A 15-GHz monolithic two-modulus prescaler

A high-speed two-modulus prescaler for divide-by-4/5 select was successfully realized adopting a new circuit design that reduces the effective fan-out of each D-flip-flop (D-FF) to one. To assure stable and high-speed operation, a low-voltage signal amplitude of 250 mV in the D-FF was adopted for both true-and-complementary and single-phase signals. Using a 70-GHz-f_T GaAs/AlGaAs HBT technology, the D-FF operated stably up to 18.6 Gb/s at designed bias voltages of 9 V with power dissipation of 0.55 W, and the prescaler operated up to 15.5 GHz with power dissipation of 1.5 W