| 摘要 |
A plurality of bus-coupler circuits (14) are connected to a bus wire (10) at different points (12) along its length. Each bus-coupler circuit (14) includes a conventional bus driver (22) which may, for example, comprise a relatively large transistor, but also a bus precharge circuit (16). The bus precharge circuit (16) in each bus-coupler circuit responds to a control signal (20) to apply a small, precharge pulse to the bus wire (10). The control signal (20) is applied to each of the bus-coupler circuits (22) in synchronism with the data (38) in such a way that electrical precharge pulses are applied to the bus wire (10) substantially simultaneously by each bus coupler at approximately the instant of time of an expected data signal transition. In this way, the bus wire (10) receives a small electrical charge (24) at the various points along its length at which the bus coupler circuits are connected. The bus is thereby precharged in anticipation of a transition. The electrical charge is insufficient to substantially change the voltage level at any given local point on the bus; however, its total effect is to significantly reduce the rise time of a bus transition. The electrical charge is sufficient to precharge the capacitive load formed by the bus wire and the bus driver transistors in the immediate vicinity of the charging point. Since the electrical precharge is injected onto the bus by each bus precharge circuit at a number of points along its length, the entire bus wire receives a charge in anticipation of a data transition at any of the circuits (14) along the bus. Consequently, a single, large bus-driver transistor is not required to change the voltage level of the entire bus.
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