JP2001308640A - Integrated temperature-compensated circuit board and temperature-compensated crystal oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized temperature compensated oscillator which brings into play the the features of a discrete type oscillator and is superior in workability. SOLUTION: The integrated temperature-compensated circuit board which is in the shape of a flat plat compensates the frequency-temperature characteristics of a crystal oscillator, has an input electrode connected with a mounted electrode of a crystal vibrator, and is composed of a laminated circuit board which has a concave section formed on the other main surface, enabling an IC which constitutes the oscillation circuit to be stored in the concave. The laminated circuit board is formed to built-in a temperature compensated device that holds at least a thermistor, of which the value of resistance changes, in response to temperature variation. The thermistor is formed on the main surface of the laminated circuit board by printing. The thermistor is formed by printing on the laminating surface of the laminated circuit board by printing or is embedded inside the board as a chip device. Adjustment resistor, which adjust the value of the resistance of the thermistor at normal temperature, is provided on the main surface of the laminated circuit board. By joining these integrated temperature compensated circuit boards with the back plane of the crystal vibrator, the temperature-compensated oscillator is constituted.

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a discrete-type temperature-compensated oscillator in an industrial technical field, and more particularly to a temperature-compensated oscillator in which a crystal unit and an element substrate are joined.

[0002] A temperature-compensated oscillator is widely used in electronic equipment used in a dynamic environment such as a mobile phone, because it compensates for an oscillation frequency that changes with temperature and stabilizes it. One of such devices is a discrete type using a thermistor whose resistance value changes with temperature.

FIGS. 6 and 7 are diagrams for explaining a conventional example. FIG. 6 is a circuit diagram of a temperature-compensated oscillator, and FIG. 7 is a structural diagram thereof. The temperature-compensated oscillator comprises a crystal oscillator 1 and a temperature-compensating circuit 2 in a dotted frame. The crystal oscillator 1 is a crystal oscillator 3
The oscillation circuit 4 is connected to the The crystal unit 3 has a mounting electrode (not shown) on the back and side surfaces, and is of a surface mounting type in which a crystal piece is hermetically sealed. The oscillation circuit 4 is composed of an IC chip 5 in which, for example, a Colpitts-type amplifier, an oscillation capacitor and a resistor (not shown) are integrated. Symbol Vcc in the figure is a power source, and OUT is an output.

The temperature compensating circuit 2 comprises a high-temperature and low-temperature thermistor 7 (ab) whose resistance changes in response to temperature and a parallel circuit of a capacitor 8. Normally, an adjusting resistor 9 for adjusting the resistance value of each thermistor 7 (ab) at normal temperature is provided by:
Insert them in series for high temperatures and in parallel for low temperatures. Then, a capacitor 10 as a frequency adjustment circuit is connected. These elements are arranged on a substrate 11 on which a circuit pattern is formed, and have a configuration in which a cover (not shown) is placed.

In such a device, the frequency temperature characteristic (FIG. 8) of the crystal oscillator 1 which has an inflection point near normal temperature of 25 ° C. and rises to the right (FIG. 8) is converted by the temperature compensation circuit 2 into a temperature range within the standard. To make it flat. That is, the reactance (capacitance) between the terminals in the temperature compensating circuit 2 changes as the resistance value of each thermistor 7 (ab) changes depending on the temperature. Specifically, the high-temperature thermistor 7a is set to have a large normal-temperature resistance value, and the low-temperature thermistor 7b is set to be small.

Thus, at a temperature higher than the normal temperature, the low-temperature thermistor 7b is short-circuited, so that the equivalent series capacitance of the capacitor 8, the short-circuit prevention capacitor 12, and the high-temperature thermistor 7a changes. In addition, when the temperature is lower than normal temperature, the high-temperature thermistor 7a is in an open state, so that the equivalent series capacitance of the capacitor 8, the short-circuit prevention capacitor 12, and the low-temperature thermistor 7b changes.

For these reasons, the load capacitance on the circuit side as viewed from between both terminals of the crystal unit 3 changes with temperature.
Therefore, if the capacitance between the terminals of the temperature compensation circuit 2 is set to increase as the temperature rises, the oscillation frequency decreases and the frequency-temperature characteristics can be flattened. The temperature compensating circuit 2 composed of this kind of passive element is called a direct type.

[0008]

[Problems to be Solved by the Invention]
However, in the temperature compensated oscillator having the above configuration, the thermistor 7 for high and low temperatures, the adjustment resistor 9, and the capacitors 8 and 12 are used.
However, since discrete components such as those described above are individually disposed on the substrate 11, workability is reduced, which is a factor that hinders miniaturization.

On the other hand, for example, a thermistor 7 (ab)
The temperature compensated oscillator in which the temperature compensation circuit 2, the oscillation circuit 4, and the frequency adjustment circuit are integrated into one chip without using the crystal oscillator 3 includes only the crystal resonator 3 and one LSI. Therefore, the size can be reduced as compared with the discrete type.

However, in this case, the temperature compensation circuit 2
Is a PN provided inside the LSI as temperature detecting means, for example.
It depends on a weak detection signal due to the temperature characteristic of the forward voltage of the junction region. Therefore, the noise component becomes relatively large with respect to the detection signal, and the noise characteristics deteriorate. In addition, there is a problem that current consumption increases because a weak detection signal is amplified and controlled. For these reasons, it was necessary to reduce the size by taking advantage of the discrete type.

(Object of the Invention) It is an object of the present invention to provide a small temperature-compensated oscillator which is excellent in workability and makes use of the features of the discrete type.

[0012]

Means for Solving the Problems (Technology of Attention) The present invention provides:
For example, as disclosed in Japanese Patent Application Laid-Open No. 10-98151, a temperature-compensated oscillator in which an oscillation circuit 4 and an IC chip 5 having a temperature compensation function are accommodated in a concave portion of a laminated substrate and bonded to the back surface of the crystal unit 3 We paid attention to.

(Solution) According to the present invention, a temperature compensation element including a thermistor 7 whose resistance value changes in response to temperature is accommodated in a concave portion of a laminated substrate in which an IC chip 5 constituting an oscillation circuit 4 is accommodated. Built-in temperature compensation integrated board 13
The fact that this is bonded to a crystal oscillator is a basic solution.

[0014]

According to the present invention, a temperature compensating element including the thermistor 7 is incorporated in a laminated substrate to form a temperature compensated integrated substrate 13.
Therefore, since the temperature compensation integrated substrate 13 may be joined to the back surface of the crystal unit 3, workability can be improved and downsizing (compacting) can be promoted. Hereinafter, an embodiment of the present invention will be described.

[0015]

1 to 3 are views for explaining one embodiment of the present invention. FIG. 1 is a sectional view of a temperature-compensated integrated substrate 13,
FIG. 2 is a plan view of the same, and FIG. 3 is a side view in which a part of the temperature compensated oscillator is cut away. The same parts as those in the prior art are denoted by the same reference numerals, and description thereof will be simplified or omitted. As described above, the temperature-compensated oscillator includes a crystal resonator 3 of a surface mount type, a Colpitts-type oscillation circuit 4 including an IC chip 5, a direct-compensation-type temperature compensation circuit 2 of a discrete type, and a frequency adjustment circuit. (See FIG. 6). In this embodiment, the temperature compensation integrated substrate 13 is bonded to the back surface of the crystal unit 3.

The temperature-compensated integrated substrate 13 is composed of a ceramic laminated substrate 14 having a circuit pattern formed on each substrate. The laminated substrate 14 has a four-layer structure. The first layer 14a has a central portion, the third layer 14c has a plurality of holes, and the second layer 14a has a plurality of holes.
b and the fourth layer 14d are flat. Then, a dielectric 15 (ab) made of ceramic or the like is buried in the hole of the third layer. Electrodes 16 for forming a capacitor are formed on a substrate serving as upper and lower surfaces of the dielectric. Each dielectric 15 (ab) corresponds to each of the capacitors 8 and 12 for temperature compensation and short circuit prevention described above.

On the substrate surface of the uppermost layer (fourth layer) 14d of the laminated substrate, a base material (metal oxide such as Mo) of the thermistor 7 (ab) for high / low temperature, an adjustment resistor 9, and a quartz oscillator 3
The connection terminal 17 connected to the mounting electrode provided on the back surface of the substrate is formed by printing together with the circuit pattern. On the bottom and side surfaces of the first layer 14a, mounting electrodes 18 for surface mounting are formed. The circuit patterns of the substrates 14 (abcd) are connected by through holes (electrode through holes) (not shown) to form a circuit of the temperature compensated oscillator. Then, after lamination, they are integrally fired, and thermistors 7 (a
b) A temperature-compensated integrated substrate 13 having the adjustment resistor 9 and the joint terminal 17 on one main surface and a concave portion on the other main surface is formed.

In such a device, the oscillation circuit 4 constituting the oscillation circuit 4 is formed in a concave portion of the temperature compensation integrated substrate 13 (laminated substrate 14).
C chip 5 and capacitor 10 as frequency adjustment circuit
To accommodate. The IC chip 5 is fixed by, for example, face-down bonding. Then, a notch (not shown) is provided in the thermistor 7 (ab) and the adjustment resistor 9 by, for example, a laser, and the thermistor 7 is operated at room temperature (about
(5 ° C.).

As a result, a capacitance characteristic with respect to temperature for compensating the frequency temperature characteristic of the temperature compensation circuit 2 is obtained. And
An insulating film such as a resin is provided on the surface of one main surface except for the joining terminal 17, for example. Finally, a mounting electrode (not shown) of the crystal resonator 3 and a bonding terminal 17 are bonded by soldering or the like, and a temperature compensation integrated substrate 13 is mounted on the bottom surface of the crystal resonator 3. In FIG. 3, reference numeral 19 denotes a crystal blank, and reference numeral 20 denotes a conductive adhesive.

With such a configuration, the temperature compensation circuit 2
The temperature compensating integrated substrate 13 is obtained by integrating the high / low temperature thermistor 7 (ab), the adjusting resistor 9 and the capacitors 8, 12 into the laminated substrate 14. And the crystal oscillator 3
Because it is bonded to the back surface of the, the plane area is reduced to make it compact. In addition, since the temperature compensation integrated substrate 13 may be prepared in advance, stocked, and joined to the crystal unit 3, workability is improved and productivity is improved.

Further, the temperature-compensated integrated substrate 13 can be handled as a one-chip element, and the number of components can be reduced to improve reliability. Since the temperature compensating circuit 2 is formed from individual elements, the noise characteristics are maintained well, the current consumption is reduced, and the features of the discrete type are maintained.

Since the thermistor 7 and the adjustment resistor 9 are provided on one main surface of the laminated substrate 14 by printing, the capacitance of the temperature compensating circuit 2 with respect to temperature can be easily adjusted by adjusting the resistance value with a laser or the like. Can be adjusted. In this example, since the base material of the thermistor 7 is formed by printing, the resistance value of the thermistor 7 itself can be adjusted and the adjustment work is facilitated.

[0023]

[Other Matters] In the above embodiment, the thermistor 7 (ab) and the adjusting resistor 9 are formed on one main surface of the laminated substrate 14 by printing, but the resistance at room temperature can be adjusted by the thermistor 7 itself as described above. Therefore, the adjusting resistor 9 may not be provided (claim 2). Further, the thermistor 7 is provided on the laminated surface of the laminated substrate 14.
The adjustment resistor 9 may be formed on one main surface by printing.

In this case, the thermistor 7 and the adjustment resistor 9 may be chip elements, and the thermistor 7 may be embedded in the hole of the third layer and the adjustment resistor 9 may be embedded in the hole of the fourth layer (uppermost layer) ( Claim 3). In short, the main surface of the laminated substrate may be configured to control the capacitance characteristics of the temperature compensation circuit 2 and adjust the resistance value of the thermistor 7. The thermistor 7 (ab) and the adjustment resistor 9 that are formed by printing may be, for example, vapor deposition and may be any film.

The mounting electrode 18 is provided on the other main surface of the laminated substrate 14 having the concave portion, and the quartz oscillator 3 is provided on one of the flat main surfaces.
And the flat surface side is bonded to the back surface of the crystal unit 3, but the mounting electrode 18 is provided on one main surface and the connection terminal 17 is provided on the other main surface, and the other main surface side is connected to the crystal unit. 3 may be bonded to the back surface. In these examples, the capacitor 8 is shared with the high / low temperature thermistor 7 to form the high / low temperature compensating circuit 2. However, a capacitor is connected in parallel to the high / low temperature thermistor 7 and these are connected in series. It can be applied to things.

The present invention is not limited to the direct type and can be applied to a so-called indirect type in which a compensation voltage is applied to a voltage variable capacitance diode (FIG. 5). That is, as shown in FIG. 4, for example, a frequency temperature characteristic having an inflection point at normal temperature, a maximum value at low temperature, and a minimum value at high temperature is targeted. The frequency temperature characteristics are defined as a low temperature region below the maximum value, a normal temperature region between the maximum value and the minimum value, and a high temperature region above the minimum value, and the thermistor 7 (abc) and the adjustment resistor 9 sensitive to the respective temperature regions.
To form a compensation voltage generation circuit.

As a result, the compensation voltage responsive to each temperature range is applied to the voltage variable capacitance diode 1 connected to the quartz oscillator 3.
9 is applied. And the voltage variable capacitance diode 19
The temperature is compensated by the change in the capacitance of. Even in such an indirect type, the temperature compensation integrated substrate 13 can be obtained by forming the thermistor 7 and the adjustment resistor 9 on the laminated substrate as described above. In this case, the voltage variable capacitance diode 19 is housed in the concave portion of the multilayer substrate 14 together with the IC chip 5 and the capacitor 10 for frequency adjustment.

The dielectric 15 (ab) corresponding to the capacitors 8 and 12 for temperature compensation and short circuit prevention is buried in the third layer hole of the laminated board 14, but the capacitor 15 is formed with electrodes in advance. May be buried. In this case, for example, a bypass capacitor between the power supply and the ground or a coupling capacitor with the next stage may be embedded.

[0029]

According to the present invention, a temperature compensation device is provided in which a temperature compensating element including a thermistor whose resistance value changes in response to temperature is housed in a laminated substrate, in which an IC chip constituting an oscillation circuit is accommodated in a concave portion of the laminated substrate. Since an integrated substrate is formed and bonded to the crystal unit, a small temperature-compensated oscillator excellent in workability and taking advantage of the discrete type can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a temperature-compensated integrated substrate explaining one embodiment of the present invention.

FIG. 2 is a plan view of a temperature-compensated integrated substrate explaining one embodiment of the present invention.

FIG. 3 is a partially cutaway side view of the temperature compensated oscillator according to one embodiment of the present invention.

FIG. 4 is another frequency temperature characteristic diagram of the crystal oscillator to which the present invention is applied.

FIG. 5 is a circuit diagram of a temperature compensated oscillator using an indirect temperature compensation circuit to which the present invention is applied.

FIG. 6 is a circuit diagram of a temperature-compensated oscillator explaining a conventional example.

FIG. 7 is a structural diagram of a temperature-compensated oscillator explaining a conventional example.

FIG. 8 is a frequency temperature characteristic diagram of a crystal oscillator explaining a conventional example.

[Explanation of symbols]

1 crystal oscillator, 2 temperature compensation circuit, 3 crystal oscillator, 4 oscillation circuit, 5 IC chip, 8, 10, 12 capacitor, 7 thermistor, 9 adjustment resistor, 11 substrate, 13 integrated temperature compensation substrate, 14 laminated substrate, Fifteen
Dielectric, 16 electrodes, 17 bonding terminals, 18 mounting electrodes, 19 quartz pieces, 20 conductive adhesive.

Claims (4)

[Claims] 1. A concave portion for compensating a frequency temperature characteristic of a crystal oscillator, having an input electrode connected to a mounting electrode of a crystal oscillator, and accommodating an IC chip constituting an oscillation circuit is provided on another main surface. A flat temperature-compensated integrated substrate comprising a laminated substrate, wherein the laminated substrate incorporates a temperature-compensating element including at least a thermistor whose resistance value changes in response to temperature. . 2. The temperature-compensated integrated substrate according to claim 1, wherein said thermistor comprises a film formed on one main surface of said laminated substrate. 3. The thermistor is formed as a film on a laminated surface of the laminated substrate, or is embedded as a chip element in the laminated substrate, and one main surface of the laminated substrate adjusts a resistance value of the thermistor at room temperature. 2. An adjustment resistor provided to the control circuit.
Temperature compensation integrated substrate. 4. A temperature-compensated oscillator comprising the temperature-compensated integrated substrate according to claim 1, 2 or 3 joined to the back surface of a crystal unit.