MAXIMUM OPERATING FREQUENCY IN SI BIPOLAR MASTER-SLAVE TOGGLE FLIP-FLOP CIRCUIT

This paper presents a propagation-delay equation which is expressed as the influence of the individual device and circuit parameters on the maximum operating frequency of Si bipolar master-slave toggle flip-flop (MS-TFF) circuit with double feedback emitter followers. This equation shows that optimizing the size of individual transistors can enhance the operating speed. Test results show a 10% increase in operating frequency by adopting this design technique. It is also shown that the time constants R(B)C(jC), R(B)C(D), tau(F), R(L)C(jC), and R(C)C(jC) of the upper-level current switch and tau(F) of the second feedback emitter follower greatly affect the operating speed of circuits using recently developed Si bipolar transistors. The results predicted by the equation are in good agreement with both the experimental ones and SPICE simulations.