On the leverage of high f/sub T/ transistors for advanced high-speed bipolar circuits

The authors present a detailed study on the leverage of high-f/sub T/ transistors for advanced high-speed bipolar circuit applications. It is shown that, for the standard ECL (emitter coupled logic) circuit, the leverage of high f/sub T/ is limited by the passive resistors (emitter-follower resistor and collector load resistor) and wire delay, especially in the low-power regime. For the standard NTL circuit, the leverage is higher due to its front-end configuration and lower power supply value. As the passive resistors are decoupled from the delay path in various advanced circuits utilizing active-pull-down schemes, the leverage of high f/sub T/ becomes more significant.<
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