JP2008028804A - Impedance circuit and signal generation circuit using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a circuit which obtains a stable frequency or a delay element when a reference frequency is obtained. <P>SOLUTION: A switchover device 5 alternately selects, in chronologic order, a first oscillation circuit 6 composed of a first impedance circuit 1 with a first temperature variation rate and a first active circuit 3, and a second oscillation circuit 7 composed of a second impedance circuit 2 with a second temperature variation rate with an opposite variation direction to that of the first temperature variation rate and a second active circuit 4. When an absolute value of a temperature coefficient of the first impedance circuit 1 is larger than a temperature coefficient of the second impedance circuit 2, an operating time of the first oscillation circuit 6 is reduced, and the rate of the operation time of the oscillation circuit is set with a rate opposite to that of the temperature coefficient so that the operating time of the second oscillation circuit 7 whose temperature coefficient is small, operates long. Since two temperature coefficients exist whose temperature variation directions are opposite, temperature variation as an average is almost removed or extremely reduced. An oscillation frequency is obtained in which the temperature variation is quite small as a time average and the temperature variation rate is improved. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an impedance circuit used in a semiconductor integrated circuit or an electric signal processing system and related to generation of a reference frequency signal, and a signal generation circuit using the impedance circuit.

  In recent semiconductor integrated circuit devices, both miniaturization and high accuracy are required. Trimming technology or the like is used as means for increasing the accuracy of circuit characteristics. Parameters that contribute to characteristics can be adjusted by trimming or the like by providing an adjustment circuit or the like. Regarding temperature fluctuations, temperature fluctuations in amplifiers and the like whose gain is determined by the ratio of the two resistors are eliminated, but some time constant (for example, resistance (R), capacitor (L), coil (C)) is obtained. In many cases, the absolute value of the element appears directly in the time constant. This absolute value can be corrected by the above-mentioned techniques such as trimming, but it is extremely difficult to stabilize the temperature fluctuation of the absolute value, and even if it is realized, the scale of the circuit for stabilization Is a large scale that cannot be neglected.

Patent Document 1 proposes a temperature compensated crystal oscillator including a compensation circuit for stabilizing the output frequency of the crystal oscillator over a desired temperature range.
Japanese Patent Laid-Open No. 11-220327

  However, when the performance specifications as a semiconductor integrated circuit device are severe, the standard value of the characteristic at the standard temperature can be adjusted by trimming or the like, but the temperature variation cannot be designed so as not to depend on the temperature in circuit design. In this case, a separate guarantee circuit is required, which is accompanied by undesirable phenomena such as an increase in chip area, an increase in power consumption, and a slowdown in circuit response.

  When the circuit design is inevitable or difficult to design, the absolute value variation of the characteristics can be adjusted by an external system using calibration, a variation correction data table, or feedback control based on the reference value. . However, for temperature fluctuations, a temperature detection circuit is required and correction can be made for the entire time by the feedback control. However, the feedback control is optimal because of the detection and confirmation method of the desired characteristics, stability and responsiveness. Absent.

  Even if temperature compensation is performed in the internal circuit under such circumstances, low power consumption is required, and in the integrated circuit of a small-scale system, mounting of the temperature compensation circuit causes a serious specification down. .

  The present invention is directed to quickly solving these complicated problems when obtaining a reference frequency, and an impedance circuit capable of obtaining a stable frequency or delay element and signal generation using the same An object is to provide a circuit.

  In order to achieve the above object, an impedance circuit according to claim 1 of the present invention includes a first impedance circuit having a time constant or a resonance frequency having a first temperature variation rate, and a first temperature variation. And a second impedance circuit having a time constant or a resonance frequency having a second temperature variation rate in a direction opposite to the rate of variation, and the first and second temperatures of the first and second impedance circuits. By adjusting the usage ratio of the first and second impedance circuits according to the fluctuation rate, the temperature fluctuation rate is obtained as an average value from the first and second temperature fluctuation rates, and the first and second temperature circuits are obtained. The impedance circuit is switched.

  An impedance circuit according to a second aspect is the impedance circuit according to the first aspect, further comprising a temperature detector for detecting an environmental temperature in which the first and second impedance circuits are placed, The temperature fluctuation rate is averaged from the first and second temperature fluctuation rates by adjusting the usage ratio of the first and second impedance circuits according to the first and second temperature fluctuation rates of the two impedance circuits. When the values are obtained as values, when the first and second temperature fluctuation rates are non-linear with respect to the temperature, the adjustment amount of the usage ratio of the first and second impedance circuits is changed according to the output of the temperature detector. And switching between the first and second impedance circuits.

  According to a third aspect of the present invention, there is provided a signal generation circuit comprising: an impedance circuit comprising the first and second impedance circuits according to the first aspect; a first oscillation circuit that oscillates using the first impedance circuit; A second oscillation circuit that oscillates using two impedance circuits, a switch that alternately switches between the first and second oscillation circuits, and a usage ratio of the first and second oscillation circuits to adjust the first usage ratio. And a control circuit for controlling the switch so as to obtain the temperature fluctuation rate as an average value from the first and second temperature fluctuation rates of the second impedance circuit.

  According to a fourth aspect of the present invention, there is provided a signal generation circuit including a first impedance circuit including the first and second impedance circuits and a temperature detector according to the second aspect, and a first impedance circuit that oscillates using the first impedance circuit. Oscillation circuit, second oscillation circuit that oscillates using second impedance circuit, switcher that alternately switches between first and second oscillation circuits, and adjustment ratio of use of first and second oscillation circuits When the first and second temperature fluctuation rates of the first and second impedance circuits are nonlinear with respect to the temperature, the usage ratio adjustment amount is changed according to the output of the temperature detector. And a control circuit for controlling the switch so as to obtain the temperature fluctuation rate as an average value from the first and second temperature fluctuation rates.

  A signal generation circuit according to claims 5 and 6 is the signal generation circuit according to claims 3 and 4, wherein the counter generation circuit counts output signals from the first and second oscillation circuits instead of the control circuit. And controlling the switch according to the counting result of the counter circuit, and further comprising a time measuring device for measuring the time for outputting signals from the first and second oscillation circuits instead of the counter circuit, The switching device is controlled by the measuring time of the device.

  According to a seventh aspect of the present invention, there is provided a signal generation circuit including a first impedance circuit having a time constant or a resonance frequency having a first temperature fluctuation rate, and a first fluctuation direction opposite to the first temperature fluctuation rate. A second impedance circuit having a time constant or a resonance frequency having a temperature variation rate of 2, an oscillation circuit that oscillates by alternately switching the first impedance circuit and the second impedance circuit by a switch; The changer is configured to obtain the temperature fluctuation rate as an average value from the first and second temperature fluctuation rates by adjusting the usage ratio of the first and second impedance circuits according to the magnitude of the temperature fluctuation rate of 2. And a control circuit for controlling.

  According to the above-described configuration, the two impedance circuits having arbitrary temperature fluctuation rates in which the fluctuation direction of the temperature fluctuation rate of the time constant or the resonance frequency is opposite are provided, and time-series in accordance with the magnitude of each temperature fluctuation rate. By using the time constant or resonance frequency or delay element to oscillate alternately by using, and adjusting the use ratio of the impedance circuit having different temperature fluctuation directions, the temperature fluctuation rate is obtained as an average value. The average value is almost “0” or “0”, and the temperature variation rate can be flattened.

  According to the present invention, it is possible to extremely flatten the temperature variation rate when obtaining the reference frequency or the delay element.

  Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram showing a schematic configuration of a signal generation circuit according to Embodiment 1 of the present invention. As shown in FIG. 1, the signal generation circuit has a time constant or resonance frequency having a first temperature variation rate, and is made based on a resistor (R), a coil (L), and a capacitor (C). The first impedance circuit 1 has a time constant or resonance frequency having a second temperature fluctuation rate that is opposite to the first temperature fluctuation rate, and is made based on R, L, and C. A second impedance circuit 2; first and second active circuits 3 and 4 for configuring an oscillator; a switch 5 for selecting a signal; and a control circuit 8 for controlling the switch 5 I have.

  Then, the output of the first oscillation circuit 6 composed of the first impedance circuit 1 and the first active circuit 3, and the output of the second oscillation circuit 7 composed of the second impedance circuit 2 and the second active circuit 4. Are selected and used by the switch 5 alternately in time series.

  For example, the first and second impedance circuits 1 and 2 can be realized by an RC circuit as shown in FIG. 2, and both the resistor (R) and the capacitor (C) can be easily formed by a discrete component or a semiconductor integrated circuit. Is obtained. As the first and second impedance circuits 1 and 2, the RC circuits shown in FIG. 2 are used, and capacitors C1 and C2 having the same temperature fluctuation are used, and a positive temperature coefficient is applied to R1 of the first impedance circuit 1. A resistor having a negative temperature coefficient is used for R2 of the second impedance circuit 2. Further, an amplifier or the like is used for the first and second active circuits 3 and 4 in FIG. 1 to constitute an oscillation circuit as shown in FIG.

  If the absolute value of the temperature coefficient of the first impedance circuit 1 is configured to be larger than the temperature coefficient of the second impedance circuit 2, the first oscillation circuit 6 that uses the first impedance circuit 1 will be described. The use time is shortened, and the use time of the second oscillation circuit 7 using the second impedance circuit 2 having a small temperature fluctuation rate is lengthened. In order to operate in this way, by setting the ratio of the usage time of the oscillation circuit at a ratio opposite to the ratio of the temperature coefficient of each time constant, the oscillation frequency has two temperature coefficients whose directions of temperature fluctuation are opposite. The temperature fluctuation as an average value is almost eliminated or greatly reduced.

  If the temperature coefficient of the time constant of the first impedance circuit 1 is +2 (s / T) and the temperature coefficient of the second impedance circuit 2 is −1 (s / T), two impedances The circuit is switched by time, and the usage time of the first impedance circuit 1 is always set to “1s” in the period b shown in FIG. 4, and the usage time of the second impedance circuit 2 is set to “2s” in the period a shown in FIG. Use to be. As a result, when the first impedance circuit 1 and the second impedance circuit 2 are switched and used, the average value of the time constant is always kept at “0” even if the temperature changes.

  According to the first embodiment, it is possible to obtain a time constant or resonance frequency with extremely small temperature fluctuation as a time average value, and there is no increase in system scale due to the provision of a special temperature compensation circuit, and temperature stability is good. A time constant or resonance frequency can be obtained.

  In the first embodiment, it has been described that the temperature coefficients of the capacitors are equal. However, when the temperature coefficients are different, the first and second impedance circuits 1 and 2 are considered in consideration of the temperature coefficients of both the resistor and the capacitor. It should be designed so that the temperature coefficient of the time constant has positive and negative.

  Further, the first and second active circuits 3 and 4 only need to obtain a gain satisfying the oscillation condition by an amplifier using the operational amplifier 13 as shown in FIG. The MOS switch 14 may be used.

  Further, the switch 5 uses a simple adder 15 as shown in FIG. 7 and applies a MOS switch 14 as shown in FIG. 8 to connect the first impedance circuit 1 and the first active circuit 3. The same can be realized by turning on / off a bias such as a power source supplied to the combined first oscillation circuit 6 and the second oscillation circuit 6 combining the second impedance circuit 2 and the second active circuit 4. is there. Each circuit function may be composed of either MOS or bipolar type. Also, the adder 15 described above can be easily realized by using an operational amplifier as shown in FIG.

  Further, an LC resonance circuit may be used as the impedance circuit, and any delay element or resonance element for controlling oscillation such as charging / discharging of a current capacitor can be applied to the technique of the present invention. Furthermore, even if the two impedance (time constant) circuits that can be realized have a difference in the temperature variation rate of the time constant, if the polarities are in the same direction, for example, as shown in FIG. The impedance (time constant) circuits 1 and 2 are constituted by an RC series circuit, and the charging bias voltage V has a temperature variation, so that the temperature variation of the bias voltage and the first impedance (time constant) circuit 1 The first and second time constants (temperature fluctuation rates) that are set so that the fluctuation polarities are different in the synthetic temperature fluctuation rate and the combined temperature fluctuation rate of the bias voltage temperature fluctuation and the second impedance (time constant) circuit 2. ).

  Further, as shown in FIG. 9B, when the delay is created by charging the first and second time constants from the current source, the two time constants are combined with the temperature fluctuation rate of the current sources I1 and I2. It suffices if the fluctuation direction of the subsequent temperature fluctuation rate is reversed. Further, as shown in FIG. 9 (c), the signals obtained from the two impedance (time constant) circuits are compared by the comparators 16 and 17, When controlling a predetermined operation, if the reference value Vr inputted to the comparators 16 and 17 has a temperature fluctuation, and the two time constants after the synthesis with the temperature fluctuation of the reference value Vr are in opposite directions, good.

  The current sources I1 and I2 described above may be equal, and the charging bias voltage V and the reference value Vr may be divided into two. Further, the description of the impedance (time constant) circuit is the same as in Embodiments 2 to 5 described later. In the first embodiment, three or more impedance circuits may be provided, and even in the case of three or more impedance circuits, the frequency of use of each impedance circuit can be changed according to the temperature variation rate of each time constant or resonance frequency. It ’s fine.

  Similarly, even if three or more impedance circuits and three active circuits are provided, each of the impedance circuits and the active circuits constitutes an oscillation circuit and oscillates according to the temperature variation rate of the impedance circuit used for each oscillation circuit. What is necessary is just to change the use frequency of a circuit.

  FIG. 10 is a block diagram showing a schematic configuration of a signal generation circuit according to Embodiment 2 of the present invention. In the second embodiment, the configuration shown in FIG. 1 of the first embodiment has a temperature detector 21 that detects the temperature of the environment in which the first and second impedance circuits 1 and 2 are placed. The point is different.

  Further, as shown in FIG. 10, first and second active circuits 3 and 4 for configuring an oscillator, a switch 5 for selecting a signal, a control circuit 8 for controlling the switch 5, A first oscillation circuit 6 composed of a first impedance circuit 1 and a first active circuit 3, and a second oscillation circuit 7 composed of a second impedance circuit 2 and a second active circuit 4 are provided. .

  The first and second oscillation circuits 6 and 7 are selected and used by the switch 5 alternately in time series, and each of the first and second impedance circuits 1 and 2 has each time constant or resonance frequency. In accordance with the first and second temperature fluctuation rates, the operation time of the oscillation circuit with the larger temperature fluctuation rate is shortened and the usage time of the oscillation circuit with the smaller temperature fluctuation rate is lengthened. Therefore, the ratio of the usage time of the first and second oscillation circuits 6 and 7 is set at a ratio opposite to the ratio between the first and second temperature fluctuation rates. As a result, because of two time constants with opposite temperature fluctuation directions, the oscillation frequency is substantially eliminated or extremely reduced as an average value.

  Furthermore, when the temperature variation rate of the time constant or resonance frequency of the first and second impedance circuits 1 and 2 is nonlinear with respect to the temperature change, the first and second impedance circuits 1 and 2 are used. When the usage ratio is constant, the temperature compensation amount becomes excessive or insufficient. For this reason, when the temperature changes based on the signal from the temperature detector 21, the usage ratios of the first and second impedance circuits 1 and 2 are adjusted according to the change in temperature. As a result, a stable oscillation frequency can be obtained even when the temperature variation of the time constant or resonance frequency of the first and second impedance circuits 1 and 2 is nonlinear with respect to the temperature.

  A configuration example of the temperature detector 21 is shown in FIG. As shown in FIG. 11, a current from a current source 23 (which may be a resistor) is passed through the PN junction diode 22. Since the potential generated at the PN junction depends on the temperature, this voltage can be detected by comparing this voltage with the reference voltage Vb using, for example, the comparator 24 and setting the reference voltage Vb to a voltage corresponding to the temperature of the temperature fluctuation. A signal for controlling the use ratio may be used based on this. Further, the use ratio may be changed by setting the time ratio of the timer or the like by changing the time ratio of the periods a and b shown in FIG.

  For example, in the temperature variation rate shown in FIG. 12, when the temperature curve of either one of the time constants changes midway (point P shown in FIG. 12), optimal averaging cannot be performed if the usage ratio is constant. In such a case, the temperature near the point P is detected, and the usage ratio of the two time constants is switched.

  As described above, according to the second embodiment, it is possible to obtain a time constant or a resonance frequency having a very small temperature variation rate as a time average value, and there is no increase in system scale due to the provision of a special temperature compensation circuit, and the temperature A stable time constant or resonance frequency can be obtained.

  In the second embodiment, three or more impedance circuits may be provided. Even in the case of three or more impedance circuits, if the frequency of use of each impedance circuit is changed according to the temperature variation rate of each time constant or resonance frequency, The frequency of use may be changed based on the signal from the temperature detector.

  If there are two or more temperature fluctuation mutation points (points corresponding to the point P shown in FIG. 12) by combining the first, second, or higher impedance circuits, a plurality of necessary mutation points can be obtained. It is only necessary to detect the temperature and change the usage ratio in accordance with the change in the temperature fluctuation rate of the impedance circuit.

  FIG. 13 is a block diagram showing a schematic configuration of a signal generation circuit according to Embodiment 3 of the present invention. As shown in FIG. 13, the third embodiment is provided with a counter 25 for counting the frequency instead of the control circuit 8 in the configuration shown in FIG. 1 of the first embodiment.

  Then, the output of the first oscillation circuit 6 composed of the first impedance circuit 1 and the first active circuit 3, and the output of the second oscillation circuit 7 composed of the second impedance circuit 2 and the second active circuit 4. Are selected and used by the switch 5 alternately in time series. The counter 25 counts one of the signals of the first and second oscillation circuits 6 and 7 selected by the switch 5, and the switch 5 uses the counter 25 to count the first and first signals. The output signals of the second oscillation circuits 6 and 7 are selected.

  Based on the temperature fluctuation rate of each of the first and second impedance circuits 1 and 2, the use time of the oscillation circuit using the impedance circuit having a large temperature fluctuation rate is shortened, and the impedance circuit having a small temperature fluctuation rate is used. Function to increase the operating time of the oscillation circuit. That is, the ratio of the usage time of the oscillation circuit using the impedance circuit having the temperature fluctuation rate is set to the ratio opposite to the ratio of the temperature fluctuation rate of each time constant or resonance frequency. As a result, when the time average of the oscillation frequency of the output signal is taken with two temperature fluctuation rates in which the temperature fluctuation directions are opposite, the temperature fluctuation is almost eliminated or extremely reduced as an average value.

  Further, the signals from the first and second oscillation circuits 6 and 7 are counted by the counter 25, and the first and second oscillation circuits 6 and 7 to be used are selected based on the counting result. Thus, a stable oscillation frequency can be obtained without receiving external control.

  For example, if the temperature coefficient of the time constant of the first impedance circuit 1 is +2 (s / T) and the temperature coefficient of the second impedance circuit 2 is −1 (s / T), the two impedance circuits As the usage time ratio, if the usage time of the first impedance circuit 1 is 1, the usage time of the second impedance circuit 2 is twice that of the first impedance circuit 1, and the first and second impedance circuits 1 and 2 are used. , 2 may be set to 1: 2. Specifically, the use period of the first impedance circuit 1 is set to “1 s” in the period b shown in FIG. 4, and the use period of the second impedance circuit 2 is set to “2 s” in the period a shown in FIG. In this case, the first and second impedance circuits 1 and 2 can be used at a ratio of 1: 2.

  Considering the case of using a 1/3 frequency dividing circuit as shown in FIG. 14, the output signal when the first and second impedance circuits 1 and 2 are alternately switched is used as shown in FIG. A signal f having a duty ratio of 2: 1 is generated, and switching is performed using the duty ratio of the signal. The period h in FIG. 15 is used for the first impedance circuit 1, and the period g is the second impedance. If the circuit 2 is controlled to be used, the usage ratio of the first and second impedance circuits 1 and 2 becomes 1: 2, and the average value of the time constant is always almost “0” even if the temperature changes. Is kept.

  As described above, according to the fourth embodiment, it is possible to obtain an oscillation circuit having an oscillation frequency with extremely small temperature fluctuation as a time average value, and there is no increase in system scale due to the provision of a special temperature compensation circuit. Even when there is no external control, it is easier to obtain an oscillation circuit with good frequency temperature stability by having a minimum function of switching the first and second oscillation circuits 6 and 7.

  In the fourth embodiment, three or more impedance circuits and active circuits may be provided, and in the case of three or more, an oscillation circuit is configured by each impedance circuit and active circuit, and is used for each oscillation circuit. What is necessary is just to change the use frequency of an oscillation circuit according to the temperature fluctuation rate of the impedance circuit which was made.

  Further, the counter 25 switches the usage time of each oscillation circuit by counting, but this counter 25 may be a circuit whose control amount can be changed or may be programmable. Further, although a 1/3 frequency divider is used to obtain a control ratio, when the input frequency is high, a prescaler may be inserted before the frequency divider, and the frequency division ratio is 1: 2. May be used instead of the 1/3 frequency divider.

  FIG. 16 is a block diagram showing a schematic configuration of a signal generation circuit according to Embodiment 4 of the present invention. As shown in FIG. 16, the fourth embodiment is provided with a time measuring device 26 instead of the counter 25 in the configuration shown in FIG. 13 of the third embodiment.

  The time measuring device 26 switches the output of the first and second transmission circuits 6 and 7 and uses each of the first and second impedance circuits 1 and 2 as in the third embodiment. Based on the temperature variation rate, the oscillation circuit using an impedance circuit having a large temperature variation rate is used for a short time, and the oscillation circuit using an impedance circuit having a small temperature variation rate is used for a long time. That is, the ratio of the usage time of the oscillation circuit using the impedance circuit having the temperature fluctuation rate is set to the ratio opposite to the ratio of the temperature fluctuation rate of each time constant or resonance frequency. As a result, when the time average of the frequencies is taken with the two temperature fluctuation rates having opposite temperature fluctuation directions, the temperature fluctuation as an average value is almost eliminated or extremely reduced.

  Further, the signal from the first and second oscillation circuits 6 and 7 is configured to select one of the first and second oscillation circuits 6 and 7 to be used by time control from the time measuring device 26. By doing so, a stable oscillation frequency can be obtained without receiving external control.

  FIG. 17 is a block diagram showing a schematic configuration of a signal generation circuit according to the fifth embodiment of the present invention. As shown in FIG. 17, a first impedance circuit 1 having a time constant or resonance frequency having a first temperature fluctuation rate, and a second temperature fluctuation rate having a fluctuation direction opposite to the first temperature fluctuation rate. The second impedance circuit 2 having a time constant or resonance frequency having the first active circuit 3 for constituting the oscillator, and the first and second impedance circuits 1 and 2 are alternately operated to make the first The first active circuit 3 includes, for example, a control circuit (not shown) and the first impedance circuit 1 by the switch 9. , 2 is used by switching the connection.

  An oscillation circuit 11 that oscillates by alternately selecting the first and second impedance circuits 1 and 2 in time series is configured, and the temperature variation rate of each of the first and second impedance circuits 1 and 2 is determined. Further, the selection time of the impedance circuit having the larger temperature variation rate is shortened, and the selection time of the impedance circuit having the smaller temperature variation rate is lengthened. That is, the ratio of the time for selecting the impedance circuit having the temperature variation rate is set to the ratio opposite to the ratio of the temperature variation rate of each time constant or resonance frequency. As a result, when the time average of the oscillation frequency of the output signal is taken with two temperature fluctuation rates in which the temperature fluctuation directions are opposite, the temperature fluctuation is almost eliminated or extremely reduced as an average value.

  As described above, according to the fifth embodiment, the active circuit used for the oscillation circuit 11 having an oscillation frequency with extremely small temperature fluctuation as a time average value can be made compact, and a special temperature compensation circuit is provided. Therefore, an oscillation circuit with good frequency temperature stability can be obtained.

  The first and second impedance circuits 1 and 2, the switch 9, and the first active circuit 3 in the fifth embodiment can be realized from the same configuration requirements as those in the first embodiment. In the fifth embodiment, three or more impedance circuits may be provided, and also in the case of three or more, an oscillation circuit can be configured by each impedance circuit and an active circuit, and the time constant of each impedance circuit or What is necessary is just to change the use frequency of each impedance circuit according to the temperature fluctuation rate which a resonant frequency has.

  FIG. 18 is a block diagram showing a system apparatus using a schematic configuration of a signal generation circuit according to Embodiment 6 of the present invention. As shown in FIG. 18, the signal generation circuit 30 described in the first to fifth embodiments is used to function as a substitute for the signal supplied from the system clock 32 provided in the system device 31. To do. For example, when the board of the system device 31 goes down and the output of the system clock 32 is lost, a clock signal is supplied to a block or circuit function that requires a clock for a protection operation or a return operation. Further, in order to perform a minimum self-operation when the system clock 32 is stopped, it is conceivable that the clock is incorporated in a necessary block. Although it is not as accurate as the system clock 32, if it is necessary for the system device 31 to easily realize a diagnosis function or the like performed in the event of a system down or a failure, the scale increases by providing a dedicated clock circuit or a board. Can be prevented, and a means for realizing a desired function can be provided.

  The signal generation circuit according to the seventh embodiment of the present invention is configured as a semiconductor integrated circuit device to realize each of the above-described embodiments.

  In recent years, electronic devices such as computers and portable terminals are often used for semiconductor integrated circuits, and are manufactured to implement the system device of the sixth embodiment by mounting the signal generation circuit described in the first to fifth embodiments. A semiconductor integrated circuit device.

  It has a time constant or resonance frequency having a temperature variation rate used in the signal generation circuit described in the first to fifth embodiments, and is made based on a resistor (R), a coil (L), and a capacitor (C). The impedance circuit thus obtained does not have to use all of R, L, and C as shown in FIGS. 19A to 19F, for example, and impedance (time constant) as shown in FIG. In the circuit, when charging is performed by applying a voltage to the upper terminal and using the charging voltage Vo at that time, the voltage first rises with the voltage Vbe of the diode Di, and then with the charging voltage Vo to the capacitor C To rise. This voltage Vbe can be used as an impedance (time constant) circuit having temperature characteristics.

  The impedance circuit and the signal generation circuit using the impedance circuit according to the present invention can extremely flatten the temperature variation rate in obtaining the reference frequency or the delay element, and are used in the semiconductor integrated circuit or the electric signal processing system. It is useful as a circuit for generating a frequency signal.

The block diagram which shows schematic structure of the signal generation circuit in Embodiment 1 of this invention. The figure which shows RC circuit of the structural example of an impedance circuit Diagram showing the configuration of the oscillation circuit Timing chart showing the period of use of two impedance circuits Diagram showing an example of an active circuit composed of operational amplifiers The figure which shows the example which comprised the switch with MOS switch The figure which shows the example which comprised the switch with the adder The figure which shows the structure which applies the MOS switch and switches with the power supply of the oscillation circuit (A) is a temperature variation of a charging bias voltage, (b) is a temperature variation of a current source, and (c) is a diagram showing a configuration example for synthesizing a temperature variation of a reference value of a comparator in an impedance circuit. The block diagram which shows schematic structure of the signal generation circuit in Embodiment 2 of this invention. Diagram showing the configuration of the temperature detector Diagram explaining the displacement point of temperature fluctuation rate The block diagram which shows schematic structure of the signal generation circuit in Embodiment 3 of this invention. The figure which shows the circuit structure of a 1/3 frequency divider. Timing chart showing a 1: 2 minute period The block diagram which shows schematic structure of the signal generation circuit in Embodiment 4 of this invention. The block diagram which shows schematic structure of the signal generation circuit in Embodiment 5 of this invention. The block diagram which shows the system apparatus using the schematic structure of the signal generation circuit in Embodiment 6 of this invention. (A) to (f) of the impedance circuit are diagrams showing a configuration example of R, L, and C.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st impedance circuit 2 2nd impedance circuit 3, 3a 1st active circuit 4 2nd active circuit 5, 9 Switch 6 1st oscillation circuit 7 2nd oscillation circuit 8 Control circuit 10, 20 Impedance Circuit 11 Oscillation circuit 13 Operational amplifier 14 MOS switch 15 Adder 16, 17, 24 Comparator 21 Temperature detector 22 PN junction diode 23 Current source 25 Counter 26 Time measuring device 30 Signal generation circuit 31 System device 32 System clock

Claims (7)

A first impedance circuit having a time constant or resonance frequency having a first temperature fluctuation rate, and a time constant or resonance frequency having a second temperature fluctuation rate opposite to the first temperature fluctuation rate. A second impedance circuit having
The first and second temperatures are adjusted by adjusting a usage ratio of the first and second impedance circuits according to the first and second temperature fluctuation rates of the first and second impedance circuits. An impedance circuit characterized in that the first and second impedance circuits are switched so as to obtain the temperature variation rate as an average value from the variation rate. A temperature detector for detecting an environmental temperature in which the first and second impedance circuits are placed;
The first and second temperature fluctuations are adjusted by adjusting the usage ratio of the first and second impedance circuits according to the first and second temperature fluctuation rates of the first and second impedance circuits. When the first and second temperature fluctuation rates have nonlinearity with respect to the temperature when the temperature fluctuation rate is obtained as an average value from the rate, an adjustment amount of the usage ratio of the first and second impedance circuits is set. 2. The impedance circuit according to claim 1, wherein the impedance circuit is switched according to an output of the temperature detector, and the first and second impedance circuits are switched.   2. An impedance circuit comprising the first and second impedance circuits according to claim 1, a first oscillation circuit that oscillates using the first impedance circuit, and a second that oscillates using the second impedance circuit. And the first and second impedance circuits by adjusting the usage ratio of the first and second oscillation circuits. A signal generation circuit comprising: a control circuit for controlling the switch so as to obtain the temperature fluctuation rate as an average value from the first and second temperature fluctuation rates.   An impedance circuit including the first and second impedance circuits and the temperature detector according to claim 2, a first oscillation circuit that oscillates using the first impedance circuit, and the second impedance circuit. A second switching circuit that oscillates in turn, a switch that alternately switches the first and second oscillation circuits, and the first and second oscillation circuits when adjusting the usage ratio of the first and second oscillation circuits. When the first and second temperature fluctuation rates of the two impedance circuits are non-linear with respect to the temperature, the adjustment amount of the use ratio is changed according to the output of the temperature detector, and the first and second And a control circuit for controlling the switch so as to obtain the temperature fluctuation rate as an average value from the temperature fluctuation rates.   4. A counter circuit for counting output signals from the first and second oscillation circuits in place of the control circuit, and controlling the switch according to a counting result of the counter circuit. Or the signal generation circuit of 4.   A time measuring device for measuring a time for outputting a signal from the first and second oscillation circuits instead of the counter circuit is provided, and the switch is controlled by a measuring time of the time measuring device. Item 6. The signal generation circuit according to Item 5.   A first impedance circuit having a time constant or resonance frequency having a first temperature fluctuation rate, and a time constant or resonance frequency having a second temperature fluctuation rate opposite to the first temperature fluctuation rate. A first impedance circuit, an oscillation circuit that alternately oscillates between the first impedance circuit and the second impedance circuit by a switch, and a magnitude of the first and second temperature fluctuation rates. And a control circuit for controlling the switch so as to obtain the temperature fluctuation rate as an average value from the first and second temperature fluctuation rates by adjusting the usage ratio of the first and second impedance circuits accordingly. A signal generation circuit comprising:

Images