| 摘要 |
<p>1,191,250. Amplifier. COMMISSARIAT A L'ENERGIE ATOMIQUE. 6 Dec., 1968 [7 Dec., 1967], No. 58100/68. Heading H3T. An amplifier has the first stage, for example, T 2 , T 3 , coupled to the second stage, comprising complementary transistors T 4 , T 5 in series by means of an intermediate circuit including a constant current transistor T 1 , complementary transistors T 6 , T 7 identical with T 4 , T 5 and each having its base and collector connected, the transistors T 6 , T 7 being connected to T 4 , T 5 bases and to a pair of voltage-defining devices, such as diodes D 3 , D 4 . The first stage, as described, is a differential amplifier. The load Z is connected to the common emitters of T 4 , T 5 , and the amplifier input is applied to T 2 , the bases of T 1 and T 3 being held at reference levels. Further transistors T 8 , T 9 may be connected in series with T 4 , T 5 respectively. The diode-connected transistors T 6 , T 7 maintain under all conditions, including variable temperature, a voltage between the bases of output transistors T 4 , T 5 which balances the sum of the emitter base voltages of the transistors T 4 , T 5 . In this way thermal runaway is prevented. Moreover, power dissipation in the output stage is largely concentrated in T 8 , T 9 whose base voltages are controlled respectively by diodes D 4 , D 3 and whose currents are effectively controlled by transistors T 4 , T 5 , so preventing thermal runaway conditions from developing in T 8 , T 9 . A resistor R enables the quiescent currents in T 6 , T 7 and T 4 , T 5 to be exactly balanced.</p> |
