Circuit device of novel constant-temperature crystal oscillator

Abstract

A traditional constant-temperature crystal oscillator circuit is improved, and the novel constant-temperature crystal oscillator circuit device comprises a signal receiving circuit, a constant-temperature control circuit, a phase difference measuring circuit, an oscillation circuit, a DA conversion circuit, an FPGA frequency dividing circuit and a power supply control circuit. According to the method, the output of the crystal oscillator is corrected through the pulse per second (1 pps) signal output by the GPS / BDS receiver, so that the crystal oscillator and the satellite are kept synchronous, the frequency deviation is compensated, and the time frequency precision requirement of a user is met.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electronic communication, in particular to a new type of constant temperature crystal oscillator circuit device. BACKGROUND

[0002] At present, in the current society of the development of the information age, many electronic devices and fields have higher and higher requirements for the stability and accuracy of clock frequency, and the time frequency standard is mainly based on atomic clock. However, cesium clock and hydrogen clock are expensive, large in size, and have high requirements for the use environment. There are also many high-precision time frequency standards required in practical application scenarios, such as high-speed traffic network, finance and power network. The power transmission network requires accuracy of ±1 µs, the high-speed digital communication system requires accuracy of ±0.5 µs, and the secondary frequency standard can meet the demand. Therefore, the crystal oscillator with low price and small size has outstanding advantages. However, the traditional crystal oscillator (OCXO and other crystal oscillators) is easily affected by aging and temperature to produce frequency offset, which makes the accuracy decrease continuously, and gradually cannot meet the user's demand with the passage of time.

[0003] Therefore, it is necessary to design a device that can improve the output stability of the secondary frequency standard and make the secondary frequency standard be widely used. SUMMARY

[0004] The present application overcomes the shortcomings of the prior art and makes the following improvements and optimizations.

[0005] The purpose of the present application is achieved by the following technical solutions: A new type of constant temperature crystal oscillator circuit device is provided, which comprises a signal receiving circuit, a constant temperature control circuit, a phase difference measurement circuit, an oscillation circuit, a DA conversion circuit, an FPGA frequency division circuit and a power supply control circuit. The signal receiving circuit is connected with the phase difference measurement circuit and the FPGA frequency division circuit respectively, the FPGA frequency division circuit is connected with the phase difference measurement circuit and the oscillation circuit respectively, the oscillation circuit is connected with the constant temperature control circuit, the power supply control circuit is connected with the DA conversion circuit, and the DA conversion circuit is connected with the oscillation circuit.

[0006] Preferably, the oscillation circuit comprises a crystal resonator X1, resistors R1-R10, capacitors C1-C8, inductors L1-L3, transistors N1 and N2.

[0007] More preferably, one end of the resistor R1 is connected with the resistor R2, the capacitor C1 and the base of the transistor N1 respectively, and the other end is connected with the resistor R4; the resistor R4 is further connected with the collector of the transistor N1, the resistor R6 and the capacitor C4 respectively; the crystal resonator X1 is connected with the capacitor C3 in series, the resistor R2 is connected with the crystal resonator X1 and the capacitor C3 in parallel, the capacitor C1 is connected with the resistor R5, the capacitor C2 and the base of the transistor N1 respectively; the resistor R5 is connected with the emitter of the transistor N1 and the resistor R3; the resistor R3 is connected with the emitter of the transistor N1; the capacitor C2 is connected with the resistor R5 and the resistor R3, and one end of the resistor R3 is grounded; the capacitor C4 is connected with the resistor R6, the resistor R7, the resistor R9 and the collector of the transistor N2; the resistor R6 is connected with the collector of the transistor N2 and the resistor R9; the resistor R9 is connected with the capacitor C6 and the collector of the transistor N2; the capacitor C6 is connected with the collector of the transistor N2 and the inductor L1; the inductor L1 is connected with the inductor L2, the inductor L3 and the capacitor C8; the inductor L2 is connected with the capacitor C7, the inductor L3 and the capacitor C8; the capacitor C7 is connected with the resistor R10; the resistor R10 is connected with the capacitor C5, the resistor R8, the resistor R7, the inductor L3 and the capacitor C8; the capacitor C5 is connected with the emitter of the transistor N2 and the resistor R8; one end of the resistor R8 is connected with the emitter of the transistor N2, and the other end is connected with the resistor R7 and grounded; the resistor R7 is connected with the capacitor C4, the resistor R6 and the collector of the transistor N2.

[0008] Preferably, the constant temperature control circuit comprises an amplification circuit, and the constant temperature control circuit provides a stable temperature environment for the standard oscillation frequency signal of the standard frequency oscillation circuit, so that the standard oscillation frequency signal is more stable.

[0009] More preferably, the amplification circuit comprises a resistor Ra, a resistor Rb, a resistor Rc, a resistor Rt, a thermistor Rt, an amplifier Na and a power supply Vc; one end of the resistor Ra is connected with the resistor Rb and the positive input end of the amplifier Na respectively, and the other end is connected with the resistor Rt, the power supply end of the amplifier Na and the power supply Vc respectively; one end of the resistor Rb is connected with the positive input end of the amplifier Na, and the other end is grounded; one end of the resistor Rc is connected with the thermistor Rt, a resistor Rd and the negative input end of the amplifier Na, and the other end is grounded; one end of the thermistor Rt is connected with the resistor Rd and the negative input end of the amplifier Na, and the other end is connected with the power supply Vc and the power supply end of the amplifier Na; one end of the resistor Rd is connected with the negative input end of the amplifier Na, and the other end is connected with the output end of the amplifier Na; the input offset end of the amplifier Na is pulled down to the ground.

[0010] Preferably, the power supply control circuit comprises an STM32 single-chip microcomputer chip, and the STM32 single-chip microcomputer chip is used for data processing, which includes calculating phase difference data to perform filtering and calculating the output of the voltage-controlled voltage control DA conversion circuit to tame the crystal oscillator.

[0011] Preferably, the signal receiving circuit is configured to send the received signal to the FPGA frequency dividing circuit and the phase difference measuring circuit.

[0012] Preferably, the FPGA frequency dividing circuit is configured to measure the phase difference between two adjacent signals in cooperation with the phase difference measuring circuit.

[0013] The present application provides a new type of constant temperature crystal oscillator circuit device, which has good long-term stability and is not affected by short-term instability of satellite signals, and can output high-precision frequency signals for a long time. The output accuracy and phase difference drift of the constant temperature crystal oscillator have achieved good results. The device is simple and convenient, and serves as a good benchmark for the subsequent secondary frequency standard taming system. BRIEF DESCRIPTION OF DRAWINGS

[0014] The present application will be further described with reference to the accompanying drawings, but the embodiments in the drawings do not constitute any limitation on the present application. For ordinary skilled in the art, other drawings can be obtained without creative labor on the basis of the following drawings.

[0015] Figure 1 FIG. 1 is a schematic diagram of the new constant temperature crystal oscillator circuit device of the present application; Figure 2 FIG. 2 is a schematic diagram of the oscillation circuit connection of the new constant temperature crystal oscillator circuit device of the present application; Figure 3 FIG. 3 is a schematic diagram of the amplification circuit connection of the new constant temperature crystal oscillator circuit device of the present application; Figure 4 FIG. 4 is a schematic diagram of the test results of a better embodiment of the new constant temperature crystal oscillator of the present application. DETAILED DESCRIPTION

[0016] The new constant temperature crystal oscillator circuit device of the present application will be further described in detail below in conjunction with specific embodiments, which are only used for comparison and explanation purposes, and the present application is not limited to these embodiments.

[0017] In the description of the present application, it should be understood that the terms "upper", "lower", "left", "right", "top", "bottom" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used for the purpose of facilitating the description of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0018] In an embodiment, a new constant temperature crystal oscillator circuit device is provided, as shown in Figure 1As shown, a new constant temperature crystal oscillator circuit device is provided, comprising a signal receiving circuit, a constant temperature control circuit, a phase difference measurement circuit, an oscillation circuit, a DA conversion circuit, an FPGA frequency division circuit and a power supply control circuit; The signal receiving circuit is connected with the phase difference measurement circuit and the FPGA frequency division circuit respectively, the FPGA frequency division circuit is connected with the phase difference measurement circuit and the oscillation circuit respectively, the oscillation circuit is connected with the constant temperature control circuit, the power supply control circuit is connected with the DA conversion circuit, and the DA conversion circuit is connected with the oscillation circuit.

[0019] The receiving circuit receives a second pulse (1pps) signal transmitted from a satellite, the FPGA frequency division circuit takes the rising edge of the 1PPS signal transmitted from the satellite as a mark of the frequency division constant temperature crystal oscillator output signal, and cooperates with the phase difference measurement circuit to measure the phase difference between two adjacent signals (between two 1PPS signals), processes the phase difference data through an STM32 single-chip microcomputer chip to obtain the output voltage required by the DA conversion circuit, controls the voltage control end of the crystal oscillator, and locks the oscillation frequency of the crystal oscillator on the satellite clock, so the device can also be called a constant temperature crystal oscillator locking device. The locked crystal oscillator improves the long-term stability and accuracy of the output signal.

[0020] Preferably, the oscillation circuit comprises a crystal resonator X1, resistors R1-R10, capacitors C1-C8, inductors L1-L3, transistors N1 and N2.

[0021] More preferably, one end of resistor R1 is connected to resistor R2, capacitor C1, and the base of transistor N1, and the other end is connected to resistor R4; resistor R4 is also connected to the collector of transistor N1, resistor R6, and capacitor C4; crystal resonator X1 is connected in series with capacitor C3, resistor R2 is connected in parallel with crystal resonator X1 and capacitor C3, capacitor C1 is connected to resistor R5, capacitor C2, and the base of transistor N1; resistor R5 is connected to the emitter of transistor N1 and resistor R3; resistor R3 is connected to the emitter of transistor N1; capacitor C2 is connected to resistor R5 and resistor R3, and one end of resistor R3 is grounded; capacitor C4 is connected to resistor R6, resistor R7, resistor R9, and the collector of transistor N2. Resistor R6 is connected to the collector of transistor N2 and resistor R9; resistor R9 is connected to capacitor C6 and the collector of transistor N2; capacitor C6 is connected to the collector of transistor N2 and inductor L1; inductor L1 is connected to inductor L2, inductor L3 and capacitor C8; inductor L2 is connected to capacitor C7, inductor L3 and capacitor C8; capacitor C7 is connected to resistor R10; resistor R10 is connected to capacitor C5, resistor R8, resistor R7, inductor L3 and capacitor C8; capacitor C5 is connected to the emitter of transistor N2 and resistor R8; one end of resistor R8 is connected to the emitter of transistor N2, and the other end is connected to resistor R7 and grounded; resistor R7 is connected to capacitor C4, resistor R6 and the collector of transistor N2.

[0022] like Figure 2 The oscillating circuit shown works on the following principle: In this embodiment, R10 is the load resistor with a value of 50Ω. The crystal resonator X1 is an SC-cut overtone crystal, and transistors N1 and N2 are 2SC3356. R1~R4 are bias resistors that provide DC bias for transistor N1. R5 is the feedback resistor, and the crystal resonator X1 plays a role in frequency stabilization. Capacitors C1 and C2 are feedback capacitors, and their ratio affects the stability of the device. Capacitor C3 is a frequency modulation capacitor used to adjust the crystal load and calibrate the output frequency.

[0023] Since the frequency stability of the oscillator is mainly determined by the Q value of the quartz crystal resonator and the 1 / f (noise) of transistors N1 and N2, the parasitic resonance mode of the crystal resonator is effectively suppressed by the feedback resistor R5, which also improves the phase noise performance. This ensures the power of the crystal oscillator output signal and provides isolation, reducing load pull.

[0024] Preferably, the constant temperature control circuit includes an amplifier circuit, which provides a stable temperature environment for the standard frequency oscillation circuit to generate a standard oscillation frequency signal, thereby making the standard oscillation frequency signal more stable.

[0025] More preferably, the amplification circuit comprises a resistor Ra, a resistor Rb, a resistor Rc, a resistor Rt, a thermistor Rt, an amplifier Na and a power supply Vc; one end of the resistor Ra is connected with the resistor Rb and the positive input terminal of the amplifier Na respectively, and the other end is connected with the resistor Rt, the power supply terminal of the amplifier Na and the power supply Vc respectively; one end of the resistor Rb is connected with the positive input terminal of the amplifier Na, and the other end is grounded; one end of the resistor Rc is connected with the thermistor Rt, a resistor Rd and the inverting input terminal of the amplifier Na, and the other end is grounded; one end of the thermistor Rt is connected with the resistor Rd and the inverting input terminal of the amplifier Na, and the other end is connected with the power supply Vc and the power supply terminal of the amplifier Na; one end of the resistor Rd is connected with the inverting input terminal of the amplifier Na, and the other end is connected with the output terminal of the amplifier Na; the input offset terminal of the amplifier Na is pulled down to the ground.

[0026] As shown in the amplification circuit, it is a direct amplification continuous temperature control circuit, which works in a direct current state, has small external interference, simple circuit and is easy to design in a small size. Figure 3

[0027] With the increase of temperature, Rt gradually decreases, and when Rt=R3, the output voltage is zero. However, the actual temperature control system needs to conduct part of the heat and generate certain dissipated heat, so the bridge needs to output a certain voltage, which is amplified to control the heating current, so that the heat generated is just equal to the heat dissipated by the constant temperature tank. In actual debugging, after the resistance value of the thermistor Rt is selected, R3 is determined according to the inflection point of the crystal, so that the constant temperature crystal oscillator has the best frequency temperature stability and short-term stability index.

[0028] Considering that the output control voltage of the actual operational amplifier circuit will produce temperature drift over time, causing the temperature of the constant temperature tank to change, a temperature drift compensation circuit is added in the circuit design, which improves the long-term stability of the temperature control circuit.

[0029] Preferably, the power supply control circuit comprises an STM32 single-chip microcomputer chip, which is used for data processing, including calculating phase difference data for filtering and calculating the output of the voltage-controlled voltage control DA conversion circuit to tame the crystal oscillator.

[0030] Preferably, the signal receiving circuit is used to send the received signal to the FPGA frequency division circuit and the phase difference measurement circuit.

[0031] Preferably, the FPGA frequency division circuit is used to cooperate with the phase difference measurement circuit to measure the phase difference between two adjacent signals.

[0032] ​The input phase difference value is subjected to data processing, and the processing result is input to the DA conversion circuit to control the crystal oscillator for the first time. Then, Kalman filtering operation is performed on each collected data, and the phase difference change is calculated. The average value of the phase difference change in 60s is used to calculate the corresponding frequency difference and pressure difference, and the constant temperature crystal oscillator is tamed.

[0033] By assuming that the frequency of the rubidium atomic clock is the standard 10MHz, the output frequency of the tamed constant temperature competition period within 24 hours is measured. The two results of the measurement are shown in Figure 4 The frequency drifts within 24 hours are 9.16E-6Hz and 1.03E-5Hz respectively, and the phase difference drifts are 79ns and 89ns respectively. The phase difference drifts within 24 hours are relatively good.

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not limited to the protection scope of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present application.

Claims

1. A circuit arrangement for a new type of thermostatic crystal oscillator, characterized by The signal receiving circuit, the constant temperature control circuit, the phase difference measuring circuit, the oscillation circuit, the DA conversion circuit, the FPGA frequency division circuit and the power supply control circuit are connected. The signal receiving circuit, the constant temperature control circuit, the phase difference measuring circuit, the oscillation circuit, the DA conversion circuit, the FPGA frequency division circuit and the power supply control circuit are connected.

2. A novel circuit arrangement for a constant temperature crystal oscillator as claimed in claim 1, characterized in that The oscillation circuit comprises a crystal resonator X1, resistors R1-R10, capacitors C1-C8, inductors L1-L3, transistors N1 and N2.

3. A novel circuit arrangement for a constant temperature crystal oscillator as claimed in claim 2, characterized in that One end of the resistor R1 is connected with the resistor R2, the capacitor C1 and the base of the transistor N1, and the other end is connected with the resistor R4; the resistor R4 is also connected with the collector of the transistor N1, the resistor R6 and the capacitor C4; the crystal resonator X1 is connected with the capacitor C3 in series, the resistor R2 is connected with the crystal resonator X1 and the capacitor C3 in parallel, the capacitor C1 is connected with the resistor R5, the capacitor C2 and the base of the transistor N1; the resistor R5 is connected with the emitter of the transistor N1 and the resistor R3; the resistor R3 is connected with the emitter of the transistor N1; the capacitor C2 is connected with the resistor R5 and the resistor R3, and one end of the resistor R3 is grounded; the capacitor C4 is connected with the resistor R6, the resistor R7, the resistor R9 and the collector of the transistor N2; the resistor R6 is connected with the collector of the transistor N2 and the resistor R9; the resistor R9 is connected with the capacitor C6 and the collector of the transistor N2; the capacitor C6 is connected with the collector of the transistor N2 and the inductor L1; the inductor L1 is connected with the inductor L2, the inductor L3 and the capacitor C8; the inductor L2 is connected with the capacitor C7, the inductor L3 and the capacitor C8; the capacitor C7 is connected with the resistor R10; the resistor R10 is connected with the capacitor C5, the resistor R8, the resistor R7, the inductor L3 and the capacitor C8; the capacitor C5 is connected with the emitter of the transistor N2 and the resistor R8; one end of the resistor R8 is connected with the emitter of the transistor N2, and the other end is connected with the resistor R7 and grounded; the resistor R7 is connected with the capacitor C4, the resistor R6 and the collector of the transistor N2.

4. The circuit arrangement of a novel constant temperature crystal oscillator according to claim 1, characterized in that, The constant temperature control circuit comprises an amplification circuit, and provides a stable temperature environment for the standard oscillation frequency signal of the standard frequency oscillation circuit, so that the standard oscillation frequency signal is more stable.

5. A novel circuit arrangement for a constant temperature crystal oscillator as claimed in claim 4, characterized in that The amplification circuit comprises a resistor Ra, a resistor Rb, a resistor Rc, a resistor Rt, a thermistor Rt, an amplifier Na and a power supply Vc; one end of the resistor Ra is connected with the resistor Rb and the positive input end of the amplifier Na respectively, and the other end is connected with the resistor Rt, the power supply end of the amplifier Na and the power supply Vc respectively; one end of the resistor Rb is connected with the positive input end of the amplifier Na, and the other end is grounded; one end of the resistor Rc is connected with the thermistor Rt, a resistor Rd and the inverting input end of the amplifier Na, and the other end is grounded; one end of the thermistor Rt is connected with the resistor Rd and the inverting input end of the amplifier Na, and the other end is connected with the power supply Vc and the power supply end of the amplifier Na; one end of the resistor Rd is connected with the inverting input end of the amplifier Na, and the other end is connected with the output end of the amplifier Na; the input offset end of the amplifier Na is pulled down to the ground.

6. A novel thermostat crystal oscillator circuit device according to claim 1, wherein, The power supply control circuit comprises an STM32 single-chip microcomputer chip, which is used for data processing, including calculating phase difference data to perform filtering and calculating the output of a voltage-controlled voltage-controlled DA conversion circuit to tame a crystal oscillator.

7. A novel thermostat crystal oscillator circuit device according to claim 1, wherein, The signal receiving circuit is used for sending the received signal to the FPGA frequency division circuit and the phase difference measurement circuit.

8. The circuit arrangement of a novel constant temperature crystal oscillator according to claim 1, characterized in that, The FPGA frequency division circuit is used for cooperating with the phase difference measurement circuit to measure the phase difference between two adjacent signals.

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