the distribution of energy potential in the transmission system; which depends on the energy potential and the bandwidth of the synchronization channel. Therefore, the creation and operation of systems need to more accurately take into account the impact of such distribution.

Full-Differential Folded-Cascode Front-End Receiver Amplifier Integrated Circuit for Capacitive Micromachined Ultrasonic Transducers.

This paper describes the design of a front-end receiver amplifier for capacitive micromachined ultrasonic transducer (CMUT). The proposed operational amplifier (op amp) consists of a full differential folded-cascode amplifier stage followed by a class AB output stage. A feedback resistor is applied between the input and the output of the op amp to make a transimpedance amplifier. We analyzed the equivalent circuit model of the CMUT element operating in the receiving mode and obtained the static output impedance and center frequency characteristics of the CMUT. The op amp gain, bandwidth, noise, and power consumption trade-offs are discussed in detail. The amplifier was fabricated using GlobalFoundries 0.18-μm complementary metal-oxide-semiconductor (CMOS) technology. The open loop gain of the amplifier is approximately 65 dB, and its gain bandwidth product is approximately 29.5 MHz. The measured input reference noise current was 56 nA/√Hz@3 MHz. The amplifier chip area is 325 μm × 150 μm and the op amp is powered by ±3.3 V, the static power consumption is 11 mW. We verified the correct operation of our amplifier with CMUT and echo-pulse shown that the CMUT center frequency is 3 MHz with 92% fractional bandwidth.

Lossless and lossy modeling of ultrasonic imaging system for immersion applications: Simulation and experimentation

The design, modeling, optimization, and development of the entire ultrasonic imaging system is a complex task which involves an understanding of acoustic physics of transducer, acoustic properties of propagating medium, transmission cables and analog front-end electronics for generating and receiving of ultrasonic signals. Such immersion systems are extensively utilized in non-destructive testing (NDT) application for flaw detection, dimensional measurements, material characterization and many more. This paper presents the one-dimensional simulation modeling of the entire ultrasonic imaging system. For validation purpose, a single channel real-time ultrasonic imaging system has been designed and developed for laboratory application which contains high voltage ultrasonic spike pulser, high voltage protection circuits, ultrasonic receiver amplifiers, co-axial cables and an ultrasonic transducer. Lossless and lossy (low-loss) simulations have been performed for ultrasonic transducer and propagation medium using the transmission line model. Effects of non-ideal, frequency-dependent and non-linear components in high voltage excitation circuit (pulser), the receiver circuit and the effects of cables are also considered for modeling and simulation. Validation results of the entire ultrasonic imaging system provide very close agreement with lossy simulated results.

DEVELOPMENT OF OPTICAL WIRELESS RECEIVER AMPLIFIER USING HYBRID ENHANCEMENT

In the new communication era, signal will be transmit to the receiver via wireless. However, the signal might be loss during the transmission. Therefore, the signal received at the receiver is totally not originally from the transmitter. In some cases the signal must be amplified. This project will focuses on the concept of wireless optical in receiver communication system. The objectives of this project is to design a receiver amplifier using hybrid bandwidth enhancement in the approximately of Giga hertz range. The receiver amplifier is designed using Micro-Cap. The configuration of this design receiver is by using combination of bootstrapping and cascade technique. Bootstrapping technique offers the reduction on the photo detector capacitances which is the main limiting factor for the bandwidth of optical wireless front-end receiver. While, the cascade technique is used to arrange the electrical components such as transistor. Using the designed receiver Bootstrap Amplifier with Double Peaking Coil has been designed and fabricated. The cut-off frequency for this circuit is 400MHz.

20–25 Gbit/s low-power inductor-less single-chip optical receiver and transmitter frontend in 28 nm digital CMOS

The design of an analog frontend including a receiver amplifier (RX) and laser diode driver (LDD) for optical communication system is described. The RX consists of a transimpedance amplifier, a limiting amplifier, and an output buffer (BUF). An offset compensation and common-mode control circuit is designed using switched-capacitor technique to save chip area, provides continuous reduction of the offset in the RX. Active-peaking methods are used to enhance the bandwidth and gain. The very low gate-oxide breakdown voltage of transistors in deep sub-micron technologies is overcome in the LDD by implementing a topology which has the amplifier placed in a floating well. It comprises a level shifter, a pre-amplifier, and the driver stage. The single-chip frontend, fabricated in a 28 nm bulk-digital complementary metal–oxide–semiconductor (CMOS) process has a total active area of 0.003 mm2, is among the smallest optical frontends. Without the BUF, which consumes 8 mW from a separate supply, the RX power consumption is 21 mW, while the LDD consumes 32 mW. Small-signal gain and bandwidth are measured. A photo diode and laser diode are bonded to the chip on a test-printed circuit board. Electro-optical measurements show an error-free detection with a bit error rate of 10−12at 20 Gbit/s of the RX at and a 25 Gbit/s transmission of the LDD.

An in-probe low-noise low-power variable-gain receive amplifier for medical ultrasound imaging using CMUT transducers

In this paper a low-power, low-noise receiver amplifier is designed for interface with capacitive micro-machined ultrasonic transducers (CMUT). In 3D in-probe ultrasound imaging systems, the interface circuit area constraint due to the specified area per CMUT element, and the circuit power constraint for each channel are the main design challenges. A fully-differential variable-gain transimpedance amplifier (VGTIA) is designed for the CMUT signal read-out. Due to the small area and low power consumption, the circuit is suitable for in-probe imaging. The VGTIA is designed for the interface with an ADC block that does the digital conversion inside the probe. The circuit is able to produce a differential output from a Zero-Bias CMUT, where the requirement for an external high voltage dc bias is eliminated. The amplifier is designed and fabricated using a 65 nm CMOS process technology. The measurement results show that the transimpedance amplifier has a gain range of 79---97 dB$$\Omega $$Ω. A noise figure (NF) of 3 dB at a 5 MHz center frequency with an only 180 $$\upmu $$μW power consumption is measured. A total area of 76$$\,\upmu $$μm$$\times $$×50$$\,\upmu $$μm is achieved which relaxes the area requirement for the following ADC block.

Attojoule Optoelectronics for Low-Energy Information Processing and Communications

Optics offers unique opportunities for reducing energy in information processing and communications while resolving the problem of interconnect bandwidth density inside machines. Such energy dissipation overall is now at environmentally significant levels; the source of that dissipation is progressively shifting from logic operations to interconnect energies. Without the prospect of substantial reduction in energy per bit communicated, we cannot continue the exponential growth of our use of information. The physics of optics and optoelectronics fundamentally addresses both interconnect energy and bandwidth density, and optics may be the only scalable solution to such problems. Here we summarize the corresponding background, status, opportunities, and research directions for optoelectronic technology and novel optics, including sub-femtojoule devices in waveguide and novel 2D array optical systems. We compare different approaches to low-energy optoelectronic output devices and their scaling, including lasers, modulators and LEDs, optical confinement approaches (such as resonators) to enhance effects, and the benefits of different material choices, including 2D materials and other quantum-confined structures. Beyond the elimination of line charging by the use optical connections, the next major interconnect dissipations are in the electronic circuits for receiver amplifiers, timing recovery and multiplexing. We can address these through the integration of photodetectors to reduce or eliminate receiver circuit energies, free-space optics to eliminate the need for timing and multiplexing circuits (while solving bandwidth density problems), and using optics generally to save power by running large synchronous systems. One target concept is interconnects from ~ 1 cm to ~ 10 m that have the same energy (~ 10fJ/bit) and simplicity as local electrical wires on chip.

Analog Circuit Blocks for 80-GHz Bandwidth Frequency-Interleaved, Linear, Large-Swing Front-Ends

Critical analog electronic circuits for a possible 80-GHz bandwidth, frequency-interleaved, PAM-4 or discrete-multitone (DMT) linear fiber-optic front-end are implemented in a 90-nm SiGe BiCMOS technology. These include a novel vertically coupled, 40–100-GHz bandpass filter, an 80-GHz bandwidth distributed optical modulator driver with a measured output compression point of 13 dBm per side, corresponding to 7 $\text{V}_{\mathrm {pp}}$ output differential swing, and a 125-GHz bandwidth PIN-diode SPST switch with a OP $_{1{-}\mathrm {dB}}$ of 23 dBm, and over 22 dB of isolation up to 160 GHz. The linear modulator driver can also be used as a high linearity (IP $_{1{-}\mathrm {dB}} = \,\, 5$ dBm per side) receiver amplifier in next-generation instrumentation systems.

A computerized tomography system for transcranial ultrasound imaging.

Hardware for tomographic imaging presents both challenge and opportunity for simplification when compared with traditional pulse-echo imaging systems. Specifically, point diffraction tomography does not require simultaneous powering of elements, in theory allowing just a single transmit channel and a single receive channel to be coupled with a switching or multiplexing network. In our ongoing work on transcranial imaging, we have developed a 512-channel system designed to transmit and/or receive a high voltage signal from/to arbitrary elements of an imaging array. The overall design follows a hierarchy of modules including a software interface, microcontroller, pulse generator, pulse amplifier, high-voltage power converter, switching mother board, switching daughter board, receiver amplifier, analog-to-digital converter, peak detector, memory, and USB communication. Two pulse amplifiers are included, each capable of producing up to 400Vpp via power MOSFETS. Switching is based around mechanical relays that allow passage of 200V, while still achieving switching times of under 2ms, with an operating frequency ranging from below 100kHz to 10MHz. The system is demonstrated through ex vivo human skulls using 1MHz transducers. The overall system design is applicable to planned human studies in transcranial image acquisition, and may have additional tomographic applications for other materials necessitating a high signal output.

A computerized tomography system for transcranial ultrasound imaging

Hardware for tomographic imaging presents both challenge and opportunity for simplification when compared with traditional pulse-echo imaging systems. Specifically, point diffraction tomography does not require simultaneous powering of elements, in theory allowing just a single transmit channel and a single receive channel to be coupled with a switching or multiplexing network. In our ongoing work on transcranial imaging, we have developed a 512-channel system designed to transmit and/or receive a high voltage signal from/to arbitrary elements of an imaging array. The overall design follows a hierarchy of modules including a software interface, microcontroller, pulse generator, pulse amplifier, high-voltage power converter, switching mother board, switching daughter board, receiver amplifier, analog-to-digital converter, peak detector, memory, and USB communication. Two pulse amplifiers are included, each capable producing up to 400 Vpp via power MOSFETS. Switching is based around mechanical relays that allow passage of 200 V, while still achieving switching times of under 2 ms, with an operating frequency ranging from below 100 kHz to 10 MHz. The system is demonstrated through ex vivo human skulls using 1 MHz transducers. The overall system design is applicable to planned human studies in transcranial image acquisition, and may have additional tomographic applications for other materials necessitating a high signal output. [Work was supported by NIH R01 EB014296.]

Single Stage RF Amplifier with High Gain for 2.4GHz Receiver Front-Ends

The paper deals with the numerical and experimental development of single stage radio frequency (RF) amplifier with high gain for 2.4GHz receiver front-ends. The work is motivated by the increasing demand of high-gain receiver amplifier in low-cost especially for wireless local area network (WLAN) application. Prior hardware realization and experimental characterization, the proposed amplifier which uses a single RF transistor of BFP420 type is numerically designed using ADS® software to satisfy the required specification. To obtain the impedance matching at ports of amplifier, microstrip lines are employed at the input and output ports. The prototype of amplifier is realized by use of a dielectric substrate of glass-reinforced epoxy lamination (FR4) board which has thickness of 0.762mm and relative permittivity of 4.3. The prototype is then experimentally characterized and demonstrates the gain of 13.35dB at frequency of 2.4GHz with the noise figure of 3.33dB, the input and output voltage standing wave ratio (VSWR) of 2.08 and 2.55, respectively.

An in-probe receiver amplifier with 3 dB noise figure and 50 dB dynamic range for medical ultrasound imaging using CMUTs

This paper presents the design and measurements of an in-probe receiver amplifier for ultrasound imaging applications using a capacitive micromachined ultrasonic transducer (CMUT). In such applications, the noise and the dynamic range play very important roles, as the former dictates the minimum input signal level and the latter defines the maximum input signal level that can be applied to a system. This work concentrates on both of these specifications. The amplifier consists of a transimpedance amplifier followed by a voltage gain stage implemented using a current feedback amplifier. It is designed and fabricated using a 180 nm CMOS process. A noise figure of 3 dB is measured for a CMUT model with 10---30 MHz frequency range. The amplifier shows a dynamic range of 50 dB with 0.8 % total harmonic distortion for the full scale input current of 7 µA peak-to-peak.

Experimental Investigation on RF Characteristics of Cryogenically-Cooled 3W-Class Receiver Amplifier Employing GaN HEMT with Blue Light LED for Mobile Base Stations

Experimental Investigation on RF Characteristics of Cryogenically-Cooled 3W-Class Receiver Amplifier Employing GaN HEMT with Blue Light LED for Mobile Base Stations

The correlated track receiver of tone track circuits

The work is devoted to further improvement of processing algorithm of checking signals of rail line. The simulation modeling of correlation track receiver of tone rail circuits has been executed; the benchmark analysis of correlation receiver and direct amplifier receiver has been executed.