Automatic Gain Control

Abstract The problem of detecting the QRS complex in the presence of noise was analysed. Most QRS detectors contain a filter to improve the signal-to-noise ratio and compare the signal with a threshold. In an earlier paper we identified an optimal filter. Various techniques to generate threshold and detector designs were studied. Automatic gain-control circuits with a fixed threshold have a very slow response to different rhythms. Automatic threshold circuits based on simple peak-detection schemes have a fast response, but are very sensitive to ...

An erbium-doped (Er-doped) fiber amplifier operating in the C-band is gain clamped, at about 26 dB with noise figures below 6 dB by multiple fiber Bragg gratings. These gratings are placed at the amplifier output with center wavelengths in between communication channels so that unwanted amplified spontaneous emission is removed but put to good use. A 0.5-dB gain compression point at -15 dBm of input signal powers for two simultaneous signal channels is also demonstrated.

A selective internal reset mechanism that allows the burst-mode TIA to recover a burst-mode signal as a stand-alone device in EPON is discussed. Using step AGC, the TIA achieves a DR of 27dB and a sensitivity of -31dBm with a PIN photodiode. Moreover, with internal reset, the loud/soft ratio is also 27dB within 100ns guard and preamble times.

Circuit and system of the Auto Gain Control (AGC) is a very important to be used in Visible Light Communication (VLC) transceiver receives the range of receivers and overcoming the near-far effect of the signal link. This paper discusses circuit design of AGC by using IC LM13700, a Trans-conductance amplifier. This IC is available in the electronic market and very low-cost. AGC is able to offer limited VLC mobility (movable) access at a certain distance and angle. We have performed an AGC circuit test that implemented in the optical link, the result shows (AVOL vs frequency) that AGC is effective to amplify the weak signal of VLC system (can be changed distance orientation up to 45 cm and angle of the receiver against The LED up to> 45 degrees.

—Visible Light Communication (VLC) as one of wireless technology must be able to offer a good capability as mobile communication system. The signal will be faded when the distance and angle of LED to photo-detector become higher at a certain distance. Other problem at VLC system is light interference noise which is caused by flicker effect from other light sources such as incandescent, fluorescent, DC-lamp (i.e. flashlight) and the sunlight. Each of lights have specific carried signal characteristics and it can influences the VLC system. In this paper we offer design of mobile VLC system based on analog domain. We use Automatic Gain Controller (AGC) circuit using commercially available IC and it will be placed at analog front-end receiver side. AGC can self-adjust its gain according to the input signal amplitude. We also design ana-log filter to eliminate all interferences noise spectrum which is existed under 50 KHz. We design both circuits, analog filter and AGC in VLC receiver system with low-cost. The test data are obtained through the simulation and achieved good results in ideal condition.

The analog front end of an echo cancellation burst mode (ECBM) transceiver operating from a single 5-V supply is described. The chip performs pulse shaping and line driving in the transmit section and hybrid function, equalization, A/D and D/A conversion, automatic gain control, threshold detection for a phase-locked loop (PLL), and wake-up in the receive section. The partitioning between analog and digital functions is explained. The analog portion of the chip is described for both the receive and transmit portions, and design considerations for the various building blocks are outlined. The chip contains 45 amplifiers of seven different types and three different types of comparators and dissipates about 160 mW in the normal operation mode and 5 mW in the power-down mode. The die area is 50000 mil2 in a 2-μm, double-poly, single-metal CMOS technology

In this paper, gain flatness is studied for simultaneous 16-ITU-T channel amplifications at C-band (1,532–1,558 nm) in a single stage EDFA for WDM application at different average inversion levels. The inversion levels are varied due to the change of the input signal levels from the targeted operating point and also for dropping few numbers of channels. Specially designed gain flattening filter (GFF) is used in order to get the flat gain with gain variation ±0.5 dB for −20 dBm/ch input signal power (total input signal power is −8.0 dBm) at a fixed average inversion level which is maintained by proper selection of optimum fibre length and pump power. A specific loss spectrum of GFF is obtained by writing a chirped fibre Bragg grating of length 20 mm. Gain variations are studied by changing the total input signal levels from −8.0 dBm to −20.0 dBm and maintained within 20.0 ± 0.5 dB by using automatic gain control (AGC) circuit. About 15 out of 16 channels are dropped and observed ± 0.5 dB gain-variation which is an important parameter in optical network system.

Expected temporal effects in a night vision goggle (NVG) include the fluorescence time constant, charge depletion at high signal levels, the response time of the automatic gain control (AGC) and other internal modulations in the NVG. There is also the possibility of physical damage or other non-reversible effects in response to large transient signals. To study the temporal behaviour of an NVG, a parametric Matlab model has been created. Of particular interest in the present work was the variation of NVG gain, induced by its automatic gain control (AGC), after a short, intense pulse of light. To verify the model, the reduction of gain after a strong pulse was investigated experimentally using a simple technique. Preliminary laboratory measurements were performed using this technique. The experimental methodology is described, along with preliminary validation data.

A performance analysis of an RF transceiver for UTRA/FDD WCDMA user equipment through simulation is presented. The main building blocks of this transceiver are power amplifier (PA), low noise amplifier (LNA), automatic gain control amplifiers (AGCs), mixers, modulator, demodulator, frequency synthesizers (oscillators and phase lock loop) and variable gain power amplifier driver. All these components are commercially available. Critical RF characteristics of the transceiver, such as adjacent channel leakage power ratio (ACLR), maximum output power, noise figure (NF), gain, 3rd order input intercept point (IIP3) and selectivity, were analysed based on commercial standard dual conversion transmitter and heterodyne receiver architectures. Results obtained from this simulation could be used as a design methodology for future RF transceiver implementation

This paper proposes a more precise way of radiofrequency output power control and sensing for mobile base station transmitters without increasing the complexity of the AGC of their power amplifier in order to overcome the design adjustment problems and the production ones. The solution presented is based on measuring both the output power RF and the current consumption of the PA. The solution has been tested on commercial GSM triple-band fixed cellular terminals and prototypes of 3G power amplifiers.