Fixed current source providing steady bias current

摘要

The circuit uses a current mirror to achieve current stability. The circuit comprises a bias current source (Vbe/R) comprises a first reference branch and a second output branch. It includes a transistor circuit (12) for correcting the output current (Iout) by use of an error current (Ierr) which is proportional to the current (Iref) which is flowing in the reference branch. The transistor circuit consists of a current mirror (T10, T11) which comprises a measuring transistor (T10) detecting the reference current (Iref) and a transistor (T11) generating the error current (Ierr). The error current (Ierr) is mixed with the collector current of a further output transistor (T2).