Automatic Gain Control System Research Articles

A novel programmable gain control low noise amplifier (PGCLNA) design for automatic gain control loop in BLE applications

Bluetooth low energy (BLE) is a widely used short-range communication protocol and BLE receivers frequently encounter transient high-power RF (radio frequency) signals from antennas, leading to receiver saturation. To address this issue, this work proposes a 2.4 GHz programmable gain control low-noise amplifier (PGCLNA), which is a key element in an automatic gain control (AGC) system for BLE receiver applications. The proposed PGCLNA achieves discrete levels of gain using the g m -boosting technique by splitting the negative feedback. The proposed circuit is simulated in UMC 180 nm technology and the maximum gain achieved is 41.4 dB, with a step decrease of 15 dB in discrete levels. The gain variations do not degrade the performance of S11, which is always less than -16 dB. The noise figure (NF) is always minimum of 5.5 dB and in high gain mode, the minimum value of NF is 1.82 dB. The third-order intercept point (IIP3) is −7.621 dBm in the best circumstances and always remains above −10.69 dBm. These results are achieved by utilising 5.4 mW power at 1.8 V of supply voltage. The circuit occupies an area of 732 μm × 771 μm. The proposed PGCLNA design offers a solution to accommodate a wide range of input signals in BLE receivers, excellent gain control, low noise and robust performance characteristics, making it an essential component in an AGC system for BLE receiver applications.

Study of Automatic Gain Control System in Broadband Radio Receiver

In modern times, almost all communication systems are digital. In the receivers of such communication systems, the analog signal is discretized and quantized using an analog-to-digital converter at an intermediate frequency. Automatic gain control is used to avoid overloading the analog-to-digital converter and to maintain intermediate frequency analog signals at a suitable fixed level. If the power of the received signals is much less than the load level of the analog-to-digital converter, the automatic gain adjustment increases the gain, reducing the quantization noise. If the received signal strength is high, the automatic gain adjustment lowers the gain so that the analog-to-digital converter is not overloaded. The accuracy of the adjustment of the transmission coefficient of the automatic adjustment of the digital amplification does not always satisfy the requirements given in real time. Based on the above, the article is devoted to the study of the digital automatic gain regulator of the broadband radio receiver.

Electro-Acoustic Path of the Detector for Detection of Small Unmanned Aerial Vehicles

Small unmanned aerial vehicles have become increasingly popular in recent years for both commercial and recreational use. However, with the onset of war, the threat of using such drones for illegal purposes such as reconnaissance operations and terrorist attacks on the most vulnerable and important targets — military equipment, government buildings, airports or places with a large concentration of people — has rapidly increased. As a result, many methods have been developed for detecting drones, but the most promising of these is considered to be the acoustic method. This article discusses the implementation of a simple and inexpensive acoustic detector with a single microphone, enabling the detection of the sound emitted by the drone engines and propellers, which can then be analyzed to determine the location and trajectory of the unmanned aircraft. To register sound waves, it was proposed to use the electret microphone CMA-4544PF-W with a foam windscreen, and to ensure a wide dynamic range and protect the detector from overload, an amplifier with an automatic gain control system with feedback regulation based on the integrated circuit MAX9814. For further digital signal processing on a PC, an analog-to-digital converter with a sampling frequency of 48 kHz and a bit depth of 16 bits will be used, as well as an external sound card CM6206 with a line input. As a result of test flights, a database of audio files of the noise of the DJI Mavic 2 Pro quadcopter was created, which is now actively used by the military for reconnaissance, the accuracy of object detection by the acoustic detector was studied. The distance from the drone to the microphone affected the accuracy of detection, and the maximum value of reliable detection was 40 meters. The device successfully performs its functions, given its low cost and ease of use, but requires improvement to enhance its characteristics. The spectra of the obtained audio recordings of quadcopter emissions make it possible to determine the main frequencies of tones, the number of which coincides with the number of electric motors and are important features for further identification of the drone.

Nonlinear Dynamics of the Primary Oscillation Circuit of a Mems Gyroscope Under the Action of Phase-locked Loop and Automatic Gain Control Systems

In this work, we study the dynamics of primary oscillations of a high-Q micromechanical resonator - a sensitive element of an RR-type MEMS gyroscope - under the action of various implementations of a phase-locked loop system operating in conjunction with an automatic gain control system for an electrostatic drive. The study of the dynamics of the object is carried out both numerically and analytically - using the averaging method. Conditions for the stability of a stationary regime in a linear approximation are obtained. The questions of accuracy of various methods of numerical solution of differential equations of the circuit of primary oscillations are considered. The influence of the mechanical nonlinearity of the resonator on the dynamics of the resonator and the control system has been studied. An implementation of a low-order PLL circuit that does not contain a double-frequency spurious signal at the output of the phase detector is proposed. The output characteristics of control systems (speed, capture bandwidth, etc.) are analyzed and qualitative conclusions are drawn about the features of the interaction between the dynamics of a mechanical oscillatory link and the PLL-ARC circuit.

Analysis and Modeling of a Directional Microwave Coupler as SMD Component

The article describes the calculation, modeling and layout of the directional coupler. In the course of the work the market analysis was carried out, the model of directional coupler in the frequency range of 2.9—4.5 GHz, the layout of the device and measuring equipment were developed. Directional couplers with different transient attenuation are widely used in the distribution circuits of antenna arrays, as well as to control the power of the radio signal propagating in the transmission line, in power meters, automatic gain control systems, radio receivers, etc. The choice of circuit solutions used for the construction of directional couplers is carried out depending on the specific technical requirements for electrical parameters, the range of operating frequencies and the capabilities of the technological base. Practically all variety of structures of directional couplers realized on elements is a result of modification of the simplest structures. The main types of directional taps include stub, single-stage and tandem-based. During the simulation, it turned out that the directional coupler based on a tandem connection of two connected transmissions with the location of the transmission lines on different layers of the multilayer printed section was suitable for this work. This is due to the fact that when modeling the directional coupler with transmission lines on one printed circuit board, The gap between these lines is too small (&10 nm), which is extremely difficult to perform on a microstrip structure.

Communication system improvement with control performance based on link quality in wireless sensor actuator networks

<span lang="EN-US">New communication and networking paradigms started with wireless sensor actuator networks (WSANs) to introduce new applications. One of these is the automatic gain control system (AGC). It will enable a high degree of the decentralized and mobile control. In this study, neural networks (NN) with fuzzy logic (one of the techniques of artificial intelligence (AI)) is used to enhance the control performance depending on the link quality. The NN and fuzzy inference system (FIS) with Mamdani’s method used to build a model reference, adaptive controller, for recompensing for delay time packets losses, and improving the reliability of WSAN. Between 88.62% and 99.99%, validation data is obtained for the medium and high conditions of operation with the proposed algorithm. Experimental and simulation results show a promising approach.</span>

Further simulations of the effect of cochlear-implant pre-processing and head movement on interaural level differences.

We simulated the effect of several automatic gain control (AGC) and AGC-like systems and head movement on the output levels, and resulting interaural level differences (ILDs) produced by bilateral cochlear-implant (CI) processors. The simulated AGC systems included unlinked AGCs with a range of parameter settings, linked AGCs, and two proprietary multi-channel systems used in contemporary CIs. The results show that over the range of values used clinically, the parameters that most strongly affect dynamic ILDs are the release time and compression ratio. Linking AGCs preserves ILDs at the expense of monaural level changes and, possibly, comfortable listening level. Multichannel AGCs can whiten output spectra, and/or distort the dynamic changes in ILD that occur during and after head movement. We propose that an unlinked compressor with a ratio of approximately 3:1 and a release time of 300–500 ms can preserve the shape of dynamic ILDs, without causing large spectral distortions or sacrificing listening comfort.

Measuring Current in a Power Converter Using Fuzzy Automatic Gain Control

The accuracy of current measurements can be increased by appropriate amplification of the signal to within the measurement range. Accurate current measurement is important for energy monitoring and in power converter control systems. Resistance and inductive current transducers are used to measure the major current in AC/DC power converters. The output value of the current transducer depends on the load motor, and changes across the whole measurement range. Modern current measurement circuits are equipped with operational amplifiers with constant or programmable gain. These circuits are not able to measure small input currents with high resolution. This article proposes a precise loop gain system that can be implemented with various algorithms. Computer analysis of various automatic gain control (AGC) systems proved the effectiveness of the Mamdani controller, which was implemented in an MCU (microprocessor). The proposed fuzzy controller continuously determines the value of the conversion factor. The system also enables high resolution measurements of the current emitted from small electric loads (≥1 A) when the electric motor is stationary.

Design of Programmable Gain Amplifier Module in Dynamic Liquid Level Tester

Oil and gas wells need to perform dynamic liquid level detection during the development to prevent inaccurate detection during drilling and damage the oil and gas field. The Program Controlled Gain Amplifier (PGA) module designed in this paper is used in the dynamic liquid level test instrument. Using STM32F4O7ZGT6 as a microcontroller (MCU), the MCU, a multi-stage variable gain amplifier and a peak detection circuit form a closed loop control, forming an automatic gain control (AGC) circuit. First, the signal output by the peak detection circuit is collected by AD, and then the entire module is in a dynamic balance state through DA feedback. This AGC system can accurately control the gain and output signal. Finally, the ratio-average filtering algorithm is used to test the experimental data. Experimental results show that the module can achieve gain control of-20∼60dB in the frequency range of 1kHz∼20MHz; the relative error of the output voltage is within 3%. This module achieves the performance indicators of broadband, high precision and high gain. Compared with the traditional module, its advantage is that it takes into account and optimizes the three performance indicators at the same time, and has better stability.

Digital AGC Circuit Design based on FPGA

Users' demand for broadband wireless and mobile is increasing, making wireless broadband access technology WiMAX, arise at the historic moment, rapid development, has become the focus of attention in the industry these two years. In this paper, based on the WiMAX transmission standard 802.16D, the AGC of channel demodulation in WiMAX receiver is described in detail. Firstly, the basic components and main characteristic indexes of the AUTOMATIC gain control system are introduced, and the output formula of AGC model is obtained through the analysis of a step-type AGC. Then the adc and AGC circuits in THE AGC system in the WiMAX receiver are introduced and analyzed theoretically. In this paper, SPW model is used to analyze the algorithm of the basic structure of AGC circuit. Combined with the simulation results, AGC circuit is explained in detail and parameters are explained. Finally, the verification results based on SPW and FPGA are given. The individual performance test of AGC is carried out through SPW, and combined with the performance test of the simulation system, it shows that AGC can work in cooperation with other modules of the system. In FPGA test, it can be proved that AGC can also work well with Verilog.

Characterization of a COTS-Based RF Receiver for Cubesat Applications.

This paper reports the experimental results of a test campaign performed on the radio-frequency (RF) receiver prototype operating at a 2025–2110 MHz frequency range, designed and fabricated for CubeSat applications. The prototype has been tested through a board-level test approach for the verification of the functional requirements and a component-level one for specific characterization measures. The tests have shown the following results: a −115–−70 dBm sensitivity range, 390 MHz intermediate frequency, a 0 dBm output power level with ±1 dB error, a 2.34 dB noise figure, and a 4.86 W power absorption. Such results have been largely achieved implementing an automatic gain control system by cascading two Commercial Off-The-Shelf (COTS) amplifiers. Moreover, an innovative technique based on RF test points has been successfully experimented and validated to measure the S-parameters of a custom low-pass filter integrated on the receiver, showing the possibility of even characterizing the single COTS components exposed to radiation through a unique board-level test setup. The technique may have a great impact on the cost reduction of electronic boards for space applications, since it would avoid using expensive evaluation boards for each COTS component that needs a radiation test.

DIGITAL AUTOMATIC GAIN CONTROL SYSTEM MODELING

The goal of automatic gain control is to maintain a constant output power level. Automatic gain control systems are used in various communication systems, both analog and digital. However, for all the variety of digital automatic gain control algorithms, the adjustment of the control parameters during the simulation process in reality is often ignored. In practice, this can lead to long-term overloads with a large change of the input signal power. There is also the risk that the model used was designed to work in linear mode only. In nonlinear mode, its behavior may not always be predictable. Research subject. The purpose of this article is to analyze digital AGC system characteristics and to model its operation in Matlab. Method. As part of the study, a Matlab model of hybrid automatic gain control system was developed. Core results. It is shown that the control time of the digital automatic gain control system with a non-linear gain control characteristic does not depend on the amplitude of the input signal. The performance of the proposed digital model is limited by the dynamic range of the linear path and the analog-to-digital converter. The mathematical dependence of the response time of the model on the input signal level change is obtained, in which the time constant of the automatic gain control filter has been replaced by the time constant of the entire automatic gain control system. Practical relevance. A digital model of hybrid automatic gain control system is proposed, which will allow to simulate digital automatic gain control systems parameters for both small and large changes in the input signal level. The results of this work are relevant to the development of digital receivers for communication systems of various purposes.

Impact of Signal Quantization on the Performance of RFI Mitigation Algorithms

Radio Frequency Interference (RFI) is currently a major problem in Communications and Earth Observation, but it is even more dramatic in Microwave Radiometry because of the low power levels of the received signals. Its impact has been attested in several Earth Observation missions. On-board mitigation systems are becoming a requirement to detect and remove affected measurements, increasing thus radiometric accuracy and spatial coverage. However, RFI mitigation methods have not been tested yet in the context of some particular radiometer topologies, which rely on the use of coarsely quantized streams of data. In this study, the impact of quantization and sampling in the performance of several known RFI mitigation algorithms is studied under different conditions. It will be demonstrated that in the presence of clipping, quantization changes fundamentally the time-frequency properties of the contaminated signal, strongly impairing the performance of most mitigation methods. Important design considerations are derived from this analysis that must be taken into account when defining the architecture of future instruments. In particular, the use of Automatic Gain Control (AGC) systems is proposed, and its limitations are discussed.

Forward masking recovery in bottlenose dolphins (Tursiops truncatus): Auditory brainstem responses to paired-click stimuli in high-pass masking noise

Adaptation is a fundamental process in the auditory system and underlies the automatic gain control system of echolocating bottlenose dolphins. As pulse-echo delay increases, auditory brainstem response (ABR) amplitudes to the echoes progressively increase. This study examined adaptation across cochlear frequency regions using a paired-click (i.e., forward masking) paradigm and high-pass masking noise. Bottlenose dolphins passively listened to paired click stimuli (20–160 kHz “pink” spectra). A “conditioning” click was followed by a “probe” click with equal amplitude and a time delay ranging from 125 to 750 μs. ABRs to click pairs were obtained with and without high-pass masking noise that precluded the basal turn of the cochlea from responding to the click stimuli. The ABR evoked by a single click (temporally aligned with the first click of the paired-click condition) was subtracted from the click-pair ABR to visualize the response evoked by the probe click. Probe ABR amplitudes recovered linearly with increasing delay relative to the conditioning click, and were approximately 70% of full response amplitude at 750-μs delay. Paired-click interval ABR amplitude recovery functions were similar for the unmasked and high-pass masked conditions. [Work sponsored by ONR.]

Model of the Digital Automatic Gain Control System of Pulse-Power Amplifiers with Bipolar Transistors for Transmitter Modules of Radar Systems

Problems in designing the systems for digital automatic control of parameters of pulse-power amplifiers of radar systems are outlined. A model of the digital automatic gain control system of pulse-power amplifiers with bipolar transistors is proposed. This system shapes the leading and trailing edges of a radio pulse and adjusts the gain within the pulse itself in order to maintain the set output power level. The behavior of the proposed model in operation with a long pulse and a train of short pulses is examined.

Variability of Hydroacoustic Noise Probability Density Function at the Output of Automatic Gain Control System

This research presents results of the estimation of temporal variability of the hydroacoustic noise probability density function (PDF) in shallow waters within the frequency band of 0.03–3.3 kHz; the studies were conducted near the Primorsky Aquarium on Russky Island, Vladivostok, Russia. Signals were received via unidirectional hydrophone and automatic gain control of the received signals. The hydrophone was attached to a drifting buoy via an elastic suspension; the received signals were transmitted by cable to a boat drifting with the buoy. The results of the comparison of the sea noise probability density function (PDF) estimates at the output of a system with automatic gain control (AGC) with similar results for a white Gaussian noise in the same frequency band are described.

High-performance programmable grounded resistor and its applications

ABSTRACTProgrammable resistor and analog computational circuits are essential for many applications such as analog signal processing units, automatic gain control, neural, fuzzy and instrumentation systems. A high-performance programmable grounded resistor (PGR) using complementary metal oxide semiconductor (CMOS) technology is proposed in this paper. A highly linear CMOS resistor with equivalent resistance ranging from 9.4 to 1.5 kΩ is obtained by cancelling the non-linear term present in the current equation of an MOSFET working in the linear region. The proposed resistor operates on both positive as well as negative input voltage. The inherited features of PGR are simplicity, extensive control voltage range, wider bandwidth and low-power dissipation. Additionally, analog computational units such as multiplier, squarer and divider are also discussed as applications of the PGR. All circuits are implemented and simulated using TSMC 0.13 µm CMOS technology in SPICE.

Dynamics of cochlear nonlinearity: Automatic gain control or instantaneous damping?

Measurements of basilar-membrane (BM) motion show that the compressive nonlinearity of cochlear mechanical responses is not an instantaneous phenomenon. For this reason, the cochlear amplifier has been thought to incorporate an automatic gain control (AGC) mechanism characterized by a finite reaction time. This paper studies the effect of instantaneous nonlinear damping on the responses of oscillatory systems. The principal results are that (i) instantaneous nonlinear damping produces a noninstantaneous gain control that differs markedly from typical AGC strategies; (ii) the kinetics of compressive nonlinearity implied by the finite reaction time of an AGC system appear inconsistent with the nonlinear dynamics measured on the gerbil basilar membrane; and (iii) conversely, those nonlinear dynamics can be reproduced using an harmonic oscillator with instantaneous nonlinear damping. Furthermore, existing cochlear models that include instantaneous gain-control mechanisms capture the principal kinetics of BM nonlinearity. Thus, an AGC system with finite reaction time appears neither necessary nor sufficient to explain nonlinear gain control in the cochlea.

A simulation analysis of the variability of the roving level hearing test.

In the study of auditory prostheses, the Speech Recognition Threshold (SRT) is the Signal to Noise Ratio (SNR) at which 50% of words are correctly identified. SRT is typically measured using an adaptive procedure wherein speech is presented at a fixed sound pressure level (SPL) and the noise level is varied according to the subject's responses. A roving level SRT test has been used by researchers with the goal of including the effectiveness of Automatic Gain Control (AGC) systems in SRT measurements. The roving method presents speech at three different SPLs with the level for each sentence chosen pseudo-randomly, while adaptively varying the SNR. This study used simulations to compare roving and fixed level SRT tests. It was found that roving level tests have significantly increased variability when there are level-dependent differences in subject scores. The interleaved level test is recommended as an alternative as it provides clear visibility of level-dependent performance and a better understanding of overall subject performance.

Implementation of an LC-VCO with Built-in AGC for Oceanographic Radar Applications

This paper presents a LC Voltage-Controlled Oscillator (LC-VCO) with an incorporated Automatic Gain Control (AGC) unit. The LC oscillator is based on the BJT cross-coupled pair topology with tuning varactors and a dual supply source so that the tuning range is maximized. The trade-off between the quality factor, tuning range and number of varactors in parallel is analyzed. In addition, the stability of the AGC system is proven by the estimation of the gain and phase margin. Finally, the phase noise (PN) LC-VCO is estimated using the Leeson model. The oscillator shows a tuning range from 4.3MHz to 6MHz (about 330,000 ppm) and an estimated phase noise of -117.2dB /Hz@ 1kHz. The system shows an improvement of 6dB compared to the same VCO without gain control. The system consumes 47mW of power from a 3V supply.