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Speed Up of TTL Circuits

IP.com Disclosure Number: IPCOM000075708D
Original Publication Date: 1971-Nov-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 25K

Publishing Venue

IBM

Related People

Gersbach, JE: AUTHOR

Abstract

The use of a transistor Q6 in place of a resistor connecting the base of transistor Q4 to ground increases the operating speed of this TTL circuit and reduces the power consumption of the circuit.

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Speed Up of TTL Circuits

The use of a transistor Q6 in place of a resistor connecting the base of transistor Q4 to ground increases the operating speed of this TTL circuit and reduces the power consumption of the circuit.

With a down signal at any of the emitters of the transistor Q1, the signal at the collector of transistor Q1 biases off transistors Q2 and Q6. With transistor Q2 biased off, transistors Q3 and Q4 are biased on by current supplied to the base of transistor Q3 through resistor R3. Thus current can flow from the +V terminal through transistor Q4 to charge the load C under these conditions. With an up signal at all the emitters of transistor Q1, the potential at the collector of transistor Q1 biases transistors Q2 and Q6 on. This supplies current to transistor Q5 which turns transistor Q5 on. Simultaneously, the potential at the bases of Q3 and Q4 are reduced to turn transistors Q3 and Q4 off.

The elimination of the resistor tying the base of transistor Q4 to ground reduces the amount of power consumed by the circuit. Furthermore, because there are two transistors Q2 and Q6 driving into the base of transistor Q5, transistor Q5 is turned on faster than was previously possible where a single transistor Q2 was employed.

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