Improved Dynamic Model of Fast-Settling Linear-in-dB Automatic Gain Control Circuit

Pan, Haizhou; Larson, L.E.

doi:10.1109/iscas.2007.377900

Cited by 4 publications

(4 citation statements)

References 7 publications

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“…In simple analytical models [2,3], Vdet is assumed to instantaneously follow the VGA output amplitude to simplify the analysis. However, practically there is a delay introduced by the detector pole that may affect the AGC loop stability [1].…”

Section: Detector Modellingmentioning

confidence: 99%

“… Automatic gain control loops are used in many systems to stabilize the signal level before analog-to-digital conversion [1][2][3]. A typical AGC loop is shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

“…Simple mathematical models describing these loops are derived in Refs. [2,3] under various small signal assumptions to linearize and simplify the problem, but for most practical cases, simulations are used to investigate the large signal…”

Section: Introductionmentioning

confidence: 99%

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Nonlinear Modelling of Automatic Gain Control Loops Considering Loop Dynamics and Stability

El-Shennawy¹,

Joram²,

Ellinger³

2017

JEE

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This work presents modelling aspects of automatic gain control (AGC) loops based on linear-in-dB variable gain amplifiers (VGAs). In these loops, the VGA control voltage is also an excellent received signal strength indicator (RSSI). The VGA gain is however nonlinearly related to the control voltage. Moreover, VGAs and detectors undergo nonlinear compression under high input amplitudes during settling transients. The main contribution in this work is a proposed nonlinear model based on simple and readily available components from the "analogLib" and "functional" libraries in CADENCE design environment -making it very easy and fast to build and simulate-that captures the nonlinear effects of AGC loops. The model is capable of verifying the AGC loop stability and capturing the loop dynamics with high accuracy compared to time consuming circuit level simulations. This provides insights into system level parameters such as AGC loop bandwidth, phase margin, settling time as well as estimating the AGC range and RSSI voltage vs. input power. Measurement results from a fabricated AGC prototype are in good agreement with simulation and modelling results thus validating the proposed modelling approach.

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Section: Detector Modellingmentioning

confidence: 99%

“… Automatic gain control loops are used in many systems to stabilize the signal level before analog-to-digital conversion [1][2][3]. A typical AGC loop is shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Nonlinear Modelling of Automatic Gain Control Loops Considering Loop Dynamics and Stability

El-Shennawy¹,

Joram²,

Ellinger³

2017

JEE

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“…В таких приемниках аналоговый сигнал дискретизируется и квантуется с использованием аналогоцифрового преобразователя (АЦП), как правило, на промежуточной частоте [3]. Для предотвращения насыщения АЦП максимальное значение аналогового сигнала на промежуточной частоте поддерживается на фиксированном уровне, обеспечивающем максимально возможное отношение сигнал/шум при отсутствии нелинейных искажений, цепью автоматической регулировки усиления (АРУ) [4].…”

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Characteristics of Digital Agc in Fixed-Point Operations

Prasolov

2019

Izv. vysš. učebn. zaved. Ross., Radioèlektron.

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Introduction. Nowadays, communication systems are mostly digital. One of the tasks of automatic gain control in digital receivers is to maintain analog signals at the appropriately fixed level, which prevents saturation of the analogto-digital converter. Most numerical algorithms are based on floating point arithmetic, and digital automatic gain control is usually implemented using fixed-point arithmetic devices such as programmable logic chips and signal processors. As consequence of fixed-point arithmetic and hardware constraints usage, the out-put significant bits should be truncated correctly. Although many studies mention digital automatic gain control, its characteristics are not considered in detail in terms of the finite capacity of calculators.Objective. The purpose of the study is to analyze dynamic characteristics of digital automatic gain control implemented on a computer for operations on numbers with fixed-point.Materials and methods. Within the frames of the study in Matlab software was developed a mathematical model of digital automatic gain control. The model was implemented on a programmable logic chip.Results. The paper shows the difference in characteristics and features of the digital automatic gain control during operations on fixed-point numbers. The study provides the assessment of the effect of fixed-point signals on the stability of the digital automatic gain control and includes the analysis of causes of spurious oscillations of the control signal.Conclusion. The study proposes the algorithm for compensation of the control signal oscillations by means of correction of the reference level of the digital automatic gain control. Further is required to verify the proposed algorithm on real signals. The results of the study are relevant in development of digital receivers for communication systems of various purposes.

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Nonlinear modelling of automatic gain control loops considering loop dynamics and stability

El-Shennawy

Joram

Ellinger

2016

2016 12th Conference on Ph.D. Research in Microelectronics and Electronics (PRIME)

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Improved Dynamic Model of Fast-Settling Linear-in-dB Automatic Gain Control Circuit

Cited by 4 publications

References 7 publications

Nonlinear Modelling of Automatic Gain Control Loops Considering Loop Dynamics and Stability

Nonlinear Modelling of Automatic Gain Control Loops Considering Loop Dynamics and Stability

Characteristics of Digital Agc in Fixed-Point Operations

Nonlinear modelling of automatic gain control loops considering loop dynamics and stability

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