SiGe Analog AGC Circuit for an 802.11a WLAN Direct Conversion Receiver

Alegre, J.P.; Celma, S.; Calvo, B.; Fiebig, N.; Halder, S.

doi:10.1109/tcsii.2008.2010173

Cited by 30 publications

(11 citation statements)

References 8 publications

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“…Compared to the AGC introduced in [6] fabricated in 0.25 mm SiGe BiCMOS technology with an active area of 0.225 mm 2 the AGC in [6] has THD of 0.9% at the lowest gain and its low and high cutoff frequencies are 68 kHz -95 MHz. The presented BGL-AGC circuit has a 0.16 mm 2 area, measured cutoff frequencies of 0.6 kHz-112 MHz and THD is 0.5% at the lowest gain.…”

Section: Experimentmentioning

confidence: 99%

Optical receiver for multicarrier modulation in short-reach communication

Atef

Swoboda²,

Zimmermann

2010

Electron. Lett.

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A high-linearity optical receiver with background-light-AGC for high PAPR signals is presented. The integrated BiCMOS optical receiver consists of a TIA with AGC, a linear amplifier and a line driver. The receiver THD is 1.7% and the third-order intermodulation is 50 dBc at 20 MHz and at an input optical power of 23.5 dBm. The thirdorder intermodulation decreases to 40 dBc at 100 MHz.Introduction: Short-range optical data transmission is attracting increasing interest in industry automation, in-car communication, and home networking. Polymer optical fibre (POF) represents an alternative to silica fibre for short-range communication and offers particular advantages. However, owing to its large numerical aperture of 0.5 and large core diameter the bandwidth of SI-POF is limited to 50 MHz/ 100 m. By use of multicarrier modulation schemes like OFDM such bandwidth limitations can be overcome. OFDM is seen as a promising technology for low-cost gigabit transmission over SI-POF [1].A major problem of OFDM is that the multicarrier signals usually have large envelope fluctuation. This means that the peak-to-average power ratio (PAPR) of multicarrier signals can be high. These large peaks increase the amount of intermodulation distortion (IMD), resulting in an increase in error rate.A high-linearity receiver with AGC is required for OFDM to reduce IMD. AGC adjusts the gain of the amplifiers to obtain the desired output signal strength. In conventional AGCs the signal amplitude is typically estimated using a peak detector. This adequately works for signal amplitudes with fixed PAPR such as sinusoids, but is unreliable for high-PAPR signals. These issues excluded the use of a conventional AGC with OFDM [2]. The wireless local area network receiver presented in [2] implemented an AGC, which uses RMS detection. This was found to be adequate for estimating the OFDM amplitude by integrating the duration of a training symbol.In this Letter we present an integrated linear optical receiver consisting of a TIA with AGC followed by an amplifier and a line driver. Additionally two main control loops are present, one for backgroundlight (BGL) cancellation and one for the gain control. The speciality of this linear optical receiver is that the gain is only controlled by BGL, which is always present in optical transmission systems owing to laser diode biasing above the threshold (limited extinction ratio). The presented BGL-AGC can achieve better linearity than peak-detecting AGC especially for pulsed signals or more general signals with high PAPR where the pulse repetition rate is low. When peak detection is used with this kind of signals, large storage capacitors would be necessary to store the peak value. Additionally, large capacitors cannot easily be charged very quickly and accurately. We do not need these large capacitors with the BGL-AGC.Nearly all previous attempts to design a linear optical receiver for short-range communication include only simulation results. No measurements have been presented to verify the optical receiver ...

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Section: Experimentmentioning

confidence: 99%

Optical receiver for multicarrier modulation in short-reach communication

Atef

Swoboda²,

Zimmermann

2010

Electron. Lett.

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“…In the same way as made for PD1, it is possible to design a fast-settling envelope detector based on the topology of PD3. This time, the new version, which is presented next, is part of the AGC proposed in [51], targeting specifically an IEEE 802.11a 5-GHz WLAN receiver application. It is implemented in SiGe technology in order to raise the range of study of this work.…”

Section: Proposed Pd3: High-g M Transconductor/current Mirror Based Pdmentioning

confidence: 99%

Automatic Gain Control

Pérez¹,

Pueyo

López

2011

Analog Circuits and Signal Processing

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), except for brief excerpts in connection with reviews or scholarly analysis. Use in connection with any form of information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed is forbidden. The use in this publication of trade names, trademarks, service marks, and similar terms, even if they are not identified as such, is not to be taken as an expression of opinion as to whether or not they are subject to proprietary rights.Printed on acid-free paper PrefaceReceivers have been a basic block in telecommunication systems since the invention of the radio in the late 19th century, acquiring an essential role in what has been called the third Communication Revolution where information is transferred via controlled waves and electronic signals. Their main function is to recover the information from the transmitted wave and convert it to electronic signals that can be understood by the succeeding electronic processing signal systems. Since the Internet revolution, new receivers appeared to connect computers one to another or to the World Wide Web, such as wireless systems, have been gaining more and more popularity over the last few years. Thus, great investments in time, effort and money from both academia and industry have been made in the development of these receivers in order to achieve fully integrated solutions in form of ASICs meeting the demand for ever increasing high performance with low cost, low voltage supply, low power consumption and reduced surface area.The design of one of these receivers include different blocks such as filters, low noise amplifiers, gain controlled amplifiers, mixers and analog to digital converters. This book is precisely focused on the analysis and design of automatic gain control, AGC, circuits with wireless receivers as the main target application. In this context, the general function of the AGC circuitry is to automatically adjust the output signal of a variable gain amplifier to an optimal rated level, for different input signal strengths. This function is essential to guarantee that the system dynamic range is neither saturated with large signals nor makes the system fall below a tolerable noise level.Specifically, some wireless applications, such as WLAN or Bluetooth, must be able to handle packets-based data transmission and orthogonal frequency division multiplexing which introduce stringent settling-time constraints. Thus, fast AGCs are primordial in those systems. It is under these conditions that feedforward AGCs present their greatest advantages as an alternative to conventional feedback AGCs. Thus, all through this book we offer a detailed study about feedforward AGCs design-both at basic AGC cells and system level-, their main characteristics and performances. vi viThe starting point is a complete review and theoretical analysis of both feedforward and feedback configurations and their behavioural modelling, issues addressed in Chap. 2.Next, basic components in gain control func...

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“…The small-signal input transconductance gm,in of the active (or slave) differential pair M"n-M"p, is given by (1) where the factor m is an integer number, VCM is the input common-mode (CM) voltage, Vs is the common-source voltage of M"n and M"p, K and VTH are the transconductance parameter and the threshold voltage of the NMOS devices. The other symbols have their usual meaning.…”

Section: Operation Principlementioning

confidence: 99%

“…Tunable transconductors are important building blocks employed in many analog circuit applications as in high frequency amplifiers [1], continuous-time filters [2,3] and variable gain amplifiers [4][5][6][7]. Transconductance adjustment is necessary for programming circuit/system parameters, like center frequency and quality factor of filters, for setting the voltage gain of amplifiers or for compensating the tolerances due to process and temperature variations [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

A versatile technique for linearly tunable transconductors

Raikos

Vlassis

2010

2010 17th IEEE International Conference on Electronics, Circuits and Systems

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A versatile technique for linearly tunable CMOS transconductors is introduced in this work. The technique uses a replica circuitry of the active transconductor circuit in master-slave configuration. The presented implementation of the master-slave technique offers the advantages of the linear tuning of the input transconductance over wide range, the stability over PVT comers and the circuit simplicity. The operation and the performance of the implementation have been verified through simulation results using standard 0.18!lm CMOS process.

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SiGe Analog AGC Circuit for an 802.11a WLAN Direct Conversion Receiver

Cited by 30 publications

References 8 publications

Optical receiver for multicarrier modulation in short-reach communication

Optical receiver for multicarrier modulation in short-reach communication

Automatic Gain Control

A versatile technique for linearly tunable transconductors

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