| 摘要 |
An output buffer provides for additional current sinking or sourcing capability by switching in an additional transistor (M6) when the output voltage (VOUT) passes a given level. This allows the output buffer to supply DC current to a load without requiring an excessively large AC drive capability, which could undesirably increase switching noise. In a typical embodiment, an inverter (104) senses when the buffer output voltage reaches its switching threshold (approximately VDD/2), and turns on the additional transistor (M6) after a given delay. For example, a CMOS output buffer driving a TTL load may obtain additional current sinking capability by this technique. On-chip buffers (e.g., bus drivers and clock drivers) can also benefit from this technique. <IMAGE>
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