Open-Loop Multiphase Clock Generator for PVT-Stable Phase Control

The patent inverts the conventional approach by using an open-loop architecture instead of closed-loop PLL/DLL. The frequency synthesizer directly generates output clocks from reference clocks through parallel delay paths without feedback control, eliminating the complexity of phase detectors, charge pumps, and loop filters while maintaining frequency synthesis functionality through controlled delay elements.

The patent segments the frequency synthesis function into multiple parallel delay paths, each generating a specific phase-shifted clock signal. By dividing the output clock into multiple branches with controlled delay elements, the system achieves multiphase clock generation without requiring complex closed-loop control mechanisms, thereby reducing circuit complexity.

The patent uses copying by replicating delay path structures in parallel, where each path is designed to produce a specific phase shift. By copying the delay element designs and configuring them with controlled delay values, the system achieves accurate phase differences that are insensitive to PVT variations, as each copied path experiences similar environmental conditions.

The patent changes the delay parameter of each parallel path to achieve different phase shifts. By controlling the delay values (e.g., through transistor width ratios or capacitor sizes) in each path, the system precisely sets phase differences between output clocks while maintaining stability against PVT variations through open-loop design.

The patent introduces dynamic control capability by making delay elements adjustable through control signals. The delay amount in each parallel path can be dynamically changed by adjusting control voltages or currents, allowing precise phase difference control while maintaining the simplicity of open-loop architecture. This dynamic adjustment compensates for any manufacturing variations.

The patent replaces physical/mechanical phase control mechanisms (such as mechanical switches or variable capacitors) with electronic control methods using transistors and capacitors in integrated circuits. The delay elements are controlled through electrical parameters (transistor widths, capacitor sizes, control voltages), enabling precise phase control without mechanical complexity.