CN114047796A - Temperature control circuit, constant temperature crystal oscillator circuit and constant temperature crystal oscillator - Google Patents
Temperature control circuit, constant temperature crystal oscillator circuit and constant temperature crystal oscillator Download PDFInfo
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- CN114047796A CN114047796A CN202210029828.4A CN202210029828A CN114047796A CN 114047796 A CN114047796 A CN 114047796A CN 202210029828 A CN202210029828 A CN 202210029828A CN 114047796 A CN114047796 A CN 114047796A
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Abstract
The invention provides a temperature control circuit, a constant temperature crystal oscillator circuit and a constant temperature crystal oscillator, wherein the temperature control circuit comprises: the device comprises a first temperature sensor, a second temperature sensor, a voltage follower, a voltage comparator, a power tube heater and a first voltage stabilizing module. According to the temperature control circuit, the constant temperature crystal oscillator circuit and the constant temperature crystal oscillator, the temperature of a to-be-controlled element can be accurately detected through the two temperature sensors, the voltage is output and buffered and isolated through the voltage follower, the input voltage is compared with the preset voltage through the voltage comparator, the operation of the power tube heater is further controlled according to the comparison result, the temperature is controlled within a stable range, the circuit is simple in structure and high in temperature control accuracy, stable voltage can be provided for each element through the first voltage stabilizing module, and the circuit works more stably and reliably.
Description
Technical Field
The invention relates to the technical field of temperature control and time frequency, in particular to a temperature control circuit, a constant temperature crystal oscillator circuit and a constant temperature crystal oscillator.
Background
At present, the temperature control technology is applied to a plurality of electronic devices, such as an oven controlled crystal oscillator, because the short stability performance of the crystal oscillator is a key factor for determining the performance of the whole machine, and the fundamental factors influencing the short stability performance mainly comprise the modulation of noise on the phase or frequency of a signal and the fluctuation of ambient temperature, therefore, the influence of reducing the noise and the temperature fluctuation on the crystal oscillator is the key for improving the short stability performance.
The existing temperature control scheme for the crystal oscillator has low temperature control precision or large thermal fluctuation in the temperature change process, and is unfavorable to the short stability.
Disclosure of Invention
The invention provides a temperature control circuit, a constant temperature crystal oscillator circuit and a constant temperature crystal oscillator, which are used for solving the defects that the temperature control precision is low or the temperature fluctuation is large in the temperature change process and the short stability is unfavorable in the conventional temperature control scheme for the crystal oscillator.
In a first aspect, the present invention provides a temperature control circuit, comprising: the device comprises a first temperature sensor, a second temperature sensor, a voltage follower, a voltage comparator, a power tube heater and a first voltage stabilizing module;
the first temperature sensor and the second temperature sensor are both connected with the input end of the voltage follower, the output end of the voltage follower is connected with the input end of the voltage comparator, the output end of the voltage comparator is connected with the power tube heater, the power tube heater is also connected with the input end of the voltage comparator, and the first voltage stabilizing module is respectively connected with the first temperature sensor, the second temperature sensor, the voltage follower, the voltage comparator and the power tube heater;
first temperature sensor locates the position that is close to by accuse temperature piece, second temperature sensor locates the edge of being controlled the temperature piece place circuit board, first temperature sensor's output voltage with the intermediate voltage of second temperature sensor's output voltage, the warp the voltage follower inputs extremely the voltage comparator, the voltage comparator is used for comparing the intermediate voltage of input with preset voltage to according to the control of comparison result the power tube heater operation.
According to the temperature control circuit provided by the invention, voltage dividing resistors are arranged among the output ends of the first temperature sensor and the second temperature sensor and the voltage follower, and the voltage dividing resistors are used for integrating the output voltage of the first temperature sensor and the output voltage of the second temperature sensor and outputting an intermediate voltage.
The arrangement of the divider resistor can prevent the influence of overvoltage or overcurrent on the normal operation of the circuit, and simultaneously, the input voltage of the voltage follower can be integrated into the intermediate voltage of the voltage follower and the circuit.
According to the temperature control circuit provided by the invention, a current-limiting resistor is further arranged between the output end of the voltage comparator and the base electrode of the power tube heater, and a feedback resistor is further arranged between the inverted input end of the voltage comparator and the emitter electrode of the power tube heater. The current limiting resistor can control the current of the circuit in starting and stable states, so that the temperature control precision is influenced, and the voltage comparator works in negative feedback due to the arrangement of the feedback resistor.
According to the temperature control circuit provided by the invention, the power tube heater comprises a plurality of power tubes which are connected in parallel, and the plurality of power tubes are respectively arranged on the circuit board where the temperature controlled piece is positioned and close to four corners.
Through reasonable setting of electrical parameters and reasonable arrangement of power tubes, higher temperature control precision can be ensured, controlled components are uniformly heated, and thermal fluctuation is effectively reduced.
In a second aspect, the invention further provides a constant-temperature crystal oscillator circuit, which includes any one of the above temperature control circuit, oscillation module and second voltage stabilization module, where the oscillation module is connected with the second voltage stabilization module, and both the first voltage stabilization module and the second voltage stabilization module are connected with an external power supply;
the temperature control circuit, the oscillation module and the second voltage stabilizing module are arranged on a crystal oscillator circuit board, and the temperature controlled part is a quartz crystal resonator in the oscillation module.
Through the setting of second voltage stabilizing module, can reduce the influence of mains voltage fluctuation to oscillation module job stabilization nature, simultaneously, the influence that ambient temperature is undulant can be reduced in the setting of accuse temperature circuit, has guaranteed the job stabilization nature of constant temperature crystal oscillator circuit to optimize short steady performance.
According to the constant-temperature crystal oscillator circuit provided by the invention, the oscillation module comprises an oscillation circuit, a buffer amplification circuit and a filter circuit;
one end of the oscillating circuit is connected with the second voltage stabilizing module, the oscillating circuit is connected with the buffering amplifying circuit in an interactive mode, and the buffering amplifying circuit is connected with the filter circuit;
the oscillating circuit comprises a triode, a first peripheral resistance unit and a frequency selection unit, wherein the first peripheral resistance unit is connected with the triode and is used for providing a static working point for the triode;
the frequency selection unit comprises a first frequency selection capacitor, a second frequency selection capacitor, a quartz crystal, a frequency modulation capacitor, a first coupling capacitor, a junction field effect transistor and a second coupling capacitor;
the first frequency-selecting capacitor is connected with the second frequency-selecting capacitor, the first frequency-selecting capacitor and the second frequency-selecting capacitor are connected with an emitting electrode of the triode, one end of the second frequency-selecting capacitor and one end of the frequency-modulating capacitor are connected with a base electrode of the triode, the other end of the frequency-modulating capacitor is connected with the quartz crystal, the quartz crystal is connected with the first coupling capacitor, the first coupling capacitor is connected with the junction field effect tube, and the junction field effect tube is connected with a collecting electrode of the triode through the second coupling capacitor.
The invention introduces the junction capacitor of the junction field effect transistor in the buffer amplifying circuit into the oscillating circuit, so that a very clean signal is obtained after the signal is filtered by the quartz crystal and is input into the buffer amplifying circuit after passing through the coupling capacitor, thereby improving the short stability performance of the whole circuit.
According to the constant-temperature crystal oscillator circuit provided by the invention, a filtering unit is further arranged between the triode and the frequency selection unit, and the first frequency selection capacitor and the second frequency selection capacitor are both connected with the emitting electrode of the triode through the filtering unit.
According to the constant-temperature crystal oscillator circuit provided by the invention, the buffer amplifying circuit comprises a junction type field effect transistor, a second peripheral resistance unit and an alternating current isolation inductor;
the second peripheral resistance unit is connected with the junction field effect transistor, the second peripheral resistance unit is used for providing a static working point for the junction field effect transistor, and the AC isolation inductor is connected with the junction field effect transistor.
According to the constant-temperature crystal oscillator circuit provided by the invention, the second voltage stabilizing module comprises a first linear voltage stabilizer and a second linear voltage stabilizer, and the first linear voltage stabilizer and the second linear voltage stabilizer are connected in parallel.
Through two linear voltage regulators connected in parallel, the second voltage-stabilizing module can provide lower noise for a power supply provided by the oscillating module, and the short-stability performance of the whole circuit is improved.
In a third aspect, the present invention further provides an oven controlled crystal oscillator including any one of the oven controlled crystal oscillator circuits described above.
According to the temperature control circuit, the constant temperature crystal oscillator circuit and the constant temperature crystal oscillator, the temperature of a to-be-controlled element can be accurately detected through the two temperature sensors, the voltage is output and buffered and isolated through the voltage follower, the input voltage is compared with the preset voltage through the voltage comparator, the operation of the power tube heater is further controlled according to the comparison result, the temperature is controlled within a stable range, the circuit is simple in structure and high in temperature control accuracy, stable voltage can be provided for each element through the first voltage stabilizing module, and the circuit works more stably and reliably.
Drawings
In order to more clearly illustrate the technical solutions of the present invention or the prior art, the drawings needed for the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.
FIG. 1 is a schematic diagram of a temperature control circuit according to the present invention;
FIG. 2 is a second schematic diagram of the temperature control circuit according to the present invention;
FIG. 3 is a schematic structural diagram of a constant temperature crystal oscillator circuit provided by the present invention;
FIG. 4 is a schematic diagram of a circuit configuration of an oscillation module;
FIG. 5 is an AC equivalent circuit schematic of the oscillator circuit;
FIG. 6 is a schematic structural diagram of a second voltage regulation module;
FIG. 7 is a schematic diagram of a circuit board structure of the oven controlled crystal oscillator circuit;
fig. 8 is a schematic diagram of the arrangement positions of the aluminum nitride ceramic and the red copper sleeve.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The temperature control circuit, the oven controlled crystal oscillator circuit and the oven controlled crystal oscillator according to the present invention will be described with reference to fig. 1 to 8.
Fig. 1 shows a temperature control circuit provided in an embodiment of the present invention, including: a first temperature sensor 101, a second temperature sensor 102, a voltage follower 103, a voltage comparator 104, a power tube heater 105 and a first voltage stabilization module 106;
the first temperature sensor 101 and the second temperature sensor 102 are both connected with an input end of a voltage follower 103, an output end of the voltage follower 103 is connected with an input end of a voltage comparator 104, an output end of the voltage comparator 104 is connected with a power tube heater 105, the power tube heater 105 is also connected with an input end of the voltage comparator 104, and a first voltage stabilizing module 106 is respectively connected with the first temperature sensor 101, the second temperature sensor 102, the voltage follower 103, the voltage comparator 104 and the power tube heater 105;
the first temperature sensor 101 is arranged at a position close to a temperature-controlled piece, the second temperature sensor 102 is arranged at the edge of a circuit board where the temperature-controlled piece is arranged, the intermediate voltage of the output voltage of the first temperature sensor 101 and the output voltage of the second temperature sensor 102 is input to the voltage comparator 104 through the voltage follower 103, and the voltage comparator 104 is used for comparing the input voltage with a preset voltage and controlling the power tube heater 105 to operate according to the comparison result.
It is understood that the intermediate voltage between the output voltage of the first temperature sensor 101 and the output voltage of the second temperature sensor 102 is an intermediate value between the output voltages of the two temperature sensors.
In an exemplary embodiment, in order to ensure stability and safety of a circuit working process, a potential pull-up resistor may be further disposed between the voltage follower 103 and the voltage comparator 104, a current limiting resistor may be further disposed between the voltage comparator 104 and the power tube heater 105, and a current of the circuit is controlled in a starting and stable state, so that temperature control accuracy is improved.
Specifically, the power tube heater 105 may include a plurality of power tubes, the plurality of power tubes are connected in parallel, and the plurality of power tubes may be respectively disposed at positions near four corners on the circuit board where the temperature-controlled member is located, so as to uniformly heat the temperature-controlled member.
Referring to fig. 2, the LDO1 is a high current regulator in the first voltage regulation module 106, the first temperature sensor 101 is disposed beside the controlled temperature component, and the second temperature sensor is disposed at the edge of the PCB board where the controlled temperature component is located, so that the first temperature sensor 101 can sense the real-time temperature near the controlled temperature component, and the second temperature sensor 102 can quickly sense the external temperature change.
When the first temperature sensor 101 and the second temperature sensor 102 sense a temperature change, output voltages of the first temperature sensor 101 and the second temperature sensor 102 are changed, the resistor R1 and the resistor R2 are peripheral resistors of the temperature sensors, the resistor R3 and the resistor R4 are divider resistors which integrate output voltages of the two temperature sensors and output an intermediate voltage, the intermediate voltage enters a non-inverting input end of a voltage follower built by an operational amplifier OPA1 to be buffered and isolated, then the potential is divided by a resistor R10 and a resistor R5 which are used as potential pull-up resistors to be pulled up to enter an inverting input end of a voltage comparator built by the operational amplifier OPA2 to be compared with a voltage division of a resistor R6 and a resistor R7 which are input to the non-inverting input end of the operational amplifier OPA2, and according to a comparison result, an output voltage of the operational amplifier OPA2 enters the power tube heater through the resistor R9 which is used as a current limiting resistor.
Fig. 2 shows an exemplary power tube heater including 4 power tubes P, and the current change of the power tubes P is converted into a voltage through a resistor R8 as a feedback resistor and fed back to the inverting input terminal of the operational amplifier OPA 2.
In the practical application process, when the temperature-controlled member is a quartz crystal, the temperature needs to be controlled to be near the inflection point temperature of the quartz crystal, the inflection point temperature is about 95 ℃, and at this time, the voltage value output by the temperature sensor is set when the partial voltage of the resistor R6 and the resistor R7 is the inflection point temperature of the crystal.
When the temperature-sensing power supply is started, the output voltages of the first temperature sensor and the second temperature sensor are small, the voltage of the non-inverting input end of the operational amplifier OPA2 is larger than that of the inverting input end, the operational amplifier OPA2 outputs high level, and after passing through the current-limiting resistor R9, the power tube P works in an amplification area to be heated; as the temperature rises, the output voltages of the two temperature sensors gradually increase, so that the voltage at the inverting input terminal of the operational amplifier OPA2 gradually increases, the output voltage of the operational amplifier OPA2 gradually decreases until the VBE voltage (i.e., the base-emitter voltage) of the power tube P is less than the turn-on voltage, the heating is stopped, and the temperature is constant around the crystal knee temperature when the voltage at the non-inverting input terminal and the voltage at the inverting input terminal of the operational amplifier OPA2 are nearly equal.
Fig. 3 shows a constant-temperature crystal oscillator circuit provided in an embodiment of the present invention, which includes any one of the above-mentioned temperature control circuit 300, an oscillation module 302, and a second voltage stabilization module 301, where the oscillation module 302 is connected to the second voltage stabilization module 301, and both the first voltage stabilization module 106 and the second voltage stabilization module 301 are connected to an external power supply;
the temperature control circuit 300, the oscillation module 302 and the second voltage stabilizing module 301 are arranged on the crystal oscillator circuit board, and the controlled temperature part is a quartz crystal in the oscillation module 302.
In the oscillation module 302 provided in this embodiment, the oscillation circuit is based on a low-noise triode and a high-Q quartz crystal resonator (i.e., a quartz crystal), a capacitance three-point oscillation circuit is built, and a signal is amplified by a jfet and then output through LC filtering.
Specifically, the oscillation module 302 in this embodiment may include an oscillation circuit 3021, a buffer amplifier circuit 3022, and a filter circuit 3023;
one end of the oscillating circuit 3021 is connected to the second voltage stabilizing module 301, the oscillating circuit 3021 is connected to the buffer amplifier circuit 3022 in an alternating manner, and the buffer amplifier circuit 3022 is connected to the filter circuit 3023;
referring to fig. 4, the oscillation circuit 3021 includes a transistor BJT, a first peripheral resistance unit and a frequency selection unit, where the first peripheral resistance unit is connected to the transistor BJT, and the first peripheral resistance unit is configured to provide a static operating point for the transistor BJT;
fig. 4 exemplarily provides a structure of the first peripheral resistor unit, which includes a resistor R11, a resistor R12, a resistor R13, a resistor R14, and a resistor R15, wherein the resistor R12 is further connected to a capacitor C8.
The frequency selection unit comprises a first frequency selection capacitor C2, a second frequency selection capacitor C3, a quartz crystal JT, a frequency modulation capacitor C4, a first coupling capacitor C5, a second coupling capacitor C8 and a junction field effect transistor JFET;
the first frequency-selecting capacitor C2 is connected with the second frequency-selecting capacitor C3, the first frequency-selecting capacitor C2 and the second frequency-selecting capacitor C3 are also both connected with an emitter of a triode BJT, one ends of the second frequency-selecting capacitor C3 and the frequency-modulating capacitor C4 are also both connected with a base of the triode BJT, the other end of the frequency-modulating capacitor C4 is connected with a quartz crystal JT, the quartz crystal JT is connected with the first coupling capacitor C5, the first coupling capacitor C5 is connected with a junction field effect transistor JFET, and the junction field effect transistor is connected with a collector JFET of the triode BJT through the second coupling capacitor C8.
The oscillating circuit shown in fig. 4 is a capacitance three-point oscillating circuit, wherein the first frequency-selecting capacitor C2 and the second frequency-selecting capacitor C3 are two capacitors of the capacitance three-point oscillating circuit, and the frequency-modulating capacitor C4, the first coupling capacitor C5, the quartz crystal JT, and the junction capacitor of the junction field effect transistor JFET and the second coupling capacitor C8 work together in an inductive state to form an inductor of the capacitance three-point oscillating circuit.
Preferably, a filtering unit is further arranged between the triode BJT and the frequency selecting unit, and the first frequency selecting capacitor C2 and the second frequency selecting capacitor C3 are both connected with the emitter of the triode BJT through the filtering unit. Referring to fig. 4, the emitter of the transistor BJT may be connected in series with the capacitor C1 through the inductor L1 for filtering, that is, the inductor L1 is connected in series with the capacitor C1 for forming a filtering unit.
Specifically, referring to fig. 4, the buffer amplifier circuit 3022 includes a JFET, a second peripheral resistance unit, and a blocking inductor;
the second peripheral resistance unit is connected with the JFET, and the second peripheral resistance unit is used for providing a static working point for the JFET and connecting the isolated inductor with the JFET.
Fig. 4 exemplarily provides a structure of the second peripheral resistor unit, which includes a resistor R16, a resistor R17, and a resistor R18, and in the circuit shown in fig. 4, the interleaved inductors are specifically referred to as an inductor L2 and an inductor L4. The resistor R16 is directly connected with the JFET, the resistor R17 is indirectly connected with the JFET through the inductor L2, the resistor R18 is indirectly connected with the JFET through the inductor L4, the inductor L3 and the resistor R16, the JFET amplifies signals, and the inductor L2 and the inductor L4 which are used as the isolation inductors both play a role in isolating alternating current signals.
Referring to fig. 4, the filter circuit 3023 includes a capacitor C6 and an inductor L3, and the capacitor C6 and the inductor L3 may form a low pass filter circuit. In addition, the capacitor C7 in fig. 4 is a coupling capacitor, and is connected to the output terminal of the circuit, and the power input terminal Vout in the circuit is connected to the second voltage stabilization module 301.
Considering the oscillation circuit of the traditional crystal oscillator, signals are output from one of three ends of the triode, and the oscillation circuit is coupled with the buffer amplifying circuit through a large capacitor, so that noise signals of the triode can enter the next stage along with the main oscillation signals, and the short stability performance of the circuit is low. For this reason, the present embodiment improves the circuit structure of the oscillation module.
FIG. 5 shows an AC equivalent circuit of the oscillator circuit of FIG. 4. referring to FIG. 5, this embodiment is implemented by combining the junction capacitance C of the FET JFET in the buffer amplifier circuitJFETAn oscillating circuit is introduced, so that a very clean signal can be obtained after the signal is filtered by a quartz crystal JT with a high Q value, and the signal is input into the next stage through a first coupling capacitor C5, thereby improving the short-stability performance of the whole circuit.
Specifically, referring to fig. 6, the second voltage stabilization module 301 in this embodiment includes a first linear voltage regulator LOD2 and a second linear voltage regulator LOD3, the first linear voltage regulator LOD2 being connected in parallel with the second linear voltage regulator LOD 3.
In this embodiment, the two linear voltage regulators are low-noise voltage regulators, one end of each of the two linear voltage regulators is connected to an external power supply, and the other end of each of the two linear voltage regulators is connected in parallel to output a voltage to the oscillation module 302. Therefore, the embodiment uses two voltage regulators connected in parallel, and can obtain lower power supply input noise, thereby improving the short-stability performance of the circuit.
In addition, an embodiment of the present invention also provides an oven-controlled crystal oscillator including any one of the oven-controlled crystal oscillator circuits described above.
The oven controlled crystal oscillator provided by the embodiment not only improves the circuit structure of the oven controlled crystal oscillator circuit, but also improves the layout design of a PCB (printed circuit board) and the design of a tube shell.
Specifically, in order to ensure that the oven controlled crystal oscillator can achieve better short stability performance through the arrangement of the oven controlled crystal oscillator circuit, the present embodiment further reasonably arranges the internal structure of the oven controlled crystal oscillator, specifically, fig. 7 shows the structural layout of the circuit board (i.e., PCB board) of the oven controlled crystal oscillator circuit.
The oscillation module is disposed on a top layer of a middle region top of the PCB 701 and isolated from peripheral devices by an isolation layer 702, so as to reduce signal interference, the quartz crystal resonator 703 is disposed in a middle portion of the middle region, 4 power tubes 704 are used to heat four corners of a bottom layer of the middle region, and in order to prevent thermal overshoot, the quartz crystal resonator 703 and the power tubes 704 are disposed on upper and lower layers of the PCB 701 respectively and conduct heat through heat conduction holes 705.
Referring to fig. 8, an aluminum nitride ceramic 801 with high thermal conductivity is further disposed between the quartz crystal resonator 703 and the PCB 701, and a layer of red copper jacket 802 with large thermal capacity and high thermal conductivity is wrapped outside the quartz crystal resonator 703. The structural layout of the whole circuit board can form a constant temperature bath structure with low temperature fluctuation, thereby improving the thermal stability of the oscillation module.
In addition, consider traditional lead wire cut straightly formula tube shell, wait when the test, whole oscillator receives the influence of power cord, electric accent line and load line great, for this reason, this embodiment uses the SMA adapter, carries out signal transmission with power cord, electric accent line and load line through the shielded wire, can avoid lead wire interference. Meanwhile, the permalloy is used as the shell material, so that the environmental interference can be effectively shielded.
Therefore, the constant temperature crystal oscillator provided by the embodiment of the invention can achieve the temperature control precision within 0.1 ℃ through the high-precision temperature control circuit built based on the temperature sensor, so that the whole product has good frequency temperature stability. Meanwhile, the quartz crystal resonator is matched with the structural design of the thermostatic bath and later-stage electric parameter debugging, so that the shell of the quartz crystal resonator can be uniformly heated, the thermal fluctuation is small, when the working temperature environment changes, the thermal overshoot is small, and the internal temperature can be quickly stabilized, thereby reducing the influence of the thermal fluctuation on the short stability of the product.
In order to test the short stability performance of the oven-controlled crystal oscillator provided by this embodiment, the short stability performance test is performed by obtaining the allen variance, which is a representation of the short stability performance of the crystal oscillator in the time domain.
In practical tests, the allen variance and phase noise test system with the model number of Microsmi 5120A is adopted to test the short-term frequency stability of the oven controlled crystal oscillator provided by the embodiment, and through actual measurement and verification, the allen variance millisecond stability of the oven controlled crystal oscillator with the frequency of 10MHz can reach 2.1 multiplied by 10 within the temperature range of-55 ℃ to 85 DEG C-11The second stability can reach 2.85 multiplied by 10 per second-13And s. In the traditional crystal oscillator, the allen variance millisecond stability of the product can only reach 1 multiplied by 10 within a relatively narrow temperature range of-40 ℃ to 70 DEG C-10Around/ms, the second stability can only reach 1 × 10-12Around/s.
Therefore, compared with the traditional crystal oscillator, the short stability of the constant temperature crystal oscillator provided by the embodiment can be obviously optimized.
In summary, the following problems are considered in the practical application of the existing crystal oscillator:
1. because the temperature control precision is low, and when the environmental temperature changes, the heat fluctuation in the thermostatic bath is large, the frequency change is large, and the short stability is deteriorated;
2. along with the rise of the temperature, the noise of the internal semiconductor element is deteriorated, the Q value of the crystal is reduced, and the short stability of the crystal oscillator is deteriorated, so that the wide temperature working temperature range is difficult to achieve;
3. the short stability performance is restricted by the structural situation of the oscillating circuit, so that the high Q crystal does not fully exert the advantages of the high Q crystal.
Therefore, the embodiment provides the temperature control circuit, the constant temperature crystal oscillator circuit and the constant temperature crystal oscillator, and by improving the temperature control circuit and the oscillation circuit, additionally arranging two voltage stabilizing modules, and simultaneously improving the layout of the internal circuit board and the shell of the crystal oscillator, better short stability performance can be achieved within a wider temperature range.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. A temperature control circuit, comprising: the device comprises a first temperature sensor, a second temperature sensor, a voltage follower, a voltage comparator, a power tube heater and a first voltage stabilizing module;
the first temperature sensor and the second temperature sensor are both connected with the input end of the voltage follower, the output end of the voltage follower is connected with the input end of the voltage comparator, the output end of the voltage comparator is connected with the power tube heater, the power tube heater is also connected with the input end of the voltage comparator, and the first voltage stabilizing module is respectively connected with the first temperature sensor, the second temperature sensor, the voltage follower, the voltage comparator and the power tube heater;
first temperature sensor locates the position that is close to by accuse temperature piece, second temperature sensor locates the edge of being controlled the temperature piece place circuit board, first temperature sensor's output voltage with the intermediate voltage of second temperature sensor's output voltage, the warp the voltage follower inputs extremely the voltage comparator, the voltage comparator is used for comparing the intermediate voltage of input with preset voltage to according to the control of comparison result the power tube heater operation.
2. The temperature control circuit according to claim 1, wherein a voltage dividing resistor is disposed between the output terminals of the first temperature sensor and the second temperature sensor and the voltage follower, and the voltage dividing resistor is configured to integrate the output voltage of the first temperature sensor and the output voltage of the second temperature sensor and output an intermediate voltage.
3. The temperature control circuit according to claim 1, wherein a current limiting resistor is further disposed between the output terminal of the voltage comparator and the base of the power tube heater, and a feedback resistor is further disposed between the inverting input terminal of the voltage comparator and the emitter of the power tube heater.
4. The temperature control circuit according to claim 1, wherein the power tube heater comprises a plurality of power tubes, the plurality of power tubes are connected in parallel, and the plurality of power tubes are respectively disposed at positions close to four corners of the circuit board where the temperature controlled member is disposed.
5. A constant temperature crystal oscillator circuit, characterized by comprising the temperature control circuit according to any one of claims 1 to 4, an oscillation module and a second voltage stabilization module, wherein the oscillation module is connected with the second voltage stabilization module, and the first voltage stabilization module and the second voltage stabilization module are both connected with an external power supply;
the temperature control circuit, the oscillation module and the second voltage stabilization module are arranged on the crystal oscillator circuit board, and the temperature controlled piece is a quartz crystal in the oscillation module.
6. The oven controlled crystal oscillator circuit according to claim 5, wherein the oscillation module comprises an oscillation circuit, a buffer amplification circuit and a filter circuit;
one end of the oscillating circuit is connected with the second voltage stabilizing module, the oscillating circuit is connected with the buffering amplifying circuit in an interactive mode, and the buffering amplifying circuit is connected with the filter circuit;
the oscillating circuit comprises a triode, a first peripheral resistance unit and a frequency selection unit, wherein the first peripheral resistance unit is connected with the triode and is used for providing a static working point for the triode;
the frequency selection unit comprises a first frequency selection capacitor, a second frequency selection capacitor, a quartz crystal, a frequency modulation capacitor, a first coupling capacitor, a junction field effect transistor and a second coupling capacitor;
the first frequency-selecting capacitor is connected with the second frequency-selecting capacitor, the first frequency-selecting capacitor and the second frequency-selecting capacitor are connected with an emitting electrode of the triode, one end of the second frequency-selecting capacitor and one end of the frequency-modulating capacitor are connected with a base electrode of the triode, the other end of the frequency-modulating capacitor is connected with the quartz crystal, the quartz crystal is connected with the first coupling capacitor, the first coupling capacitor is connected with the junction field effect tube, and the junction field effect tube is connected with a collecting electrode of the triode through the second coupling capacitor.
7. The constant-temperature crystal oscillator circuit according to claim 6, wherein a filter unit is further disposed between the triode and the frequency selection unit, and the first frequency selection capacitor and the second frequency selection capacitor are both connected to an emitter of the triode through the filter unit.
8. The constant-temperature crystal oscillator circuit according to claim 6, wherein the buffer amplifying circuit comprises a junction field effect transistor, a second peripheral resistance unit and an isolating inductor;
the second peripheral resistance unit is connected with the junction field effect transistor, the second peripheral resistance unit is used for providing a static working point for the junction field effect transistor, and the AC isolation inductor is connected with the junction field effect transistor.
9. The constant temperature crystal oscillator circuit according to claim 5, wherein the second voltage stabilizing module comprises a first linear voltage regulator and a second linear voltage regulator, and the first linear voltage regulator is connected in parallel with the second linear voltage regulator.
10. An oven controlled crystal oscillator comprising an oven controlled crystal oscillator circuit as claimed in any one of claims 5 to 9.
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| CN202210029828.4A CN114047796B (en) | 2022-01-12 | 2022-01-12 | Temperature control circuit, constant temperature crystal oscillator circuit and constant temperature crystal oscillator |
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| CN202210029828.4A CN114047796B (en) | 2022-01-12 | 2022-01-12 | Temperature control circuit, constant temperature crystal oscillator circuit and constant temperature crystal oscillator |
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| CN114047796B CN114047796B (en) | 2022-04-05 |
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| CN114545998A (en) * | 2022-04-27 | 2022-05-27 | 成都世源频控技术股份有限公司 | Self-adaptive protection temperature control circuit of constant temperature crystal oscillator and implementation method |
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