JPS5941906A - Adjusting method of oscillation frequency of crystal oscillator - Google Patents

Abstract

PURPOSE:To adjust the oscillation frequency with the oscillation start voltage lowered and the operating current consumption reduced, by forming an electrode pattern on one substrate to provide an input-side capacitor and an output-side capacitor together. CONSTITUTION:Lower electrodes 2 and 3 are formed on the upper face of a substrate 1, and a dielectric layer 4 is formed on electrodes 2 and 3. An upper electrode 5 is formed on the layer 4. An input-side trimmer capacitor C3 is constituted with electrodes 2 and 3 and the layer 4, and an output-side trimmer capacitor C4 is constituted with electrodes 3 and 5 and the layer 4. Capacitors C3 and C4 are so set that areas of electrodes 2 and 3 facing the electrode 5 are equal to each other and their electric capacities are equal to each other. Electric capacities of capacitors C3 and C4 are adjusted by cutting the electrode 5 as shown by an alternate long and two short dashes line. Since the electrode 5 is cut from the end part in parallel, electric capacities of capacitors C3 and C4 are reduced equally. By this adjustment, the oscillation start voltage is lowered, and the operating current is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of adjusting the oscillation frequency of a crystal oscillator.

Conventionally, a crystal oscillator is a crystal oscillator Qt+ as shown in the first diagram.
It consists of a resistor R, CMOS inverter ``io'' input side trimmer capacitor C1 + output side capacitor 02.The desired oscillation frequency is set by adjusting the capacitance of the input side trimmer capacitor C8. The capacitance of the output side capacitor C2 is 5PF, 20
PF, and the input side trimmer capacitor C8 is 5 to 20PF.
The oscillation start voltage VDD when adjusted within the range of
In the figure, the operation WN and the flow D are shown in FIG. As is clear from the figure, the oscillation start voltage VDD is high when the difference between the capacitance values of the two capacitors is large, and the operating current consumption IID is high when the difference between the capacitance values of the two capacitors is large. . In other words, it has been found that as the difference in capacitance between the input side trimmer capacitor C1 and the output side capacitor C2 increases, the oscillation characteristics of the crystal oscillator deteriorate.

The present invention eliminates the above drawbacks and provides an adjustment method that can adjust the oscillation frequency while keeping the oscillation start voltage low and the operating current consumption small.

An embodiment of the present invention will be described in detail below.

In FIG. 4, Q is a crystal resonator, R is a resistor, and V is a 0M0S inverter.

a, , C4 are input side trimmer capacitors.

This is the output side trimmer capacitor. The above components are connected as shown to form a crystal oscillation circuit. Here, input side trimmer capacitor 0. The output side trimmer capacitor C4 will be explained with reference to FIGS. 5 and 6. 1 is a substrate made of alumina, etc., and the -F side of this substrate has a lower part? t#i2.3 is formed by printing conductive paste. beneath%! A dielectric layer 4 is formed on top of the poles 2 and 3 by printing alumina paste or the like. Further, on the upper part of the dielectric layer 4, there is an upper part 'P! Pole 5 is likewise formed by printing conductive paste. 6 and 7 are end electrodes, which are formed by printing conductive paste on the ends of the substrate 1.

The end '@pole 6 is connected to the lower electrode 2.3, and the end electrode 7 is connected to the upper electrode 5. The input trimmer capacitor C3 is composed of a lower electrode 2, an upper electrode 5, and a dielectric layer 4 between these electrodes, and the output trimmer capacitor C4 is composed of a lower electrode 3, an upper electrode 5, and a dielectric layer 4 between these electrodes. It is composed of a dielectric layer 4. In the input side trimmer capacitor C3 and the output side trimmer capacitor 04, the lower electrode 2.3 and the upper electrode 5 have the same opposing area and are set to have the same capacitance.

And the adjustment of the capacitance of these trimmer capacitors is
Laser beam as shown in Figure 5 dotted chain line.

This is done by cutting the upper electrode 5 using the Sandgerast method or the like. This disconnection is done by upper electric! ! Since the cut is made parallel to the end of j'45, the capacitance values of both the input side trimmer capacitor O8 and the output side trimmer capacitor 04 are equally reduced. By adjusting the two capacitors in this manner, the oscillation frequency of the crystal oscillator is increased and adjusted. FIGS. 7 and 8 show i) from the oscillation start voltage VDD and operating current consumption when the oscillation frequency is adjusted in this manner. As is clear from the figure, the input side trimmer capacitor is 03, and the output side trimmer capacitor is 0.
Even if 4 is adjusted, the oscillation start voltage VDD is low, and D is smaller than the operating current consumption. Even if the oscillation frequency is adjusted by adjusting the load capacitance in this way, the crystal oscillator continues to oscillate with good oscillation characteristics.

Note that the capacitance values of the input-side trimmer capacitor and the output-side trimmer capacitor do not have to be equal, and as shown in FIG. ．．
The capacitance value may be slightly larger than the capacitance value of the output side trimmer capacitor 06. In this case as well, if you want to adjust the capacitance, cut the copper wire parallel to each other as shown in the two-point copper wire.
Adjustments are made so that the capacitance values of both trimmer capacitors are both reduced.

As described above, according to the present IJJ, when adjusting the oscillation frequency of the crystal oscillator by adjusting the load capacitance, the oscillation frequency of the crystal oscillator can be adjusted without increasing the oscillation start voltage of the crystal oscillator or increasing the operating current consumption. oscillation with excellent oscillation characteristics.

[Brief explanation of drawings]

Fig. 1 is an electric circuit diagram of a conventional crystal oscillator, Fig. 2 is its load capacitance 1 oscillation start voltage characteristic diagram, Fig. 3 is its load capacitance and operating current consumption characteristic diagram, and Fig. 4 is the crystal oscillator of the present invention. 5 is a front view of an embodiment of trimmer capacitors on the input side and output side, and FIG.
7 is the load capacitance 9 oscillation start voltage characteristic diagram, FIG. 8 is the load capacitance and operating current consumption characteristic diagram, tg
FIG. 9 is a front view of another embodiment of the input side and output side trimmer capacitors. Q...Crystal oscillator R...Resistance v Medium -...0M0S Innograph C3w'11...Input side capacitor O,, a,
・・・・・・Output side capacitor 2, 3・・・・・・Lower electrode 4・・・・・・・・・Dielectric layer 5・・・・・・・・・Top Electrode device Upper applicant Seikosha Co., Ltd.

Claims (2)

[Claims] (1) In a crystal oscillator having a crystal resonator, its oscillation circuit, and an input-side capacitor and an output-side capacitor of the oscillation circuit, the input-side capacitor and the output-side capacitor should form electrode patterns on one substrate. A method for adjusting the oscillation frequency of a crystal oscillator, characterized in that the oscillation frequency is adjusted by cutting the N electrode pattern and reducing the capacitance of both the input side capacitor and the output side capacitor. (2) The method for adjusting the oscillation frequency of a crystal oscillator according to claim 1, wherein the input-side capacitor and the output-side capacitor have the same capacitance.