Master–slave JK from latches: build and simulate it online
Two D latches on opposite clock phases make an edge-triggered flip-flop; D = J·Q̄ + K̄·Q makes it a JK.
Build the master–slave jk from latches in the free online simulator — it checks your circuit automatically.
What you need
- 3 logic switches labelled J, K, CLK
- 1 probes labelled Q
- 2 D latches
- a NOT gate
- 2 AND gates
- 1 OR gate
Step by step
- Inputs and outputs. From the Logic section of the library, drop digital inputs (0/1 boxes) or logic switches for the inputs, and digital outputs or probes for the outputs; give each its label in the inspector (the checker finds them by label). Switches J, K, CLK; Probe Q
- Master and slave. The master latch is open while CLK is LOW (EN = NOT CLK); the slave while CLK is HIGH. Master Q → slave D. 2 D latches, 1 NOT for the clock
- The JK logic. The master’s D = J·Q̄ + K̄·Q, from the slave’s Q. 2 AND, 1 OR, NOT for K and for Q
- Prove it. Set, hold, reset, toggle, toggle.
Expected sequence
| # | inputs | clock | Q |
|---|---|---|---|
| 1 | J=1 K=0 | ↑ | 1 |
| 2 | J=0 K=0 | ↑ | 1 |
| 3 | J=0 K=1 | ↑ | 0 |
| 4 | J=1 K=1 | ↑ | 1 |
| 5 | J=1 K=1 | ↑ | 0 |
Frequently asked questions
How do you build a master–slave jk from latches?
Two D latches on opposite clock phases make an edge-triggered flip-flop; D = J·Q̄ + K̄·Q makes it a JK. In short: inputs and outputs, then master and slave, then the jk logic, then prove it.
How does a master–slave jk from latches behave clock by clock?
It is checked over 5 steps: J=1 K=0, J=0 K=0, J=0 K=1, J=1 K=1, …. The table on this page shows the expected Q after each clock.
What parts do you need for a master–slave jk from latches?
2 D latches; a NOT gate; 2 AND gates; 1 OR gate — plus logic switches for the inputs and probes for the outputs.
Can I simulate a master–slave jk from latches online for free?
Yes. Open it in the BitForBytes Embedded Lab, a free browser-based circuit and logic simulator: drag in the gates, wire them, and press "Check my circuit" — every clock cycle is simulated and marked for you. No download or sign-up needed.
Part of DSD 31 · Master–slave flip-flops in the free BitForBytes digital system design course.