JP2004343733A - Temperature compensated oscillator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a circuit configuration suited to be formed into IC, which is further small-sized and the cost of which is reduced and can deal with much more requested specifications, in a temperature compensated oscillator utilizing a MOS capacitor. <P>SOLUTION: A frequency/temperature compensation circuit which is inserted and connected to the oscillation loop of a piezoelectric oscillator for frequency/temperature compensation, is a parallel circuit parallelly connecting a serial circuit in which one terminal of a fixed capacitor is connected to the anode terminal of a first MOS capacitor element, and a second MOS capacitor to connect the anode terminal of the second MOS capacitor element with the gate terminal of the first MOS capacitor element, and the temperature compensated oscillator is configured to feed a reference voltage signal with a fixed voltage value to the connecting point of the gate terminal of the first MOS capacitor element and the anode terminal of the second MOS capacitor element, to feed a first control voltage signal to the anode terminal of the first MOS capacitor element, and to feed a second control voltage signal to the gate terminal of the second MOS capacitor element. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an oscillator using a piezoelectric element such as a crystal, and more particularly to a temperature-compensated oscillator suitable for ICs, which can perform frequency temperature compensation with a simple circuit configuration.

  In recent years, in oscillators using piezoelectric elements, for example, crystal oscillators, not only frequency stability, but also demands for downsizing and price reduction are strict. It has been desired to improve the noise ratio characteristics (C / N characteristics) that did not exist. Although the output frequency of the oscillator changes due to various factors, even in a crystal oscillator having a relatively high frequency stability, there are frequency fluctuations due to changes in conditions such as ambient temperature, power supply voltage and output load. Various things are taken. For example, with respect to a temperature change, a temperature compensation circuit is added to the crystal oscillator, and the load capacitance in the oscillation loop of the temperature compensation crystal oscillator (hereinafter, referred to as TCXO) is changed to cancel the temperature-frequency characteristic inherent in the crystal resonator. In some cases, the load capacity is controlled in response to a temperature change.

  One of them is a direct type compensation, which is configured by connecting a temperature compensation circuit in series with a crystal oscillator as shown in FIG. 12. Generally, the temperature compensation circuit is composed of a chip thermistor and a chip capacitance element. Are connected in series with a high-temperature section compensation circuit and a low-temperature section compensation circuit, each of which has a basic configuration in which are connected in parallel. This method is widely used in the field of mobile phones and the like because of its simple configuration and easy downsizing. However, in this method, since the resistance value of the thermistor is inserted into the oscillation loop, the high Q that the crystal unit originally has deteriorates, and the resistance value of the thermistor changes with temperature. Also fluctuate significantly with this.

On the other hand, there is an indirect compensation as shown in FIG. For example, as shown in FIG. 14, for a frequency characteristic of a crystal resonator that changes in a curve with respect to temperature, a control voltage signal that similarly changes is applied to a varicap diode or MOS capacitor inserted in an oscillation loop. The temperature is compensated by supplying to a sensitive variable capacitance circuit such as an element. In this indirect compensation, there is a type in which the temperature compensation circuit is formed into an IC and is downsized for use in the field of mobile phones and the like. In this method, a control voltage signal to be supplied is stored as digital data in a ROM or the like, and data is read out in accordance with a temperature change to generate a control voltage signal.
However, in this method, if noise peculiar to a digital signal or the like is superimposed on this control voltage signal, it is output as an oscillation signal as it is, and the C / N characteristic is significantly deteriorated.
Therefore, there is a method in which the control voltage signal to be supplied is derived in an analog manner. This is a complex logic circuit realized by making full use of IC technology, and basically uses a high-sensitivity variable capacitance circuit, so it is necessary to thoroughly eliminate noise signals mixed in the control voltage signal. It can be said that there is a problem in improving the C / N characteristics.

  A solution to these problems is disclosed in JP-A-2001-60828 filed by the present applicant. This is a direct TCXO utilizing a curved capacitance change inherent in a MOS capacitance element. The principle will be described below in detail with reference to the drawings. Now, consider temperature compensation of a crystal oscillator having a temperature frequency characteristic as shown in FIG. This is because the frequency decreases in a low-temperature part below normal temperature (reference temperature: 25 ° C.) in a curved manner, the frequency displacement is small near normal temperature, and the frequency increases in a curved manner in a high temperature above normal temperature. It is a function curve.

  Therefore, attention has been paid to the characteristics of the MOS capacitance element exhibiting a capacitance change as shown in FIG. This is a relationship between the gate voltage (hereinafter simply referred to as gate voltage) based on the anode voltage of the MOS capacitance element and the capacitance value appearing at both ends of the MOS capacitance element. , The change is small and decreases sharply as the gate voltage increases, and the capacitance value is low at Vb, and the change is small. Here, as the capacitance characteristics of the MOS capacitance element, various types are known, such as those having a change gradient in a direction opposite to this, and those having a change curve parallel-translated in the horizontal axis direction. This is an example. . Now, when the gate voltage is changed from Va 'to Va as shown in the figure, the capacitance value sharply increases, and the capacitance value increases as the gate voltage decreases, and the change becomes small. This curved portion is referred to as (A). On the other hand, when the gate voltage is changed from Vb to Vb ', the capacitance value is small and the change is small, but increases rapidly as the gate voltage decreases. This curved portion is referred to as (B).

  Here, two MOS capacitors having the above characteristics were used, and one was added so that as the temperature increased from low to high, one changed the gate voltage from Va ′ to Va, and the other changed linearly from Vb to Vb ′, respectively. In this case, when the temperature / capacitance value characteristics of the two are overwritten, the result is as shown in FIG. If one of the curve portions (A) is incorporated as a low-temperature portion compensation circuit and the other curve portion (B) is incorporated as a high-temperature portion compensation circuit in a part of the load capacitance of the oscillation circuit, the circuit shown in FIG. The temperature compensation of the crystal unit having the temperature characteristic of the following function curve can be performed.

  The operation will be described below based on an example of a temperature / temperature compensation circuit using this MOS capacitance element. FIG. 17 shows a configuration in which a high-temperature part compensation circuit and a low-temperature part compensation circuit using a crystal unit and a MOS capacitor for an amplifier are connected in series. The high-temperature MOS capacitor MH and the low-temperature MOS capacitor ML are both connected in series in the same polarity direction, and the low-temperature MOS capacitor ML includes a sensitivity adjustment fixed capacitor Cf1 connected in series, and the high-temperature MOS capacitor A fixed capacitance element for sensitivity adjustment Cf2 is connected in parallel to MH. Then, temperature compensation control voltage signals VL and VH are supplied from the temperature sensor and the control circuit to the two MOS capacitors via an input resistor R, and a connection point between the two MOS capacitors is connected via an input resistor R. Thus, the reference voltage signal Vref is supplied.

  In this compensation circuit, in response to the temperature change from low to high, the gate voltage based on the anode voltage of the low-temperature MOS capacitor ML is changed from Va ′ to Va, and the anode of the high-temperature MOS capacitor MH is changed. Consider that the gate voltage based on the voltage is linearly changed from Vb to Vb '. Then, here, since Vref is supplied to the gate terminal of the low-temperature MOS capacitive element ML, the control voltage signal VL that linearly increases from (Vref−Va ′) to (Vref−Va) is supplied to the anode terminal. On the other hand, since Vref is supplied to the anode terminal of the high-temperature MOS capacitive element MH, a control voltage signal VH that linearly decreases from (Vref + Vb) to (Vref + Vb ′) is supplied to the gate terminal. . Then, the series combined capacitance of the temperature / capacitance characteristic curves (A) and (B) shown in FIG. 15 is inserted into the oscillation loop, and the crystal unit having a cubic function curve as shown in FIG. Can be compensated for.

  Here, the sensitivity adjustment fixed capacitance elements Cf1 and Cf2 are provided with a degree of freedom so that the shape of each compensation characteristic curve can be set arbitrarily, and this utilizes the property of the series-parallel combined capacitance value. is there. Now, in the low-temperature part compensation circuit, for example, it is assumed that the value of the fixed capacitance element Cf1 at room temperature and the value of the low-temperature MOS capacitance element ML are almost the same, and the behavior of this series combined capacitance value will be examined. The value of the MOS capacitor increases from a small value from a low temperature to a normal temperature, and increases at a normal temperature and a temperature higher than the normal temperature. Therefore, in the series combined capacitance value, the change in the value of the MOS capacitor becomes dominant at a low temperature, and the value of the MOS capacitor becomes large at a normal temperature and a temperature higher than the normal temperature. The change is limited by the value of the element. Conversely, in the high temperature section compensation circuit, assuming that the value of the fixed capacitance element Cf2 and the value of the high temperature MOS capacitance element MH at room temperature are almost the same, the value of the MOS capacitance element becomes smaller from low temperature to room temperature. At this time, the value of the fixed capacitance element is dominant and its change is small. At a temperature higher than the normal temperature, the change of the MOS capacitance element becomes dominant as the value of the MOS capacitance element increases. By adjusting the values of the fixed capacitance elements Cf1 and Cf2 for sensitivity adjustment using such properties, it is possible to obtain a temperature compensation capacitance curve that is more suited to the curve of the crystal resonator.

As described above, when this principle is used, when compared with the conventional indirect type compensation, a control voltage signal similar to this is not generated for the cubic curve compensation of the crystal resonator, and the linear Since it is only necessary to generate a temperature / voltage signal, the compensation circuit becomes extremely simple. In the C / N characteristic, the control voltage signal does not include a digital signal, and the voltage sensitivity of the MOS capacitance element included in the oscillation loop can be set to almost zero around the room temperature, which is the most frequently used, so that it is very good. Characteristics. Also, when compared with the conventional direct compensation, not only the merit of downsizing due to the fact that it can be easily integrated into an IC, but also the resistance component of the thermistor is not included in the oscillation loop, so Since the Q value can be maintained as it is, it is possible to further maintain good C / N characteristics, it is possible to reduce power consumption required for maintaining oscillation, and there is no fluctuation in output level due to temperature. As described above, the direct temperature compensation method using the MOS capacitance element has several advantages over the conventional indirect compensation method and direct compensation method.
JP 2001-60828 A

  Therefore, by utilizing the compensation principle disclosed in Japanese Patent Application Laid-Open No. 2001-60828, which is considered to be the most excellent temperature compensation method at present, further miniaturization and cost reduction are pursued, and the oscillator can cope with more required specifications. There has been a demand for a specific circuit configuration.

  In order to solve the above-mentioned problem, the invention according to claim 1 is a frequency temperature compensation circuit for performing frequency temperature compensation by inserting and connecting in an oscillation loop of a piezoelectric oscillator, wherein the frequency temperature compensation circuit is A series circuit in which one terminal of a fixed capacitance element is connected to the anode terminal of one MOS capacitance element and a second MOS capacitance element are connected to each other by connecting the anode terminal of the second MOS capacitance element to the gate terminal of the first MOS capacitance element. And a reference voltage signal having a constant voltage value is supplied to a connection point between a gate terminal of the first MOS capacitance element and an anode terminal of the second MOS capacitance element. A first control voltage signal is supplied to an anode terminal of the first MOS capacitance element, and a second control voltage signal is supplied to a gate terminal of the second MOS capacitance element. It is a symptom.

  According to a second aspect of the present invention, there is provided a temperature compensated oscillator having a structure in which an oscillation circuit, a DC blocking fixed capacitance element, a frequency temperature compensation circuit, and a piezoelectric vibrator are connected in series. A circuit includes a series circuit in which one terminal of a fixed capacitance element is connected to an anode terminal of a first MOS capacitance element, and a second MOS capacitance element. The anode terminal of the second MOS capacitance element has an anode terminal of the first MOS capacitance. A parallel circuit connected in parallel so as to be connected to a gate terminal of the element, wherein a reference voltage having a constant voltage value is provided at a connection point between the gate terminal of the first MOS capacitor and the anode terminal of the second MOS capacitor; A voltage signal is supplied, a first control voltage signal is supplied to an anode terminal of the first MOS capacitance element, and a second control voltage signal is supplied to a gate terminal of the second MOS capacitance element. And It is characterized in that.

  According to a third aspect of the present invention, there is provided a temperature compensation oscillator having a structure in which a Colpitts oscillation circuit, a frequency temperature compensation circuit, and a piezoelectric vibrator are connected in series, wherein the frequency temperature compensation circuit comprises a first MOS transistor. A series circuit in which one terminal of a fixed capacitance element is connected to the anode terminal of the capacitance element and a second MOS capacitance element are connected with the anode terminal of the second MOS capacitance element being connected to the gate terminal of the first MOS capacitance element. And a reference voltage signal having a constant voltage value is supplied to a connection point between a gate terminal of the first MOS capacitance element and an anode terminal of the second MOS capacitance element. A first control voltage signal is supplied to an anode terminal of the first MOS capacitance element, and a second control voltage signal is supplied to a gate terminal of the second MOS capacitance element; or I The frequency temperature compensation circuit includes a series circuit in which one terminal of a fixed capacitance element is connected to an anode terminal of a first MOS capacitance element, and a parallel circuit of a second MOS capacitance element and a fixed capacitance element. A series circuit in which the gate terminal of the first MOS capacitor and the anode terminal of the second MOS capacitor are connected in series, wherein the gate terminal of the first MOS capacitor and the second MOS capacitor are connected. A reference voltage signal having a constant voltage value is supplied to a connection point with the anode terminal of the first MOS capacitor, a first control voltage signal is supplied to the anode terminal of the first MOS capacitor, The Colpitts oscillation circuit includes a transistor and a via for supplying a bias voltage to a base of the transistor. A fixed circuit for direct current blocking between a connection point between the base of the transistor and a bias circuit and the other terminal of a series circuit including two fixed capacitance elements each having one terminal connected to the ground. An element is inserted and connected, and a connection point between the series circuit composed of the two fixed capacitance elements and the DC blocking fixed capacitance element is connected to the frequency temperature compensation circuit.

  The invention according to claim 4 is a temperature-compensated oscillator having a structure in which an oscillation circuit, a frequency temperature compensation circuit, and a piezoelectric vibrator are connected in series, wherein the oscillation circuit comprises a transistor and a base of the transistor. And a bias circuit for supplying a bias voltage to the first MOS capacitor, wherein the frequency temperature compensation circuit includes a series circuit in which one terminal of the fixed capacitor is connected to the anode terminal of the first MOS capacitor, and a second MOS transistor. A capacitor connected in parallel so that an anode terminal of the second MOS capacitor is connected to a gate terminal of the first MOS capacitor; and a second circuit connected to the anode terminal of the first MOS capacitor. A first control voltage signal, and a second control voltage signal to a gate terminal of the second MOS capacitance element. It is characterized by being configured to provide a bias voltage signal of the bias circuit constituting the oscillator circuit to a connection point between the gate terminal and the anode terminal of the second MOS capacitance element.

  The invention according to claim 5 is a temperature compensation oscillator having a structure in which an oscillation circuit, a frequency temperature compensation circuit, a piezoelectric vibrator, and a frequency external voltage control circuit are connected in series, wherein the frequency temperature compensation circuit Is a series circuit in which one terminal of a fixed capacitance element is connected to the anode terminal of a first MOS capacitance element and a second MOS capacitance element. The anode terminal of the second MOS capacitance element is connected to the first MOS capacitance element. And a reference voltage having a constant voltage value at a connection point between the gate terminal of the first MOS capacitance element and the anode terminal of the second MOS capacitance element. A first control voltage signal is supplied to an anode terminal of the first MOS capacitor, and a second control voltage signal is supplied to a gate terminal of the second MOS capacitor. Also Alternatively, the frequency temperature compensation circuit may include a series circuit in which one terminal of the first fixed capacitance element is connected to the anode terminal of the first MOS capacitance element, and a second fixed capacitance element connected to the second fixed capacitance element. A series circuit in which a parallel circuit with a capacitor is connected in series so that a gate terminal of the first MOS capacitor and an anode terminal of the second MOS capacitor are connected; A reference voltage signal having a constant voltage value is supplied to a connection point between the gate terminal of the first MOS capacitor and the anode terminal of the second MOS capacitor, and a first control voltage signal is supplied to the anode terminal of the first MOS capacitor. And a second control voltage signal is supplied to a gate terminal of the second MOS capacitance element. The frequency external voltage control circuit is configured to supply an external control voltage to a gate terminal of the MOS capacitance element. And supplied the item, or the voltage value to the anode terminal is supplied an external control voltage signal to the gate terminal of the MOS capacitor element is characterized by comprising a structure for supplying a reference voltage signal is constant.

  The invention according to claim 6 is a temperature compensated oscillator having a structure in which an oscillation circuit, a frequency external voltage control circuit, a fixed capacitance element, a frequency temperature compensation circuit, and a piezoelectric vibrator are connected in series, The oscillation circuit includes at least a transistor and a bias circuit for supplying a bias voltage to a base of the transistor. The frequency temperature compensation circuit includes a fixed capacitance element connected to an anode terminal of the first MOS capacitance element. A parallel circuit in which a series circuit having one terminal connected thereto and a second MOS capacitor are connected in parallel such that an anode terminal of the second MOS capacitor is connected to a gate terminal of the first MOS capacitor; A reference voltage signal having a constant voltage value is supplied to a connection point between the gate terminal of the first MOS capacitor and the anode terminal of the second MOS capacitor, and the first M A configuration in which a first control voltage signal is supplied to an anode terminal of the S capacitance element and a second control voltage signal is supplied to a gate terminal of the second MOS capacitance element; The temperature compensation circuit includes a series circuit in which one terminal of the first fixed capacitance element is connected to an anode terminal of the first MOS capacitance element, and a parallel circuit of the second MOS capacitance element and the second fixed capacitance element. A series circuit in which the gate terminal of the first MOS capacitor and the anode terminal of the second MOS capacitor are connected in series so that the gate terminal of the first MOS capacitor is connected to the second terminal of the second MOS capacitor. A reference voltage signal having a constant voltage value is supplied to a connection point of the MOS capacitor with an anode terminal, a first control voltage signal is supplied to an anode terminal of the first MOS capacitor, and the second MOS Capacitive element A configuration for supplying a second control voltage signal to a gate terminal, wherein the frequency external voltage control circuit supplies an external control voltage signal to a gate terminal of a MOS capacitor, and an anode terminal to the oscillation circuit. The connection is characterized in that a bias voltage signal of the transistor is supplied.

  According to a seventh aspect of the present invention, there is provided an oscillation circuit, a fixed capacitance element, a parallel circuit in which a frequency temperature compensation circuit and a frequency external voltage control circuit are connected in parallel, or a frequency temperature compensation circuit and the frequency external voltage control circuit. A temperature-compensated oscillator having a structure in which a series circuit connected in series and a piezoelectric vibrator are connected in series, wherein the frequency temperature compensation circuit connects one terminal of the fixed capacitance element to an anode terminal of the first MOS capacitance element. A parallel circuit in which the connected series circuit and the second MOS capacitor are connected in parallel such that the anode terminal of the second MOS capacitor is connected to the gate terminal of the first MOS capacitor; A reference voltage signal having a constant voltage value is supplied to a connection point between the gate terminal of the first MOS capacitor and the anode terminal of the second MOS capacitor. And a second control voltage signal is supplied to a gate terminal of the second MOS capacitance element, and the frequency external voltage control circuit comprises a MOS capacitance element. An external control voltage signal is supplied to the gate terminal of the frequency temperature compensation circuit, and a connection point between the gate terminal of the first MOS capacitance element and the anode terminal of the second MOS capacitance element is connected to the anode terminal. Wherein the reference voltage signal of the frequency temperature compensation circuit is supplied.

  The invention according to claim 8 is a temperature compensated oscillator having a structure in which an oscillation circuit, a parallel circuit in which a frequency temperature compensation circuit and a frequency external voltage control circuit are connected in parallel, and a piezoelectric vibrator are connected in series. The oscillation circuit includes at least a transistor and a bias circuit for supplying a bias voltage to the base of the transistor, and the frequency temperature compensation circuit includes a fixed capacitance element connected to an anode terminal of the first MOS capacitance element. And a second MOS capacitor connected in parallel so that an anode terminal of the second MOS capacitor is connected to a gate terminal of the first MOS capacitor. Supplying a first control voltage signal to an anode terminal of the first MOS capacitance element and supplying a second control voltage signal to a gate terminal of the second MOS capacitance element The frequency external voltage control circuit supplies an external control voltage signal to a gate terminal of a MOS capacitance element, and an anode terminal of the gate terminal of the first MOS capacitance element of the frequency temperature compensation circuit. And a connection point between the transistor and the anode terminal of the second MOS capacitance element, and the connection point is connected to the oscillation circuit to supply a bias voltage signal for the transistor.

  The invention according to claim 9 is a temperature compensation oscillator having a structure in which a Colpitts oscillation circuit, a piezoelectric vibrator, a frequency temperature compensation circuit, and a fixed capacitance element are connected in series, wherein the frequency temperature compensation circuit is A series circuit in which one terminal of a fixed capacitance element is connected to the anode terminal of the first MOS capacitance element and a second MOS capacitance element, the anode terminal of the second MOS capacitance element being connected to the anode terminal of the first MOS capacitance element A reference voltage signal having a constant voltage value at a connection point between a gate terminal of the first MOS capacitor and an anode terminal of the second MOS capacitor, which is a parallel circuit connected in parallel so as to be connected to a gate terminal. And a first control voltage signal is supplied to an anode terminal of the first MOS capacitance element, and a second control voltage signal is supplied to a gate terminal of the second MOS capacitance element. Alternatively, the frequency temperature compensation circuit may include a series circuit in which one terminal of the first fixed capacitance element is connected to the anode terminal of the first MOS capacitance element, and a second fixed capacitance element connected to the second fixed capacitance element. A series circuit in which a parallel circuit with a capacitor is connected in series so that a gate terminal of the first MOS capacitor and an anode terminal of the second MOS capacitor are connected; A reference voltage signal having a constant voltage value is supplied to a connection point between the gate terminal of the first MOS capacitor and the anode terminal of the second MOS capacitor, and a first control voltage signal is supplied to the anode terminal of the first MOS capacitor. And a second control voltage signal supplied to the gate terminal of the second MOS capacitance element, wherein the Colpitts oscillation circuit is connected between the base and the emitter of the transistor. A first capacitance circuit, and a second capacitance circuit connected between the emitter and the ground, the first capacitance circuit including a MOS capacitance element, and a gate of the MOS capacitance element. By supplying a control voltage signal to the terminal, the capacitance value of the first capacitance circuit can be varied.

  An invention according to claim 10 is a temperature compensation oscillator having a structure in which a Colpitts oscillation circuit, a frequency temperature compensation circuit, and a piezoelectric vibrator are connected in series, wherein the frequency temperature compensation circuit comprises a first MOS transistor. A series circuit in which one terminal of a fixed capacitance element is connected to the anode terminal of the capacitance element and a second MOS capacitance element are connected with the anode terminal of the second MOS capacitance element being connected to the gate terminal of the first MOS capacitance element. And a reference voltage signal having a constant voltage value is supplied to a connection point between a gate terminal of the first MOS capacitance element and an anode terminal of the second MOS capacitance element. A first control voltage signal is supplied to an anode terminal of the first MOS capacitance element, and a second control voltage signal is supplied to a gate terminal of the second MOS capacitance element; or The frequency temperature compensation circuit comprises a series circuit in which one terminal of the first fixed capacitance element is connected to the anode terminal of the first MOS capacitance element, and a second MOS capacitance element and a second fixed capacitance element. A series circuit in which a parallel circuit is connected in series so that a gate terminal of the first MOS capacitor and an anode terminal of the second MOS capacitor are connected; Supplying a reference voltage signal having a constant voltage value to a connection point of the second MOS capacitance element with the anode terminal, supplying a first control voltage signal to the anode terminal of the first MOS capacitance element, A second control voltage signal is supplied to a gate terminal of a second MOS capacitance element, and the Colpitts oscillation circuit includes a first capacitance connected between a base and an emitter of the transistor. And a second capacitor circuit connected between the emitter and the ground, the second capacitor circuit including a MOS capacitor, and a control voltage signal connected to a gate terminal of the MOS capacitor. Is supplied, the capacitance value of the first capacitance circuit can be varied.

  According to an eleventh aspect of the present invention, in the temperature compensated oscillator according to any one of the first to tenth aspects, the gate terminal and the anode terminal of the MOS capacitor are all connected to opposite polarities. I have.

The invention according to claim 12 is a temperature-compensated oscillator having a structure in which a Colpitts oscillation circuit, a piezoelectric vibrator, a frequency temperature compensation circuit, and a fixed capacitance element are connected in series, wherein the frequency temperature compensation circuit is A fixed capacitance element is connected to an anode terminal of the first MOS capacitance element, and a gate terminal of the first MOS capacitance element is connected to an anode terminal of a second MOS capacitance element. A reference voltage signal having a constant voltage value is supplied to a connection point between the gate terminal of the MOS capacitance element and the anode terminal of the second MOS capacitance element, and the first voltage is supplied to the anode terminal of the first MOS capacitance element. A control voltage signal is supplied, and a second control voltage signal is supplied to a gate terminal of the second MOS capacitance element.
The Colpitts oscillation circuit includes at least a first capacitance circuit connected between the base and the emitter of the transistor, and a second capacitance circuit connected between the emitter and the ground,
The first capacitance circuit includes an external voltage control circuit using a MOS capacitance element, and a capacitance value of the first capacitance circuit can be varied by supplying a control voltage signal to a gate terminal of the MOS capacitance element. Features.

The invention according to claim 13 is a temperature-compensated oscillator having a structure in which a Colpitts oscillation circuit, a frequency temperature compensation circuit, and a piezoelectric vibrator are connected in series,
The frequency temperature compensation circuit includes a series circuit in which one terminal of a fixed capacitance element is connected to an anode terminal of a first MOS capacitance element, and a second MOS capacitance element. A parallel circuit is connected in parallel so as to be connected to the gate terminal of the first MOS capacitor, and a voltage value is applied to a connection point between the gate terminal of the first MOS capacitor and the anode terminal of the second MOS capacitor. A constant reference voltage signal is supplied, a first control voltage signal is supplied to an anode terminal of the first MOS capacitance element, and a second control voltage signal is supplied to a gate terminal of the second MOS capacitance element. It has a configuration to
The Colpitts oscillation circuit includes at least a first capacitance circuit connected between the base and the emitter of the transistor, and a second capacitance circuit connected between the emitter and the ground,
The second capacitance circuit may include an external voltage control circuit using a MOS capacitance element, and a capacitance value of the first capacitance circuit may be varied by supplying a control voltage signal to a gate terminal of the MOS capacitance element. Features.

An invention according to claim 14 is a temperature compensated oscillator having a structure in which a Colpitts oscillation circuit, a frequency temperature compensation circuit, and a piezoelectric vibrator are connected in series, wherein the frequency temperature compensation circuit comprises a first MOS transistor. A series circuit in which a fixed capacitance element is connected to an anode terminal of the capacitance element, and a gate terminal of the first MOS capacitance element is connected to an anode terminal of a second MOS capacitance element. A reference voltage signal having a constant voltage value is supplied to a connection point between a gate terminal and an anode terminal of the second MOS capacitance element, and a first control voltage signal is supplied to an anode terminal of the first MOS capacitance element. And providing a second control voltage signal to a gate terminal of the second MOS capacitance element.
The Colpitts oscillation circuit includes at least a first capacitance circuit connected between the base and the emitter of the transistor, and a second capacitance circuit connected between the emitter and the ground,
The second capacitance circuit may include an external voltage control circuit using a MOS capacitance element, and a capacitance value of the first capacitance circuit may be varied by supplying a control voltage signal to a gate terminal of the MOS capacitance element. Features.

  According to a fifteenth aspect of the present invention, of the MOS capacitors constituting the frequency temperature compensation circuit, a fixed capacitor is fixed in series to the first MOS capacitor, and fixed in parallel to the second MOS capacitor. It is characterized in that a capacitance element is connected.

  The invention according to claim 16 is characterized in that the polarity of each of the MOS capacitors constituting the frequency temperature compensation circuit is reversed.

  According to a seventeenth aspect of the present invention, the polarity of the frequency external voltage control circuit or the MOS capacitor constituting the external voltage control circuit is reversed. Compensated oscillator.

  An invention according to claim 18 is a frequency temperature compensation circuit for performing frequency temperature compensation by being inserted into an oscillation loop of a piezoelectric oscillator, wherein the frequency temperature compensation circuit comprises an anode of a first MOS capacitive element. A series circuit in which one terminal of a fixed capacitance element is connected to a terminal and a second MOS capacitance element are connected in parallel such that the anode terminal of the second MOS capacitance element is connected to the gate terminal of the first MOS capacitance element. And supplying a reference voltage signal having a constant voltage value to a connection point between a gate terminal of the first MOS capacitance element and an anode terminal of the second MOS capacitance element. The first control voltage signal is supplied to the anode terminal of the capacitor and the second control voltage signal is supplied to the gate terminal of the second MOS capacitor.

  The invention according to claim 19 is characterized in that the polarity of each of the MOS capacitors constituting the frequency temperature compensation circuit is reversed.

  According to a twentieth aspect of the present invention, a primary temperature compensating variable capacitance element is connected in series with the frequency temperature compensating circuit, and a voltage from a primary temperature compensating voltage source whose voltage changes linearly with temperature is supplied. The voltage is applied to the primary temperature compensating variable capacitance element.

  As described above, in the temperature compensated oscillator using the compensation principle disclosed in Japanese Patent Application Laid-Open No. 2001-60828, various circuit configurations using MOS capacitance elements are proposed while pursuing further miniaturization and lower cost. As a result, it has become possible to realize a temperature-compensated oscillator that can meet more required specifications.

Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.
FIG. 1 is a circuit diagram showing a first embodiment of the present invention. The TCXO shown in this example has a Colpitts oscillation circuit Os1, a DC blocking fixed capacitance element C3, a temperature compensation circuit Co1, and a crystal unit X connected in series. It is an application of the invention.

In the Colpitts oscillation circuit Os1, the collector of the oscillation amplification transistor TR1 is connected to a power supply, grounded at a high frequency via a bypass capacitor Cc, and the base is appropriately biased by resistors R1 and R2. , A first fixed capacitor C1 is connected, an emitter resistor Re and a second fixed capacitor C2 are connected in parallel between the emitter and the ground, and the oscillation output is supplied from the emitter to the DC blocking fixed capacitor Co. Is configured to be taken out through the device. Further, a temperature compensating circuit Co1 and a crystal resonator X are connected to the base of the transistor TR1 via a DC blocking fixed capacitance element C3.
The temperature compensation circuit Co1 is composed of a series connection circuit of a low-temperature part compensation MOS capacitance element ML and a sensitivity adjustment fixed capacitance element C4, and a parallel connection of a high-temperature part compensation MOS capacitance element MH. The capacitance element ML and the high-temperature MOS capacitance element MH have different polarities.

  Further, a low-temperature section control voltage signal VL is supplied via an input resistor R4 to a connection point between the anode terminal side of the low-temperature MOS capacitance element ML and the fixed capacitance element C4. The high-temperature section control voltage signal VH is supplied to the gate terminal via the input resistor R5. A reference voltage signal Vref is supplied to the gate terminal of the low-temperature MOS capacitor ML and the anode terminal of the high-temperature MOS capacitor MH via the input resistor R6.

  Since the operation of the Colpitts oscillation circuit Os1 is already well known, a description thereof will be omitted, and the temperature compensation circuit Co1, which is a feature of the present invention, will be described in detail. The principle of using the characteristics of the MOS capacitance element for the temperature compensation circuit is as described in the above-mentioned conventional technology. This embodiment is different from the conventional example in that the compensation circuits are arranged in parallel and the sensitivity adjustment fixed capacitor is used. The element C4 is different in that the element C4 is commonly used for the low-temperature part compensation and the high-temperature part compensation.

First, the difference between the case where each compensation circuit is connected in series and the case where they are connected in parallel will be described. Considering the nature of the series-parallel combined capacitance value, a small change in capacitance value is dominant when multiple capacitive elements are connected in series, and a large change in capacitance value is dominant when connected in parallel. Is well known. Therefore, when the MOS capacitance element having the capacitance characteristic as shown in FIG. 15 described in the prior art is used, the capacitance value of the low-temperature part compensation circuit is larger than that of the high-temperature part compensation circuit in most of the temperature range. Are connected in series, the change in capacitance of the high-temperature portion compensation circuit has a large effect, and therefore, the compensation sensitivity of the high-temperature portion tends to increase as the whole compensation circuit. Conversely, when these are connected in parallel, the change in capacitance of the low-temperature section compensation circuit has a large effect, and the low-temperature section compensation sensitivity tends to increase.
However, if the load capacitance of the entire compensation circuit is constant, connecting the low-temperature part compensation circuit and the high-temperature part compensation circuit in parallel makes it possible to design the capacitance value of each compensation circuit to be small. Accordingly, the capacitance value of each MOS capacitance element and the value of the sensitivity adjustment fixed capacitance element can be designed to be smaller than the case where they are connected in series, so that the size of the IC can be reduced. The fixed capacitance element C4 for sensitivity adjustment is connected in series to the low-temperature part compensation MOS capacitance element ML and connected in parallel to the high-temperature part compensation MOS capacitance element MH. The sensitivity adjustment in the low-temperature part and the high-temperature part described in (1) can be performed simultaneously by one capacitance element. For this reason, it is possible to eliminate one fixed capacitance element having the largest occupied area when forming an IC, and it is possible to further reduce the size of the IC.
Further, the MOS capacitance element has a characteristic that the voltage variable sensitivity deteriorates in proportion to the amplitude of the AC component superimposed on the control voltage signal. Here, when the compensating circuits are connected in parallel to shunt the AC component, the amplitude of the AC component superimposed on each control voltage signal of each MOS capacitor decreases, so that the voltage of each MOS capacitor changes. Deterioration of sensitivity can be alleviated.

Here, the bias circuit of the amplifier has been described by taking a current feedback type fixed bias circuit as an example, but the present invention is not limited to this, and a self-bias circuit or a simple fixed bias circuit may be used, and a cascode type may be used. An oscillation circuit may be used. As described above, since the MOS capacitors ML and MH have the opposite characteristics, the polarities thereof may be reversed. Here, even if the arrangement of the crystal unit X and the fixed capacitance element C3 is exchanged, or the direction of the temperature compensation circuit Co1 is reversed, the effect of this temperature compensation circuit does not change.

FIG. 2A is a circuit diagram showing a second embodiment of the present invention, in which a temperature compensation circuit Co1 and a crystal resonator X are connected in series to a Colpitts oscillation circuit Os2. This temperature compensation circuit Co1 is a parallel connection temperature compensation circuit similar to that described in the first embodiment. In this circuit diagram, the position of the DC blocking fixed capacitance element C3 is different from that of the first embodiment. That is, a connection point 1 between the bias resistors R1 and R2 connected to the base of the transistor TR1 forming the Colpitts oscillation circuit Os1 and a fixed capacitance element C1 provided on the temperature compensation circuit Co1 side from the connection point 1 A fixed capacitance element C3 for blocking the DC, that is, blocking the base bias and the DC component of each control voltage signal supplied to the temperature compensation circuit Co, is inserted between the connection point 2 to the base. It is. (For the sake of simplicity, the Colpitts oscillation circuit Os2 including the DC blocking fixed capacitance element C3 is hereinafter referred to.)
By thus removing the fixed capacitance element C3 from the load capacitance in the oscillation loop, the compensation sensitivity of the temperature compensation circuit Co1 increases, and the overall load capacitance can be designed to be small, so that the IC can be downsized.
Since the fixed capacitance element C3 is inserted between the connection point 1 between the base and the bias resistor of the transistor TR1 and the connection point 2 between the base and the fixed capacitance element C1 as described above, the base and the emitter of the transistor TR1 are connected. The capacitor Cbc is connected in series. Here, the value of the fixed capacitance element C3 is preferably as large as possible in order to input an oscillation signal to the amplifier, but it is currently assumed to be about several tens of pF in consideration of miniaturization of the IC. On the other hand, since Cbc is usually a small value of several pF, the series combined capacitance value of C3 and Cbc also becomes a small value. Therefore, the influence on the fixed capacitance element C1 connected in parallel with these is very small.
This effect is not limited to this example, and the same effect can be obtained when the temperature compensation circuit Co1 in FIG. 2A is replaced with the series temperature compensation circuit described in the related art as shown in FIG. 2B. In addition, when an external control circuit or the like to be described later is added, it is effective in a circuit configuration in which it is necessary to connect a fixed capacitance element for blocking a DC signal component such as each control voltage signal.

FIG. 3 is a circuit diagram showing a third embodiment of the present invention, in which a temperature compensation circuit Co2 and a crystal resonator X are connected in series to a Colpitts oscillation circuit Os1.
The temperature compensation circuit Co1 is composed of a series connection circuit of a low-temperature part compensation MOS capacitance element ML and a sensitivity adjustment fixed capacitance element C4, and a parallel connection of a high-temperature part compensation MOS capacitance element MH. The capacitance element ML and the high-temperature MOS capacitance element MH have different polarities.
Further, a low-temperature section control voltage signal VL is supplied via an input resistor R4 to a connection point between the anode terminal side of the low-temperature MOS capacitance element ML and the fixed capacitance element C4. The high-temperature section control voltage signal VH is supplied to the gate terminal via the input resistor R5. Here, the connection point between the gate terminal of the low-temperature MOS capacitance element ML and the anode terminal of the high-temperature MOS capacitance element MH of the temperature compensation circuit Co2 is connected to the base of the transistor TR1 which is the input of the Colpitts oscillation circuit Os1. , And a reference voltage signal. This is different from the first embodiment in that the value of the reference voltage signal Vref having a constant voltage value is set as the base bias of the transistor TR1, thereby allowing the reference voltage signal Vref and the DC blocking fixed capacitance element C3 to be connected to each other. The difference is that they have been deleted. (Hereinafter, for simplicity, the reference voltage signal Vref is deleted, and this temperature compensation circuit that does not require the DC blocking fixed capacitance element C3 is referred to as a temperature compensation circuit Co2.) This simplifies the compensation voltage signal generation circuit. In addition, power saving and downsizing of the IC become possible, and the effect of downsizing the IC due to the elimination of the fixed capacitance element C3 is great.

FIG. 4 is a circuit diagram showing a fourth embodiment of the present invention. The Colpitts oscillation circuit Os1 includes a DC blocking fixed capacitance element C3, a temperature compensation circuit Co1, a crystal oscillator X, an external control circuit Vc1, Are connected in series. The external control circuit Vc1 supplies an external control voltage signal Vafc to the gate terminal side of the MOS capacitive element MA via the input resistor R7, is connected to the crystal oscillator X, and has one anode terminal side grounded. This is different from the first embodiment in that an external control circuit Vc1 is added. If the voltage / capacity characteristics of the MOS variable element MA with high variable sensitivity and excellent linearity are used, excellent linearity can be obtained. Frequency external variable becomes possible. (Or it can be said that an AFC: Automatic Frequency Control function with excellent linearity is added.) Further, this external control circuit Vc1 is connected to the anode electrode of the MOS capacitor element like the external control circuit Vc2 shown in FIG. By supplying and adjusting the reference voltage signal Varef via the resistor R8, it is possible to use an arbitrary curve portion of the capacitance characteristic of the MOS capacitance element MA for frequency control, and to manufacture the curve of each MOS capacitance element MA. It is also possible to correct the error. Furthermore, if the configuration in which the external control circuits Vc1 and Vc2 are connected in parallel is used, the frequency can be adjusted more accurately, so that the center frequency can be finely adjusted. Here, in the manufacturing process of the IC, it is easier to manufacture the MOS capacitance element than to manufacture the fixed capacitance element. Therefore, the control voltage signals supplied to both terminals of the external control circuits Vc1 and Vc2 are each set to a constant voltage. Alternatively, by setting one terminal to a constant voltage and grounding the other terminal, the MOS capacitance element MA can be used as a fixed capacitance element. Further, even when the temperature compensation circuit Co1 in FIG. 4 is the series temperature compensation circuit described in the related art as shown in FIG.

FIG. 6 is a circuit diagram showing a fifth embodiment of the present invention. In the Colpitts oscillation circuit Os1, an external control circuit Vc1, a DC blocking fixed capacitance element C5, a temperature compensation circuit Co1, a quartz oscillator X Are connected in series. This supplies the base bias of the transistor TR1 as a reference voltage signal to the anode terminal of the MOS capacitance element MA, and has an adjustment function like the external control circuit Vc2. There is an effect of eliminating the element C3. Further, even when the temperature compensation circuit Co1 in FIG. 5 is the series temperature compensation circuit described in the related art as shown in FIG. Attention is now paid to the voltage applied to both ends of the crystal unit X having this configuration. In FIG. 4 of the fourth embodiment, the reference voltage signal Vref of the temperature compensation circuit is applied to both ends of the crystal unit X. And an external control voltage signal Vafc are applied. Since the voltage of the external control voltage signal Vafc is individually set at the time of use at the customer, the voltage applied to both ends of the crystal unit X is not determined at the time of design. On the other hand, in the case of FIG. 6 of the fifth embodiment (and FIGS. 1 and 2 described above), the crystal resonator X is inserted between the reference voltage signal Vref of the temperature compensation circuit and the ground. Here, assuming that the reference voltage signal number Vref is set to several volts, a voltage of several volts is applied to both ends of the crystal oscillator X when the power supply of the TCXO is turned on. Has the effect of increasing the start-up characteristics of the oscillation circuit, and has the effect of always being stabilized irrespective of the value of the external control voltage signal Vafc. This effect is not limited to this example, and the oscillation circuit, the temperature compensation circuit, the crystal unit, and the external control circuit are connected to each other when the voltage applied to both ends of the crystal unit is turned on within a range where the DC signals do not interfere with each other. What is necessary is just to arrange so that it may become a high and stable value. For example, it is assumed that the high-temperature part control voltage signal VH and the low-temperature part control voltage signal VL of this temperature compensation circuit are set to be almost 0 V in a temperature range near room temperature. On the other hand, when the reference voltage signal Varef of the external control circuit Vc2 shown in FIG. 5A is designed to be several volts, the high-temperature section control voltage signal VH or the low-temperature section control voltage signal VL and the external control circuit Vc2 If the circuit arrangement is such that the crystal resonator X is inserted between the reference voltage signal Varef and the reference voltage signal Varef, the same effect as described above can be expected in a temperature range near room temperature.

FIG. 7 is a circuit diagram showing a sixth embodiment of the present invention. In the Colpitts oscillation circuit Os1, a DC blocking fixed capacitance element C3, a temperature compensation circuit Co1, an external control circuit Vc2, a quartz oscillator X Are connected in series. The configurations of the Colpitts oscillation circuit Os1, the external control circuit Vc2, and the temperature compensation circuit Co1 are as described above. The anode electrode of the MOS capacitance element MA of the external control circuit Vc2 is connected to the MOS capacitance element ML of the temperature compensation circuit Co1. The reference voltage signal Vref of the temperature compensation circuit Co1 is supplied by connecting to the connection point between the gate electrode of the MH and the anode electrode of the MH. The control voltage signal Vafc is supplied and connected to the crystal unit X. This is different from the fourth embodiment in that the reference voltage signal Varef of the external control circuit Vc2 is adjusted to the reference voltage signal Vref of the temperature compensation circuit Co1 and shared. This makes it possible to delete one reference voltage signal supplied to the external control circuit or the temperature compensation circuit.

FIG. 8 is a circuit diagram showing a seventh embodiment of the present invention. In the Colpitts oscillation circuit Os1, a series connection circuit of an external control circuit Vc1 and a DC blocking fixed capacitance element C5, and a temperature compensation circuit Co2 are connected in parallel. The connected circuits are connected, and a crystal resonator X is further connected in series. The configurations of the external control circuit Vc1 and the temperature compensation circuit Co2 are as described above. The anode electrode of the MOS capacitance element MA of the external control circuit Vc1 is connected to the gate electrode of the MOS capacitance element ML of the temperature compensation circuit Co2 and the anode electrode of the MH. , And further connected to the base of a transistor TR1 which is an input of the Colpitts oscillation circuit Os1. This is made possible by adjusting both the reference voltage signal Vref of the temperature compensation circuit Co2 and the reference voltage signal Varef of the external control circuit Vc1 to be equal to the base bias of the transistor TR1. With this configuration, it is possible to eliminate the two reference voltage signals of the temperature compensation circuit Co2 and the external control circuit Vc1, and the two DC blocking fixed capacitance elements. This configuration has the effect of lowering the load capacitance value of the entire oscillation loop as compared with the case where the external control circuit Vc1 is connected in series with the temperature compensation circuit Co2 as in the fourth and fifth embodiments. As a result, the values of the MOS capacitors and fixed capacitors of the temperature compensation circuit Co2 and the external control circuit Vc1 can be reduced, and the size of the IC can be reduced. Further, as described in the first embodiment, by connecting the respective circuits in parallel, the AC components flowing through the respective MOS capacitance elements are shunted, so that the AC components superimposed on the respective control voltage signals are obtained. Is reduced, it is possible to alleviate the deterioration of the voltage variable sensitivity of each MOS capacitor. Also, here, the parallel circuit of the temperature compensation circuit Co2 and the external control circuit Vc1 has been described. However, the temperature compensation circuit Co2 may be a series compensation circuit shown in FIG. The external control circuit Vc2 also has the effect of the above-described parallel connection, that is, the effect of reducing the load capacitance value of the entire oscillation loop, and the effect of alleviating the deterioration of the voltage variable sensitivity of each MOS capacitor.

FIG. 9A is a circuit diagram showing an eighth embodiment of the present invention, in which a Colpitts oscillation circuit Os3, that is, a MOS capacitance element forming an external control circuit Vc1 in place of the fixed capacitance element C1 of the Colpitts oscillation circuit Os2. The MA is arranged, and the crystal unit X, the temperature compensation circuit Co1, and the DC blocking fixed capacitance element C5 are connected in series. As in the Colpitts oscillation circuit Os2 described in the second embodiment, the Colpitts oscillation circuit Os3 has a DC blocking fixed capacitance element C3 incorporated therein. Further, in this embodiment, instead of the fixed capacitance element C1 of the Colpitts oscillation circuit described in the second embodiment, the MOS capacitance element MA is connected to the gate electrode between the resonator X and the DC blocking fixed capacitance element C3. Inserted in the direction to connect to the point. An external control voltage signal Vafc is supplied to the gate electrode via an input resistor R7, and the frequency can be adjusted and the negative resistance of the Colpitts oscillation circuit Os3 can be adjusted. This is an effective means when using quartz oscillators of different frequency bands in the same IC. On the other hand, since the anode electrode of this MOS capacitance element MA is connected to the emitter of transistor TR1, the reference voltage of this MOS capacitance element MA can be adjusted within the range in which the emitter voltage can be adjusted. It is also possible to use a capacitance characteristic curve. FIG. 9B is a diagram when Vref of the temperature compensation circuit Co1 shown in FIG. 9A is set to 0 V, and a connection point between the low-temperature section control voltage signal VL and the high-temperature section control voltage signal VH is grounded. is there. This makes it possible to eliminate the fixed capacitance element C5, the input resistance R6, and the reference voltage signal Vref.

FIG. 10 is a circuit diagram showing a ninth embodiment of the present invention, in which a Colpitts oscillation circuit Os4, that is, a MOS capacitance element MA constituting an external control circuit Vc1 is arranged in place of the fixed capacitance element C2 of the Colpitts oscillation circuit Os2. In addition, the temperature compensation circuit Co1 and the crystal resonator X are connected in series. As in the second embodiment, the Colpitts oscillation circuit Os4 has a DC blocking fixed capacitance element C3 incorporated therein. Further, in this embodiment, instead of the fixed capacitance element C2 of the Colpitts oscillation circuit described in the second embodiment, a MOS capacitance element MA is inserted so that its anode electrode is connected to the emitter of the transistor TR1. The gate electrode is supplied with an external control voltage signal Vafc via an input resistor R7 and is grounded via a DC blocking fixed capacitance element C5. This has the same effect as that of the eighth embodiment, that is, the frequency can be adjusted, and the negative resistance of the Colpitts oscillation circuit Os2 can be adjusted. This is an effective means when used with the same IC. Also in this case, since the anode electrode of the MOS capacitor MA is connected to the emitter of the transistor TR1, if the reference voltage of the MOS capacitor MA is adjusted within a range where the emitter voltage can be adjusted, an arbitrary capacitance characteristic curve can be used. It is also possible.

FIG. 11 is a circuit diagram showing a tenth embodiment of the present invention, in which a Colpitts oscillation circuit Os5, that is, a MOS capacitance element MA forming an external control circuit Vc1 is arranged in place of the fixed capacitance element C2 of the Colpitts oscillation circuit Os2. In addition, the temperature compensation circuit Co1 and the crystal resonator X are connected in series. The Colpitts oscillation circuit Os5 has a DC blocking fixed capacitance element C3 incorporated therein similarly to the one described in the second embodiment. In this embodiment, similarly to the ninth embodiment, a MOS capacitance element MA is inserted instead of the fixed capacitance element C2 of the Colpitts oscillation circuit in such a direction that its anode electrode is connected to the emitter of the transistor TR1. . The gate electrode is supplied with an external control voltage signal Vafc via an input resistor R7, and is grounded via a DC blocking fixed capacitance element C5, and further connected to a temperature compensation circuit Co1 of the crystal unit X. Connected to the terminal on the opposite side of the terminal. This has the same effect as that of the eighth embodiment, that is, the frequency can be adjusted and the negative resistance of the Colpitts oscillation circuit Os5 can be adjusted. Is an effective means when using the same IC. Also in this case, since the anode electrode of the MOS capacitor MA is connected to the emitter of the transistor TR1, if the reference voltage of the MOS capacitor MA is adjusted within a range where the emitter voltage can be adjusted, an arbitrary capacitance characteristic curve can be used. It is also possible. This embodiment differs from the eighth embodiment in that the DC blocking fixed capacitance element C5 is removed from the oscillation loop, and as a result, the overall load capacitance can be reduced. It is possible to reduce the size of the IC by reducing the values of the MOS capacitor and the fixed capacitor.

  In the eighth, ninth and tenth embodiments, only the parallel temperature compensation circuit Co1 is used as the capacitance circuit in the oscillation loop, except for the capacitance circuits included in the Colpitts oscillation circuits Os3, Os4 and Os5 as described above. As described above, this may be replaced with the series temperature compensation circuit shown in FIG. 2B, or a capacitance circuit in which the above-mentioned external control circuit Vc1 or Vc2 is arbitrarily connected in series or parallel to these temperature compensation circuits. However, the effect of the Colpitts oscillation circuits Os3, Os4, and Os5 as described above does not change. In the first to tenth embodiments, the direction of the polarity of each MOS capacitance element is an example, and the same effect can be obtained even when the direction is reversed depending on the capacitance / voltage characteristics of the MOS capacitance element. Can be

By the way, the description has been made so far on the case where the temperature-frequency characteristic has a relatively gentle gradient near normal temperature as shown in FIG. 14, but the temperature-frequency characteristic near normal temperature as shown in FIG. In some cases, a steeply changing crystal oscillator must be used.
At this time, a situation may occur in which the above-described temperature compensation circuit alone cannot completely compensate for the gradient of the temperature-frequency characteristic near room temperature, that is, the primary component.
Therefore, as shown in FIG. 19A, a primary temperature compensating variable capacitance element M1 (in this example, a MOS capacitance element is used) is connected in series between the temperature compensation circuit Co1 and the crystal unit X. By supplying a voltage Vf from a primary temperature compensation voltage source (not shown) whose voltage changes linearly with temperature, even if the temperature-frequency characteristic changes sharply near normal temperature, this is compensated. It was possible to do.
At this time, the voltage Vf changes linearly with respect to the temperature as shown in FIG. 19B, and the primary component of the temperature-frequency characteristic is compensated based on the relationship between the voltage Vf and the oscillation frequency shown in FIG. Can be.
The circuit of FIG. 19A is a modification of the circuit of FIG. 1, but the same effect can be obtained by applying the compensation using the primary temperature compensating variable capacitance element M1 to other embodiments. Can be
Further, the variable capacitor M1 for primary temperature compensation may be shared with the MOS capacitor MA for frequency adjustment shown in FIGS. 4 to 11, and in this case, the voltage for frequency adjustment and the primary component are used. May be added and applied.
Further, an AFC circuit may be combined with the primary temperature compensation voltage source to supply a frequency control voltage from outside the oscillator.
If the slope of the primary component is up to about ± 0.2 ppm / ° C., the slope of the voltage Vf for compensating the primary component can be suppressed to a small value. It is not necessary to increase the noise, and the generation of noise can be reduced, so that the phase noise hardly deteriorates.

First embodiment of the present invention Second embodiment of the present invention Third embodiment of the present invention Fourth embodiment of the present invention Application of the fourth embodiment of the present invention Fifth embodiment of the present invention Sixth embodiment of the present invention Seventh embodiment of the present invention Eighth embodiment of the present invention Ninth embodiment of the present invention Tenth embodiment of the present invention Example of conventional series compensation circuit Example of conventional indirect compensation circuit Example of temperature characteristics of crystal unit Example of voltage / capacitance characteristics of MOS capacitive element Illustration of utilization of MOS capacitance element for temperature compensation Conventional example of temperature compensated oscillator using MOS capacitance element Examples of other temperature characteristics of crystal units Modification of the first embodiment of the present invention

Explanation of reference numerals

C1, C2, C3, C4, C5, Co, Cc, C: fixed capacitance element, R1, R2, R3, R4, R5, R6, R7, R8, Re, R: fixed resistance element, ML, MH, MA, M1: MOS capacitance element, VL, VH, Vref, Varef: control voltage signal, Vcc: power supply, OUT: output terminal, TR1: transistor, X: crystal Vibrator.

Claims (20)

  A temperature-compensated oscillator having a structure in which an oscillation circuit, a DC blocking fixed capacitance element, a frequency temperature compensation circuit, and a piezoelectric vibrator are connected in series, wherein the frequency temperature compensation circuit is a first MOS capacitance element A series circuit in which one terminal of the fixed capacitance element is connected to the anode terminal of the second MOS capacitance element and the second MOS capacitance element are connected such that the anode terminal of the second MOS capacitance element is connected to the gate terminal of the first MOS capacitance element. A parallel circuit connected in parallel, supplying a reference voltage signal having a constant voltage value to a connection point between a gate terminal of the first MOS capacitance element and an anode terminal of the second MOS capacitance element; A first control voltage signal is supplied to an anode terminal of the MOS capacitance element, and a second control voltage signal is supplied to a gate terminal of the second MOS capacitance element. Oscillator. A temperature-compensated oscillator having a structure in which a Colpitts oscillation circuit, a frequency temperature compensation circuit, and a piezoelectric vibrator are connected in series,
The frequency temperature compensation circuit includes a series circuit in which one terminal of a fixed capacitance element is connected to an anode terminal of a first MOS capacitance element, and a second MOS capacitance element. A parallel circuit is connected in parallel so as to be connected to the gate terminal of the first MOS capacitor, and a voltage value is applied to a connection point between the gate terminal of the first MOS capacitor and the anode terminal of the second MOS capacitor. A constant reference voltage signal is supplied, a first control voltage signal is supplied to an anode terminal of the first MOS capacitance element, and a second control voltage signal is supplied to a gate terminal of the second MOS capacitance element. It has a configuration to
The Colpitts oscillation circuit includes at least a transistor and a bias circuit for supplying a bias voltage to a base of the transistor. One terminal is connected to a connection point between the base of the transistor and the bias circuit, and ground. A DC blocking fixed capacitance element is inserted and connected between the other terminal of the series circuit including the two fixed capacitance elements,
A temperature-compensated oscillator, wherein a connection point between the series circuit composed of the two fixed capacitance elements and the DC blocking fixed capacitance element is connected to the frequency temperature compensation circuit. A temperature compensated oscillator having a structure in which a Colpitts oscillation circuit, a frequency temperature compensation circuit, and a piezoelectric vibrator are connected in series, wherein the frequency temperature compensation circuit has a fixed capacitance element connected to an anode terminal of a first MOS capacitance element. And a series circuit in which the gate terminal of the first MOS capacitor is connected to the anode terminal of the second MOS capacitor. The gate terminal of the first MOS capacitor is connected to the second MOS capacitor. A reference voltage signal having a constant voltage value is supplied to a connection point of the element with the anode terminal, a first control voltage signal is supplied to the anode terminal of the first MOS capacitance element, and the second MOS capacitance element is supplied. And a configuration for supplying a second control voltage signal to the gate terminal of
The Colpitts oscillation circuit includes at least a transistor and a bias circuit for supplying a bias voltage to a base of the transistor. One terminal is connected to a connection point between the base of the transistor and the bias circuit, and ground. A DC blocking fixed capacitance element is inserted and connected between the other terminal of the series circuit including the two fixed capacitance elements,
A temperature-compensated oscillator, wherein a connection point between the series circuit composed of the two fixed capacitance elements and the DC blocking fixed capacitance element is connected to the frequency temperature compensation circuit.   An oscillation circuit, a frequency temperature compensation circuit, and a piezoelectric vibrator, a temperature-compensated oscillator having a structure in which the oscillation circuit includes a transistor and a bias for supplying a bias voltage to a base of the transistor. At least one of a series circuit in which one terminal of a fixed capacitance element is connected to an anode terminal of a first MOS capacitance element, and a second MOS capacitance element. A parallel circuit in which an anode terminal of the capacitor is connected in parallel so as to be connected to a gate terminal of the first MOS capacitor; a first control voltage signal is supplied to an anode terminal of the first MOS capacitor; A second control voltage signal is supplied to a gate terminal of the second MOS capacitor; and a gate terminal of the first MOS capacitor is connected to the second terminal. Temperature compensation oscillator, characterized by being configured to provide a bias voltage signal of the bias circuit constituting the oscillator circuit to a connection point between the anode terminal of the OS capacitive element. An oscillation circuit, a frequency temperature compensation circuit, a piezoelectric vibrator, and a frequency external voltage control circuit, a temperature-compensated oscillator having a structure connected in series,
The frequency temperature compensation circuit includes a series circuit in which one terminal of a fixed capacitance element is connected to an anode terminal of a first MOS capacitance element, and a second MOS capacitance element. A parallel circuit is connected in parallel so as to be connected to the gate terminal of the first MOS capacitor, and a voltage value is applied to a connection point between the gate terminal of the first MOS capacitor and the anode terminal of the second MOS capacitor. A constant reference voltage signal is supplied, a first control voltage signal is supplied to an anode terminal of the first MOS capacitance element, and a second control voltage signal is supplied to a gate terminal of the second MOS capacitance element. It has a configuration to
A configuration in which the frequency external voltage control circuit supplies an external control voltage signal to the gate terminal of the MOS capacitor, or a reference that supplies an external control voltage signal to the gate terminal of the MOS capacitor and has a constant voltage value to the anode terminal. A temperature-compensated oscillator having a configuration for supplying a voltage signal. An oscillator having a structure in which an oscillation circuit, a frequency temperature compensation circuit, a piezoelectric vibrator, and a frequency external voltage control circuit are connected in series, wherein the frequency temperature compensation circuit includes a first MOS capacitance element. A series circuit in which a fixed capacitance element is connected to an anode terminal, and a gate terminal of the first MOS capacitance element is connected to an anode terminal of a second MOS capacitance element. Supplying a reference voltage signal having a constant voltage value to a connection point of the second MOS capacitance element with the anode terminal, supplying a first control voltage signal to the anode terminal of the first MOS capacitance element, A configuration for supplying a second control voltage signal to the gate terminal of the second MOS capacitance element;
A configuration in which the frequency external voltage control circuit supplies an external control voltage signal to the gate terminal of the MOS capacitor, or a reference that supplies an external control voltage signal to the gate terminal of the MOS capacitor and has a constant voltage value to the anode terminal. A temperature-compensated oscillator having a configuration for supplying a voltage signal. An oscillation circuit, a frequency external voltage control circuit, a fixed capacitance element, a frequency temperature compensation circuit, and a temperature-compensated oscillator having a structure in which a piezoelectric vibrator is connected in series, wherein the oscillation circuit includes a transistor, At least a bias circuit for supplying a bias voltage to the base of the transistor,
The frequency temperature compensation circuit includes a series circuit in which one terminal of a fixed capacitance element is connected to an anode terminal of a first MOS capacitance element, and a second MOS capacitance element. A parallel circuit is connected in parallel so as to be connected to the gate terminal of the first MOS capacitor, and a voltage value is applied to a connection point between the gate terminal of the first MOS capacitor and the anode terminal of the second MOS capacitor. A constant reference voltage signal is supplied, a first control voltage signal is supplied to an anode terminal of the first MOS capacitance element, and a second control voltage signal is supplied to a gate terminal of the second MOS capacitance element. The frequency external voltage control circuit supplies an external control voltage signal to a gate terminal of a MOS capacitive element and connects the anode terminal to the oscillation circuit. Temperature compensation oscillator, characterized in that it has supplied a bias voltage signal transistor.   An oscillation circuit, a frequency external voltage control circuit, a fixed capacitance element, a frequency temperature compensation circuit, and a temperature-compensated oscillator having a structure in which a piezoelectric vibrator is connected in series, wherein the oscillation circuit includes a transistor, A bias circuit for supplying a bias voltage to a base of the transistor, wherein the frequency temperature compensation circuit connects a fixed capacitance element to an anode terminal of the first MOS capacitance element; The gate terminal of the element is a series circuit in which the anode terminal of the second MOS capacitance element is connected, and a voltage is applied to a connection point between the gate terminal of the first MOS capacitance element and the anode terminal of the second MOS capacitance element. A reference voltage signal having a constant value is supplied, a first control voltage signal is supplied to an anode terminal of the first MOS capacitor, and a gate of the second MOS capacitor is supplied. The frequency external voltage control circuit supplies an external control voltage signal to a gate terminal of a MOS capacitance element and connects the anode terminal to the oscillation circuit. A bias voltage signal for the transistor is supplied. An oscillation circuit, a fixed capacitance element, a parallel circuit in which a frequency temperature compensation circuit and a frequency external voltage control circuit are connected in parallel, or a series circuit in which the frequency temperature compensation circuit and the frequency external voltage control circuit are connected in series; And a temperature-compensated oscillator having a structure in which
The frequency temperature compensation circuit includes a series circuit in which one terminal of a fixed capacitance element is connected to an anode terminal of a first MOS capacitance element, and a second MOS capacitance element. A parallel circuit is connected in parallel so as to be connected to the gate terminal of the first MOS capacitor, and a voltage value is applied to a connection point between the gate terminal of the first MOS capacitor and the anode terminal of the second MOS capacitor. A constant reference voltage signal is supplied, a first control voltage signal is supplied to an anode terminal of the first MOS capacitance element, and a second control voltage signal is supplied to a gate terminal of the second MOS capacitance element. The frequency external voltage control circuit supplies an external control voltage signal to a gate terminal of a MOS capacitance element, and the first M of the frequency temperature compensation circuit to an anode terminal. By connecting the connection point between the anode terminal of the gate terminal and the second MOS capacitance element of S capacitance element, the temperature compensation oscillator is characterized in that supplies the reference voltage signal of the frequency temperature compensation circuit. An oscillation circuit, a parallel circuit in which a frequency temperature compensation circuit and a frequency external voltage control circuit are connected in parallel, and a piezoelectric vibrator, a temperature-compensated oscillator having a structure in which the oscillation circuit is connected in series, wherein the oscillation circuit includes a transistor, A bias circuit for supplying a bias voltage to the base of the transistor,
The frequency temperature compensation circuit includes a series circuit in which one terminal of a fixed capacitance element is connected to an anode terminal of a first MOS capacitance element, and a second MOS capacitance element. A parallel circuit connected in parallel so as to be connected to a gate terminal of the first MOS capacitor, supplying a first control voltage signal to an anode terminal of the first MOS capacitor, A second control voltage signal supplied to a gate terminal, wherein the frequency external voltage control circuit supplies an external control voltage signal to a gate terminal of a MOS capacitor, and the frequency temperature compensation circuit supplies an anode terminal to the anode terminal. Connecting a connection point between a gate terminal of the first MOS capacitance element and an anode terminal of the second MOS capacitance element of the circuit, and further connecting the connection point to the oscillation circuit; Temperature compensation oscillator, characterized in that it has supplied a bias voltage signal of the transistor Ri. A Colpitts oscillation circuit, a piezoelectric vibrator, a frequency temperature compensation circuit, and a fixed capacitance element, a temperature-compensated oscillator having a structure connected in series,
The frequency temperature compensation circuit includes a series circuit in which one terminal of a fixed capacitance element is connected to an anode terminal of a first MOS capacitance element, and a second MOS capacitance element. A parallel circuit is connected in parallel so as to be connected to the gate terminal of the first MOS capacitor, and a voltage value is applied to a connection point between the gate terminal of the first MOS capacitor and the anode terminal of the second MOS capacitor. A constant reference voltage signal is supplied, a first control voltage signal is supplied to an anode terminal of the first MOS capacitance element, and a second control voltage signal is supplied to a gate terminal of the second MOS capacitance element. It has a configuration to
The Colpitts oscillation circuit includes at least a first capacitance circuit connected between the base and the emitter of the transistor, and a second capacitance circuit connected between the emitter and the ground,
The first capacitance circuit includes an external voltage control circuit using a MOS capacitance element, and a capacitance value of the first capacitance circuit can be varied by supplying a control voltage signal to a gate terminal of the MOS capacitance element. Characteristic temperature compensated oscillator. A temperature-compensated oscillator having a structure in which a Colpitts oscillation circuit, a piezoelectric vibrator, a frequency temperature compensation circuit, and a fixed capacitance element are connected in series, wherein the frequency temperature compensation circuit comprises an anode of a first MOS capacitance element. A fixed capacitance element is connected to a terminal, and a gate terminal of the first MOS capacitance element is a series circuit connected to an anode terminal of a second MOS capacitance element, wherein the gate terminal of the first MOS capacitance element is connected to the gate terminal of the first MOS capacitance element. A reference voltage signal having a constant voltage value is supplied to a connection point with the anode terminal of the second MOS capacitance element, and a first control voltage signal is supplied to an anode terminal of the first MOS capacitance element. A second control voltage signal is supplied to the gate terminal of the second MOS capacitor.
The Colpitts oscillation circuit includes at least a first capacitance circuit connected between the base and the emitter of the transistor, and a second capacitance circuit connected between the emitter and the ground,
The first capacitance circuit includes an external voltage control circuit using a MOS capacitance element, and a capacitance value of the first capacitance circuit can be varied by supplying a control voltage signal to a gate terminal of the MOS capacitance element. Characteristic temperature compensated oscillator. A temperature-compensated oscillator having a structure in which a Colpitts oscillation circuit, a frequency temperature compensation circuit, and a piezoelectric vibrator are connected in series,
The frequency temperature compensation circuit includes a series circuit in which one terminal of a fixed capacitance element is connected to an anode terminal of a first MOS capacitance element, and a second MOS capacitance element. A parallel circuit is connected in parallel so as to be connected to the gate terminal of the first MOS capacitor, and a voltage value is applied to a connection point between the gate terminal of the first MOS capacitor and the anode terminal of the second MOS capacitor. A constant reference voltage signal is supplied, a first control voltage signal is supplied to an anode terminal of the first MOS capacitance element, and a second control voltage signal is supplied to a gate terminal of the second MOS capacitance element. It has a configuration to
The Colpitts oscillation circuit includes at least a first capacitance circuit connected between the base and the emitter of the transistor, and a second capacitance circuit connected between the emitter and the ground,
The second capacitance circuit may include an external voltage control circuit using a MOS capacitance element, and a capacitance value of the first capacitance circuit may be varied by supplying a control voltage signal to a gate terminal of the MOS capacitance element. Characteristic temperature compensated oscillator. A temperature compensated oscillator having a structure in which a Colpitts oscillation circuit, a frequency temperature compensation circuit, and a piezoelectric vibrator are connected in series, wherein the frequency temperature compensation circuit has a fixed capacitance element connected to an anode terminal of a first MOS capacitance element. And a series circuit in which the gate terminal of the first MOS capacitor is connected to the anode terminal of the second MOS capacitor. The gate terminal of the first MOS capacitor is connected to the second MOS capacitor. A reference voltage signal having a constant voltage value is supplied to a connection point of the element with the anode terminal, a first control voltage signal is supplied to the anode terminal of the first MOS capacitance element, and the second MOS capacitance element is supplied. And a configuration for supplying a second control voltage signal to the gate terminal of
The Colpitts oscillation circuit includes at least a first capacitance circuit connected between the base and the emitter of the transistor, and a second capacitance circuit connected between the emitter and the ground,
The second capacitance circuit may include an external voltage control circuit using a MOS capacitance element, and a capacitance value of the first capacitance circuit may be varied by supplying a control voltage signal to a gate terminal of the MOS capacitance element. Characteristic temperature compensated oscillator.   A fixed capacitance element is connected in series to the first MOS capacitance element and a fixed capacitance element is connected in parallel to the second MOS capacitance element among the MOS capacitance elements constituting the frequency temperature compensation circuit. The temperature-compensated oscillator according to any one of claims 1 to 14, wherein:   15. The temperature compensated oscillator according to claim 1, wherein the polarity of each of the MOS capacitors constituting the frequency temperature compensation circuit is reversed.   15. The temperature-compensated oscillator according to claim 5, wherein the polarity of the frequency external voltage control circuit or the MOS capacitor constituting the external voltage control circuit is reversed.   A frequency temperature compensation circuit for performing frequency temperature compensation by being inserted and connected into an oscillation loop of a piezoelectric oscillator, wherein the frequency temperature compensation circuit connects one terminal of a fixed capacitance element to an anode terminal of a first MOS capacitance element. A parallel circuit in which the connected series circuit and the second MOS capacitor are connected in parallel such that the anode terminal of the second MOS capacitor is connected to the gate terminal of the first MOS capacitor; A reference voltage signal having a constant voltage value is supplied to a connection point between the gate terminal of the MOS capacitance element and the anode terminal of the second MOS capacitance element, and the first voltage is supplied to the anode terminal of the first MOS capacitance element. A frequency temperature compensation circuit, comprising: a configuration for supplying a control voltage signal and a second control voltage signal to a gate terminal of the second MOS capacitance element.   19. The frequency temperature compensation circuit according to claim 18, wherein the polarity of each of the MOS capacitors constituting the frequency temperature compensation circuit is reversed. A primary temperature compensating variable capacitance element is connected in series with the frequency temperature compensating circuit, and a voltage from a primary temperature compensating voltage source whose voltage changes linearly with temperature is applied to the primary temperature compensating variable capacitance element. 18. The temperature-compensated oscillator according to claim 1, wherein the temperature-compensated oscillator is applied.

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