A novel prescaler for silicon bipolar multi-Gigahertz applications

High-speed prescalers are critical blocks when designing circuits for multi-GHz applications as well as for new optical-fiber networks. In this paper, an enhancement technique is shown for Si-bipolar E²CL dividers. The proposed circuit allows high-speed operation despite a low supply voltage while it avoids using emitter followers which could lead to dangerous unwanted oscillations. A divide-by-8 prescaler was fabricated in a 46-GHz-f_T Si-bipolar technology to work within a 10-GHz output frequency PLL. Measurements show the circuit works reliably up to 12 GHz and can still operate at 11 GHz with a supply voltage as low as 2.7 V.