JPS5737913A - Electric power amplifying circuit - Google Patents

Abstract

PURPOSE:To eliminate the necessity to put a nonlinear element into a signal route, by connecting transistors in parallel to the transistors of the driver stage and then supplying a certain level of voltage to the bases of these transistors connected in parallel. CONSTITUTION:Transistors (TR)21 and 22 are provided in parallel to TRs1 and 3, respectively. When the positive input signal is applied via constant current sources 8 and 9, the potential at a point D of connection increases. As a result, the TRs 2 and 4 are turned on to extract the output current to a load 14. When this output current increases, the both-end voltage of a resistor 17 increases. But the TR21 is turned off since the potential of a constant voltage source 15 is constant. At the same time, the TR22 is turned on since the potential of a constant voltage source 16 is constnt. Thus a TR5 is never cut off. On the other hand, adverse action to the application of a positive input signal is carried out with application of the negative input signal. Thus the TRs3 and 5 are turned on with the TR22 turned off, respectively, and at the same time, the TR21 is turned on to avoid the cutoff of the TR4. In such way, the noncutoff action can be attained for the TR of the output stage.