| 摘要 |
<p>A current source arrangement comprises a first and a second transistor (T1, T2) arranged in cascode between an output terminal (2) and the negative power-supply terminal (3). The arrangement further comprises a current mirror circuit, a current source (I1) connected to the positive power-supply terminal (5) being connected to an input current path which comprises a third transistor (T4) connected as a diode, a fourth transistor (Ts) connected as a diode, and the collector-emitter path of a fifth transistor (T6), which input current path is coupled to a second current path comprising a sixth transistor (T7) whose base is connected to the base of the third transistor (T4), a resistor (R1), and a seventh transistor (T8) connected as a diode, whose base is connected to the base of the fifth (T6) and the second transistor (T21. Further, the base of the first transistor (T1) is connected to the emitter of the sixth transistor (T7). In this arrangement the collector-emitter voltage of the second transistor (T2) is equal to the collector-emitter voltage of the fifth transistor (T6), which is equal to the voltage across the resistor (R,). If the voltage across this resistor (R1) is substantially lower than one base-emitter voltage a comparatively low voltage is obtained on the collector of the first transistor (T,). Moreover, the ratio between the currents through the second and the fifth transistor (T2, Te) is defined accurately by the ratio between the emitter areas of these transistors.</p> |
