[0038] In order to make the purpose of the present application, the technical solution and advantages more clear, the following will be combined with the specific embodiments of the present application and the corresponding drawings of the technical solution of the application is clearly and completely described. Obviously, the embodiments described are only a portion of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without doing creative labor, are within the scope of protection of the present application.
[0039] The following in conjunction with the accompanying drawings, a detailed description of the technical solution provided by each embodiment of the present application.
[0040] The present invention provides a CHIP packaging scheme for a chip atomic clock dedicated servo control chip, and designed a test method suitable for the SIP chip.
[0041] The technical embodiments of the present invention are as follows:
[0042] SIP is a new packaging technology based on system minimization, which packs multiple IC dies and possible passive components in the same substrate to form a standardized chip with a system-based function, and is a semiconductor technology that can achieve system-on-chip integration. This scheme is based on SIP package design technology for chip atomic clock special servo control chip packaging design, in which the MCU, op amp, gate, DAC, inverter and switch and other bare chips are integrated, to achieve the physical system signal acquisition and processing, drive control, physical system temperature signal acquisition and processing, temperature control and drive current generation and other functions.
[0043] Servo control circuit block diagram is attached Figure 1 As shown, the configuration circuits in the figure are placed outside the chip, and the rest is packaged inside the chip. All of the configuration circuits shown in the figure consist of capacitors, resistors, and inductors, which can be easily adjusted by placing them outside the chip. Specifically, by adjusting the first configuration circuit can adjust the amplitude of the photometric signal; adjusting the second configuration circuit can change the laser driving voltage; adjusting the third configuration circuit, the fourth configuration circuit can change the physical system and laser temperature control coefficient, affecting the temperature control accuracy; adjusting the fifth configuration circuit can change the radio frequency signal amplitude. Because the operating temperature point of each physical system and laser is different, and the driving voltage of the laser and the power intensity of the RF signal need to be adjusted according to the debugging phenomenon when it is combined with the physical system, and these adjustments can be achieved by changing the parameters of the corresponding configuration circuit. Such a packaging method is mainly to package the bare core of the core device and the inherent configuration circuit of the device, and the configuration circuit part to be adjusted during the debugging process is placed outside the chip, which can cure the inherent core circuit design to the greatest extent, and at the same time has a stronger universality than the scheme of all circuits being packaged inside the chip.
[0044] Figure 2 Block diagrams of specific SIP are given, such as Figure 2 As shown, the architecture and functions of the dedicated servo control chip for the atomic clock of the chip are further described as follows:
[0045] Photometric signal acquisition circuit: The circuit scheme first preprocesses the photoelectric signal of the input signal of the two frequencies, and then acquires the high-precision ADC, and sends the acquired digital amount to the MCU microcontroller for data processing.
[0046] VCSEL laser drive circuit and crystal oscillator drive circuit: The MCU will calculate the feedback output, control two high-precision DACs, and the outputs of the two DACs are connected to the voltage control end of the crystal oscillator and the control end of the VCSEL drive circuit respectively, to complete the laser frequency locking and microwave frequency locking.
[0047] Temperature acquisition circuit of physical system: The temperature of the physical system also needs to be controlled by the MCU microcontroller. The temperature of the laser and the absorber bubble is converted to a voltage signal by the temperature sensor, which is acquired by two ADCs and input to the MCU microcontroller for PID data processing.
[0048] Drive circuit of temperature-controlled heating: The MCU is heated by the heating control amount obtained by the PID algorithm, and the TEC of the VCSEL and the power tube of the absorbing bubble are heated by two DAC feedbacks.
[0049] Control circuit of uniform magnetic field: The MCU outputs accurate values to the DAC, controls the magnetic field synthesis circuit, and generates a constant magnetic field with high accuracy.
[0050] The present invention adopts SIP integration technology, in the chip design process mainly follows the principle of the main core chip and the inherent configuration circuit in the integrated module, the part of the configuration circuit that needs to adjust the parameters is external to the SIP chip, in order to enhance the adjustability of the overall function of the chip, and the compatibility and applicability of different physical systems.
[0051] attach Figure 3 Designed for SIP chip layout, attached Figure 4 A design for the package of the module. The chip mainly integrates the switch, transistor, op amp, MCU, inverting gate, gate and other bare chips and some configuration circuits of each module, and uses WB to establish electrical interconnection with the substrate.
[0052] Please propose the chip atomic clock dedicated servo control chip test method, which includes the following steps:
[0053] First, the chip size test: use the vernier caliper to measure the length, width and height of the chip atomic clock special servo control chip.
[0054] Second, power supply and power consumption test: equipment connection such as Figure 6 As shown, the chip atomic clock special servo control chip is installed on the test board for testing, the DC voltage source provides power to the test board; reads the voltage value and current value of the DC voltage source, calculates the power consumption; if there is accidental interference to make the system unstable, repeat the test; after the test is completed, disconnect the system connection.
[0055] Third, the functional test steps are as follows:
[0056] Step 11: Device connection such as Figure 7 As shown, the chip atomic clock special servo control chip is installed on the test board for testing, the test board is placed in the high and low temperature box, and the DC voltage source supplies the test board. After the temperature of the physical system is stabilized, the ambient temperature T is detected by reading the high and low temperature chamber temperature display 0 , the absorption bubble temperature T is obtained by the corresponding thermistor resistance 1 and laser temperature T 2 ；
[0057] Step 12: Adjust the temperature of the high and low temperature chamber so that the ambient temperature is T′ 0 After the temperature of the physical system is stabilized, the absorption bubble temperature T′ is obtained by the corresponding thermistor resistance value. 1 and laser temperature T′ 2 ；
[0058] According to equation (2), the absorption bubble temperature control accuracy C is calculated 1 and laser temperature control accuracy C 2 ；
[0059] C 1 ＝ΔT 1 /ΔT 0 (1)
[0060] C 2 ＝ΔT 2 /ΔT 0 (2)
[0061] where ΔT 0 ＝T′ 0 -T 0 ，ΔT 1 ＝T′ 1 -T 1 ，ΔT 2 ＝T′ 2 -T 2 。
[0062] Step 13: The laser frequency servo loop completes the acquisition, processing and control of the atomic absorption spectrum signal, obtains the differential signal of the atomic absorption spectrum, and observes the locking of the laser frequency;
[0063] Step 14: The laser frequency servo loop completes the acquisition, processing and control of the CPT resonance spectrum signal, obtains the differential signal of the CPT resonance spectrum, and observes the locking of the crystal oscillator frequency;
[0064] Step 15: Using the standard 1PPS signal, the 1PPS taming calibration loop completes the detection, processing and feedback of the time interval error, the whole clock completes the taming function, and the counter is used to measure the synchronization error between the atomic clock of the chip and the standard 1PPS signal;
[0065] Step 16: Realize 1PPS time synchronization and atomic clock frequency calibration, and use the frequency tester to measure the frequency accuracy of the chip atomic clock;
[0066] Step 17: The RF phase-locked loop completes the frequency doubling of the 10MHz signal and measures the output frequency using the spectrometer;
[0067] Step 18: Change the control word, use the spectrometer to measure the output frequency change, and calculate the signal resolution;
[0068] Step 19, the atomic clock online debugging and working status normal output indicates that the RS232 communication function is normal.
[0069] Fourth, the operating temperature test steps are as follows:
[0070] Step 21: Test the device connection, such as Figure 5 As shown, the high and low temperature test environment is used Figure 8 The thermal flow cover temperature control system shown places the chip on the test equipment and adjusts the heat flow cover to the appropriate angle to completely cover the device under test.
[0071] The heat flow hood system begins to work, the compressed air is heated or cooled to the appropriate temperature by the heat flow hood system, and the heat exchange is continuously sprayed into the heat flow hood cavity at high speed, and the temperature control probe is monitored at the same time;
[0072] After a certain period of time, the temperature in the cavity reaches the specified index temperature, reaches the thermal equilibrium, and when the stable temperature is reached, it lasts for 1min to test the functions of the device;
[0073] Step 22: Integrate circuit test: Switch the MCU control on the test board to the PD test channel by selecting one of the four analog switches. The output triangle wave of the signal generator is applied to the PD_Input pin, and converted into a square wave signal by the integration circuit in the dedicated servo control chip. Use the oscilloscope to observe the square wave signal output test point CPTDC, if it is a square wave, the integration circuit in the chip is functionally normal;
[0074] Step 23: Filter circuit test: The MCU control on the test board selects one of the four analog switches and switches to the PDInput test channel. The signal generator output fre1/fre2 sine wave signal is applied to the PDInput pin for the dedicated servo control chip for analog-to-digital conversion, and the oscilloscope test output test points AC1 and AC2 are used to record the amplitude and frequency information; the information collected by the MCU in the dedicated servo control chip is sent to the host computer to display the amplitude and frequency information. If the error between the data tested by the oscilloscope and the data collected by the special servo control chip is less than a certain threshold, the function of the in-chip filter circuit is normal;
[0075] Step 24, R_TEC circuit test: The MCU control on the test board selects one of the four analog switches and switches to the R_TEC test channel. The signal generator outputs a fre1 sine wave signal applied to the R_TEC test pin, and the TEC+ is output after the signal processing is completed by a dedicated servo control chip. Use the oscilloscope to test the TEC + pin, compare the input and output signals, if the error is less than a certain threshold, it is considered to be functionally normal;
[0076] Step 25, TEMP_CELL circuit test: The MCU on the test board controls the analog switch of each of the four, and switches to the TEMP_CELL test channel. The signal generator outputs a fre1 sine wave signal applied to the TEMP_CELL pin, and the output CELL_TC after the signal processing is completed by a dedicated servo control chip. Use the oscilloscope to test the CELL_TC pins, compare the input and output signals, if the error is controlled within a certain threshold, it is considered to be functionally normal;
[0077] Step 26, 1PPS_IN circuit test: the MCU output high level signal on the test board is applied to the 1PPS_IN pin; the MCU in the dedicated servo control chip applies a low level to the P1 signal, and after the comparison circuit in the chip, the VO_PPS is low for the MCU in the chip to be collected, and the acquisition result should be low; the MCU output high level signal on the test board is applied to the 1PPS_IN pin; the MCU in the chip applies a high level to the P1 signal. After the in-chip comparison circuit, the VO_PPS is high for the MCU in the chip to collect, and the acquisition result should be high;
[0078] Step 27, IO function test: PLL_LD, LOCK, PLL_LE and other pins lead out to the MCU on the test board, loopback test, if the data is normal, it is considered to be functional;
[0079] Step 28, current source test: the voltage of the LT_VDC pin of the DAC in the chip is the input voltage of the constant current source, the multimeter is used to measure the LT_VDC pin, the output current of the IDC pin can be calculated according to the theory, and the IDC pin current can be tested by using the multimeter, and the constant current source can be judged whether the constant current source is working normally by comparing the theoretical value and the test value;
[0080] Step 29, voltage source test: the use of a multimeter to test the C + pin voltage, compare the measured value and the theoretical value, if the amplitude error is less than a certain threshold, the voltage source is considered to be working normally;
[0081] After the test, disconnect the system.
[0082] In summary, the SIP packaging method of the chip atomic clock special servo control chip proposed in the present invention can greatly reduce the volume and power consumption of the atomic clock, which is of great significance for the development of the current chip atomic clock and the development of weapon models.
[0083] The SIP package design of the present invention mainly comprises a core chip and an inherent configuration circuit, the partial configuration circuit of the relevant module is placed outside the chip, so that the partial resistance parameters are convenient and adjustable, and the adjustability of the overall function of the chip is enhanced, and the compatibility and applicability of different physical systems.
[0084] The present invention proposes a complete set of test methods for the SIP chip, which can effectively examine the size, power consumption, function and other indicators of the chip.
[0085] It should also be noted that the term "comprising", "containing" or any other variation thereof is intended to cover non-exclusive inclusion, so that a process, method, commodity or device comprising a series of elements includes not only those elements, but also other elements not expressly listed, or elements inherent in such processes, methods, goods or equipment. In the absence of further restrictions, the elements defined by the statement "comprising a ...", do not exclude the existence of additional identical elements in the process, method, commodity or equipment that includes the elements.
[0086] The above is only an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of this application shall be included within the scope of the claims of this application.
