Development of a Very Accurate and Electrically Frequency-Adjustable Quartz Oscillator

Abstract

A miniature quartz oscilltor with high frequency stability and low power dissipation for mobile telecommunication has been developed, using a miniaturized GT-cut quartz resonator (MGQ), a newly designed CMOS oscillator IC with a constant low voltage source and a floating MOS variable capacitor (PEAC) for frequency adjustment. At oscillation frequency of 2.1 MHz and supply voltage of 5 V, the quartz oscillator has frequency stability of ± 3 ppm over the temperature of -30 to +75 ℃, current consumption of 350 μA and shock resistance of 125 cm against random drop on a concrete floor. Almost all of the electrical components are integrated and they are contained in a HC-49U type metal case with the size of 13.2 x 10.9 x 4.5 mm. Other features of this quartz oscillator realized by employing the PEAC are very fine adjustability of the oscillation frequency, and complete hermeticity and immersed washability of the oscillator in the assembly line.