Dual-mode delay chip RCL oscillator frequency calibration device
By designing the frequency calibration device of the RCL oscillator for dual-mode delay chip, using constant temperature control and pulse heat heating technology, the problem of frequency instability of RC oscillator is solved, and the frequency calibration effect with high accuracy and high shock resistance is achieved.
Patent Information
- Application Number
- CN202510252887.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-05
- Publication Date
- 2025-06-20
AI Technical Summary
The frequency of the RC oscillator is unstable when the temperature and power supply voltage change, resulting in insufficient accuracy and cannot meet the accuracy requirements of the fuze delay.
A dual-mode delay chip RCL oscillator frequency calibration device is designed, and a dual-mode delay chip constant temperature control device, a dual-mode delay chip constant temperature calibration control box and a control and data acquisition host are used to achieve high stability and high accuracy frequency calibration through temperature traversal and pulse heat heating.
With the RC oscillation clock as the reference, it achieves 50-80PPM timing accuracy and 2000G shock resistance, which significantly improves the product's accuracy and anti-interference ability, and reduces energy consumption and cost.
Smart Images
Figure CN120185552A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of clock source design, and particularly relates to a frequency calibration device for a dual-mode delay chip RCL oscillator. Background Art
[0002] To achieve precise electronic delay with high reliability and high shock resistance, it is envisioned to use an RC oscillator as the clock source for precise delay. However, it is well known in the integrated circuit design industry that although RC oscillation has the advantage of high reliability, it has a serious drawback: low accuracy. The current highest level in the industry is ±1.5%, which seriously does not meet the accuracy requirements of fuze delay.
[0003] To solve this problem, the factors causing insufficient accuracy of RC oscillation are analyzed:
[0004] First, the discreteness in the manufacturing process, there will be an error of 1 - 2% between chips.
[0005] Second, the RC oscillation varies greatly with temperature. According to the actual measurement of this tape-out, at -45°C, the RCL frequency is about 521Khz, while at room temperature it is about 501Khz. A temperature difference of 70°C results in a frequency change of 20 / 501 = 4%.
[0006] Third, the RC oscillation frequency changes with the change of power supply voltage. In integrated circuit design, by improving the accuracy of the reference source and then the accuracy of the LDO power supply, the change of RC oscillation with voltage can be greatly reduced. In this case, the change of power supply voltage can also be attributed to - temperature. Summary of the Invention
[0007] (1) Technical Problems to be Solved
[0008] The technical problem to be solved by the present invention is how to provide a frequency calibration device for a dual-mode delay chip RCL oscillator to solve the problem of insufficient accuracy of RC oscillation.
[0009] (2) Technical Solutions
[0010] To solve the above technical problems, the present invention proposes a frequency calibration device for a dual-mode delay chip RCL oscillator, and the device includes: a refrigeration / heating thermostat, a dual-mode delay chip constant temperature calibration control box, and a control and data acquisition host;
[0011] The refrigeration / heating constant temperature controller is used to provide a heat circulation medium with a relatively constant temperature. The heat circulation medium is transported through a pipeline into the dual-mode delay chip constant temperature calibration control box, enters the copper constant temperature platform, and then flows back to the refrigeration / heating constant temperature controller again. There is a circulation pump inside the refrigeration / heating constant temperature controller to provide the power for the circulation of the heat circulation medium, and the temperature of the copper constant temperature platform is controlled within the set target range through the heat circulation medium.
[0012] The dual-mode delay chip constant temperature calibration control box is internally equipped with a copper constant temperature platform. A measurement support PCB is closely attached to the upper surface of the copper constant temperature platform. A large number of dual-mode delay chip test sockets are installed on the measurement support PCB. Each socket is installed with a chip to be tested, and the chip to be tested is a dual-mode delay chip; the measurement support PCB provides the wiring lines for driving each socket and leads them out to the FPC leads at the edge; the driving and measurement signals of the chip are led out of the dual-mode delay chip constant temperature calibration control box through the traces on the support PCB and the FPC leads and are connected to the sockets on the constant temperature calibration control and measurement PCB circuit board fixed on the outer side of the dual-mode delay chip constant temperature calibration control box.
[0013] The control and data acquisition host is connected to the constant temperature calibration control and measurement PCB circuit board through a communication line and is used to control the temperature of the copper constant temperature platform. At each temperature point, while ensuring that the temperature fluctuation is small enough, the host drives and reads the internal temperature measurement values of each chip to be tested through the constant temperature calibration control and measurement PCB circuit board and measures the internal clock frequency values of each chip to be tested.
[0014] (III) Beneficial effects
[0015] The present invention proposes a dual-mode delay chip RCL oscillator frequency calibration device. The good effects of the present invention and the comparison with similar products are as follows:
[0016] 1. The refrigeration and temperature control involved in the present invention are jointly completed by a temperature controller and the pulse heating of the heating metal lines manufactured on the support PCB, while traditional temperature control only uses a temperature controller with conventional PID temperature control. There are many disadvantages in the traditional PID temperature control method: First, the system will have temperature oscillations. To eliminate the oscillations, a long time of temperature tracking is required, which will result in a large amount of energy consumption and lengthen the time required for temperature traversal, greatly restricting the production efficiency; Second, even in the stable stage of PID, there are still large fluctuations in the temperature of the constant temperature platform. At present, the temperature control system using the adaptive PID algorithm internationally can reach a best level of 0.005 °C / S, which is still far from the temperature control stability requirement of the present invention; Third, the cost is high. High-stability PID temperature control requires precise measurement and optimized adaptive control algorithms, so the cost is high.
[0017] The present invention uses the pulse heat heating method to achieve temperature rise, uses the thermal inertia of the platform and heat preservation measures to achieve high temperature stability, and achieves the purpose of high-stability temperature control with its low cost. Moreover, the size of the thermal pulse can be precisely controlled, and the temperature rise step can be made infinitely small. Therefore, the method involved in the present invention is very helpful for improving production efficiency and product precision.
[0018] 2. The present invention relates to a design method of a constant temperature box body, which adopts a double-layer heat preservation method. The inner layer heat preservation uses foamed ethylene propylene diene monomer rubber with good heat resistance and heat preservation performance; the outer layer heat preservation uses a composite material of aluminum foil and foamed EVA. The present invention uses good heat preservation to achieve high temperature stability. Compared with the traditional PID stability, the present invention has lower energy consumption and higher stability.
[0019] 3. The present invention relates to a method for accurately measuring frequency, which uses the counting, comparison output and capture input functions of the timer of the MCU to achieve accurate frequency measurement with the support of a high-precision reference clock. It has the advantages of low price, small volume and convenient docking with a PC. While the traditional method of using a frequency meter for measurement not only has a large volume and high cost, but also is very difficult to achieve docking with a PC.
[0020] 4. The present invention relates to a method for calibrating the RC oscillation clock of a chip through temperature traversal. This method is to gradually increase the temperature from the lowest to the highest in a constant temperature box body according to a set step size. In each temperature step, under the condition of ensuring high temperature stability, accurately measure the internal temperature measurement value of the chip and the frequency value of the RC clock, establish the FREQ(T) function (frequency - temperature function) of the chip, and then download each point of the function into the chip. Then, the chip uses digital algorithms internally to achieve frequency calibration and timing calibration.
[0021] By using the method involved in the present invention, it is possible to achieve a good effect of obtaining a timing accuracy of 50 - 80 PPM when using the internal RC clock of the chip. While the traditional RC oscillator timing can only reach an accuracy of 1%, which is 1 / 100 of the method involved in the present invention.
[0022] The method for calibrating the RC oscillation frequency of the chip involved in the present invention through temperature traversal can achieve precise timing with high stability and high seismic resistance under the condition of using the RC oscillation clock as the reference. The accuracy reaches 50 - 80 PPM, and the seismic resistance reaches 2000G. While the traditional scheme needs to use a crystal oscillator as the clock source to achieve this accuracy, and the seismic resistance of the crystal oscillator is only 150G. This is a great advantage of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1 is the design block diagram of the present invention;
[0024] Figure 2Schematic diagram of the frequency measurement circuit;
[0025] Figure 3 Clock diagram of the frequency measurement circuit;
[0026] Figure 4 Waveform diagram of the pin output. Specific implementation manners
[0027] To make the objectives, content and advantages of the present invention clearer, the following further describes in detail the specific implementation manners of the present invention with reference to the accompanying drawings and embodiments.
[0028] To solve the problem of insufficient precision of the RC oscillation, the present invention proposes the following solutions:
[0029] First, the chip internally has a precise temperature measurement function and can sense its own temperature. The designed target parameters are as follows: within the range of -45 - 85°C, the temperature measurement precision reaches 1 / 4095 = 0.03°C. After converting the noise, the temperature measurement precision is not less than 0.1°C.
[0030] Within this temperature range, the original precision of the RCL clock is: ±5%, and the rate of change with temperature is: 769 PPM / °C.
[0031] If the chip temperature measurement precision reaches 0.1°C, the delay precision can be adjusted to: 76.9 PPM ≈ 80 PPM.
[0032] The current chip fabrication fully proves that the idea of the project team is correct. The chip delay precision can indeed be adjusted to about 80 PPM, which can fully meet the delay precision requirements of the fuse.
[0033] Second, perform point-by-point RC frequency measurement on the chip within the full temperature range to form a temperature - RCL frequency correction table.
[0034] In the design, the project team left an 8192-point correction table for the chip. Within the range of -45 - 85°C, there is one correction point every 0.0159°C. In theory, the delay precision can be corrected to: 12 PPM. However, considering the temperature measurement noise interference, the actual situation cannot reach this precision. The actual measurement of the current chip fabrication proves that the delay precision that can be achieved after fine adjustment is about 80 - 100 PPM, which is consistent with the expectations of the project team.
[0035] The temperature calibration device involved in the present invention is to achieve the following function: obtain the functional relationship between the internal temperature measurement ADC of the chip and the RCL oscillation frequency every 0.0159°C within the range of -45 - 85°C. That is, establish the function: FREQ = f(Tadc).
[0036] The present invention provides a frequency calibration device for a dual-mode delay chip RCL oscillator, comprising: a refrigeration / heating thermostat controller, a dual-mode delay chip constant-temperature calibration control box, and a control and data acquisition host;
[0037] The refrigeration / heating thermostat controller is used to provide a heat cycle medium with relatively constant temperature. The heat cycle medium is transported through a pipeline into the dual-mode delay chip constant-temperature calibration control box, enters the copper constant-temperature platform, and then flows back to the refrigeration / heating thermostat controller again. There is a circulation pump inside the refrigeration / heating thermostat controller to provide the power for the circulation of the heat cycle medium, and the temperature of the copper constant-temperature platform is controlled within a set target range through the heat cycle medium;
[0038] The dual-mode delay chip constant-temperature calibration control box is internally equipped with a copper constant-temperature platform. A measurement support PCB is closely attached to the upper surface of the copper constant-temperature platform. A large number of dual-mode delay chip test sockets are installed on the measurement support PCB, and each socket is installed with a chip to be tested. The chip to be tested is a dual-mode delay chip; the measurement support PCB provides the wiring lines for driving each socket and leads them out to the FPC leads at the edge; the driving and measurement signals of the chip are led out of the dual-mode delay chip constant-temperature calibration control box through the traces on the support PCB and the FPC leads and are connected to the sockets on the constant-temperature calibration control and measurement PCB circuit board fixed on the outer side of the dual-mode delay chip constant-temperature calibration control box;
[0039] The control and data acquisition host is connected to the constant-temperature calibration control and measurement PCB circuit board through a communication line and is used to control the temperature of the copper constant-temperature platform. At each temperature point, on the premise of ensuring that the temperature fluctuation is small enough, the host drives and reads the internal temperature measurement value of each chip to be tested through the constant-temperature calibration control and measurement PCB circuit board and measures the internal clock frequency value of each chip to be tested.
[0040] Embodiment 1:
[0041] The present invention provides a frequency calibration device for a dual-mode delay chip RCL oscillator, and the specific design is as follows:
[0042] 1. Design block diagram
[0043] The device includes three parts: a refrigeration / heating thermostat controller, a dual-mode delay chip constant-temperature calibration control box, and a control and data acquisition host, hereinafter referred to as the "thermostat", "constant-temperature box", and "host" for short.
[0044] 2. Design principle
[0045] (1) Refrigeration and temperature control
[0046] The refrigeration / heating thermostat provides a thermally cycled medium with a relatively constant temperature. Silicone oil is used as the thermally cycled medium. The silicone oil is transported through pipes into the internal constant temperature calibration control box of the dual-mode delay chip, enters the copper constant temperature platform, and then flows back to the refrigeration / heating thermostat again. There is a circulation pump inside the refrigeration / heating thermostat that can provide the power for the silicone oil circulation. Through the silicone oil (thermally cycled medium), the temperature of the copper constant temperature platform can be controlled within the set target range.
[0047] In addition, to improve the efficiency during the heating process, heating metal lines are fabricated on the measurement support PCB inside the constant temperature box. Since the measurement support PCB is in close contact with the copper constant temperature platform, the heat generated by the heating metal lines on the measurement support PCB when powered on can be quickly transferred to the copper constant temperature platform, thus achieving a higher heating and temperature rise efficiency.
[0048] The thermostat and the heating metal lines on the measurement support PCB jointly achieve the temperature control of the copper constant temperature platform.
[0049] (2) Driving and calibration data measurement of the dual-mode delay chip
[0050] A copper constant temperature platform is installed inside the constant temperature box. A measurement support PCB is closely attached to the upper surface of the copper constant temperature platform. A large number of dual-mode delay chip test Sockets, abbreviated as Sockets, are installed on the measurement support PCB. One chip to be tested (hereinafter referred to as the chip for the dual-mode delay chip) can be installed on each Socket.
[0051] The measurement support PCB provides the wiring lines for driving each Socket and leads them out to the edge FPC leads, that is, the "dual-mode delay chip measurement control FPC lead-out line", hereinafter referred to as: FPC lead. FPC is a flexible multi-strand metal lead supported by an insulating film and is usually used to connect a large number of electrical signals.
[0052] Through the traces on the support PCB and the FPC leads, the driving and measurement signals of the chip can be led out of the constant temperature box and connected to the sockets on the "constant temperature calibration control and measurement PCB circuit board" (abbreviated as the measurement and control PCB) fixed on the outer side of the constant temperature box.
[0053] There is a control MCU and a precision clock source on the measurement and control PCB. Under the control of the MCU, the internal temperature measurement data of each chip to be tested can be read, and the chip can be driven to output its internal clock signal. At the same time, when the MCU uses the precision clock source as a reference, it can accurately measure the frequency of the internal clock signal output by the chip.
[0054] The principle of the frequency measurement circuit is as Figure 2 、 3 shown:
[0055] Figure 3 Among them, U17 is a TCXO clock source with an oscillation frequency of 25Mhz and an accuracy of ±0.25PPM. After being isolated and driven by the amplifier U2, it is provided to pin 5 of U21 of the single-chip microcomputer MCU as the working clock of the MCU.
[0056] The frequency signal to be measured, FREQ-IN, is connected to pin 14 of U21. This pin of the MCU is initialized as Timer0-Etr, that is, the external clock input of Timer0 of the MCU; pins 20 and 21 of U21 are directly connected. Pin 20 of U21 is initialized as the Tim5 CapA function, that is, the external capture input A channel of Timer5; while pin 21 of U21 is initialized as the Tim0 cmpA function, that is, the comparison output A channel of Timer0.
[0057] Measurement principle:
[0058] The frequency FREQ-IN to be measured is used as the Timer0-Etr signal. Timer0 is initialized to the external counting mode, and the counting period is selected as 50000. At the same time, the Tim0 cmpA function is enabled to output a PWM signal on pin 21 of U21. The comparison value is set to any value within 50000, preferably 10000. After such settings, the waveform output on pin 21 of U21 is as Figure 4 shown:
[0059] Since pins 20 and 21 of U21 are short-circuited, the output signal of pin 21 of U21 is provided to pin 20 of U21 as the input signal of the external capture channel A of Timer5.
[0060] Pin 20 of U21 is initialized as the external capture signal A of Timer5, and rising edge capture is used. The current count value of Timer5 can be latched during capture. Timer5 itself is initialized to the internal counting mode, and the counting clock source comes from the 25Mhz TCXO clock. Therefore, the difference in the Timer5 counts obtained by the two rising edge captures of pin 20 of U21 is the time value in units of the 25Mhz period (0.04uS) between the two rising edges of the pulses.
[0061] Assume that the difference in the count values captured by Timer5 twice = N, then the represented time = N * 0.04uS. This time is the time for 50000 cycles of the frequency FREQ to be measured. Thus, the period Tf of the frequency to be measured is calculated as Tf = N * 0.04uS / 50000, and the frequency FREQ to be measured = 1 / Tf = 1250000 / N. Thus, the purpose of measuring the frequency is achieved.
[0062] (3) Control and data acquisition host
[0063] The so-called control means: controlling the temperature of the copper constant temperature platform inside the constant temperature box. The design purpose of this device is to achieve: internal clock source frequency calibration of the dual-mode delay chip within the full temperature range. Therefore, it is required that the temperature of the copper constant temperature platform must start from the lowest (-45°C), and gradually rise to the highest temperature (85°C) in a certain step size. At each temperature point, the internal temperature measurement data of the chip needs to be read, and the internal clock frequency of the chip is measured.
[0064] The so-called data acquisition means: at each temperature point, while ensuring that the temperature fluctuation is small enough, the host drives through the measurement and control PCB to read the internal temperature measurement value of each chip to be tested, and measures the internal clock frequency value of each chip to be tested, obtaining a sample point (T, FREQ). If the temperature rise per step is set to 0.25°C, then for the range from -45 to 85°C, traversing each temperature point, 520 (T, FREQ) sample points can be obtained.
[0065] (4) The temperature of the copper constant temperature platform is constant
[0066] At each temperature point, the host needs to collect the sample point data of all chips to be tested in the constant temperature box. Since the number of chips to be tested in the box is large (usually 81 pieces), and data acquisition takes a certain amount of time. Calculated according to the fact that it takes 0.5 - 1 second to collect the data of one chip, and adopting a multi-channel parallel acquisition scheme, such as 4-channel parallel acquisition, the required acquisition time is 10 - 20 seconds. During the chip data acquisition period, it is required that the temperature of the copper constant temperature platform is in a stable state, and the stability of the temperature must meet the requirements of the chip calibration accuracy. According to our calculation, during the chip data acquisition period, the temperature stability of the copper constant temperature platform must be <0.00032°C / S, that is, the second stability index of the temperature <0.00032°C.
[0067] This is achieved through three technical means:
[0068] First, temporarily cut off the medium circulation of the thermostat during the measurement to avoid the temperature control fluctuation of the thermostat affecting the second stability index;
[0069] Second, when designing and manufacturing, use a copper constant temperature platform with a mass greater than a certain threshold, so that the copper constant temperature platform has a large thermal inertia. The actually manufactured copper constant temperature platform has a mass of 20 Kg and a thermal inertia of 7900 J / °C;
[0070] Thirdly, adopt good heat preservation measures. In the present invention, the dual-mode delay chip constant temperature calibration control box adopts a double-layer heat preservation method. The inner layer uses foamed ethylene propylene diene monomer (EPDM) rubber. The reason is that EPDM rubber has better temperature resistance characteristics and can work in the temperature range of -80 - 130 °C. The outer layer uses a composite material of aluminum foil and foamed ethylene-vinyl acetate (EVA). Foamed EVA has good heat preservation performance, but its working temperature is relatively low, and the maximum temperature resistance is only 90 °C. Therefore, it can be used as the outer layer for heat preservation. The aluminum foil can provide infrared reflection ability and block the heat exchange formed by infrared radiation inside and outside the constant temperature box.
[0071] Example 2:
[0072] (1) The present invention relates to a method for efficient temperature control and temperature stability, specifically: using a thermostat and heating metal lines on a supporting printed circuit board (PCB) to jointly control the temperature of a copper constant temperature platform. Refrigeration is mainly achieved by the thermostat, while heating is mainly achieved by the heating metal lines on the PCB. By inputting a heat pulse, the temperature rise of the platform is realized. This not only improves efficiency but also enables accurate and simple control of the temperature rise; using a copper constant temperature platform with a large mass and large thermal inertia to prevent the rapid temperature fluctuation of the constant temperature platform caused by external heat; adopting a double-layer heat preservation measure, with the inner layer using foamed EPDM rubber with good temperature resistance and large thermal resistance, and the outer layer using a composite material of aluminum foil and foamed EVA. On the one hand, utilize the good heat preservation characteristics of foamed EVA, and on the other hand, adopt the emission effect of aluminum foil to block the internal and external infrared exchange.
[0073] (2) The present invention relates to a method for controlling temperature with heat pulses. This method is realized by inputting an electric heating pulse to the heating metal lines on the measurement support PCB installed on the upper surface of the copper constant temperature platform in the constant temperature box. By controlling the time width of the heating pulse, the input heat can be quantitatively controlled, that is, the so-called precise heat pulse is used to control the temperature. Compared with the feedback-type PID temperature control, this temperature control method is simpler to implement, but the second-level stability index of the temperature is better, which is more conducive to the accurate measurement and calibration of the chip clock frequency.
[0074] (3) The present invention relates to a method for accurately measuring and calibrating the RC clock source of a chip: accurate measurement and calibration within the full temperature range. As is well known, although the RC oscillator has the advantages of simple circuit, easy integration, and good shock resistance, the frequency of the RC oscillator will change with the supply voltage and temperature. The present invention relates to a method for accurately calibrating the internal RC oscillator of a chip: by measuring the frequency of the internal RC clock source of the chip at each temperature point and the internal temperature measurement data of the chip, the FREQ(T) function (frequency - temperature function) of the chip is obtained, and then the precise calibration of the RC oscillation of the chip is realized through digital means, so as to achieve precise delay with the RC clock source as a reference.
[0075] (4) The present invention relates to an accurate frequency measurement method using an MCU supported by a precision clock source. On the measurement and control PCB of the device, by using the external clock counting of Timer 0 of the MCU and the compare output function of Timer 0, the conversion of the external clock counting to the pulse edge can be achieved. The number of cycles between the two output pulse edges can be set. In the present invention, 50,000 is adopted. Then, the capture input of Timer 5 is used to measure the real time between the two pulse edges, so as to obtain the real time of 50,000 clock cycles to be measured, and thus accurately measure the frequency.
[0076] Good effects of the present invention and comparison with similar products:
[0077] 1. For the refrigeration and temperature control involved in the present invention, it is jointly completed by a temperature controller and the pulse heating of the heating metal wires manufactured on the supporting PCB, while traditional temperature control only uses a temperature controller to adopt conventional PID temperature control. There are many disadvantages in the traditional PID temperature control method: First, the system will have temperature oscillation. To eliminate the oscillation, a long time of temperature tracking is required, which will lead to a large amount of energy consumption and lengthen the time required for temperature traversal, greatly restricting the production efficiency. Second, even in the stable stage of PID, there are still large fluctuations in the temperature of the constant temperature platform. At present, the best level of the temperature control system adopting the adaptive PID algorithm in the world can reach 0.005 °C / S, which is still far from the temperature control stability requirement of the present invention. Third, the cost is high. High-stability PID temperature control requires precise measurement and optimized adaptive control algorithms, so the cost is high.
[0078] The present invention uses the pulse heat heating method to achieve temperature rise, uses the thermal inertia of the platform and heat preservation measures to achieve high temperature stability, and achieves the purpose of high-stability temperature control with its low cost. Moreover, the size of the heat pulse can be precisely controlled, and the temperature rise step can be made infinitely small. Therefore, the method involved in the present invention is very helpful for improving production efficiency and product accuracy.
[0079] 2. The present invention relates to a design method of a constant temperature box, which adopts a double-layer heat preservation method. The inner layer heat preservation uses foamed ethylene propylene diene monomer rubber with good heat resistance and heat preservation performance; the outer layer heat preservation uses a composite material of aluminum foil and foamed EVA. The present invention uses good heat preservation to achieve high temperature stability. Compared with traditional PID stability, the present invention has lower energy consumption and higher stability.
[0080] 3. The present invention relates to a method for measuring frequency with high precision, which uses the counting, compare output and capture input functions of the timer of the MCU to achieve accurate frequency measurement with the support of a high-precision reference clock. It has the advantages of low price, small volume and convenient connection with a PC. While traditional frequency measurement using a frequency meter not only has a large volume and high cost, but also is very difficult to connect with a PC.
[0081] 4. The present invention relates to a method for calibrating the RC oscillation clock of a chip through temperature traversal. This method is to gradually increase the temperature from the lowest to the highest in a constant temperature chamber according to a set step size. Within each temperature step, under the condition of ensuring high temperature stability, the internal temperature measurement value of the chip and the frequency value of the RC clock are accurately measured to establish the FREQ(T) function (frequency-temperature function) of the chip. Then, each point of the function is downloaded into the chip, and the chip then uses digital algorithms to achieve frequency calibration and timing calibration.
[0082] By adopting the method of the present invention, it is possible to achieve a good effect of obtaining a timing accuracy of 50 - 80 PPM when using the internal RC clock of the chip. The timing of the traditional RC oscillator can only reach an accuracy of 1%, which is 1 / 100 of the method of the present invention.
[0083] The method for calibrating the RC oscillation frequency of the chip through temperature traversal according to the present invention can achieve precise timing with high stability and high seismic resistance under the condition of using the RC oscillation clock as the reference. The accuracy reaches 50 - 80 PPM, and the seismic resistance reaches 2000G. While for the traditional scheme to achieve this accuracy, a crystal oscillator needs to be used as the clock source, and the seismic resistance of the crystal oscillator is only 150G. This is a great advantage of the present invention.
[0084] The above is only the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.
Claims
1. A dual-mode delay chip RCL oscillator frequency calibration device, characterized in that: The device comprises: a refrigeration / heating constant temperature controller, a dual-mode delay chip constant temperature calibration control box, and a control and data acquisition host; The refrigeration / heating thermostat is used to provide a relatively constant temperature heat circulation medium. The heat circulation medium is transported to the dual-mode delay chip constant temperature calibration control box through a pipeline, enters the copper constant temperature platform, and then flows back to the refrigeration / heating thermostat. There is a circulation pump inside the refrigeration / heating thermostat to provide power for the heat circulation medium to circulate. The temperature of the copper constant temperature platform is controlled within the set target range through the heat circulation medium. The dual-mode delay chip constant temperature calibration control box has a copper constant temperature platform installed inside, a measurement support PCB is installed closely on the surface of the copper constant temperature platform, a large number of dual-mode delay chip test sockets are installed on the measurement support PCB, and a chip to be tested is installed on each socket, and the chip to be tested is a dual-mode delay chip; the measurement support PCB provides wiring lines for driving each socket, and leads out to the FPC leads on the edge; the chip driving and measurement signals are led out to the outside of the dual-mode delay chip constant temperature calibration control box through the wiring on the support PCB and the FPC leads, and are connected to the socket on the measurement PCB circuit board fixed to the constant temperature calibration control on the outer side of the dual-mode delay chip constant temperature calibration control box; The control and data acquisition host is connected to the constant temperature calibration control and measurement PCB circuit board through a communication line, and is used to control the temperature of the copper constant temperature platform. At each temperature point, while ensuring that the temperature fluctuation is small enough, the host drives the constant temperature calibration control and measurement PCB circuit board to read the internal temperature measurement value of each chip to be tested, and measures the internal clock frequency value of each chip to be tested.
2. The dual-mode delay chip RCL oscillator frequency calibration device as claimed in claim 1, characterized in that: Silicone oil is used as the heat circulation medium.
3. The dual-mode delay chip RCL oscillator frequency calibration device as claimed in claim 1, characterized in that: Heating metal lines are manufactured on the measurement support PCB. Since the measurement support PCB and the copper constant temperature platform are in close contact, the heat generated by the heating metal lines on the measurement support PCB is quickly transferred to the copper constant temperature platform when power is turned on; the cooling / heating constant temperature controller and the heating metal lines on the measurement support PCB jointly realize the temperature control of the copper constant temperature platform.
4. The dual-mode delay chip RCL oscillator frequency calibration device as claimed in claim 3, characterized in that: Thermal pulse temperature control is achieved by inputting an electric heating pulse into the heating metal lines on the measurement support PCB installed on the surface of the copper constant temperature platform in the dual-mode delay chip constant temperature calibration control box, and quantitatively inputting heat by controlling the time width of the heating pulse.
5. The dual-mode delay chip RCL oscillator frequency calibration device as claimed in claim 1, characterized in that: The constant temperature calibration control and measurement PCB circuit board has a control MCU and a precision clock source. Under the control of the MCU, the internal temperature measurement data of each chip to be tested is read, and the chip is driven to output its internal clock signal. At the same time, the MCU uses the precision clock source as a reference to accurately measure the frequency of the internal clock signal output by the chip.
6. The dual-mode delay chip RCL oscillator frequency calibration device as claimed in claim 5, characterized in that: U17 is a TCXO clock source. After being isolated and driven by amplifier U2, it is provided to pin 5 of U21 of the microcontroller MCU as the working clock of the MCU. The frequency signal to be measured is FREQ-IN connected to pin 14 of U21. This pin of the MCU is initialized to Timer0-Etr, which is the external clock input of timer 0 of the MCU. Pin 20 of U21 is directly connected to pin 21 of U21. Pin 20 of U21 is initialized to Tim5 CapA function, which is the external capture input A channel of timer 5. Pin 21 of U21 is initialized to Tim0 cmpA function, which is the comparison output A channel of timer 0.
7. The dual-mode delay chip RCL oscillator frequency calibration device as claimed in claim 6, characterized in that: On the constant temperature calibration control and measurement PCB circuit board, the external clock count of the MCU's timer 0 and the comparison output function of timer 0 are used to realize the conversion of the external clock count to the pulse edge, set the number of cycles N between the two output pulse edges, and then use the capture input of timer 5 to measure the real time between the two pulse edges, so as to obtain the real time of N clock cycles to be measured, so as to accurately measure the frequency.
8. The dual-mode delay chip RCL oscillator frequency calibration device as claimed in claim 1, characterized in that: The temperature control of the copper constant temperature platform includes: in order to realize the internal clock source frequency calibration of the dual-mode delay chip within the full temperature range, the temperature of the copper constant temperature platform must start from the lowest temperature and gradually rise to the highest temperature according to a certain step length. At each temperature point, the internal temperature measurement data of the chip needs to be read to measure the internal clock frequency of the chip.
9. The dual-mode delay chip RCL oscillator frequency calibration device as claimed in claim 8, characterized in that: By measuring the frequency of the chip's internal RC clock source at each temperature point and the chip's internal temperature measurement data, the chip's FREQ(T) function, i.e., the frequency-temperature function, is obtained, and then precise calibration of the chip's RC oscillation is achieved through digital methods.
10. The dual-mode delay chip RCL oscillator frequency calibration device according to any one of claims 1 to 9, characterized in that: During the measurement, the medium circulation of the refrigeration / heating thermostat is temporarily cut off to prevent the temperature fluctuation of the refrigeration / heating thermostat from affecting the second stability index; during the design and manufacturing, a copper thermostat platform with a mass greater than a certain threshold is used, so that the copper thermostat platform has a larger thermal inertia; the dual-mode delay chip thermostat calibration control box adopts a double-layer insulation method, the inner layer insulation adopts foamed EPDM rubber, and the outer layer adopts aluminum foil and foamed EVA composite material.