Two gates and a microprocessor form digital PLL

摘要

You CAN USE Microchip's low-cost PIC16F818 microprocessor and a pair of gates to construct a digital PLL that can clean noisy digital signals over a range of 4 to 40 kHz. Featuring programmable lock range, phase differential, and loop gain, the digital-PLL engine and lock detector can extract clock and data information from noisy, short-range radio signals (Figure 1). When you construct it using a QFN-packaged microprocessor and discrete single-gate logic devices, the circuit occupies a pc-board area that's approximately as large as an aspirin.