Introduction / Context:
Counter identification questions test your understanding of how flip-flops are interconnected. Without the original figure, we apply the Recovery-First Policy and infer the most common textbook arrangement: a minimal ripple (asynchronous) counter using two cascaded flip-flops where the output of one stage clocks the next.
Given Data / Assumptions:
- First flip-flop is clocked by an external clock.
- Second flip-flop is clocked by the output (usually Q) of the first stage.
- No additional gating suggests synchronous decoding is absent.
- Only two stages are implied, producing 2 bits of count (00 to 11).
Concept / Approach:
In an asynchronous (ripple) counter, not all flip-flops share the same clock; instead, each subsequent stage is triggered by the previous stage's transition. With two flip-flops, the modulus is 2^2 = 4, representing a two-bit counter. Synchronous counters require a common clock and added gating logic to drive each T or J-K input simultaneously.
Step-by-Step Solution:
Recognize ripple connection: clock of stage 2 is driven by the output of stage 1.Count width: two flip-flops → 2 bits → modulus 4.Absence of shared clock/gating → asynchronous, not synchronous.Therefore, the most reasonable identification is a two-bit asynchronous binary counter.
Verification / Alternative check:
List the expected output sequence: Q1 (LSB) toggles every clock; Q2 toggles on Q1 transitions → sequence 00, 01, 10, 11, then repeat.
Why Other Options Are Wrong:
three-bit synchronous binary counter: Requires three stages and a common clock with gating.eight-bit asynchronous binary flip-flop: Size and terminology are incorrect (it would be an eight-bit counter, not a “flip-flop”).four-bit asynchronous binary counter: Would need four stages, not two.
Common Pitfalls:
Confusing ripple (clock-by-output) with synchronous (common clock).Assuming more bits than actually present in the schematic.
Final Answer:
two-bit asynchronous binary counter
Discussion & Comments