| 摘要 |
An amplifier has a complementary differential input stage (S1 to S3), two stages (S4, S5) of voltage amplification, and two stages (S6, S7) of current amplification. Compared with a conventional amplifier, additional diodes are included so that any path (e.g. S1 to S7) between the supply rails (V+, V-) can be divided in four quarters (P1 to P4) each containing the same number of diodes, base-emitter junctions or the like, and each containing the same number of resistors, collector-emitter junctions or the like. The long-tail nodes (LT1, LT2) of the input stage are tied together by a pair of diodes (D5a, D5b) or the like. Additional connections (C3 to C10) are made between the input stage and the voltage amplification stages. To counteract the imbalance caused by these connections, compensating diodes (D37a to D38b) are included between the loads and complementary long-tails in the input stage. The transistors in the voltage and current amplification stages are arranged as modified forms of Darlington pair (e.g. T9, T11; T13, T15) and as modified forms of Sziklai pair (e.g. T11, T13). A feedback circuit (R33, R34) is arranged to place as great a load on the amplifier as the output load (R35, R36). Other modifications may be made to the loads and the long-tails of the input stage, and to the input biassing. |
