An original buffer circuit for medium and high-power applications

We present the dc characteristics of a an output stage and buffer circuit for medium to high-power applications that provides near optimal performance over a wide range of power levels and frequencies, while avoiding the use of output feedback resistors and/or thermistors for thermal compensation. The circuit uses a complementary emitter follower that operates in class-AB mode, with identical matched devices used in the bias and output stages. It provides an excellent impedance conversion between the input and output stages. For instance the load decoupling is greater than 45 dB for a circuit that uses the Tip29,30 standard complementary transistor pair. Also, the power transmission efficiency between the source and the load is maximized without the usual losses and/or distortions.