Inside ECL gates Which of the following circuit features is not part of emitter-coupled logic (ECL) gate design?

Introduction / Context:Emitter-coupled logic (ECL) is a very high-speed bipolar logic family that avoids transistor saturation by using differential pairs biased with constant current. Its internal building blocks are characteristic and differ from TTL structures such as totem-pole outputs.

Given Data / Assumptions:

• ECL uses differential pairs, reference biasing, and emitter followers for buffering and level shifting.
• Totem-pole outputs are typical of TTL, not ECL.

Concept / Approach:

ECL logic levels are produced by steering current in a differential amplifier stage. Outputs are typically buffered by emitter followers to provide low output impedance and fast edges. A bias network establishes reference voltages. There is no need for the saturated pull-up/pull-down arrangement (totem-pole) used in TTL.

Step-by-Step Solution:

Verification / Alternative check:

Standard ECL schematics confirm differential pairs and emitter followers; TTL diagrams show totem-pole NPN stages—clearly different approaches.

Why Other Options Are Wrong:

• Differential amplifier, bias circuit, emitter follower are hallmark ECL elements that enable its speed.

Common Pitfalls:

• Assuming all high-speed logic uses totem-pole outputs; ECL does not.

Final Answer:

Totem-pole circuit