| 摘要 |
A transconductance amplifier having a variable transconductance is provided, said amplifier comprising a differential stage (T1, T2) having a first differential output coupled to an output terminal (3) <u>via</u> a first current mirror (T5, T6, T61..T6N) and a second differential output coupled to said output terminal (3) <u>via</u> a second (T7, T8) and third current mirror (T9, T10, T101..T10N) said first (T5, T6, T61..T6N) and a third (T9, T10, T101..T10N) current mirrors having multiple output branches for selectively supplying output currents to the output terminal (3) in response to a binary transconductance control signal. In this way a digital control of the variable transconductance is realised, which can be used advantageously in a variable gain stage and in an automatic gain control comprising such a variable gain stage. |
