Phase synthesis using coupled PLLs

We present the detailed design and measurement results for a phase synthesizer using coupled Phase Locked Loops (PLLs) suitable for analog beam forming. It is shown that this architecture achieves a phase shift of ±180°, which is a significant improvement over conventional coupled-PLLs which are limited to ±90°. A two-PLL system has been implemented using off the shelf components. The system synchronizes at 25 MHz and generates a steady-state phase difference in the range ±180° using an adjustable DC control current.