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Autogain (ACG) Circuits
 

Last Updated: November 30, 2017 07:38 AM




Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students & inventors:

AGC Circuit -  SSB SSB Transceiver-Receiver Section:  The AGC circuit uses a dual op-amp IC.  The first stage amplifies the receive audio   (taken from the hot side of the AF gain control).  The output from this stage is converted to a DC   (ish) signal by a voltage doubling rectifier.  The final stage is a DC amplifier.  A nice feature of the circuit, is that the meter is automatically set at zero, in the absence of any signal.  I used an LF353 dual op-amp.  Most fet input dual op-amps should work in this circuit, or you can use a pair of single op-amps. __ Designed by EI9GQ homebrew radio

Automatic Gain Control ACG -  This project is a digital Automatic Gain Control   (AGC) system using a PIC16F876 MCU.  The ability to set the gain level in a circuit and have it control itself is a very useful function.  This circuit is a building block of another project I am working on.  A 30W power amp for either the PCS, iDEN or CDMA frequency bands.  I will settle on one of those frequencies sometime soon. __ Designed by steevn.geo @ yahoo.com

Circuit lets AGC Amp hold its gain -  EDN-Design Ideas 01/19/2015    AGC amps respond to signal level.  This Design Idea allows gain to be held despite a changing level.   AGC (automatic gain control) amplifiers are frequently used devices.  Their gain is a function of the level of their input signal.  The main function of AGC amplifiers is compression of a signal, but sometimes the gain needs to be temporarily frozen.  This Design Idea provIdeas just this function.__ Circuit Design by Vladimir Rentyuk

Circuit Provides 70 DB Of AGC -  EDN-Design Ideas -- 02/02/12   A comparator autoranges to ensure that the automatic-gain-control section sees a signal between −60 and −25 dBm, keeping the FET in its linear region.  __ Circuit Design by Ben Segal, Telecommunications Technology, Sunnyvale, CA

Digital Automatic Gain Control ACG -  This project is a digital Automatic Gain Control   (AGC) system using a PIC16F876 MCU.  The ability to set the gain level in a circuit and have it control itself is a very useful function.  This circuit is a building block of another project I am working on.  A 30W power amp for either the PCS, iDEN or CDMA frequency bands.  I will settle on one of those frequencies sometime soon. __ Designed by steevn.geo @ yahoo.com

Eliminating Front-End Overload with RF AGC -  A Kenwood L-07TII I once owned had very high sensitivity on the bench. But with an outdoor antenna connected, it showed a fatal flaw: background noise on strong signals, and no hint of weak signals that other tuners received clearly. These symptoms suggested front-end overload. __ Designed by Brian Beezley K6STI

Full-Wave Active Rectifier Requires No Diodes -  A full-wave rectifier can be built without using any diodes.  It exploits the fact that the output voltage of certain single- supply op amps is effectively clamped to ground (0 V) when the input signal goes negative. __ Designed by Anthony H. Smith

Full-wave rectifier has programmable gain -  11/09/00 EDN-Design Ideas The traditional approach to the design of a full-wave rectifier(Figure 1) is to set the gains of IC1 and IC2 to 1 and use the.   PDF contains multiple circuits, scroll to find the one of interest__ Circuit Design by Chuck and Chris Wojslaw, Xicor Inc, Milpitas, CA

Gain-of-three Amplifier requires no external resistors -  17-Aug-06 EDN-Design Ideas One IC provIdeas wideband amplification and minimizes parts count__ Circuit Design by Marián Stofka, Slovak University of Technology, Bratislava, Slovakia

Gain-of-two instrumentation Amplifier uses no external resistors -  02/15/07  EDN-Design Ideas Two ICs deliver precision gain with no external components.  An instrumentation amplifier offers precise gain without feedback resistors, and, at any value of gain, it provIdeas high input impedances at its noninverting and inverting inputs.  In a typical IC instrumentation amplifier, a single resistor that connects across two gain-adjustment pins determines the circuit's overall gain.  Integrated versions of most instrumentation amplifiers allow the pins to remain open for unity gain but require finite-value gain-setting resistors for gains exceeding one.  __ Circuit Design by Marián Štofka, Slovak University of Technology, Bratislava, Slovakia

Gain-programmable offers performance & flexibility -  25-Nov-04 EDN-Design Ideas You can use a standard precision instrumentation amplifier, such as the INA118 or AD623, as a gain-programmable amplifier with high accuracy and wide gain range.  However, the gain range of such parts is fixed at certain values, limiting their flexibility.  To solve the problem, a usual way is to use a gain-adjustable circuit controlled by a microcomputer(Figure 1)__ Circuit Design by Luo Bencheng, Key Laboratory of Mental Health, Institute of Psychology, Chinese Academy of Sciences

High-frequency AGC has digital control -  05/21/98 Design Ideas(Multiple circuits listed, scroll to find this one)  Many systems, especially communications, require AGC that functions at 50 MHz.  Self-calibrating systems, such as automatic test equipment, need this high-frequency response but also require digital control of the AGC output voltage.  During the calibration cycle, the test equipment calculates the AGC output voltage necessary to achieve the accuracy requirements and then increments the AGC output voltage until the system is within specifications.  The AGC circuit in Figure 1 uses a DAC to accomplish the digital control, and because the DAC is the reference input of the AGC circuit, the DAC ultimately sets the AGC output voltage.__ Circuit Design by Ron Mancini, Harris Semiconductor, Melbourne, FL

High-Frequency VGA has Digital Control -  07/18/96  EDN-Design Ideas You can use variable-gain amplifiers (VGAs) in many types of systems, such as radio receivers, in which the input signal voltage depends on an uncontrolled variable, such as distance to the transmitter.  In this type of system, you can use a VGA to ensure that the input signal amplitude matches the input voltage range of key components, such as ADCs and DACs, thereby maximizing the converters' dynamic range.__ Circuit Design by Ron Mancini, Harris Semiconductor, Melbourne, FL

Improving Selectivity with IF AGC -  After installing narrower ceramic IF filters in my Sony ST-S555ES tuner, adjacent-channel selectivity was 32 dB at the standard 45 dBf test level. But it fell to just 22.5 dB at 75 dBf. The problem was evident for signals on the air as well as with instruments. __ Designed by Brian Beezley K6STI

Low-Noise AC Amplifier has digital control of gain & bandwidth -  02/05/04 EDN-Design Ideas In low-noise analog circuits, a high-gain amplifier serves at the input to increase the SNR.  The input signal level determines the input-stage gain; low-level signals require the highest gain.  It is also standard practice in low-__ Circuit Design by Philip Karantzalis, Linear Technology App Note, Milpitas, CA,

Provide 70 DB of ACG -  02/02/12  EDN-Design Ideas A comparator autoranges to ensure that the automatic-gain-control section sees a signal between −60 and −25 dBm, keeping the FET in its linear region.  The circuit diagrammed in the figure provIdeas a 70-dB automatic-gain-control range for input voltages of −60 to +10 dBm over a bandwidth of 55 Hz to 15 kHz.  The worst-case distortion is 3%, but distortion typically measures less than 1% in the 100-Hz to 10-kHz range.  __ Circuit Design by Ben Segal, Telecommunications Technology, Sunnyvale, CA

Sync Separator Includes AGC -  05/11/95 EDN-Design Ideas This sync separation circuit has a gain-control circuit that helps to stabilize the sync-separation function__ Circuit Design by Dana Romero, Salt Lake City, UT-- 05/11/95

Wideband AGC has 60-dB dynamic input rang -  10/10/96 EDN-Design Ideas  Automatic-gain-control(AGC] circuits serve in many applications to maintain signals at fixed levels.  However, in applications such as digital-receiver circuits and back-channel modems, the function of the AGC often aims more at increasing dynamic input range through the controlled application of both gain and attenuation.  In this type of application, the AGC is usually upstream of a high-speed ADC.  The__ Circuit Design by Carl Dickey, National Semiconductor, Comlinear Division


AutoGain (AGC) Circuits


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