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Questions tagged [automatic-gain-control]

For questions about automatic gain control (AGC) circuits.

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Amplifier limiter using LM13700

Does someone has the knowledge of a schematic for a audio limiter circuit using LM13700? I found one on the internet, but it has the limitation that is not adequate for audio signals with a lot of low ...
Thomaz Lopes's user avatar
1 vote
1 answer
90 views

Automatic attenuation of audio signal to fixed amplitude

I have an audio amplifier and one of those cheap Chinese Bluetooth audio receivers. The output of the receiver is way above audio line level, about 7V peak to peak. When using that as input for the ...
lulle2007200's user avatar
2 votes
2 answers
122 views

Converting AGC Schematic from Single Sided to Dual Sided Supply

I am working with the attached circuit, sourced from here: Original This circuit is designed for a single sided power supply and has worked very well for me in the past. For a new project, I would ...
Telluride's user avatar
2 votes
2 answers
148 views

RC oscillator loop stability with AGC

I am trying to design a sine wave oscillator. The frequency is about 10 kHz (not critical), the distortion should be reasonable but not necessarily super good (say under 1%). However, the amplitude ...
Hyp's user avatar
  • 877
0 votes
2 answers
195 views

Design an AGC circuit for microphone using JFET

At the beginning of the circuit, I designed a 20Hz to 20kHz second-order Butterworth bandpass filter circuit, and then I tried to pass the filtered signal through an AGC circuit to achieve a smooth ...
Jeremy Wang's user avatar
2 votes
1 answer
179 views

Design of a band-pass filter with automatic gain control using a JFET

I have implemented this circuit which is supposed to do AGC and filter out the signal between 20 Hz-20 kHz, but it seems have some problems. The bandpass filter works well, but the agc circuit doesn't ...
Jeremy Wang's user avatar
0 votes
2 answers
188 views

What resistor value could I use to replace this S-Meter?

I'm designing a 40m radio. The schematic I'm using as reference uses a galvanometer ("S") for measuring the signal level. I'm trying to replace it with a sense resistor and an LM358 to read ...
Arheisel's user avatar
1 vote
0 answers
170 views

AGC circuit for a spectrum analyzer - seeking recomendations

I want to build a spectrum analyzer for my car stereo. 5 bands, left & right channels represented individually, 20 LEDS per band using cascading LM3915s per band and channel. (Yes, 20 LM3915s, 200 ...
Super-Dave's user avatar
1 vote
1 answer
324 views

How does AGC work in this circuit?

I've got this audio amplifier board, which contains exactly the following circuit: I'm trying to understand this circuit, and the "AGC Control" part (highlighted in blue) has me the most ...
Christopher H.'s user avatar
0 votes
0 answers
94 views

Why is my voltage pulsing when using a DAC as an input to an OTA?

I'm using the LM13700 in an automatic gain control configuration to adjust the volume of a speaker based on the audio level perceived by the microphone. Both amplifiers on the chip are used: one to ...
meekeech's user avatar
0 votes
3 answers
123 views

Automatic Gain Compensation of Difference Amplifier [closed]

I want to know about the possible solutions to achieve precise automatic gain correction of the difference amplifier ? Description: I am using a differential amplifier and all resistors have 1% ...
Khalil's user avatar
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0 answers
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Questions to a VGA

I found this VGA from texas instruments. On page 34 you can see a AGC (automatic gain control) loop, does this set the output voltage (Vout) to the Vref voltage? The VCA821 needs a bipolar supply ...
electrococuk's user avatar
0 votes
2 answers
397 views

How can Gilbert Cell circuit provide linear gain variation even though ID-gm relationship is nonlinear?

How can Gilbert Cell circuit provide linear gain variation even though ID-gm relationship is nonlinear? As I undertstand it, the vcontrol (the voltage at the gate of M5 and M6) changes the biasing ...
Codelearner777's user avatar
0 votes
0 answers
35 views

AGC (automatic gain control) circuit for brushless phase measurement?

Intro: I am projecting a Brushless motor driver which relevant specs here are basically: use with 6v to 60v. To make it work the circuit's microcontroller needs to analyze the signal that comes from ...
Emanuel M's user avatar
  • 178
2 votes
2 answers
584 views

Automatic gain controller gain action

Can you guys explain to me how the turning on of Q2 and the charging of C2 increases the vgs of the FET? An equation would be helpful.
Paumdrdo's user avatar
3 votes
3 answers
3k views

Design of an Automatic Gain Control Using a JFET

simulate this circuit – Schematic created using CircuitLab I have implemented the above circuit which is supposed to amplify a negative 200kHz sinusoid to constant amplitude even if the ...
Simon Sultana's user avatar
0 votes
0 answers
99 views

Calculating the gain of a transistor in VGA

This paper is from IEEE: The gain of the first VGA is expressed as \$ A_1 = \frac{gm_1 R_1}{1+gm_1 R_2+\frac{R_2}{ro_1}} \$ However, I thought that since the (DC) current source at the source of ...
Alper91's user avatar
  • 1,293
-1 votes
1 answer
175 views

AGC (Automatic Gain Controller) for DTMF (Dual Tone Multiple Frequency) [closed]

I would like to know if there exist any IC or circuit that can provide AGC ('Automatic Gain Control') functionality for DTMF (Dual Tone Multiple Frequency) input signal. We need AGC specifically for ...
Aravind D. Chakravarti's user avatar
1 vote
1 answer
510 views

Audio volume levelling / AGC for spectrum analyser

I'm busy building a preamp, and want to include an LED-matrix spectrum analyser on the front panel (for aesthetics, not accuracy!) I've set up a circuit that uses a couple of MSGEQ7 chips to analyse ...
abza's user avatar
  • 664