Temperature-compensated voltage-controlled oscillator

Abstract

To oscillate a VCO at a desired frequency without performing adjustment work for each temperature.SOLUTION: A voltage controlled oscillator with temperature compensation according to the present disclosure includes a voltage controlled oscillator that oscillates at a frequency according to a control voltage, a memory unit that stores, for each temperature, a range designation voltage designating a control voltage range corresponding to a frequency range from a start oscillation frequency to an end oscillation frequency of the voltage controlled oscillator, a temperature measuring unit that measures the temperature of the voltage controlled oscillator, a voltage control unit that reads the range designation voltage from the memory unit according to the temperature measured by the temperature measuring unit, determines the control voltage range from the read range designation voltage, and sweeps and outputs the control voltage at a constant cycle within the control voltage range, and a DA conversion unit that converts the control voltage output from the voltage control unit into an analog signal and inputs the analog signal to the voltage controlled oscillator.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a temperature-compensated voltage-controlled oscillator that oscillates at a desired frequency regardless of the temperature of the voltage-controlled oscillator. [Background technology]

[0002] A radio altimeter measures altitude by changing the frequency of a transmission signal using a voltage-controlled oscillator (hereinafter abbreviated as "VCO"). The VCO oscillates at a frequency that corresponds to an input control voltage. A frequency adjustment device that adjusts the oscillation frequency of the VCO to a desired frequency is known (see, for example, Patent Document 1).

[0003] A device according to the related art includes a low-impedance reference voltage generating circuit, a differential amplifier, a fixed resistor, and a PROM (programmable read-only memory). In the device according to the related art, the output of the low-impedance reference voltage generating circuit is connected to the positive input of the differential amplifier, the output terminal of the differential amplifier is connected to the negative input of the differential amplifier for feedback, and the output terminal of the differential amplifier is connected to ground via a fixed resistor. The output from the PROM and the output of the temperature compensation circuit are connected between the low-impedance reference voltage generating circuit and the positive input of the differential amplifier. The low-impedance reference voltage generating circuit generates a voltage using a power supply voltage and a fixed resistor. The temperature compensation circuit can be exemplified by a thermistor or the like.

[0004] The device according to the related art inputs a control voltage to a VCO with the above configuration and causes the VCO to oscillate at a desired frequency. Specifically, in order to suppress variations in the control voltage due to variations in the characteristics of components such as operational amplifiers, fixed resistors, and thermistors, the device according to the related art stores a correction current value that takes into account variations in the characteristics of the components in a PROM (programmable read-only memory), and corrects the control voltage using the correction current. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 9-246958 Summary of the Invention [Problem to be solved by the invention]

[0006] However, related technologies require adjustment work, such as measuring the VCO's oscillation frequency and storing the correction current value that results in the desired frequency in a PROM. Moreover, the frequency that a VCO outputs in response to a control voltage is determined by the VCO's characteristics, but these characteristics change with the VCO's temperature, so adjustment work is required for each VCO temperature change, which creates the problem of taking a long time to complete.

[0007] In order to solve the above problem, an object of the present disclosure is to make a VCO oscillate at a desired frequency without performing adjustment work for each temperature. [Means for solving the problem]

[0008] In order to achieve the above object, the temperature-compensated voltage-controlled oscillator of the present disclosure measures the temperature of the VCO and generates a control voltage by a digital circuit using the measured temperature.

[0009] Specifically, the temperature-compensated voltage-controlled oscillator according to the present disclosure comprises: a voltage-controlled oscillator that oscillates at a frequency according to a control voltage; a memory unit that stores, for each temperature, a range designation voltage that designates a control voltage range corresponding to a frequency range from a start oscillation frequency to an end oscillation frequency of the voltage-controlled oscillator; a temperature measurement unit for measuring the temperature of the voltage-controlled oscillator; a voltage control unit that reads out the range designation voltage from the memory unit in accordance with the temperature measured by the temperature measurement unit, determines the control voltage range from the read out range designation voltage, and sweeps and outputs the control voltage within the control voltage range at a constant period; a DA conversion unit that converts the control voltage output by the voltage control unit into an analog signal and inputs the analog signal to the voltage controlled oscillator; Equipped with.

[0010] In the temperature-compensated voltage-controlled oscillator according to the present disclosure, The range specifying voltages may be an offset voltage and a frequency change voltage.

[0011] In the temperature-compensated voltage-controlled oscillator according to the present disclosure, The range specification voltages may be a start control voltage corresponding to the start oscillation frequency and an end control voltage corresponding to the end oscillation frequency.

[0012] In the temperature-compensated voltage-controlled oscillator according to the present disclosure, The voltage control unit may autonomously sweep the control voltage at the constant cycle.

[0013] In the temperature-compensated voltage-controlled oscillator according to the present disclosure, The voltage control unit may receive an activation signal and sweep the control voltage at the constant cycle starting from the activation signal that has been received.

[0014] The above inventions can be combined as much as possible. [Effects of the Invention]

[0015] According to the present disclosure, it is possible to make a VCO oscillate at a desired frequency without performing adjustment work for each temperature. [Brief explanation of the drawings]

[0016] [Figure 1] 1 shows an example of a schematic configuration of a temperature-compensated voltage-controlled oscillator according to an embodiment. [Figure 2] 4 shows an example of a control voltage versus frequency characteristic according to the embodiment. [Figure 3] 4 shows an example of a control voltage versus frequency characteristic according to the embodiment. [Figure 4] 4 shows an example of a control voltage versus frequency characteristic according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the present disclosure is not limited to the embodiments shown below. These implementation examples are merely illustrative, and the present disclosure can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art. Note that components with the same reference numerals in this specification and drawings indicate the same components.

[0018] (Embodiment) An example of the schematic configuration and usage of the control voltage compensation device according to this embodiment is shown in Figure 1. The temperature-compensated voltage-controlled oscillator 10 according to this embodiment includes a voltage-controlled oscillator 15 that oscillates at a frequency according to a control voltage, a memory unit 11 that stores, for each temperature, a range-specifying voltage that specifies a control voltage range corresponding to the frequency range from the start oscillation frequency to the end oscillation frequency of the voltage-controlled oscillator 15, a temperature measurement unit 12 that measures the temperature of the voltage-controlled oscillator 15, a voltage control unit 13 that reads the range-specifying voltage from the memory unit 11 according to the temperature measured by the temperature measurement unit 12, determines a control voltage range from the read range-specifying voltage, and sweeps and outputs the control voltage within the control voltage range at a constant interval, and a DA conversion unit 14 that converts the control voltage output by the voltage control unit 13 into an analog signal and inputs it to the voltage-controlled oscillator 15.

[0019] The VCO 15 oscillates at a frequency corresponding to the control voltage. An example of the correspondence between the control voltage input to the VCO 15 according to this embodiment and the frequency at which the VCO 15 oscillates is shown in FIGS. 2 to 4. As shown in FIGS. 2 to 4, the frequency at which the VCO oscillates is assumed to have a linear relationship with the input control voltage. In FIGS. 2 to 4, the minimum value of the frequency at which the VCO oscillates is the start oscillation frequency f1, and the maximum value is the end oscillation frequency f2. The frequency range from the start oscillation frequency f1 to the end oscillation frequency f2 is determined in advance based on the device in which the VCO is used, such as the frequency range required by a radio altimeter. Hereinafter, "VCO temperature" will be abbreviated as "temperature," and "the line representing the correspondence between control voltage and frequency" will be abbreviated as "control voltage vs. frequency line."

[0020] A range designation voltage that designates a control voltage range corresponding to a frequency range from the start oscillation frequency f1 to the end oscillation frequency f2 is acquired in advance for each temperature, and the range designation voltage is stored for each temperature in the memory unit 11. Specific examples of the range designation voltage for each temperature stored in the memory unit 11 will be described below with reference to Figs. 2 to 4, but the present invention is not limited to these.

[0021] 2B and 2C are diagrams showing control voltage versus frequency lines at temperatures T1 and T2, respectively. As shown in FIGS. 2B and 2C, the control voltage versus frequency lines change depending on the temperature T, and the control voltage range corresponding to the frequency range from the start oscillation frequency f1 to the end oscillation frequency f2 may also change. Therefore, the memory unit 11 may store, as range specification voltages, the start control voltage Vmin(T) corresponding to the start oscillation frequency f1 and the end control voltage Vmax(T) corresponding to the end oscillation frequency f2, as shown in FIG. 2A, for each temperature T.

[0022] The memory unit 11 may store, as range specification voltages, a starting control voltage Vmin(T) and a frequency change voltage ΔV(T) representing the width of the control voltage range corresponding to the starting oscillation frequency f1 to the ending oscillation frequency f2 for each temperature T, as shown in FIG. 3.

[0023] 4A and 4B show the temperature T B 1 shows a control voltage vs. frequency line at temperature T B is the reference temperature. Reference temperature T B The starting control voltage Vmin(T B ) is used as the reference voltage, and the difference between this and the starting control voltage Vmin(T) at temperature T is the offset voltage V off (T). In this case, the starting control voltage Vmin(T) at any temperature T is B ) and offset voltage V off Therefore, the memory unit 11 stores the start control voltage Vmin(T B ) and the offset voltage V for each temperature T off(T) and the frequency change voltage ΔV(T).

[0024] The temperature measuring unit 12 measures the temperature of the VCO 15. An example of the temperature measuring unit 12 is a thermistor.

[0025] The voltage control unit 13 reads the range designation voltage for temperature T stored in the memory unit 11 based on the temperature T measured by the temperature measurement unit 12, and calculates the control voltage range for temperature T corresponding to the frequency range from the start oscillation frequency f1 to the end oscillation frequency f2 from the range designation voltage.The voltage control unit 13 then sweeps and outputs the control voltage within the control voltage range for temperature T at a constant period.

[0026] For example, if the memory unit 11 stores the start control voltage Vmin(T) and the end control voltage Vmax(T) for each temperature T as shown in (A) of Figure 2, the voltage control unit 13 reads out the start control voltage Vmin(T) and the end control voltage Vmax(T) from the memory unit 11 according to the temperature T measured by the temperature measurement unit 12, and sweeps and outputs the control voltage at a constant period within the control voltage range from the start control voltage Vmin(T) to the end control voltage Vmax(T), thereby making it possible to continuously change the oscillation frequency of the VCO 15 from the start oscillation frequency f1 to the end oscillation frequency f2.

[0027] Voltage control unit 13 may automatically sweep the control voltage at a constant cycle based on a clock signal, or may receive an activation signal and sweep the control voltage at a constant cycle starting from the input activation signal.

[0028] The DA conversion unit 14 converts the control voltage, which is a digital signal output by the voltage control unit 13, into an analog signal and inputs it to the VCO 15.

[0029] The temperature-compensated voltage-controlled oscillator 10 according to this embodiment generates a control voltage without using an operational amplifier or fixed resistor. That is, the temperature-compensated voltage-controlled oscillator 10 according to this embodiment generates a control voltage by performing digital-to-analog conversion on a digital signal corresponding to a control voltage value stored in a table in the memory unit 11. This prevents variations due to components such as an operational amplifier or fixed resistor, and eliminates the need for adjustment work regardless of these components.

[0030] Furthermore, in the temperature-compensated voltage-controlled oscillator 10 according to this embodiment, the voltage control unit 13 calculates the control voltage range according to the temperature of the VCO 15 from the range-specified voltage for each temperature stored in the memory unit 11, and can generate a control voltage corresponding to the frequency range from the start oscillation frequency f1 to the end oscillation frequency f2, eliminating the need for adjustment work for each temperature.

[0031] As described above, the present disclosure makes it possible to make a VCO oscillate at a desired frequency without performing adjustment work for each temperature. [Industrial Applicability]

[0032] The temperature-compensated voltage-controlled oscillator according to the present disclosure can be applied to the measurement instrument industry. [Explanation of symbols]

[0033] 10: Temperature compensated voltage controlled oscillator 11: Memory section 12:Temperature measurement part 13: Voltage control section 14: DA conversion section 15: Voltage controlled oscillator

Claims

1. a voltage-controlled oscillator that oscillates at a frequency according to a control voltage; a memory unit that stores, for each temperature, a range designation voltage that designates a control voltage range corresponding to a frequency range from a start oscillation frequency to an end oscillation frequency of the voltage-controlled oscillator; a temperature measurement unit for measuring the temperature of the voltage-controlled oscillator; a voltage control unit that reads out the range designation voltage from the memory unit in accordance with the temperature measured by the temperature measurement unit, determines the control voltage range from the read out range designation voltage, and sweeps and outputs the control voltage within the control voltage range at a constant period; a DA converter that converts the control voltage output by the voltage controller into an analog signal and inputs the analog signal to the voltage-controlled oscillator; A temperature compensated voltage controlled oscillator comprising:

2. The range-specifying voltages are the offset voltage and the frequency change voltage.

2. The temperature compensated voltage controlled oscillator according to claim 1.

3. The range-specifying voltage is a start control voltage corresponding to the start oscillation frequency and an end control voltage corresponding to the end oscillation frequency.

2. The temperature compensated voltage controlled oscillator according to claim 1.

4. The voltage control unit voluntarily sweeps the control voltage at the constant period.

4. The temperature-compensated voltage-controlled oscillator according to claim 1.

5. The voltage control unit receives an activation signal and sweeps the control voltage at the constant period starting from the activation signal.

4. The temperature-compensated voltage-controlled oscillator according to claim 1.

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