Differential Input - Current Dumping
This may be the one that I will build someday.
25 times voltage gain. On par with other amps.
Differential input, no DC offset issue.
Adjustable bias (through R17).
THD@10KHz, -90dB with 0 bias; <-100dB with some bias.
CFP in input stage removes the effects of re. Thus, the Gm of the input stage totally depends on the degeneration resistor. 10Ohm in my case. You need this accurate Gm to calculate the "Nulling Bridge".
This may be the one that I will build someday.
25 times voltage gain. On par with other amps.
Differential input, no DC offset issue.
Adjustable bias (through R17).
THD@10KHz, -90dB with 0 bias; <-100dB with some bias.
CFP in input stage removes the effects of re. Thus, the Gm of the input stage totally depends on the degeneration resistor. 10Ohm in my case. You need this accurate Gm to calculate the "Nulling Bridge".
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Joined 2009
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These circuits usually send me to re-read the feed forward article that first revealed the operation of the quad design.
Nice combination of AC and DC feedback to kill that DC offset.
But some will balk at the large electrolytic.
Jan
Ohh yes, there are many solutions. But some will not like an electrolytic in the signal chain no matter how well regarded.
Jan
Jan
... 5 capacitors at about $ 10 each. Ouch! Although it will come with a bragging factor, it's not for me.
Jan
Jan
Even with traditional feedback network with 1K and 24K, the cap that connects to the ground has to be at least 47uf to 100uf range.
PS: I use 2Hz to calculate the -3dB for feedback network, instead of 20Hz, considering there will be multiple high pass networks in your system. The feedback network just one of them.
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