| 摘要 |
<p>1,170,524. Transistor amplifiers. H. H. SCOTT Inc. 14 June, 1967, No. 27398/67. Heading H3T. In a transistor amplifier having a base bias signal input circuit comprising a variable resistance device S with two parallel circuit legs connected to the end terminals of the device S to act as current return paths and a resistor R 2 connected between the movable terminal of the variable resistance device S and a current supply lead, one of the circuit legs includes a variable resistance unidirectional conducting device D which undergoes changes in conductance with temperature in substantially the same manner as the transistor and the resistance of the resistor R is very large compared with the resistance of the circuit between the resistor and the current return lead so that the current drawn by the two circuit legs is maintained substantially constant. The diode D can be of the same material as the transistor. The diode D is forward biased and by adjusting resistor 6 the bias is adjusted to ensure matching of the circuit to transistors of different properties and production tolerances. The circuit is shown using two PNP transistors 1, 1<SP>1</SP> having similar input circuits D, 6 and D<SP>1</SP>, 6<SP>1</SP> fed in push pull from a transformer T. In a single transistor amplifier 1 (Fig. 1, not shown), resistors R 1 and R 3 may be removed. In an alternative push pull arrangement (Fig. 2, not shown), using an NPN and PNP transistors operation in class A, B or beyond is possible.</p> |
