阅读说明：本技术 一种高精度低温漂的振荡器 (High-precision low-temperature-drift oscillator ) 是由 黄俊钦 李瑞兴 戴国梁 于 2020-06-16 设计创作，主要内容包括：本发明提出的一种高精度低温漂的振荡器,包括：电流源、电容充放电模块、比较器模块、RS锁存器、反相器和驱动模块；比较器模块包括两个比较器,两个比较器的输出端分别连接RS锁存器的两个输入端；反相器的输入端和输出端分别连接RS锁存器的输出端和驱动模块的输入端,驱动模块的输出端用于输出振荡信号。本发明通过比较器模块实现对电容充放模块的充放电压进行控制,有利于充放电压的幅值进行控制,提高信号控制精度,并降低温度影响,从而实现高精度,低温漂的OSC频率值。且,通过比较器的设置,可进一步提高电路的PSR电源电压抑制比,以降低电源噪声对OSC频率的影响。(The invention provides a high-precision low-temperature-drift oscillator, which comprises: the device comprises a current source, a capacitance charge-discharge module, a comparator module, an RS latch, an inverter and a driving module; the comparator module comprises two comparators, and the output ends of the two comparators are respectively connected with the two input ends of the RS latch; the input end and the output end of the phase inverter are respectively connected with the output end of the RS latch and the input end of the driving module, and the output end of the driving module is used for outputting an oscillation signal. The invention realizes the control of the charge and discharge voltage of the capacitance charge and discharge module through the comparator module, is beneficial to controlling the amplitude of the charge and discharge voltage, improves the signal control precision, and reduces the temperature influence, thereby realizing the OSC frequency value with high precision and low temperature drift. In addition, the PSR power supply voltage suppression ratio of the circuit can be further improved through the arrangement of the comparator, so that the influence of power supply noise on the OSC frequency is reduced.)

1. An oscillator with high precision and low temperature drift, comprising: the device comprises a current source, a capacitance charge-discharge module, a comparator module, an RS latch, an inverter and a driving module;

the comparator module comprises two comparators, and the output ends of the two comparators are respectively connected with the two input ends of the RS latch; the input end and the output end of the phase inverter are respectively connected with the output end of the RS latch and the input end of the driving module, and the output end of the driving module is used for outputting an oscillation signal;

the capacitor charging and discharging module adopts a double-capacitor charging and discharging structure, and comprises a first control node (A) and a second control node (B) which are used for controlling the charging and discharging of the capacitor, and also comprises a first detection node (C) and a second detection node (D) which are used for detecting the charging and discharging current;

the current source is connected with the capacitor charging and discharging module and used for charging; the first detection node (C) is connected with the input end of one comparator, and the second detection node (D) is connected with the input end of the other comparator; the rest input ends of the two comparators are connected with reference voltage; the first control node (A) and the second control node (B) are respectively connected with the input end and the output end of the phase inverter in an equipotential mode.

2. The oscillator with high precision and low temperature drift as claimed in claim 1, wherein the reference voltages connected to the two comparators are equal.

3. The oscillator with high precision and low temperature drift as claimed in claim 2, further comprising a constant temperature voltage source, wherein the constant temperature voltage source is respectively connected with the two comparators for providing reference voltages.

4. The oscillator with high precision and low temperature drift as claimed in claim 1, wherein the current source is a controllable current source.

5. The oscillator with high precision and low temperature drift as claimed in claim 1, wherein the capacitance charging and discharging module further comprises a first capacitor (C1), a second capacitor (C2), a first NMOS transistor (M1), a second NMOS transistor (M2), a third PMOS transistor (M3), and a fourth PMOS transistor (M4); the first detection node (C) is respectively connected with the source electrode of the first NMOS transistor (M1) and the drain electrode of the third PMOS transistor (M3), and is grounded after being connected with the first capacitor (C1) in series; the first control node (A) is respectively connected with the base of the first NMOS transistor (M1) and the base of the third PMOS transistor (M3); the second detection node (D) is respectively connected with the source electrode of the second NMOS transistor (M2) and the drain electrode of the fourth PMOS transistor (M4), and is grounded after being connected with the second capacitor (C2) in series; the second control node (B) is connected to the base of the second NMOS transistor (M2) and the base of the fourth PMOS transistor (M4), respectively. The drain electrode of the first NMOS transistor (M1) and the drain electrode of the second NMOS transistor (M2) are grounded, and the source electrode of the third PMOS transistor (M3) and the source electrode of the fourth PMOS transistor (M4) are connected with a current source for charging;

the charging and discharging time of the first capacitor (C1) and the second capacitor (C2) is the same.

Technical Field

The invention relates to the technical field of oscillating circuits, in particular to a high-precision low-temperature-drift oscillator.

Background

With the development of integrated circuit technology, the increase of IC function requirements and the increasing of IC integration level, the integrated design of SOC system integrated with analog circuit and digital circuit is the mainstream development trend of IC design at present; the OSC oscillator is a basic analog unit, mainly used for providing a clock signal to a digital circuit, and is a basic condition for the digital circuit to work normally, and the performance of the OSC oscillator directly affects the overall performance of the digital circuit, so that the OSC oscillator plays a very important role in modern IC design.

The OSC oscillator essentially generates an oscillation signal of a stable frequency and a stable Duty Cycle (Duty Cycle/Duty Cycle), and the stability of the frequency value is a key performance index; however, in practical applications, the frequency and duty cycle of the OSC oscillator will vary due to variations in power supply voltage, temperature, process, etc., resulting in a certain deviation between the actual frequency and the target frequency value, and the influence of these factors is reduced by optimizing the OSC architecture, so that the frequency and duty cycle of the OSC oscillator are more stable, and the performance of the digital circuit and the entire system is further improved, which is a subject of research in the field of OSC oscillators.

Performance indexes of the OSC oscillator mainly include a frequency value, stability with temperature, stability with power supply voltage, power consumption of a circuit, and the like; the OSC oscillator is usually implemented by an analog circuit, which needs to be considered and compromised among various influencing factors such as power consumption, power supply disturbance, gain, accuracy, and the like; the OSC oscillator architectures employed will also vary with the requirements of different performance levels.

As shown in fig. 1, the oscillator based on the schmitt trigger is a commonly used oscillator, and includes a current source, a capacitor charging and discharging module, a schmitt trigger, an RS latch, and an inverter. During specific work, the voltages of the first detection node C and the second detection node B are frequently turned over through charging and discharging of the capacitor, so that oscillation is realized; the output end of the RS latch and the output end of the inverter are respectively connected with the first control node A and the second control node B and are used for controlling the charging and discharging of the first capacitor C1 and the second capacitor C2.

Schmitt is adopted, and the abrupt change input-output characteristic of a Schmitt structure is utilized, namely when the input voltage reaches the turnover threshold voltage of the Schmitt structure, the output voltage can be directly turned over abruptly, so that an ideal periodic rectangular pulse signal can be obtained.

The output frequency of the OSC oscillator is related to the size of a current source for charging a capacitor, a switching voltage, and a capacitor, and it is necessary to ensure that these parameters are not changed substantially to ensure the stability of the OSC output frequency; the change of the Current source can be adjusted in a Current Trimming mode, but the switching threshold voltage of the schmitt structure is determined by the threshold voltage of the MOS transistor, and the threshold voltage of the MOS transistor is influenced by the process and the temperature, which results in lower accuracy of the output frequency of the OSC and lower sensitivity to the temperature.

Disclosure of Invention

Based on the technical problems in the background art, the invention provides a high-precision low-temperature-drift oscillator.

The invention provides a high-precision low-temperature-drift oscillator, which comprises: the device comprises a current source, a capacitance charge-discharge module, a comparator module, an RS latch, an inverter and a driving module;

the comparator module comprises two comparators, and the output ends of the two comparators are respectively connected with the two input ends of the RS latch; the input end and the output end of the phase inverter are respectively connected with the output end of the RS latch and the input end of the driving module, and the output end of the driving module is used for outputting an oscillation signal;

the capacitor charging and discharging module adopts a double-capacitor charging and discharging structure, and comprises a first control node and a second control node for controlling the charging and discharging of the capacitor, and also comprises a first detection node and a second detection node for detecting the charging and discharging current;

the current source is connected with the capacitor charging and discharging module and used for charging; the first detection node is connected with the input end of one comparator, and the second detection node is connected with the input end of the other comparator; the rest input ends of the two comparators are connected with reference voltage; the first control node and the second control node are respectively connected with the input end and the output end of the phase inverter in an equipotential mode.

Preferably, the reference voltages applied by the two comparators are equal.

Preferably, the device further comprises a constant temperature voltage source, and the constant temperature voltage source is respectively connected with the two comparators for providing reference voltage.

Preferably, the current source is a controllable current source.

Preferably, the capacitance charge-discharge module further comprises a first capacitor, a second capacitor, a first NMOS transistor, a second NMOS transistor, a third PMOS transistor and a fourth PMOS transistor; the first detection node is respectively connected with the source electrode of the first NMOS transistor and the drain electrode of the third PMOS transistor and is grounded after being connected with the first capacitor in series; the first control node is respectively connected with the base electrode of the first NMOS transistor and the base electrode of the third PMOS transistor; the second detection node is respectively connected with the source electrode of the second NMOS transistor and the drain electrode of the fourth PMOS transistor and is grounded after being connected with the second capacitor in series; the second control node is respectively connected with the base of the second NMOS transistor and the base of the fourth PMOS transistor. The drain electrode of the first NMOS transistor and the drain electrode of the second NMOS transistor are grounded, and the source electrode of the third PMOS transistor and the source electrode of the fourth PMOS transistor are connected with a current source for charging;

the charging and discharging time of the first capacitor is the same as that of the second capacitor.

According to the oscillator with high precision and low temperature drift, the comparator module is used for controlling the charge-discharge voltage of the capacitor charge-discharge module, so that the amplitude of the charge-discharge voltage can be controlled, the signal control precision is improved, the temperature influence is reduced, and the OSC frequency value with high precision and low temperature drift is realized. In addition, the PSR power supply voltage suppression ratio of the circuit can be further improved through the arrangement of the comparator, so that the influence of power supply noise on the OSC frequency is reduced. At the same time, due to the reference voltage V_REFThe change along with the temperature is small, so that the influence of the temperature on the flip voltage of the oscillator is reduced, the temperature sensitivity of the oscillator is reduced, and the low-temperature drift characteristic of the output OSC frequency is realized.

Drawings

FIG. 1 is a schematic diagram of an OSC oscillator using Schmidt;

fig. 2 is a schematic structural diagram of a high-precision low-temperature-drift oscillator according to the present invention.

Detailed Description

Referring to fig. 2, the oscillator with high precision and low temperature drift provided by the invention comprises: the device comprises a current source, a capacitor charge-discharge module, a comparator module, an RS latch, an inverter and a driving module.

The comparator module comprises two comparators, and the output ends of the two comparators are respectively connected with the two input ends of the RS latch; the input end and the output end of the phase inverter are respectively connected with the output end of the RS latch and the input end of the driving module, and the output end of the driving module is used for outputting an oscillation signal.

Specifically, the oscillator with high precision and low temperature drift provided in this embodiment is obtained by improving the oscillator based on the schmitt trigger shown in fig. 1, the capacitor charge-discharge module, the RS latch, and the inverter of the oscillator with high precision and low temperature drift are all applied in the prior art, and the RS latch is composed of two nor gates.

The capacitor charging and discharging module adopts a double-capacitor charging and discharging structure, and comprises a first control node A and a second control node B which are used for controlling the charging and discharging of the capacitor, and also comprises a first detection node C and a second detection node D which are used for detecting the charging and discharging current. Specifically, the capacitor charging and discharging module further includes a first capacitor C1, a second capacitor C2, a first NMOS transistor M1, a second NMOS transistor M2, a third PMOS transistor M3, and a PMOS transistor M. The first detection node C is respectively connected with the source electrode of the first NMOS transistor M1 and the drain electrode of the third PMOS transistor M3, and is grounded after being connected with the first capacitor C1 in series; the first control node A is connected to the base of the first NMOS transistor M1 and the base of the third PMOS transistor M3, respectively. The second detection node D is respectively connected to the source of the second NMOS transistor M2 and the drain of the fourth PMOS transistor M4, and is grounded after being connected in series with the second capacitor C2; the second control node B is connected to the base of the second NMOS transistor M2 and the base of the fourth PMOS transistor M4, respectively. The drain of the first NMOS transistor M1 and the drain of the second NMOS transistor M2 are both grounded, and the source of the third PMOS transistor M3 and the source of the fourth PMOS transistor M4 are both connected to a current source for charging.

The first detection node C is connected with the input end of one comparator, and the second detection node D is connected with the input end of the other comparator; the residual input ends of the two comparators are connected with a reference voltage V_REF(ii) a The first control node A and the second control node B are respectively connected with the input end and the output end of the phase inverter in an equipotential mode.

Therefore, in the embodiment, the comparator module is used for controlling the charge and discharge voltage of the capacitor charge and discharge module, so that the amplitude of the charge and discharge voltage is favorably controlled, the signal control precision is improved, and the temperature influence is reduced, thereby realizing the high-precision low-temperature drift OSC frequency value. In addition, the PSR power supply voltage suppression ratio of the circuit can be further improved through the arrangement of the comparator, so that the influence of power supply noise on the OSC frequency is reduced. At the same time, due to the reference voltage V_REFThe change along with the temperature is small, so that the influence of the temperature on the flip voltage of the oscillator is reduced, the temperature sensitivity of the oscillator is reduced, and the low-temperature drift characteristic of the output OSC frequency is realized.

In this embodiment, the reference voltage V connected to the two comparators_REFAre equal. Specifically, in this embodiment, the apparatus further includes a constant-temperature voltage source, and the constant-temperature voltage source is respectively connected to the two comparators for providing the reference voltage V_REF. Therefore, the constant-temperature voltage source is used for providing the constant-temperature voltage as the reference voltage, so that the stability of the reference voltage accessed by the comparator is further ensured, the influence of the temperature on the switching threshold voltage of the OSC is further reduced, the sensitivity of the OSC to the temperature is further reduced, and the effect of low temperature drift is improved.

In this embodiment, the current source is a controllable current source. Therefore, the frequency value of the OSC can be adjusted by adjusting the charging current, the resistance of the oscillator to adverse factors such as process deviation is improved, the frequency value of the OSC can be adjusted back to a design target value when the frequency value of the OSC deviates, and the accuracy of the OSC oscillator is improved.

In this embodiment, the first capacitor C1 and the second capacitor C2 have the same charging and discharging time so as to realize a periodic rectangular pulse signal.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention are equivalent to or changed within the technical scope of the present invention.