A 23.6 GHz sub-half-micrometer E/D MODFET divide-by-32/64 static prescaler

An application-ready prescaler with performance competitive with state-of-the-art R&D dividers was designed to be a high-performance replacement for standard ECL parts in instruments. It is fabricated in a proven self-aligned contact sub-half-micrometer GaAs-based enhancement/depletion-mode (E/D-mode) MODFET IC process that utilizes sidewall-spacer self-alignment technology to obtain 0.3-0.5 μm gate length with conventional high-throughput contact lithography. With pseudomorphic InGaAs channels, 30 MHz to 23.6 GHz prescaler operation is demonstrated at room temperature. The performance improves at 0°C, while at 70°C the upper frequency typically drops by 2 GHz. Correct high-speed pulse-mode operation requires (1) presetting which does not degrade the performance and (2) suppression of self-oscillation during quiet periods between pulse bursts. The circuit design provides for both, and pulse-mode operation without ringing, or pulse loss, at 22.4 GHz (present testing limit) has been confirmed