Class AB Amplifier

I haven't designed an amp in a while. Thought I'd brush up on my skills. Some of the specs: - Input Sensitivity - 1,06Vrms - Input Impedance - ~10kOhm - Gain - 15.5 (23.7dB) - Output Impedance - 4/8ohm - Output Power - 66Wrms - Drawn Power - 111Wavg - Efficiency - 60% - Class A region - 3W - Frequency Response - <1Hz - 45kHz at -3dB - THD+N - 0.05% - Slew rate - around 1.5V/uS - Ripple Rejection - -50dB Some tips and remarks: - If you want to have the LED's constant and not blinking at bass frequencies i suggest you AC shunt them with a large cap (1mF) - Usually the 2x 150kOhm resistors should be somewhat lower, for instance 33-100kohm but EC doesn't always cope with these resistors being too low of a value. Anyway 150k also works great. - I've chosen a bootstrap topology for the output stage because EC is quite temperamental with constant current sources and it takes forever to get it working. Anyway it's a choice of preference whether to use CCS or Bootatrap i usual prefer CCS - Keep the 10k resistor at the input. Since this amplifier requires 1.5V for full output you'll need a preamp. I suggest you match the Impedance to 10k, rather than removing the resistor. It improves the ripple rejection from -20dB to -50dB which is a major improvement. - For the supply filtering I suggest no less 4.7mF, the best is 10mF. I keep a rule of thumb for every 1A 1.5mF. This doesn't always apply but for power amps it works.

published 10 years ago