Power Amplifier IC with unity voltage gain ..... ?

[muhammad-ahsan-khan]

Does someone know the part number of Power Amplifier IC with unity voltage gain ..... ?

 

[Audioguru]

Nobody wants a power amplifier that has unity gain. Then when it is fed directly from an MP3 player its output would be very low.

For example, 100W into 8 ohms is a sine wave of 28.3V RMS. The output from an MP3 player is 0.2V RMS. This amplifier needs to have a gain of at least 141 times.

Most amplifier circuits oscillate at a very high frequency if their gain is reduced to 10 times to 20 times by adding more negative feedback.

 

[FvM]

Of course, there may be reasons to operate a power amplifier chip or hybrid module at unity gain. As the compensation is usually for a gain of 10 or 20 minimum, you have to lower the loop gain artificially for high frequency to achieve stability. Also the input voltage range must be considered. An inverting amplifier configuration with a RC tap to reduce the loop gain is the easiest way. Also simply dividing and reamplifying the input works, of course.

 

[Audioguru]

True,
You want a 20mW power (?) amplifier to have unity gain, then an input of only 0.16V RMS will drive it to full output.

 

[Kral]

muhammad-ahsan-khan,
Apex microtechnology offers several Power Op Amps that are internally compensated for unity gain stability. For example, the PA75. Visit Apex at **broken link removed**
Regards,
Kral

 

[kwkam]

Power amplifier with unity gain stable is use to drive some low impedance load. For example, motor

 

[Audioguru]

A linear power amplifier would waste a lot of power and the motor would not have any torque if the amplifier reduces the supply voltage to the motor.

Pulse-Width-Modulation is usually used to efficiently and powerfully vary the speed of a motor.

 

[chennakeshav]

I required a power amplifier(can be a IC, FET/BJT citcuitry) with unity voltage gain to work with 5 ohm load, without voltage drop. Any body have suggestions.

 

[Audioguru]

Most power amp circuits have enough gain to deliver full output when the input signal is only line level of about 0.4V p-p.

You don't say how much power you need.

Use an attenuator made with two resistors at the input of any power amp to reduce its gain to unity.