Schottky Ttl 1970s Redesign Input Structures for Schottky Ttl

# Schottky TTL (early 1970s): Step 11 — Redesign Input Structures for Schottky TTL

Redesign Input Structures for Schottky TTL. Schottky TTL's input stage builds on standard TTL's multi-emitter input transistor (the structure that implements the AND function ahead of the phase splitter) but adds two refinements.

## 1. Input Clamp Diodes and the Multi-Emitter Transistor
Schottky TTL's input stage builds on standard TTL's multi-emitter input transistor (the structure that implements the AND function ahead of the phase splitter) but adds two refinements. First, Schottky input-clamp diodes are placed from each input pin to ground, oriented to clamp negative input excursions (commonly caused by transmission-line ringing on a fast-switching bus) at a shallow negative voltage, protecting the input transistor's emitter-base junction from reverse breakdown and suppressing input-induced ringing before it propagates into the gate. Second, because the multi-emitter input transistor's own base-collector junction is subject to the same saturation/storage-time concern as the output-stage transistors, it typically receives the same Schottky base-collector clamp used elsewhere in the gate, so the speed improvement is not undone by a slow input stage feeding a fast output stage.

## 2. Real Diagram: Schottky TTL Input Stage Schematic

Schottky TTL Input Stage: Multi-Emitter Transistor and Clamp Diodes input clamp diodes at each pin, B-C clamp on the input transistor itself multi-emitter input transistor input A input clamp input B B-C clamp input-side clamps protect against ringing; the B-C clamp keeps the input stage itself fast

## 3. Why the Input Side Could Not Be an Afterthought
Early Schottky TTL designs that clamped only the output stage found that the input stage's own switching speed became the new bottleneck, since removing a few nanoseconds of output-stage storage time has little practical value if the signal still takes the same few nanoseconds to propagate through an unclamped input transistor first. This end-to-end discipline — clamp every node in the signal path that would otherwise saturate, not just the most visible one — recurs throughout Schottky TTL's internal design and is part of why the family required a genuine process and circuit redesign rather than a single added component.

## 4. Companion Diagram: Stage Sequence and Trend Summary

Schottky TTL (early 1970s): Step 11 stage sequence and schematic outcome trend for this step Input Clamp Diodes an… 1 Schottky TTL Input St… 2 Why the Input Side Co… 3 Companion Diagram 4 sequence progression outcome trend (schematic) companion diagram: stage sequence and schematic trend for this step

## Redesign Input Structures for Schottky TTL's Place in the Process Lineage
This is step 11 of 20 in the Schottky TTL (early 1970s) series, extending the clamping discipline established for the output stage in Step 6 to the gate's input structure.

Take schottky ttl 1970s redesign input structures for schottky ttl further

Ask the copilot about this term, or have our engineers assess it against your process.

Ask CFSGPT about this → Request a technical assessment → Open the CFS app