Implementation method of high-precision oscillator

Abstract

The invention discloses an implementation method of a high-precision oscillator, and the method employs a through-hole resistor to replace a poly resistor, thereby reducing the influence of the packaging stress and temperature change on the frequency stability. A wide-range positive-temperature current generator and a zero-temperature current source are constructed, and stable current output with adjustable temperature is realized through an OPA negative feedback and current copying technology; bias current is generated through positive temperature and negative temperature current operation, and comparator delay change caused by temperature drift is compensated; a hole resistance monitoring system is combined, and real-time detection and feedback adjustment of a resistance value are realized through constant-current injection and ADC measurement; and finally, the PLL frequency multiplication module is utilized to flexibly adjust the output frequency, so that the frequency precision requirements of different products are met, and the oscillator design with high stability, high consistency and high precision is realized.

Description

Technical Field

[0001] The present invention relates to the field of electronic technology, and particularly to a method for implementing a high-precision oscillator. Background Art

[0002] In today's high-precision electronic systems, as a clock and reference frequency source, the performance of an oscillator directly affects the stability and reliability of the system. However, traditional oscillators face two key problems in practical applications: one is that the absolute value of the frequency is easily affected by process deviations, package stress, and changes in high and low temperature environments; the other is that it is difficult to control the frequency-temperature characteristic, resulting in unstable performance in a wide temperature range. These problems severely limit the application of oscillators in high-precision scenarios such as industrial control, communication, and aerospace. There is an urgent need for a high-precision oscillator solution that can effectively suppress temperature drift and take process tolerance into account.

[0003] Currently, most mainstream technologies use poly resistors or MOS resistors as key temperature-sensitive components. However, these resistors are prone to resistance value drift during processes such as high-temperature soldering and temperature cycling, thereby affecting the stability of frequency output. At the same time, some technologies control the temperature coefficient of the oscillator by adding a temperature compensation circuit, but the compensation method is often single and cannot take into account the non-linear characteristics of positive and negative temperature changes, resulting in the frequency stability still being difficult to meet the high-precision requirements. In addition, traditional oscillators often lack a dynamic monitoring mechanism for the actual changes in resistors during implementation, and the deviations in the manufacturing process cannot be effectively compensated, ultimately affecting product consistency and mass producibility. Summary of the Invention

[0004] In order to overcome the shortcomings and deficiencies of the prior art, the present application proposes a method for implementing a high-precision oscillator.

[0005] A method for implementing a high-precision oscillator includes the following steps:

[0006] Step S1: Use a via resistor to replace the poly resistor to reduce the influence on the absolute value of the oscillator frequency and temperature characteristics in the case of resistor deformation caused by package stress, reflow soldering, and high and low temperature factors;

[0007] Step S2: Build a wide-range positive temperature current generator, input a signal, use the negative feedback characteristic of the OPA, generate a wide-range positive temperature current through the internal current replication function, and adjust the relevant coefficients according to different processes and product requirements to obtain the positive temperature current in the required temperature range;

[0008] Step S3: Use the VBG to generate a zero-temperature current and output it to the core part of the oscillator for charging and discharging, and at the same time make a current proportional to the charging and discharging current act on the hole resistor to generate a reference voltage for the core part of the oscillator;

[0009] Step S4: Let the positive temperature current be operated with the current generated by the wide-range positive temperature current generator to generate a negative temperature current with an opposite temperature coefficient. Superimpose the negative temperature current and the wide-range positive temperature current to obtain a bias current. By adjusting the ratio of the two, different temperature characteristic currents that meet the requirements of the comparator delay temperature characteristics are obtained.

[0010] Step S5: Construct a via resistance monitoring system. In the test mode, inject a constant current source current into the via resistance, and send the voltage formed at both ends of the via resistance to the ADC after being driven by the BUF to measure the via resistance value.

[0011] Step S6: Process the output frequency of the oscillator through the PLL. Keep the core part of the oscillator unchanged, and by adjusting the multiplication factor of the PLL, make the final output frequency meet the requirements of different products for the frequency.

[0012] Further, the input signal of the wide-range positive temperature current generator is k·V BG , and utilize the negative feedback characteristic of the OPA to make the current flowing through the via resistance R nt0 Among them, V is the bandgap reference voltage, V BG is the voltage across the diode (the same function can also be achieved by using a triode or MOS device), k is an adjustment coefficient, and a wide-range positive temperature current WIPT is output through the internal current replication function. The value range of k is [k BE , k min , k max , k min , k max is determined according to different processes and product requirements. Under the preset process, if is a specific value of the bandgap reference voltage under this process, V BE takes values at different temperatures as corresponding to temperature T1, corresponding to temperature T2. Change the value of k to make I(Wipt0) change and adjust the temperature coefficient of WIPT to meet the requirements of different products for positive temperature current in different temperature ranges.

[0013] Further, in the process of generating the reference voltage of the oscillator core part, the reference voltage V REF = k1·I C1 , where k1 is a proportionality coefficient, and the value range is [k 1min , k 1max , which is determined by the characteristics of the via resistance R CT and the requirements of the oscillator core part for the reference voltage; I C1 is the zero-temperature current I ZT as the identifier when it is used as the charge and discharge current. When the oscillator is working, I ZT is stably output to the core part. By controlling k1 and IC1 value, the generated V REF is stable and meets the amplitude requirement of the reference voltage for the core part of the oscillator.

[0014] Further, when generating the negative temperature current WINT, the positive temperature current is operated with the WIPT module through a specific operation circuit. The operation formula is WINT = WIPT · a - b, where a and b are operation coefficients. The value range of a is [a min , a max , and the value range of b is [b min , b max . The specific values are determined according to the circuit design. In the circuit, by adjusting the values of a and b, the generated WINT has the opposite temperature coefficient to WIPT, and then WINT and WIPT are superimposed to generate the bias current I Ctrim , I Ctrim = WIPT + WINT. By adjusting the ratio of WIPT and WINT in I Ctrim , it is used to meet the requirement of the bias current for the comparator delay temperature characteristic.

[0015] Further, in the hole resistance monitoring system, the current value of the constant current source I cont is I contset is a value preset in advance according to the resistance value range of the hole resistance R CT and the measurement accuracy of the ADC. When measuring the resistance value of the hole resistance, according to Ohm's law where V RCT is the voltage across R CT . In the test mode, the switch ST2 is disconnected and ST1 is closed. I cont is injected into R CT , and a voltage V CT is generated across R RCT . It is sent to the ADC through the BUF drive. By measuring the obtained V RCT , combined with the known , the resistance value of R CT is calculated to monitor the resistance value stability of the through-hole resistance in real-time during production and manufacturing.

[0016] Further, during the PLL frequency doubling process, the frequency doubling factor is P, N is an integer, and the value range is P min , P max , N min , N max is determined according to the frequency requirements of different products. The output frequency of the core part of the oscillator is f(OSC_OUT), and the final output frequency For the frequency requirements of different products, by adjusting The value is such that F meets the specific frequency index of the product while keeping the core part of the oscillator working stably, which is used to ensure the consistency of oscillator performance.

[0017] Further, the bias current I of the temperature compensation comparators CMP0T / CMP1T Ctrim has a trimming range of This trimming range is determined according to the temperature characteristic compensation requirement of the comparator delay and the overall performance requirement of the oscillator. In the circuit, by changing the value of I Ctrim , the response time of the comparator is adjusted, and the relationship satisfies t response = m·I Ctrim + n, where t response is the comparator response time, m and n are coefficients related to the circuit characteristics of the comparator. The value range of m is [m min , m max , and the value range of n is [n min , n max . By trimming I within the range. Ctrim .

[0018] Further, the relationship between the wide-range temperature adjustment current bias I Ctrim and the temperature characteristic of the comparator delay satisfies the formula where ΔT dct is the comparator delay of the calibratable temperature characteristic, and α, β, and γ are coefficients related to the circuit design. The value range of α is [α min , α max , the value range of β is [β min , β max , and the value range of γ is [γ min , γ max . During the operation of the circuit, by changing the value of I Ctrim , ΔT dct is changed according to this formula to compensate for the temperature characteristic of the oscillator.

[0019] Further, the overall frequency formula of the oscillator is where R CT is the via resistance, C A is the capacitor related to charge and discharge in the oscillator, ΔT dct is the comparator delay of the calibratable temperature characteristic, and ΔT dx is the delay of the remaining logic circuits except the comparator. By changing the value of R CT , is adjusted, and then the absolute value of the frequency is adjusted; by adjusting ΔT dct , the temperature characteristic of the oscillator is compensated; when adjusting ΔT dct , for ΔT dxCompensation is carried out.

[0020] Beneficial effects:

[0021] The present invention proposes a method for implementing a high-precision oscillator. By constructing modules such as a wide-range positive-temperature current source, a zero-temperature current source, a negative-temperature current operation circuit, a via resistance monitoring system, and a temperature compensation comparator, and cooperating with an adjustable proportionality coefficient k and a frequency multiplication factor, the oscillator can still output accurate and stable frequency signals in different process batches and wide temperature ranges. This method effectively overcomes the problems in traditional oscillators where the poly resistor changes due to environmental factors such as reflow soldering, high and low temperatures, resulting in an absolute shift in the oscillation frequency and temperature drift. Through the construction of currents with complementary temperature coefficients, a reference voltage is generated and injected into the core of the oscillator, significantly improving the frequency stability; using an ADC to monitor the via resistance value to achieve online feedback adjustment effectively solves the problem of poor consistency caused by manufacturing deviations; introducing a temperature compensation comparator to adjust the comparator delay according to the bias current further optimizes the temperature characteristic control; at the same time, PLL frequency multiplication processing ensures that the output frequency is adjustable and meets the requirements of various products. The overall solution improves the absolute accuracy of the oscillator frequency while significantly reducing the impacts caused by temperature changes, process fluctuations, etc., enhancing the reliability, consistency, and batch controllability of the oscillator, and is applicable to electronic system applications with extremely high requirements for frequency stability, having significant engineering practical value and promotion potential. Description of the drawings

[0022] Figure 1 is the flowchart of the method of the present invention;

[0023] Figure 2 is the schematic diagram of the oscillator principle of the present invention;

[0024] Figure 3 is the schematic diagram of the newly added module of the oscillator of the present invention;

[0025] Figure 4 is the wide-range positive-temperature current generator of the present invention;

[0026] Figure 5 is the schematic diagram of the principle of the reference voltage and wide-range temperature adjustment current generator of the present invention;

[0027] Figure 6 is the diagram of the via resistance detection system of the present invention; Detailed implementation manners

[0028] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The following further describes the present application in detail with reference to the drawings and specific embodiments.

[0029] Figure 1As shown in the figure, an embodiment of the present application provides a method for implementing a high-precision oscillator, and the method includes the following steps:

[0030] Step S1: Use a via resistor to replace the poly resistor to reduce the impact on the absolute value of the oscillator frequency and the temperature characteristics in the case of resistor deformation caused by package stress, reflow soldering, and high and low temperature factors;

[0031] Specifically, in oscillator design, package stress, the reflow soldering process, and high and low temperature environments will all cause the resistor to deform, and this deformation will have a significant impact on the absolute value of the oscillator frequency and the temperature characteristics. When facing these factors, the resistance value of the poly resistor (polysilicon resistor) changes significantly, resulting in unstable oscillator performance.

[0032] The via resistor is a more stable type of resistor. It is usually made of metal or alloy. Compared with the poly resistor, it is less sensitive to package stress, reflow soldering, and high and low temperature changes. When using the via resistor to replace the poly resistor, during the packaging process, the via resistor can better resist the stress caused by the shrinkage or expansion of the packaging material and reduce the change in the resistance value. In the high-temperature environment of reflow soldering, the via resistor has higher thermal stability and small resistance fluctuations. During the high and low temperature cycling process, the range of its resistance value change is also much smaller than that of the poly resistor. For example, in the temperature range of -40°C to 125°C, the resistance value change rate of the poly resistor may reach ±10% or even higher, while the resistance value change rate of the via resistor can be controlled within ±1%. This makes the absolute value of the oscillator frequency more stable, significantly improves the temperature characteristics, and thus improves the accuracy of the oscillator.

[0033] Step S2: Build a wide-range positive temperature current generator, input a specific signal, use the negative feedback characteristic of OPA, generate a wide-range positive temperature current through the internal current replication function, and adjust the relevant coefficients according to different processes and product requirements to obtain the positive temperature current in the required temperature range;

[0034] Specifically, the wide-range positive temperature current generator is a key component of a high-precision oscillator. Its main function is to generate positive temperature currents in different temperature ranges to meet the requirements of different processes and products.

[0035] During the building process, a specific signal needs to be input first. This signal can be a voltage signal with a fixed frequency and amplitude as the input excitation of the entire generator. Using the negative feedback characteristic of OPA (operational amplifier) can ensure the stability of the output. When the output current changes, OPA will adjust through the negative feedback mechanism to keep the output near the set value. The internal current replication function can copy and amplify the input small current signal to generate a wide-range positive temperature current.

[0036] Different processes and products have different requirements for the temperature range and magnitude of the positive temperature current. By adjusting the relevant coefficients, such as changing the values of components like resistors and capacitors, the temperature characteristics of the positive temperature current can be precisely controlled. For example, for some products that are more sensitive to temperature changes, in the temperature range of -20°C to 80°C, the change rate of the positive temperature current may be +0.5% per degree Celsius. By reasonably adjusting the relevant coefficients, such temperature characteristic requirements can be achieved, providing a stable and appropriate positive temperature current for the subsequent circuit.

[0037] Step S3: Use the VBG to generate a zero-temperature current and output it to the core part of the oscillator for charging and discharging. At the same time, make a current that is in a specific proportion to the charging and discharging current act on the hole resistor to generate a reference voltage for the core part of the oscillator.

[0038] Specifically, the VBG (bandgap reference) is a circuit that can generate a stable voltage independent of temperature. In a high-precision oscillator, using the VBG to generate a zero-temperature current is of great significance.

[0039] The zero-temperature current refers to a current whose magnitude does not change with temperature. Outputting the zero-temperature current generated by the VBG to the core part of the oscillator for charging and discharging can ensure that the charging and discharging process of the core part of the oscillator is not affected by temperature. Since the stability of the charging and discharging current is directly related to the frequency stability of the oscillator, the use of the zero-temperature current can improve the frequency accuracy of the oscillator.

[0040] At the same time, make a current that is in a specific proportion to the charging and discharging current act on the hole resistor. Since the hole resistor has high stability, according to Ohm's law (V = IR), when the resistor is stable, by controlling the current magnitude, a stable reference voltage can be generated. This reference voltage provides a stable potential reference for the core part of the oscillator, further ensuring the stable performance of the oscillator. For example, in practical applications, by precisely designing the circuit, the ratio of the charging and discharging current to the current acting on the hole resistor is 1:2. In this way, according to the required reference voltage value, the resistance value and current magnitude of the hole resistor can be accurately controlled to generate a reference voltage that meets the requirements.

[0041] Step S4: Let the positive temperature current perform an operation with the current generated by the wide-range positive temperature current generator to generate a negative temperature current with an opposite temperature coefficient. Superimpose the negative temperature current and the wide-range positive temperature current to obtain a bias current. By adjusting the ratio of the two, different temperature characteristic currents that meet the requirements of the comparator delay temperature characteristics are obtained.

[0042] Specifically, in the oscillator, different circuit parts have different requirements for temperature characteristics. To meet the requirements of the comparator delay temperature characteristics, a current with specific temperature characteristics needs to be generated.

[0043] First, perform an operation on the positive temperature current and the current generated by the wide-range positive temperature current generator. By reasonably designing the operation circuit, such as using subtraction operation or proportional operation, etc., a negative temperature current with an opposite temperature coefficient can be generated. The characteristic of the negative temperature current is that its magnitude decreases as the temperature increases, which is opposite to the temperature characteristic of the positive temperature current.

[0044] Then, superimpose the negative temperature current and the wide-range positive temperature current to obtain a bias current. By adjusting the ratio of the two, currents with different temperature characteristics can be obtained. For example, if a bias current with a larger current at low temperature and a smaller current at high temperature is required, the ratio of the negative temperature current can be appropriately increased; conversely, if a bias current with a larger current at high temperature and a smaller current at low temperature is required, the ratio of the negative temperature current can be decreased. This method of adjusting the temperature characteristic of the bias current by superimposing currents with different temperature characteristics can flexibly meet the delay characteristic requirements of the comparator in different temperature environments, thereby improving the overall performance of the oscillator.

[0045] Step S5: Construct a via resistance monitoring system. In the test mode, inject a constant current source current into the via resistance, and send the voltage formed at both ends of the via resistance to the ADC after being driven by a BUF to measure the via resistance value;

[0046] Specifically, in the actual application of the oscillator, the resistance value stability of the via resistance is crucial for the performance of the oscillator. Constructing a via resistance monitoring system can monitor the change of the via resistance value in real time to ensure the normal operation of the oscillator.

[0047] In the test mode, inject a constant current source current into the via resistance. The magnitude of the constant current source current is fixed, which is to ensure the accuracy of the measurement. According to Ohm's law, when a constant current is injected, a voltage proportional to the resistance value will be formed at both ends of the via resistance. Send this voltage to the ADC (analog-to-digital converter) after being driven by a BUF (buffer).

[0048] The function of the BUF is to enhance the driving ability of the signal to ensure that the voltage signal can be stably transmitted to the ADC. The ADC converts the analog voltage signal into a digital signal, so that the resistance value of the via resistance can be accurately measured. By monitoring the resistance value of the via resistance in real time, abnormal resistance values caused by factors such as package stress and temperature change can be detected in time. For example, if it is found that the resistance value of the via resistance exceeds the normal range, the oscillator can be adjusted or repaired in time to ensure the stability and reliability of its performance.

[0049] Step S6: Process the output frequency of the oscillator through a PLL. Keep the core part of the oscillator unchanged, and adjust the multiplication factor of the PLL to make the final output frequency meet the frequency requirements of different products.

[0050] Specifically, a PLL (Phase-Locked Loop) is a circuit that can precisely control and adjust the signal frequency. In a high-precision oscillator, by processing the output frequency of the oscillator through a PLL, the final output frequency can meet the frequency requirements of different products.

[0051] The working principle of the PLL is to automatically adjust the frequency of the output signal by comparing the phases and frequencies of the input signal and the feedback signal, so that it maintains a certain multiple relationship with the frequency of the input signal. In oscillator applications, without changing the core part of the oscillator, by adjusting the multiplication factor of the PLL, the final output frequency can be changed.

[0052] For example, if the frequency output by the core part of the oscillator is 1 MHz and the required output frequency for a certain product is 10 MHz, then the multiplication factor of the PLL can be set to 10. In this way, the PLL will multiply the 1-MHz signal output by the core part of the oscillator to 10 MHz for output. In this way, without changing the core circuit structure of the oscillator, the output frequency can be flexibly adjusted to meet the diverse frequency requirements of different products in different application scenarios, improving the versatility and applicability of the oscillator.

[0053] Preferably, the input signal of the wide-range positive-temperature current generator is k·V BG , and by using the negative feedback characteristic of the OPA, the hole resistance R nt0 has a current flowing through it where, V BG is the bandgap reference voltage, V BE is the voltage across the diode, k is the adjustment coefficient, and the wide-range positive-temperature current WIPT is output through the internal current replication function. The value range of k is [k min , k max , k min , k max is determined according to different processes and product requirements. Under the preset process, if is a specific value of the bandgap reference voltage under this process, V BE takes values at different temperatures as corresponding to temperature T1, corresponding to temperature T2. By changing the value of k, the I (Wipt0) changes, and the temperature coefficient of WIPT is adjusted to meet the requirements of different products for positive-temperature current in different temperature ranges.

[0054] Preferably, during the generation of the reference voltage, the reference voltage V REF = k1·I C1 , where k1 is the proportionality coefficient, and the value range is [k 1min , k 1max , and it is determined by the hole resistance R CTIt is determined by the characteristics of C1 and the requirement of the oscillator core part for the reference voltage; I ZT As the identification when it is the charge and discharge current. When the oscillator is working, I ZT is stably output to the core part. By precisely controlling the values of k1 and I C1 , it is ensured that the generated V REF is stable and meets the amplitude requirement of the reference voltage for the oscillator core part, ensuring the normal operation of the oscillator.

[0055] Preferably, when generating the negative temperature current WINT, the positive temperature current is operated with the WIPT module through a specific operation circuit. The operation formula is WINT = WIPT·a - b, where a and b are operation coefficients. The value range of a is [a min , a max , and the value range of b is [b min , b max . The specific values are determined according to the circuit design. In the actual circuit, by adjusting the values of a and b, the generated WINT has the opposite temperature coefficient to WIPT, and then WINT and WIPT are superimposed to generate the bias current I Ctrim , I Ctrim = WIPT + WINT. By adjusting the ratio of WIPT and WINT in I Ctrim , the requirement of the comparator delay temperature characteristic for the bias current is met.

[0056] Preferably, in the via resistance monitoring system, the current value of the constant current source I cont is I c s o et nt (I contset is a value preset in advance according to the resistance value range of the via resistance R CT and the measurement accuracy of the ADC). When measuring the resistance value of the via resistance, according to Ohm's law where V RCT is the voltage across R CT . In the test mode, the switch ST2 is disconnected and ST1 is closed. I cont is injected into R CT , and a voltage V CT is generated across R RCT . It is sent to the ADC through the BUF drive. By measuring the obtained V RCT , combined with the known , the resistance value of R CT is calculated, so as to monitor the resistance value stability of the through-hole resistance in the production and manufacturing in real time.

[0057] Preferably, during the PLL frequency multiplication process, the frequency multiplication factor is (P, N are integers), and its value range is P min , P max , N min , N max Determined according to the frequency requirements of different products. The output frequency of the core part of the oscillator is f(OSC_OUT), and the final output frequency In practical applications, for the frequency requirements of different products, by adjusting the value, make F meet the specific frequency index of the product, and at the same time keep the core part of the oscillator working stably to ensure the consistency of the oscillator performance.

[0058] Preferably, the bias current I of the temperature compensation comparator CMP0T / CMP1T Ctrim has a trimming range of This trimming range is determined according to the temperature characteristic compensation requirements of the comparator delay and the overall performance requirements of the oscillator. In the circuit, by changing I Ctrim the value, adjust the response time of the comparator, and its relationship satisfies t response = m·I Ctrim + n, where t response is the comparator response time, m, n are coefficients related to the circuit characteristics of the comparator, and the value range of m is [m min , m max , and the value range of n is [n min , n max . By trimming I within the range of Ctrim , the temperature characteristic of the comparator response time can be effectively adjusted, and then the temperature characteristic of the oscillator can be compensated.

[0059] Preferably, the relationship between the wide-range temperature adjustment current bias I Ctrim and the temperature characteristic of the comparator delay satisfies the formula where, ΔT dct is the comparator delay for calibrating the temperature characteristic, and α, β, γ are coefficients related to the circuit design. The value range of α is [α min , α max , the value range of β is [β min , β max , and the value range of γ is [γ min , γ max . During the operation of the circuit, by changing the value of I Ctrim , change ΔT dct according to this formula to achieve precise compensation of the temperature characteristic of the oscillator and ensure the frequency stability of the oscillator in different temperature environments.

[0060] Preferably, the overall frequency formula of the oscillator is Among them, R CT is the via resistance, C A is the capacitor related to charge and discharge in the oscillator, ΔT dct is the comparator delay with calibratable temperature characteristics, and ΔT dx is the delay of the remaining logic circuits except the comparator. By changing the value of R CT , the can be adjusted, and further the absolute value of the frequency can be adjusted; by adjusting ΔT dct , the temperature characteristics of the oscillator can be compensated; since ΔT dx has a limited impact on the oscillator performance, when adjusting ΔT dct , a certain degree of compensation can also be performed on ΔT dx to ensure the optimization of the overall performance of the oscillator.

[0061] Preferably, each module in the circuit, including the wide-range positive-temperature current generator, zero-temperature charging current generator, via resistance reference voltage generator, wide-range negative-temperature current generator, wide-range temperature-adjusting current bias, via resistance monitoring system, and PLL, is integrated using a specific integrated circuit process. The power consumption P chip of the integrated chip satisfies the formula [L min , L max ; W is the chip width, and the value range is [W min , W max . By optimizing the integration process and circuit layout, the chip size is reduced, the power consumption is lowered, the stability and reliability of the circuit are improved, and it is convenient for large-scale production and application.

[0062] As Figure 2 shown, for the high-precision oscillator of the present invention, compared with the conventional RC oscillator, VREF adopts the via resistance RCT architecture, the generation of IC1 is also directly related to the via resistance, and the temperature characteristics of the bias current ICtrim of the comparators CMP0T / CMP1T can be trimmed, that is, the response time temperature characteristics of CMP0T / CMP1T can be adjusted. After the OSC_OUT is output, the frequency is multiplied by the PLL and then output. For the detailed principle, see the following sub-module introduction

[0063] As Figure 3 shown, the overview of the newly added functional modules of the high-precision oscillator of the present invention includes a wide-range positive-temperature current generator (WIPT), a zero-temperature charging current generator (IC1), a via resistance reference voltage generator (VREF-RCT), a wide-range negative-temperature current generator (WINT), a wide-range temperature-adjusting current bias (ICtrim), and a via resistance monitoring system.

[0064] As Figure 4As shown in the figure, it is a wide-range positive temperature current generator. The input signal is k*VBG. Assuming the voltage across diode D1 (which can also be a BJT or MOS) is VBNT, according to the negative feedback characteristic of the OPA, the current flowing through the hole resistance Rpt0 can be deduced as I(Wipt0) = (k*VBG - VBE) / Rpt0. After the internal current replication function (Replica Wipt0), a wide-range positive temperature current WIPT is output. The coefficient k can be adjusted according to different processes and products to obtain the positive temperature current within the required temperature range.

[0065] Example: Assume that for a certain process, VBG = 1.2V, VBE = 0.75V @ -40°C, and VBE = 0.35V @ 150°C. Different k values can obtain positive temperature currents with different temperature coefficients (ranges) as shown in the following figure. It can be seen that adjusting k can effectively broaden the positive temperature change range to achieve the goal.

[0066] As Figure 5 shown, the new functional module of the high-precision oscillator has the following functions:

[0067] ①. Use VBG to generate a zero-temperature current IZT, and this current is output to the core part of the oscillator for charge and discharge use (i.e., IC1).

[0068] ②. The current proportional to IC1 acts on the hole resistance RCT to generate the reference voltage VREF of the core part of the oscillator, that is, VREF = k1*IC1

[0069] ③. This positive temperature current operates with the WIPT module to generate a negative temperature current WINT with an opposite temperature coefficient. Then, WIPT and WINT are superimposed to generate the CMP0T / CMP1T bias current ICtrim. Finally, by trimming, setting the ratio of WIPT and WINT can obtain currents with different temperature characteristics to meet the requirements of the comparator delay temperature characteristics.

[0070] As Figure 6 shown, the principle of the hole resistance monitoring system is to monitor the core resistance RCT of the RC oscillator. When entering the test mode, switch ST2 is disconnected and ST1 is closed. The constant current source Icont injects current into RCT, and the voltage formed across RCT is sent to the ADC through BUF drive, and then the value of the hole resistance can be measured. During mass production, information such as the hole resistance value and temperature characteristics can be monitored as needed to timely grasp the stability of the through-hole resistance during production and manufacturing.

[0071] PLL: The main function of the PLL in the present invention is to perform frequency multiplication on the output frequency. Different products have different frequency requirements. To ensure the consistency of oscillator performance, the core part of the oscillator remains unchanged. By adjusting the frequency multiplication factor of the PLL, i.e., the multiplication factor P / N, where P and N are integers. The final output frequency is F = f(OSC_OUT) * P / N.

[0072] A method for implementing a high-precision oscillator according to the present invention has the following theoretical derivation expressions where RCT is the via resistance, and the design is to adjust the absolute value of the frequency by adjusting this via resistance. ΔTdct can calibrate the comparator delay of the temperature characteristics, and by adjusting the wide-range bias current, the temperature characteristics of this delay can be changed, thereby compensating for the oscillator temperature characteristics. ΔTdx is the delay of the remaining logic circuits except the comparator, and this delay is generally very small and has a limited impact on the oscillator performance. Of course, it can also be compensated by adjusting ΔTdct.

[0073] Obviously, those skilled in the art can make various changes and modifications to this application without departing from the scope of this application. Thus, if these modifications and variations of this application fall within the scope of this application and its equivalent technologies, this application is intended to include these changes and variations.

[0074] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various equivalent changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalent scope.

Claims

1. A method for implementing a high-precision oscillator, characterized in that It includes the following steps: Step S1: Use via resistance to replace poly resistance to reduce the influence on the absolute value of the oscillator frequency and temperature characteristics in case of resistance deformation caused by package stress, reflow soldering, and high and low temperature factors; Step S2: Build a wide-range positive temperature current generator, input a signal, and use the negative feedback characteristic of OPA to generate a wide-range positive temperature current through the internal current replication function. Adjust the relevant coefficients according to different process and product requirements to obtain the positive temperature current in the required temperature range; Step S3: Use VBG to generate zero temperature current and output it to the core part of the oscillator for charging and discharging. At the same time, make the current proportional to the charging and discharging current act on the hole resistance to generate the reference voltage of the core part of the oscillator; Step S4: Let the positive temperature current operate with the current generated by the wide-range positive temperature current generator to generate a negative temperature current with an opposite temperature coefficient. Superimpose the negative temperature current and the wide-range positive temperature current to obtain a bias current. By adjusting the ratio of the two, different temperature characteristic currents that meet the requirements of the comparator delay temperature characteristics are obtained; Step S5: Build a hole resistance monitoring system. In the test mode, inject a constant current source current into the hole resistance, drive the voltage formed at both ends of the hole resistance through BUF and send it to the ADC to measure the resistance value of the hole resistance; Step S6: Process the output frequency of the oscillator through PLL. Keep the core part of the oscillator unchanged and adjust the frequency multiplication factor of PLL to make the final output frequency meet the frequency requirements of different products.

2. The implementation method of a high-precision oscillator according to claim 1, characterized in that, The input signal of the wide-range positive-temperature current generator is k·V BG , and the OPA negative feedback characteristic is utilized to make the hole resistance R nt0 carry a current wherein, V BG is the bandgap reference voltage, V BE is the voltage across the diode, k is the adjustment coefficient, and the wide-range positive-temperature current WIPT is output through the internal current replication function. The value range of k is [k min , k max , k min , k max is determined according to different processes and product requirements. Under the preset process, if is a specific value of the bandgap reference voltage under this process, V BE takes values at different temperatures as corresponding to the temperature T1, corresponding to the temperature T2. By changing the value of k, the change of I(Wipt0) is made, and the temperature coefficient of WIPT is adjusted to meet the requirements of different products for the positive-temperature current in different temperature ranges.

3. The implementation method of a high-precision oscillator according to claim 1, characterized in that, During the process of generating the reference voltage of the oscillator core part, the reference voltage V REF = k1·I C1 , where k1 is a proportionality coefficient, and its value range is [k 1min , k 1max , which is determined by the characteristics of the hole resistance R CT and the requirements of the oscillator core part for the reference voltage; I C1 is the zero-temperature current I ZT as the identifier when it is used as the charge and discharge current. When the oscillator is working, I ZT is stably output to the core part. By controlling the values of k1 and I C1 , the generated V REF is stable and meets the amplitude requirements of the oscillator core part for the reference voltage.

4. The implementation method of a high-precision oscillator according to claim 1, characterized in that When generating the negative-temperature current WINT, the positive-temperature current is operated with the WIPT module through a specific operation circuit. The operation formula is WINT = WIPT·a - b, where a and b are operation coefficients. The value range of a is [a min , a max , and the value range of b is [b min , b max . The specific values are determined according to the circuit design. In the circuit, by adjusting the values of a and b, the generated WINT has the opposite temperature coefficient to that of WIPT. Then, WINT and WIPT are superimposed to generate the bias current I Ctrim , I Ctrim = WIPT + WINT. By adjusting the ratio of WIPT and WINT in I Ctrim , it is used to meet the requirements of the comparator delay temperature characteristic for the bias current.

5. The implementation method of a high-precision oscillator according to claim 1, characterized in that, In the hole resistance monitoring system, the constant current source I cont has a current value of I contset is a value preset according to the resistance value range of the hole resistance R CT and the measurement accuracy of the ADC. When measuring the resistance value of the hole resistance, according to Ohm's law where V RCT is the voltage across R CT . In the test mode, the switch ST2 is disconnected and ST1 is closed. I cont is injected into R CT , and a voltage V CT is generated across R RCT . It is driven by BUF and sent to the ADC. Through the measured V RCT , combined with the known , the resistance value of R CT is calculated, which is used to monitor the resistance value stability of the via hole resistance in real-time production and manufacturing.

6. The implementation method of a high-precision oscillator according to claim 1, characterized in that, During the PLL frequency multiplication process, the frequency multiplication factor is P, where N is an integer and the value range is P min , P max , N min , N max determined according to the frequency requirements of different products. The output frequency of the core part of the oscillator is f(OSC_OUT), and the final output frequency For the frequency requirements of different products, by adjusting the value, make F meet the specific frequency index of the product, and at the same time keep the core part of the oscillator working stably, which is used to ensure the consistency of the oscillator performance.

7. The implementation method of a high-precision oscillator according to claim 1, characterized in that, The trimming range of the bias current I of the temperature compensation comparators CMP0T / CMP1T Ctrim is This trimming range is determined according to the temperature characteristic compensation requirements of the comparator delay and the overall performance requirements of the oscillator. In the circuit, by changing the value of I Ctrim , the response time of the comparator is adjusted, and the relationship satisfies t response = m·I Ctrim + n, where t response is the comparator response time, m and n are coefficients related to the comparator circuit characteristics, the value range of m is [m min , m max , and the value range of n is [n min , n max . By trimming I within the range of Ctrim .

8. The implementation method of a high-precision oscillator according to claim 1, characterized in that, Wide-range temperature-adjustable current bias I Ctrim The relationship with the comparator delay temperature characteristic satisfies the formula where ΔT dct is the comparator delay of the calibratable temperature characteristic, and α, β, γ are coefficients related to the circuit design. The value range of α is [α min , α max , the value range of β is [β min , β max , and the value range of γ is [γ min , γ max . During the circuit operation, by changing the value of I Ctrim , ΔT dct is changed according to this formula to compensate for the oscillator temperature characteristic.

9. The implementation method of a high-precision oscillator according to claim 1, characterized in that, The overall frequency formula of the oscillator is where R CT is the via resistance, C A is the capacitor related to charge and discharge in the oscillator, ΔT dct is the comparator delay with calibratable temperature characteristics, ΔT dx is the delay of the remaining logic circuits except the comparator. By changing the value of R CT , adjust and then adjust the absolute value of the frequency; by adjusting ΔT dct , compensate for the temperature characteristics of the oscillator; when adjusting ΔT dct , also compensate for ΔT dx .

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