A digitally temperature compensated compact PLL module

This paper describes our new compact Phase-Locked Loop (PLL) module with high free-running frequency accuracy over a wide temperature range. In order to improve the temperature characteristics of the conventional PLL circuit, a digital temperature compensation circuit has been newly added to it. In addition, this compensation circuit has been installed in our new custom PLL-LSI, as contributes to the down-sizing of the module. Important features for the PLL module with the LSI and a 16.384 MHz fundamental AT-cut crystal unit are high free-running frequency accuracy (with changing temperature: ±0.5 ppm from -40°C to +85°C, and with changing supply voltage: ±0.2 ppm at +3.3 V± 5%), small size (20 mm×20 mm×8.5 mm), low power consumption (43 mW), and low supply voltage operation (+3.3 V). This module generates a 2.048 MHz clock synchronized to an input clock frequency of 8 kHz