References about Chopper Amplifier

[ambreesh]

If some one has designed a chopper amplifier, could you suggets a good reading on it.
And is a normal amplifier sandwiched between modulator and demodulator a chopper amplifier.

 

[nand_gates]

Re: Chopper Amplifier

HI,
Tonns of material is available on Chopper amplifiers search using Goole!!
Here is a link on one such search
https://www.national.com/onlineseminar/2004/chopperamps/chopper.html

 

[tia_design]

Re: Chopper Amplifier

In google, there are so many chopper staff. By the way, you chopping frequency should be high than corner frequency, and chopper amp generaly for low frequenct use.

 

[flatulent]

Re: Chopper Amplifier

In general you are using a double side band modulator to get your low frequency (or DC) input signal higher in frequency so it can be amplified as an AC signal. This way you are out of the 1/f noise region of the amplifier and the DC offset and drift of the amplifier does not come into play. At the output of the amplifier you synchronously demodulate the signal to get back to the lower frequency. In the era of valves/tubes this DC drift was very large.

Since this is a modulation process, you need the chopping frequency to be much higher than the input signal so that it does not fold over at DC and also so the harmonics can be filtered out. Since most choppers modulate a square wave carrier oscillator, there are harmonics of the square wave that are modulated.

2x is the minimum frequency (chopping/input) ratio to prevent spectrum overlap and you should be 3x to allow filtering the higher spectrums out.

In the old days the choppers were mechanical relays that vibrated. These had very little DC offset (in the microvolt range.) If you use semiconductor choppers, there will be more.

 

[tia_design]

Re: Chopper Amplifier

here is one paper

 

[tia_design]

Re: Chopper Amplifier

This is a very good paper on chopper