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Help amplifier

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mohdi35

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hello

pls. tell me how i can wire an inverter (digital logic NOT gate) as an amplifier.
or any materials that'll explain how to do this.

Thanks
 
Two resistors and a Cmos inverter make an analog linear amplifier. its input impedance is low and its output impedance is high. Its voltage gain changes when its supply voltage changes. It has high distortion when the signal level is high.
 

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hello

pls. tell me how i can wire an inverter (digital logic NOT gate) as an amplifier.
or any materials that'll explain how to do this.

Thanks

I've seen it done years ago in a few circuits. It involved biasing the input pin with a DC voltage and AC coupling a signal input via a capacitor. Seemed to give 20-40db gain as I recall, but not very stable, pretty temp and circuit sensitive. Not a viable option over the zillion of great op amps available.

If you look at many of the crystal oscillator circuits that use a logic gate as a gain stage they essential do the same thing to get the circuit to start and oscillate, however it's certainly not linear once reaching full stable output.

Lefty
 
Two resistors and a Cmos inverter make an analog linear amplifier. its input impedance is low and its output impedance is high. Its voltage gain changes when its supply voltage changes. It has high distortion when the signal level is high.

pls. how can i have a better explanation of this, especially if i wish to modify/change the gain of the amplifier
 
I've seen it done years ago in a few circuits. It involved biasing the input pin with a DC voltage and AC coupling a signal input via a capacitor. Seemed to give 20-40db gain as I recall, but not very stable, pretty temp and circuit sensitive. Not a viable option over the zillion of great op amps available.

If you look at many of the crystal oscillator circuits that use a logic gate as a gain stage they essential do the same thing to get the circuit to start and oscillate, however it's certainly not linear once reaching full stable output.

Lefty

thank you. but i need to know the maths behind using the NOT gate as an amplifier pls.
 
is there someplace like an application note where i can get the details?

As using a digital gate in a analog application is a unusual application, the original chip manufacture is not likely to have any application notes or specifications to help with your request. This kind of circuit is the result of experimentation by hobbyist or students and you are really on your own in trying to get the specific information you are requesting. Your best bet would be to build the unit and then using measurement and component value substitution, trying to find the formulas you are seeking.

Good luck

Lefty
 
As using a digital gate in a analog application is a unusual application, the original chip manufacture is not likely to have any application notes or specifications to help with your request. This kind of circuit is the result of experimentation by hobbyist or students and you are really on your own in trying to get the specific information you are requesting. Your best bet would be to build the unit and then using measurement and component value substitution, trying to find the formulas you are seeking.

Good luck

Lefty

Thanks Leftyretro:)
 
I got the circuit from an RCA applications note. It was long before computers and RCA don't make Cmos inverters anymore.
The gain is determined by the supply voltage and the ratio of the feedback to the input resistor values.
Try it.
 
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