| 摘要 |
A full-wave rectifier circuit (500) includes a cross-coupled differential pair circuit (501) coupled to a bias circuit (510). At least one constant current source (512, 514) couples to the base of each transistor (506, 508) in the cross-coupled pair circuit (501). A differential pair of transistors (502, 504) drive the cross-coupled pair circuit (501). Cross-coupled devices (506, 508) are used as positive feedback to increase gain for small amplitude signals and to degenerate the devices (502, 504) of the full-wave rectifier. Using this design very precise rectification can be achieved even for thetai<VT. Specifically, the bias circuit (510) includes a current source which supplies alpha multiplied by the current supplied by the current source (512, 514) connected to the base of the transistors (506, 508) in the cross-coupled pair circuit (501). By choosing an appropriate value of alpha, a unity magnitude slope close to the origin is achieved.
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