| 摘要 |
A class AB output stage includes an amplifying stage adapted to produce first (9) and second (10) output signals which incrementally increase and decrease in response to an incremental increase and decrease, respectively, of a first input signal (Iin1) and/or a second input signal (Iin2) A gate of a pull-up transistor (14) is coupled to receive the second signal (10), and a gate of a pull-down transistor (12) is coupled to receive the first signal (9). A first feedback circuit includes a first current sensing transistor (11) having a gate and source connected to the gate and source, respectively, of the pull-down transistor (12) and a drain coupled to a first control input (7) of the amplifying stage and operative to increase the gate voltage of the first current sensing transistor (11) only until its drain current increases to a first predetermined value representative of a minimum desired quiescent current in the pull-down transistor (12). A similar second feedback circuit operates to decrease the gate voltage of the second current sensing transistor (13) only until its drain current increases to a second predetermined value representative of a minimum desired quiescent current in the pull-up transistor.
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