Injection locked frequency divider

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In electronics, an injection locked frequency divider (ILPD) is a technique that allows for precise frequency monitoring and modulation. It was invented as an improvement over the Phase-locked loop (PLL) technique due to its greatly reduced power consumption.

This technique was perfected in early 2006 by Hui Wu and will likely be included in upcoming wireless communications devices such as cell phones and wifi enabled devices.

Details

A highly accurate reference clock (such as a crystal oscillator) is hooked up to a PLL to multiply the frequency to a suitably high range. Rather than the standard PLL procedure of sampling the frequency with every oscillation, the ILPD then splits the signal. One output connects to a frequency divider which brings the signal back to the original clock frequency where the rest of the standard PLL maintains the original frequency based on the reference clock. The other part of the signal goes to a separate frequency divider which is tuned to the selected frequency to be used in the final outgoing signal. Due to the clock sampling being done at frequencies hundreds to millions of times less frequently then in a standard PLL system, significant power savings are achieved.

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