| 摘要 |
<p>A low level, low power, direct coupled integrated class B amplifier having a dual channel three stage preamplifier and a pair of output transistors, one for each channel. In each channel, a DC negative feedback loop connects the collector of the last stage preamplifier transistor to the base of the first stage preamplifier transistor to regulate the DC levels, and a resistive AC negative feedback loop connects the output transistor collector to the first preamplifier transisitor collector to reduce the gain dependence of the channel on the current through the output transistor, thus enabling very low idle currents for the output transistors and also providing low distortion output. The resistor in each AC feedback loop is a floating tub resistor to enable it to be taken more than .6 volts above the battery voltage. Common mode rejection is provided for at least two of the three preamplifier transistors of each channel.</p> |
