CN114153260A

CN114153260A - High-precision oscillator

Info

Publication number: CN114153260A
Application number: CN202111436013.XA
Authority: CN
Inventors: 李飞; 宿晓锋; 钱翼飞
Original assignee: Shanghai Huali Microelectronics Corp
Current assignee: Shanghai Huali Microelectronics Corp
Priority date: 2021-11-29
Filing date: 2021-11-29
Publication date: 2022-03-08

Abstract

The present invention provides a high-precision oscillator, comprising: the temperature coefficient gating control circuit comprises a clock oscillator, a low dropout linear regulator, a band gap reference circuit and a temperature coefficient gating control signal generating circuit, wherein the band gap reference circuit provides a first bias current signal with a temperature coefficient to compensate frequency deviation of the clock oscillator along with temperature change; the temperature coefficient gating control signal generated by the temperature coefficient gating control signal generating circuit is loaded to the temperature coefficient gating control end of the band gap reference circuit, so that the temperature coefficient gating control signal of the corresponding temperature interval at the current ambient temperature is used as the temperature coefficient gating control signal of the band gap reference circuit. The invention can compensate the frequency deviation of the clock oscillator along with the temperature change, so as to reduce the frequency deviation of the clock oscillator along with the temperature change and improve the frequency precision of the clock signal output by the clock oscillator.

Description

High-precision oscillator

Technical Field

The invention relates to the technical field of electronics, in particular to a high-precision oscillator.

Background

The clock Oscillator (OSC) is used for generating a clock signal with a certain frequency. When the oscillator is used alone, the frequency of the output clock signal is affected by voltage, process and temperature, and particularly in high-precision circuit design, under the conditions of different voltages, different process angles and different temperatures, the frequency deviation is large, so that the precision of the oscillator is affected. The frequency deviation of the oscillator output is mainly caused by two reasons, one is that the frequency deviation is generated along with the voltage change, and particularly, the power supply is unstable; the other is that frequency deviation is generated along with temperature change. Fig. 11 is a schematic diagram comparing the frequency deviation of the clock oscillator before frequency compensation in different process corners at different voltages and different temperatures, where the abscissa represents the temperature and the ordinate represents the percentage of the frequency deviation, and the different process corners are represented by corner, where TT represents the typical value of the process, FF represents the fastest process, SS represents the slowest process, and the different voltages are represented by the maximum voltage max, the minimum voltage min, and the typical voltage typ, respectively. Referring to fig. 11, in the clock oscillator, under different voltages and different process angles and different temperatures, the maximum frequency deviation (maximum percentage-minimum percentage of frequency deviation) exceeds 15%, and the voltage fluctuation, the temperature variation and the different process angles are affected to different degrees, wherein the frequency effect is more obvious when the voltage fluctuation is larger. Therefore, there is a need in the art to calibrate the frequency offset of the oscillator.

Disclosure of Invention

The invention aims to provide a high-precision oscillator to solve the problem that frequency deviation is greatly influenced by different voltages, different process angles and different temperatures.

To achieve the above object, the present invention provides a high-precision oscillator, comprising:

a clock oscillator which outputs a clock signal CLKOUT having a certain frequency;

the low dropout linear regulator is used for providing power supply for the clock oscillator;

a band gap reference circuit, which provides a first bias current signal Temp IBIAS1 with temperature coefficient to compensate the frequency deviation of the clock oscillator along with the temperature variation;

the temperature coefficient gating control signal generating circuit comprises a temperature sensor, an encoder and a decoder, wherein the temperature detection range of the temperature sensor is divided into a plurality of temperature intervals, each temperature interval is encoded through the encoder, the encoder is decoded through the decoder to form a temperature coefficient gating control signal, and the temperature coefficient gating control signal is loaded to a temperature coefficient gating control end CTRL < M of the band gap reference circuit: and 0>, taking the temperature coefficient gating control signal of the corresponding temperature interval at the current ambient temperature as the temperature coefficient gating control signal of the bandgap reference circuit, so that the bandgap reference circuit generates a first bias current signal with a specific temperature coefficient to compensate the frequency deviation of the clock oscillator along with the temperature change.

Further, according to the high-precision oscillator provided by the invention, the bandgap reference circuit provides the second bias current signal IBIAS2 and the reference voltage signal VREF to provide the reference voltage signal and the reference current signal for the low dropout linear regulator, so that the output frequency of the low dropout linear regulator generates a smaller frequency deviation along with voltage fluctuation and the low dropout linear regulator generates a smaller frequency deviation under different process angles.

Further, the invention provides a high-precision oscillator, wherein the bandgap reference circuit comprises:

an operational amplifier AMP, PMOS tubes M1, M2 and M4, PNP type triodes Q1 and Q2 and a resistor R;

the sources of the PMOS tubes M1, M2 and M4 are all connected with a power supply;

the gates of the PMOS tubes M1, M2 and M4 are connected with the output end of the operational amplifier AMP;

a common connection point of the drain electrode of the PMOS pipe M1 and the emitter electrode of the triode Q1 is connected with one input end of the operational amplifier AMP;

the drain electrode of the PMOS tube M2 is connected with the emitter electrode of the triode Q2 through a resistor R, and the common connection point of the drain electrode of the PMOS tube M2 and the resistor R is connected with the other input end of the operational amplifier AMP;

the base and the collector of the triode Q1 are grounded, and the base and the collector of the triode Q2 are grounded;

a first temperature coefficient control circuit TSET-A is respectively connected between the common connection point of the drain electrode of the PMOS tube M1 and the emitter electrode of the triode Q1 and the ground, and between the common connection point of the drain electrode of the PMOS tube M2 and the resistor and the ground;

the drain of the PMOS transistor M4 outputs a first bias current signal Temp IBIAS1 with a temperature coefficient.

Further, the high-precision oscillator provided by the invention, the bandgap reference circuit further comprises:

the source of the PMOS tube M5 is connected with a power supply, the gate of the PMOS tube M5 is connected with the output end of the operational amplifier AMP, and the drain of the PMOS tube M5 outputs a second bias current signal IBIAS 2.

a PMOS tube M3, wherein the source electrode of the PMOS tube M3 is connected with a power supply, and the grid electrode of the NMOS tube M3 is connected with the output end of the operational amplifier AMP;

a second temperature coefficient control circuit TSET-B is connected between the drain electrode of the PMOS tube M3 and the ground, a reference voltage signal VREF is output from a common connection point of the drain electrode of the PMOS tube M3 and the second temperature coefficient control circuit, and the second temperature coefficient control circuit TSET-B controls the output of the reference voltage signal through a gating control signal CTRL < M:0 >.

a resistor R24 is connected between the drain of the PMOS transistor M3 and the ground, and a common connection point of the drain of the PMOS transistor M3 and the resistor R24 outputs a reference voltage signal VREF.

Further, in the high-precision oscillator according to the present invention, the first temperature coefficient control circuit TSET-a includes:

m +1 serially connected resistors are recorded as resistors R0-RM, and the M +1 serially connected resistors form a resistor string which comprises an upper end and a lower end;

m + 1N type switch tubes are marked as NM0-NMM, the source electrode of each switch tube is connected with the lower end of the resistor string, the drain electrode of each switch tube is connected with the upper end of a resistor with the same serial number in the resistor string, and the grid electrode of each switch tube is a temperature coefficient gating control end.

Further, the present invention provides a high precision oscillator, wherein the clock oscillator comprises:

the current gating control circuit FTRIM, the waveform shaping circuit LOGIC, the NMOS tubes M30 and M31 and the capacitor CB;

the current output end I1 of the current gating control circuit FTRIM is connected with the waveform shaping circuit LOGIC;

the current output end I2 of the current gating control circuit FTRIM is grounded through a capacitor CB;

the grid electrode of the NMOS tube M31 is connected with the output end of the waveform shaping circuit LOGIC, the source electrode of the NMOS tube M31 is grounded, and the drain electrode of the NMOS tube M31 is connected with the common connection point of the current gating control circuit FTRIM and the capacitor CB;

the gate of the NMOS transistor M30 is connected to the common connection point of the current gating control circuit ftim and the capacitor CB, the source of the NMOS transistor M30 is grounded, and the drain of the NMOS transistor M30 is connected to the common connection point of the current gating control circuit ftim and the waveform shaping circuit LOGIC.

Further, the present invention provides a high precision oscillator, wherein the current gating control circuit ftim includes:

the first current mirror circuit comprises NMOS tubes N1 and N2, the sources of the NMOS tubes N1 and N2 are grounded, the gates of the NMOS tubes N1 and N2 are connected with the drain of the NMOS tube N1 after being shorted, the drain of the NMOS tube N1 is the current input end of the current gating control circuit FTRIM, and the current input end is connected with the first bias current signal Temp IBIAS1 with a temperature coefficient;

the second current mirror circuit comprises PMOS tubes P1 and P2, the sources of the PMOS tubes P1 and P2 are connected with a power supply, the gates of the PMOS tubes P1 and P2 are connected with the drain of the PMOS tube P1 after being shorted, the drain of the PMOS tube P1 is connected with the drain of an NMOS tube N1 of the first current mirror circuit, and the drain of the PMOS tube P2 is a current output end I1 of the current gating control circuit FTRIM;

the PMOS transistors are N +1 and are marked as PM0-PMN, the grid electrode of each PMOS transistor in the N +1 PMOS transistors is connected with the grid electrodes of the PMOS transistors P1 and P2, and the source electrode of each PMOS transistor in the N +1 PMOS transistors is connected with a power supply;

the N + 1P-type switching tubes are marked as F0-FN, the source electrode of each switching tube in the N +1 switching tubes is connected with the drain electrode of the PMOS tube with the same serial number in the N +1 PMOS tubes, the drain electrode of each switching tube in the N +1 switching tubes is in short circuit connection with the current output end I2 of the current gating control circuit FTRIM, and the grid electrode of each switching tube in the N +1 switching tubes is the current gating control end FTRIM < N >.

Further, the present invention provides a high precision oscillator, wherein the low dropout regulator comprises:

an operational amplifier A1, a PMOS tube P3, resistors R11 and R12;

the inverting input end of the operational amplifier A1 is connected with the reference voltage signal VREF;

operational amplifier A1 output and PMOS pipe P3's grid connection, PMOS pipe P3's source connect the power VCC, PMOS pipe P3's drain electrode connects resistance R11, resistance R11 passes through resistance R12 ground connection, operational amplifier A1's in-phase input with resistance R11 and resistance R12's point of common connection are connected, PMOS pipe P3's drain electrode and resistance R11's point of common connection do low dropout linear regulator's output, the output has voltage signal VOUT.

Compared with the prior art, the high-precision oscillator provided by the invention has the advantages that the temperature coefficient gating control signal generating circuit is used for acquiring the ambient temperature and generating the temperature coefficient gating control signal, so that the temperature coefficient gating control signal is loaded to the temperature coefficient gating control end CTRL < M of the band gap reference circuit: and 0> is used as a temperature coefficient gating control signal of the bandgap reference circuit, so that the bandgap reference circuit generates a first bias current signal with a temperature coefficient to compensate the frequency deviation of the clock oscillator along with the temperature change, so as to reduce the frequency deviation of the clock oscillator along with the temperature change and improve the frequency precision of the clock signal output by the clock oscillator. That is, the present invention has an advantage of high accuracy of the output clock signal.

To achieve the above object, the present invention further provides a high-precision oscillator, including:

a band-gap reference circuit, which provides a first bias current signal IBIAS1 to compensate the frequency deviation of the clock oscillator along with the temperature variation;

the temperature coefficient gating control signal generating circuit comprises a temperature sensor, an encoder and a decoder, wherein the temperature detection range of the temperature sensor is divided into a plurality of temperature intervals, each temperature interval is encoded through the encoder, the encoder is decoded through the decoder to form a temperature coefficient gating control signal, and the temperature coefficient gating control signal is loaded to a current gating control end FTRIM < N: and 0> compensating the frequency deviation of the clock oscillator along with the temperature change by taking the temperature coefficient gating control signal of the corresponding temperature interval at the current ambient temperature as the current gating control signal of the clock oscillator.

an operational amplifier AMP, PMOS tubes M1, M2 and M4, PNP type transistors Q1, Q2, and resistors R, R21, R22 and R24;

a resistor R21 is connected between the common connection point of the drain electrode of the PMOS tube M1 and the emitter electrode of the triode Q1 and the ground, and a resistor R22 is connected between the common connection point of the drain electrode of the PMOS tube M2 and the resistor and the ground;

the drain of the PMOS transistor M4 outputs a first bias current signal IBIAS 1.

Further, the high-precision oscillator provided by the invention further comprises:

an operational amplifier A1, a PMOS tube P3, resistors R11 and R12;

Compared with the prior art, the high-precision oscillator provided by the invention has the advantages that the frequency deviation of the clock oscillator along with the temperature change is primarily compensated through the first bias current signal output by the band-gap reference circuit, and then the ambient temperature is collected through the temperature coefficient gating control signal generating circuit and the temperature coefficient gating control signal is generated to be used as the current gating control signal of the clock oscillator so as to finely compensate the frequency deviation of the clock oscillator along with the temperature change, so that the frequency precision of the clock signal output by the clock oscillator is improved.

Drawings

FIG. 1 is a schematic diagram of a frame structure of a high-precision oscillator according to an embodiment;

FIG. 2 is a block schematic diagram of a temperature coefficient strobe control signal generation circuit;

FIG. 3 is a schematic diagram of a bandgap reference circuit of an embodiment;

FIG. 4 is a schematic diagram of a bandgap reference circuit of another embodiment;

FIG. 5 is a schematic diagram of a bandgap reference circuit of yet another embodiment;

FIG. 6 is a schematic diagram of a temperature coefficient control circuit;

FIG. 7 is a schematic diagram of the structure of the clock oscillator;

FIG. 8 is a schematic diagram of a current gating circuit;

FIG. 9 is a principal node schematic of a low dropout linear regulator;

FIG. 10 is a schematic diagram of a component frame structure of a high-precision oscillator according to another embodiment;

FIG. 11 is a graph showing a comparison of the frequency deviation of a clock oscillator at different voltages and at different process angles and at different temperatures before frequency compensation;

FIG. 12 is a schematic diagram comparing the frequency deviation of the high precision oscillator of one embodiment after frequency compensation for different temperatures at different process angles and at different voltages;

FIG. 13 is a schematic diagram comparing the frequency deviation of a clock oscillator at different process angles and different temperatures at different voltages after frequency compensation in another embodiment of a high precision oscillator;

FIG. 14 is a simulated graph of a first bias current signal having a temperature coefficient versus a reference voltage signal having an uncorrected temperature coefficient as a function of temperature;

fig. 15 is a graph of a simulation of a first bias current signal having a temperature coefficient and a reference voltage signal after correcting the temperature coefficient as a function of temperature.

Detailed Description

The structure and method for forming a via hole in a metal line according to the present invention will be described in detail with reference to the accompanying drawings and embodiments. Advantages and features of the present invention will become apparent from the following description and from the claims. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention.

Example one

Referring to fig. 1 to fig. 2, an embodiment of a high precision oscillator 100 includes a clock oscillator OSC, a low dropout regulator LDO, a bandgap reference circuit BGR, and a temperature coefficient gating control signal generating circuit TS.

Wherein the clock oscillator OSC outputs a clock signal CLKOUT having a certain frequency.

The low dropout regulator LDO provides power supply for the clock oscillator OSC, i.e., outputs a regulated voltage signal VOUT to the clock oscillator OSC.

Wherein the bandgap reference circuit BGR provides the first bias current signal Temp IBIAS1 with a temperature coefficient to compensate for frequency deviation of the clock oscillator OSC with temperature variation. The method specifically comprises the following steps: the frequency deviation of the clock oscillator OSC with temperature variation is compensated by the frequency of the first bias current signal Temp IBIAS1 being opposite to the output frequency of the clock oscillator OSC.

The temperature coefficient gating control signal generation circuit TS comprises a temperature sensor 41, an encoder 42 and a decoder 43, a temperature detection range of the temperature sensor 41 is divided into a plurality of temperature intervals, each temperature interval is encoded by the encoder 42, the encoding of the encoder 42 is decoded by the decoder 43 to form a temperature coefficient gating control signal, and the temperature coefficient gating control signal is loaded to a temperature coefficient gating control terminal CTRL < M of the bandgap reference circuit BGR: and 0>, the temperature coefficient gating control signal of the corresponding temperature interval at the current ambient temperature is used as the temperature coefficient gating control signal of the band gap reference circuit BGR, so that the band gap reference circuit BGR generates a first bias current signal with a specific temperature coefficient to compensate the frequency deviation of the clock oscillator OSC along with the temperature change. Wherein the temperature coefficient gating control end and the temperature coefficient gating control signal adopt the same mark CTRL < M:0> is explained, namely the temperature coefficient gating control signal CTRL < M is loaded on the temperature coefficient gating control end: 0 >.

Wherein the temperature sensor 41 may be a voltage type temperature sensor or the like, and the encoder 42 and the decoder 43 may be a microprocessor or the like including a function of performing encoding and decoding. The encoder 42 may be an n-bit encoder and the corresponding decoder 42 may be 2ⁿAnd (5) decoding. For example: the temperature interval is divided into 8 temperature intervals, the temperature interval can be coded through a three-bit coder 42, the coding is decoded into eight bits through a three-eight decoder 42, the decoded signal is a temperature coefficient gating control signal, and the temperature coefficient gating control signal is loaded to the temperature of the band gap reference circuit BGRDegree coefficient gating control terminal CTRL<M：0>. When the encoder 42 and the decoder 43 are microprocessors, the temperature coefficient gating control terminal CTRL can be loaded to the bandgap reference circuit BGR by means of a bus<M：0>. An example of the temperature interval division, encoding and decoding of the temperature coefficient gating control signal generation circuit TS may be as shown in table 1 below:

value of voltage	Temperature interval	Encoding	Decoding
				809.7	-40～-20	000	CTRL0
775.5	-20～0	001	CTRL1
				741.0	0～20	010	CTRL2
706.4	20～40	011	CTRL3
				671.7	40～60	100	CTRL4
636.9	60～80	101	CTRL5
				602.1	80～100	110	CTRL6
567.2	80～125	111	CTRL7

TABLE 1

Table 1 shows that a voltage-type temperature sensor is used, but not limited to this type of temperature sensor, and other types of temperature sensors are also applicable, and the number of temperature intervals is 8, but not limited to 8, and can be adjusted according to actual needs, and the larger the number of temperature intervals is, the better the effect of temperature on frequency compensation is. The upper limit value and the lower limit value of the temperature range are merely examples, and may be adjusted according to the detection range of the temperature sensor. Each decoding corresponds to a temperature coefficient gating control end CTRL < M >.

Referring to fig. 1, in order to reduce the influence of different process corners and different voltages on the frequency deviation, in the high-precision oscillator 100 according to an embodiment of the present invention, the bandgap reference circuit BGR provides a second bias current signal IBIAS2 and a reference voltage signal VREF to provide a reference voltage signal and a reference current signal for the low dropout regulator LDO, so that the output frequency of the low dropout regulator LDO generates a smaller frequency deviation along with voltage fluctuation and the low dropout regulator LDO generates a smaller frequency deviation under different process corners.

Referring to fig. 3 to 4, in order to generate the first bias current signal Temp IBIAS1 having a temperature coefficient. In the high-precision oscillator 100 according to the first embodiment of the present invention, the band gap reference circuit BGR includes:

the base and the collector of the triode Q1 are grounded GND, and the base and the collector of the triode Q2 are grounded GND;

a first temperature coefficient control circuit TSET-A is respectively connected between the common connection point of the drain electrode of the PMOS tube M1 and the emitter electrode of the triode Q1 and the ground GND and between the common connection point of the drain electrode of the PMOS tube M2 and the resistor and the ground GND;

Referring to fig. 5 to fig. 6, the first temperature coefficient control circuit TSET-a includes:

m +1 resistors connected in series, denoted as resistors R0-RM, wherein the M +1 resistors connected in series form a resistor string, and the resistor string comprises an upper end PLUS and a lower end MINUS; the upper end PLUS is connected with the common connection point of the drain electrode of the PMOS tube M2 and the resistor R, and the lower end MINUS is grounded GND;

the N-type switching tubes are M +1 and are recorded as NM0-NMM, the source electrode of each switching tube is connected to the lower end of the resistor string, the drain electrode of each switching tube is connected to the upper end of a resistor with the same serial number as the resistor string, the grid electrode of each switching tube is a temperature coefficient gating control end CTRL < M >, namely the resistor RM corresponds to the switching tube NMM, the drain electrode of the switching tube NMM is connected to the upper end of the resistor RM, and at the moment, the switching tube NMM enables the resistor RM not to be connected into or connected into the resistor string through connection or disconnection; the switch tube NM0 corresponds to the resistor R0, the drain of the switch tube NM0 is connected to the upper end of the resistor R0, and the whole resistor string is in a connected or non-connected state through the connection or disconnection of the switch tube NM 0; the switch tube NM1 corresponds to the resistor R1, the drain of the switch tube NM1 is connected to the upper end of the resistor R1, whether the resistors R1-RM are connected in the resistor string is controlled by the connection or disconnection of the switch tube NM1, and the corresponding relations and principles of the other switch tubes NM 2-NMM-1 and the resistors R2-RM-1 are the same. That is, the resistance value of the resistor string is changed to be associated with the ambient temperature by turning on or off the switching tubes NM0-NMM, so that the accuracy of the first bias current signal Temp IBIAS1 having a temperature coefficient is improved, and the frequency deviation of the clock signal output by the clock oscillator is reduced. TSET _ A can obtain different gating resistances by controlling different CTRL M +1 gears, thereby obtaining different compensation current temperature coefficients.

Referring to fig. 3 to fig. 4, in order to provide the second bias current signal IBIAS2, in the high-precision oscillator 100 according to the first embodiment of the present invention, the bandgap reference circuit BGR further includes:

The band gap reference circuit BGR controls the resistor array switch of TSET _ A by selecting different CTRL < M:0> gears, so that first bias current signals Temp IBIAS1 with different temperature coefficients are obtained. The temperature coefficient of the OSC module is compensated by selecting the most appropriate temperature coefficient current from the different temperature coefficient currents through the PMOS pipe M5 for being mirrored out to be used by the LDO and the OSC through the PMOS pipe M4 for being temperature compensated. The resistor array switch is the first temperature coefficient control circuit TSET-a.

Referring to fig. 3, in order to reduce or eliminate the influence of the temperature coefficient on the reference voltage signal VREF, the high-precision oscillator 100 according to the first embodiment of the present invention may further include:

a PMOS tube M3, wherein the source electrode of the PMOS tube M3 is connected with a power supply, and the grid electrode of the NMOS tube M3 is connected with the output end of the operational amplifier AMP; a second temperature coefficient control circuit TSET-B is connected between the drain electrode of the PMOS tube M3 and the ground GND, a common connection point of the drain electrode of the PMOS tube M3 and the second temperature coefficient control circuit outputs a reference voltage signal VREF, and the second temperature coefficient control circuit TSET-B controls the output of the reference voltage signal through a gating control signal CTRL < M:0 >. The second temperature coefficient control circuit TSET-B may control the resistor array with a temperature coefficient through the gate control signal CTRL < M:0>, and reduce or eliminate the temperature coefficient generated at the drain of the PMOS transistor M3 through the resistor connected to the resistor array with the temperature coefficient, thereby generating a reference voltage signal VREF without the temperature coefficient or with a low temperature coefficient, and preventing the output voltage VOUT of the LDO from being affected by the temperature coefficient. The resistor array can be composed of a switch tube and a series resistor, a parallel resistor or a series-parallel resistor. Wherein TSET _ B is used to generate a reference voltage signal VREF with or without a lower temperature coefficient for use by the LDO.

FIG. 14 is a simulated graph of the first bias current signal Temp IBIAS1 with temperature coefficient versus the reference voltage signal VREF without temperature coefficient correction, and FIG. 15 is a simulated graph of the first bias current signal with temperature coefficient and the reference voltage signal after temperature coefficient correction versus temperature; the left ordinate is the current value, the right ordinate is the voltage value, and the abscissa is the temperature value. Referring to fig. 14, when the second temperature coefficient control circuit TSET-B is not introduced to correct the temperature coefficient of the reference voltage signal VREF, the temperature coefficient of VREF attaching to Temp IBIAS1 tends to change synchronously, which results in the output voltage VOUT of the LDO varying with the temperature by 10.2mv (102.5ppm), and it can be seen that VOUT has large fluctuation for a high-precision circuit. In general, it is not desirable that the VOUT voltage has a temperature coefficient, so as to avoid the frequency deviation of the clock oscillator OSC caused by the large fluctuation of the output voltage VOUT of the LDO, and therefore, the VREF needs to be corrected. Referring to fig. 15, after the second temperature coefficient control circuit TSET-B is introduced, the reference voltage signal VREF is similar to a parabolic shape, the variation of the output voltage VOUT of the LDO with temperature is 1.7mv (17.3ppm), the temperature coefficient of the reference voltage signal VREF is optimized by nearly 10 times, and the influence of the temperature coefficient is cancelled or reduced, so that the temperature coefficient of the reference voltage signal VREF is reduced or eliminated, and the frequency deviation of the OSC output clock signal is small after the reference voltage signal VREF is provided to the LDO.

Referring to fig. 4, in order to reduce or eliminate the influence of the temperature coefficient on the reference voltage signal VREF, the high-precision oscillator 100 according to the first embodiment of the present invention may further include:

a PMOS tube M3, wherein the source electrode of the PMOS tube M3 is connected with a power supply, and the grid electrode of the NMOS tube M3 is connected with the output end of the operational amplifier AMP; a resistor R24 is connected between the drain of the PMOS transistor M3 and the ground GND, and a common connection point of the drain of the PMOS transistor M3 and the resistor R24 outputs a reference voltage signal VREF. At this time, the reference voltage signal VREF is offset by the resistor R24 according to the temperature coefficient generated by the first temperature coefficient control circuit TSET-a controlling the PMOS transistor M3 to be turned on through the output terminal of the operational amplifier AMP, so that the reference voltage signal VREF has no temperature coefficient or has a low temperature coefficient, and the output voltage VOUT of the LDO is prevented from being influenced by the temperature coefficient.

Referring to fig. 7, in the high-precision oscillator 100 according to the first embodiment of the present invention, the clock oscillator OSC includes:

the current output end I2 of the current gating control circuit FTRIM is grounded to GND through a capacitor CB;

the grid electrode of the NMOS tube M31 is connected with the output end of the waveform shaping circuit LOGIC, the source electrode of the NMOS tube M31 is grounded GND, and the drain electrode of the NMOS tube M31 is connected with the common connection point of the current gating control circuit FTRIM and the capacitor CB;

the gate of the NMOS transistor M30 is connected to the common connection point of the current gating control circuit ftim and the capacitor CB, the source of the NMOS transistor M30 is grounded GND, and the drain of the NMOS transistor M30 is connected to the common connection point of the current gating control circuit ftim and the waveform shaping circuit LOGIC.

Referring to fig. 8, the current gating control circuit ftim includes:

the first current mirror circuit comprises NMOS tubes N1 and N2, sources of the NMOS tubes N1 and N2 are grounded GND, gates of the NMOS tubes N1 and N2 are connected with a drain of the NMOS tube N1 after being shorted, the drain of the NMOS tube N1 is a current input end of the current gating control circuit FTRIM, and the current input end is connected with the first bias current signal Temp IBIAS1 with a temperature coefficient;

The switch tube F0 and the PMOS tube PM0 form a path, the switch tube F1 and the PMOS tube PM1 form a path, and so on, the switch tube FN and the PMOS tube PMN form a path, and the corresponding path is controlled to be turned on or off according to a control signal loaded by the current gating control end ftim < N:0>, so that the current of the current output end I2 is adjusted, and the frequency deviation of the clock oscillator OSC is calibrated. I.e., calibrated to a desired frequency (e.g., a 16M clock oscillator) via ftim < N:0>, TEMP IBIAS1 provided via BGR provides OSC temperature compensation. The method specifically comprises the following steps: the PM0-PMN has different mirror currents through two mirror current circuits, the on-off conditions of F0-FN tubes can be controlled by controlling N +1 different gears, so that different currents can be obtained, and finally the frequency can be calibrated to a desired frequency.

Referring to fig. 9, in the high precision oscillator 100 according to the first embodiment of the present invention, the low dropout regulator LDO mainly includes:

an operational amplifier A1, a PMOS tube P3, resistors R11 and R12;

operational amplifier A1 output and PMOS pipe P3's grid connection, PMOS pipe P3's source connect the power VCC, PMOS pipe P3's drain electrode connect resistance R11, resistance R11 passes through resistance R12 ground connection GND, operational amplifier A1's in-phase input with resistance R11 and resistance R12's point of common connection are connected, PMOS pipe P3's drain electrode and resistance R11's point of common connection do the output of low dropout linear regulator LDO, the output has voltage signal VOUT. I.e., VREF of BGR, is used as reference voltage of LDO, and VOUT provides stable voltage to OSC after LDO processing. The LDO may be connected to a power VCC generated by an ac power adapter, or may be connected to a power VDD generated by a dc power, which should not be construed as a limitation of the present invention.

The low dropout linear regulator LDO is well known in the art.

Referring to fig. 1, in the high-precision oscillator 100 according to the first embodiment of the present invention, the temperature coefficient gating control signal generating circuit TS collects the ambient temperature and generates the temperature coefficient gating control signal, so that the temperature coefficient gating control signal is loaded to the temperature coefficient gating control terminal CTRL < M of the band gap reference circuit BGR: 0> as the temperature coefficient gate control signal CTRL < M of band gap reference circuit BGR: 0> to enable the bandgap reference circuit BGR to generate the first bias current signal Temp IBIAS1 with a temperature coefficient to compensate for the frequency deviation of the clock oscillator OSC with temperature variation, so as to reduce the frequency deviation of the clock oscillator OSC with temperature variation and improve the frequency accuracy of the clock signal CLKOUT output by the clock oscillator OSC. That is, the present invention has an advantage of high accuracy of the output clock signal CLKOUT.

In the high-precision oscillator 100 according to the first embodiment of the present invention, the voltage compensation is performed on the clock oscillator OSC by the stable voltage VOUT output by the low dropout regulator LDO, so as to prevent the frequency deviation of the clock signal CLKOUT output by the clock oscillator OSC from being affected by the large fluctuation of the output voltage of the external power supply module.

In the high-precision oscillator 100 provided in the first embodiment of the present invention, the second bias current IBIAS2 and the reference voltage signal VREF generated by the bandgap reference circuit BGR are used to increase the reference current signal and the reference voltage signal for the low dropout regulator LDO, so that the deviation of the reference signal of the low dropout regulator LDO is small under the condition of different process angles and different voltages, thereby ensuring that the deviation of the voltage signal output by the low dropout regulator LDO is small, and realizing that the frequency deviation of the clock signal CLKOUT output by the clock oscillator OSC is small along with the small voltage fluctuation.

Referring to fig. 12, according to the high-precision oscillator 100 provided by the first embodiment of the present invention, the maximum frequency deviation is 0.6%, and compared with the maximum frequency deviation of the clock oscillator OSC alone of fig. 11, the maximum frequency deviation is reduced by 0.9%, and the frequency deviation of the clock oscillator OSC is optimized, so that the frequency precision of the clock output is improved.

Example two

Referring to fig. 10, to achieve the object of the present invention, a second embodiment of the present invention provides a high precision oscillator 200, which is an improvement of the first embodiment and includes a clock oscillator OSC, a low dropout regulator LDO, a bandgap reference circuit BGR, and a temperature coefficient gate control signal generating circuit TS. The difference is that the connection relationship of the temperature coefficient gate control signal generation circuit TS is changed.

Wherein the low dropout linear regulator LDO provides a power supply for the clock oscillator OSC.

The bandgap reference circuit BGR provides a first bias current signal IBIAS1 to compensate for frequency deviation of the clock oscillator OSC with temperature variation. Wherein the frequency of the first bias current signal is opposite to the output frequency of the clock oscillator OSC.

The temperature coefficient gating control signal generating circuit TS includes a temperature sensor 41, an encoder 42, and a decoder 43, divides a temperature detection range of the temperature sensor 41 into a plurality of temperature intervals, encodes each temperature interval by the encoder 42, decodes the encoded by the encoder 42 by the decoder 43 to form a temperature coefficient gating control signal, and loads the temperature coefficient gating control signal to a current gating control terminal ftim < N of the clock oscillator OSC: and 0> compensating the frequency deviation of the clock oscillator OSC along with the temperature change by taking the temperature coefficient gating control signal of the corresponding temperature interval at the current ambient temperature as the current gating control signal of the clock oscillator OSC.

An example of the temperature interval division, encoding and decoding of the temperature coefficient gating control signal generation circuit TS may be as shown in table 2 below:

value of voltage	Temperature interval	Encoding	Decoding
				809.7	-40～-20	000	FTRIM0
775.5	-20～0	001	FTRIM1
				741.0	0～20	010	FTRIM2
706.4	20～40	011	FTRIM3
				671.7	40～60	100	FTRIM4
636.9	60～80	101	FTRIM5
				602.1	80～100	110	FTRIM6
567.2	80～125	111	FTRIM7

TABLE 2

Table 2 shows that the voltage-type temperature sensor is adopted, but the present invention is not limited to this type of temperature sensor, and other types of temperature sensors are also applicable, the number of temperature intervals is divided into 8, but not limited to 8, and the temperature intervals can be adjusted according to actual needs, and the larger the number of temperature intervals is, the better the effect of temperature on frequency compensation is. The upper limit value and the lower limit value of the temperature range are merely examples, and may be adjusted according to the detection range of the temperature sensor. The voltage value is not limited to a specific point value, but may be an interval value. Each decoding corresponds to a current gating control terminal FTRIM < N >.

Referring to fig. 5, in order to provide the first bias current signal IBIAS1 without temperature coefficient compensation, the high-precision oscillator 200 according to the second embodiment of the present invention includes:

a resistor R21 is connected between the common connection point of the drain electrode of the PMOS tube M1 and the emitter electrode of the triode Q1 and the ground GND, and a resistor R22 is connected between the common connection point of the drain electrode of the PMOS tube M2 and the resistor and the ground GND;

In order to increase the second bias current signal IBIAS2, referring to fig. 5, in the high-precision oscillator 200 according to the second embodiment of the present invention, the bandgap reference circuit BGR further includes:

In order to provide the reference voltage signal VREF without temperature coefficient compensation, the high-precision oscillator 200 according to the second embodiment of the present invention, the bandgap reference circuit BGR further includes:

a PMOS tube M3, wherein the source electrode of the PMOS tube M3 is connected with a power supply, and the grid electrode of the NMOS tube M3 is connected with the output end of the operational amplifier AMP; a resistor R24 is connected between the drain of the PMOS transistor M3 and the ground GND, and a common connection point of the drain of the PMOS transistor M3 and the resistor R24 outputs a reference voltage signal VREF.

Referring to fig. 10 and fig. 7 to fig. 8, in the high-precision oscillator 200 according to the second embodiment of the present invention, the clock oscillator OSC and the current-gating control circuit ftim are the same as those of the first embodiment, except that the current-gating control terminal ftim < N:0> is provided by the temperature coefficient gating control signal generating circuit TS, and the frequency deviation of the clock oscillator OSC can be directly calibrated through FTRIM < N:0> at different temperatures. Wherein the current gating control terminal and the current gating control signal use the same label FTRIM < N:0>, representing the current gating control signal FTRIM < N:0> is loaded to the current gate control terminal.

Referring to fig. 10, in the high-precision oscillator 200 according to the second embodiment of the present invention, the first bias current signal IBIAS1 output by the bandgap reference circuit BGR primarily compensates for the frequency deviation of the clock oscillator OSC generated along with the temperature change, and then the temperature coefficient gating control signal generating circuit TS collects the ambient temperature and generates the temperature coefficient gating control signal as the current gating control signal ftim < N of the clock oscillator OSC: 0> to finely compensate for frequency deviation of the clock oscillator OSC with temperature variation, thereby improving frequency accuracy of the clock oscillator OSC output clock signal CLKOUT.

Referring to fig. 13, in the high-precision oscillator 200 according to the second embodiment of the present invention, the temperature coefficient compensation is directly performed on the clock oscillator OSC by the temperature coefficient gating control signal generating circuit TS, so that the maximum frequency deviation is 0.35%, and compared with the maximum frequency deviation of the single clock oscillator OSC of fig. 11, the maximum frequency deviation is reduced by 14.65%, and the frequency deviation of the clock oscillator OSC is optimized, thereby improving the frequency precision of the clock output.

The above description is only for the purpose of describing the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention, and any variations and modifications made by those skilled in the art based on the above disclosure are within the scope of the appended claims.

Claims

1. A high-precision oscillator, comprising:

2. A high-precision oscillator, comprising:

3. The high accuracy oscillator of claim 1 or 2, wherein the bandgap reference circuit provides a second bias current signal IBIAS2 and a reference voltage signal VREF to provide a reference voltage signal and a reference current signal for the low dropout linear regulator, such that the output frequency of the low dropout linear regulator produces less frequency deviation with voltage fluctuation and the low dropout linear regulator produces less frequency deviation under different process angles.

4. The high accuracy oscillator of claim 1, wherein the bandgap reference circuit comprises:

5. The high accuracy oscillator of claim 1, wherein the bandgap reference circuit comprises:

6. The high accuracy oscillator of claim 4 or 5, wherein the bandgap reference circuit further comprises:

7. The high accuracy oscillator of claim 4, wherein the bandgap reference circuit further comprises:

8. The high accuracy oscillator of claim 4 or 5, wherein the bandgap reference circuit further comprises:

9. The high accuracy oscillator of claim 4, wherein the first temperature coefficient control circuit TSET-a comprises:

10. The high precision oscillator of claim 1 or 2, wherein the clock oscillator comprises:

11. The high accuracy oscillator of claim 10, wherein the current gating control circuit FTRIM comprises:

12. The high accuracy oscillator of claim 1 or 2, wherein the low dropout linear regulator comprises:

an operational amplifier A1, a PMOS tube P3, resistors R11 and R12;