TECHNICAL INFORMATION

Published in "AEI February 2004"
Tiny Quartz Devices Play Huge Role in Communication Terminals

Quartz devices are used to convert accurate mechanical vibrations into electric signals,and they are used for generating synchronous reference signals for various ICs, color reference signals for images and also for clocks. Without this quartz device, high performance computers and mobile phones are mere boxes; thus they are indispensable key devices in present-day society. Quartz devices include quartz resonators, quartz oscillators and others, which are required to be small in size and to feature improved performance to respond to high functional and high performance terminals capable of high-speed data communication.

DAISHINKU's DSX321G quartz resonators correspond
to the wide range of industry top class

Quartz Resonators: DSX321G, DSX321SL

Quartz resonators are required to be reduced in the size of their low frequency bands, and at the same time they are required to be small-sized and low-profiled. AT-cut quartz resonators exhibit a temperature characteristic of a cubical curve, and their frequency-temperature characteristic is excellent over a wide temperature range. However, frequencies are in reverse proportion to the thickness of a quartz plate. Thus, the smaller the size of a quartz resonator is, the more difficult it is to realize low frequency band resonators. Therefore, the point in the development of low frequency 2 band resonators is how to reconcile the conflicting characteristics of enlarging the size of a quartz plate while reducing the external dimensions of a quartz product. DAISHINKU CORP. has developed DSX321G, a 3225 size product (3.2×2.5mm) that realizes the industry's top level wide range of 10 to 50MHz and low impedance of 80Ω at 12MHz, while maintaining the mechanical strength of its package and widening the mounting area of its quartz plate (Fig.1).

Fig.1: External view of DSX321G
At the same time, DAISHINKU has also developed DSX321SL. This quartz resonator features a wide range (13 to 50MHz) and has low profile (0.5mm(typ.)). In developing the DSX321SL, special attention was paid to its low frequency band (Table 1).
Table 1: General specifications of DSX321G/DSX321SL
Item DSX321G / DSX321SL
Oscillation mode Fundamental
Load capacitance Series, 8pF, 10pF, 12pF
Drive level 10μW (300μW MAX.)
Frequency tolerance ±10ppm to ±50ppm (at 25°C)
Frequency-temperature
characteristic		 ±20ppm
(Ref. to 25°C)		 ±30ppm
(Ref. to 25°C)
Operating
temperature range		 -10 to +60°C -30 to +85°C
Storage
temperature range		 -40 to +85°C

Quartz Oscillators: DSA322MA, DSV321ST

Quartz oscillators are increasing their importance as reliable high precision frequency signal sources and as key parts for communication equipment. Like quartz resonators, they are also required to be small in size and low-profiled. In recent years, however, they have been higher-density mounted, containing peripheral functions. DAISHINKU's DSA322MA, a 3225-sized temperature-compensated crystal oscillator (TCXO) with voltage-control functions, has been developed to respond to the reduction in sizes of Personal Digital Cellular (PDC), GSM, and CDMA terminals and other products. The DSA322MA contains two TCXO output ports having a buffered-amplifier in addition to its original VC-TCXO function. The size enlargement due to these new self-contained functions is absorbed by adopting flip chip mounting technology. Its performance is the same as that of the company's previous product (with the chip separated from the quartz piece). It features an one-piece structure with the chip and the quartz piece contained in the same package, reducing the number of its component parts (Fig.2).

Fig.2: External view of DSA322MA

Meanwhile, DAISHINKU developed DSV321ST (VCXO) as a measure against noise from the application circuits in mobile phones, and to prevent the deterioration of the performance of mobile phones by controlling the high harmonics component of operating clock frequencies (joint use of software is necessary). With a function capable of shifting its oscillation frequency more than -100ppm by using an external control terminal, it is a 3225 size quartz oscillator developed as a clock for application circuits such as a camera module (Fig.3).
As for plans in the coming years, DAISHINKU hopes to develop smaller quartz devices to add to its 3225-size product line.
Fig.3: External view of DSV321ST