CN113517879B - Oscillator circuit and chip - Google Patents

Abstract

The invention provides an oscillator circuit and a chip. The oscillator circuit outputs an oscillation signal based on the voltage of the capacitor, and the capacitor is charged and discharged in a mode of combining three constant currents, so that the cycle precision of the oscillation signal is improved; the current value of one of the three constant currents can be changed according to the frequency adjusting signal, so that the frequency of the oscillating signal is changed. Meanwhile, the charging and discharging states of the capacitor are switched by combining the variable voltage detection point and the voltage comparison module, so that the circuit structure is simplified. The configuration solves the problems that the frequency of the oscillator circuit in the prior art is difficult to adjust and the precision is difficult to ensure, and simplifies the circuit structure.

Description

Oscillator circuit and chip

Technical Field

The invention relates to the technical field of power supply chips, in particular to an oscillator circuit and a chip.

Background

When a conventional switching power supply chip works internally, an oscillator circuit is required to generate periodic triangular wave signals and rectangular wave signals for determining the switching period of the chip, digital logic signal time sequence control and the like, and the oscillator circuit is a core circuit module in the switching power supply chip.

Conventional oscillators are RC oscillators, ring oscillators, crystal oscillators. The stability and frequency of the RC oscillator are greatly influenced by the manufacturing process and the working voltage; ring oscillators have difficulty in achieving lower frequencies and adjusting frequencies; the frequency of the crystal oscillator is related to the selected crystal device, the frequency band is narrow, and the crystal oscillator is only suitable for the fixed frequency mode; in the conventional MOS (metal-oxide semiconductor field effect transistor) process, the parasitic capacitance of the device is large, the device is not completely isolated, the design difficulty and the circuit scale are increased in the application with high frequency, and the production cost is high.

That is to say, the oscillator circuit in the prior art has a great difficulty in frequency adjustment and is difficult to ensure precision.

Disclosure of Invention

The invention provides an oscillator circuit and a chip, which aim to solve the problems that in the prior art, the frequency of the oscillator circuit is difficult to adjust and the precision is difficult to ensure.

In order to solve the technical problem, the invention provides an oscillator circuit, which comprises a frequency adjusting module, a charging and discharging module, a voltage comparing module and a variable voltage detecting point; wherein the content of the first and second substances,

the charge-discharge module is used for outputting a first constant current to the frequency adjustment module;

the frequency adjusting module is used for limiting the current value of the first constant current to at least two preset values based on a frequency adjusting signal;

the charging and discharging module comprises a constant current input end, a capacitor and a discharging branch circuit; the constant current input end is used for acquiring a second constant current; when the discharge branch is switched off, the difference value between the second constant current and the first constant current charges the capacitor; when the discharge branch circuit is conducted, the capacitor outputs a third constant current to the discharge branch circuit, and the difference value between the sum of the first constant current and the third constant current and the second constant current discharges the capacitor;

the voltage comparison module comprises a first comparison end and a second comparison end; when the voltage of the first comparison end is less than or equal to the voltage of the second comparison end, the voltage comparison module outputs a first level and drives the discharge branch circuit to be switched off; otherwise, the voltage comparison module outputs a second level and drives the discharging branch to be conducted, wherein the second level is opposite to the first level; the first comparison end is used for obtaining the voltage of the capacitor, and the second comparison end is used for obtaining the voltage of the variable voltage detection point;

the variable voltage monitoring point is configured to output a first reference voltage when the voltage comparison module outputs the first level, and otherwise, output a second reference voltage; the first reference voltage is greater than the second reference voltage;

the oscillator circuit outputs an oscillation signal based on a voltage value of the capacitor.

Optionally, the oscillator circuit further includes a reference current module, where the reference current module is configured to output the reference current based on a reference voltage, the reference current includes the second constant current, the reference current module includes a variable resistance module, the variable resistance module includes at least two external resistance ports and at least one fusible conductive wire, and the variable resistance module adjusts the reference current based on a resistance value connected to the external resistance ports and an on-off state of the fusible conductive wire.

Optionally, the variable resistance module includes a first resistor, a second resistor, a third resistor and a fourth resistor; wherein the content of the first and second substances,

the first end of the first resistor is used for connecting other elements of the reference current module, the first end of the second resistor is connected with the second end of the first resistor, the first end of the third resistor is connected with the second end of the second resistor, the first end of the fourth resistor is connected with the second end of the third resistor, and the second end of the fourth resistor is used for grounding;

the second end of the first resistor is configured as an external resistor port, the second end of the second resistor is configured as an external resistor port, the second end of the third resistor is configured as an external resistor port, the second end of the first resistor and the second end of the second resistor are connected through the fusible wire, the second end of the second resistor and the second end of the third resistor are connected through the fusible wire, and the second end of the third resistor and the second end of the fourth resistor are connected through the fusible wire.

Optionally, the reference current module further includes a first triode, a second triode, a third triode, a fourth triode, a fifth triode, a sixth triode and a seventh triode; wherein the content of the first and second substances,

the first triode is a PNP triode, an emitting electrode of the first triode is used for being connected with a power supply, and a base electrode of the first triode is connected with a collector electrode of the first triode;

the second triode is an NPN triode, the base of the second triode is used for acquiring the reference voltage, and the collector of the second triode is connected with the collector of the first triode;

the first end of the first resistor is connected with the emitting electrode of the second triode;

the third triode, the fourth triode, the fifth triode, the sixth triode and the seventh triode are PNP type triodes, emitting electrodes of the third triode, the fourth triode, the fifth triode, the sixth triode and the seventh triode are all used for connecting a power supply, bases of the third triode, the fourth triode, the fifth triode, the sixth triode and the seventh triode are all connected with a base electrode of the first triode, and collecting electrodes of the third triode, the fourth triode, the fifth triode, the sixth triode and the seventh triode are all used for outputting the reference current.

Optionally, the frequency adjustment module is configured to limit a current value of the first constant current to two preset values based on a frequency adjustment signal, where the frequency adjustment signal includes a high level signal and a low level signal; the frequency adjusting module comprises an eighth triode, a ninth triode and a thirteenth triode; wherein the content of the first and second substances,

the eighth triode is an NPN triode, a collector of the eighth triode is used for acquiring the reference current, a base of the eighth triode is used for acquiring the frequency adjustment signal, and an emitter of the eighth triode is used for grounding;

the ninth triode is an NPN type triode, a collector of the ninth triode is connected with a collector of the eighth triode, a base of the ninth triode is connected with a collector of the ninth triode, and an emitter of the ninth triode is used for being grounded;

the thirteenth polar tube is an NPN type polar tube, a collector electrode of the thirteenth polar tube is used for obtaining the first constant current, a base electrode of the thirteenth polar tube is connected with a base electrode of the ninth polar tube, and an emitting electrode of the thirteenth polar tube is used for grounding.

Optionally, the oscillation signal includes a first oscillation signal and a second oscillation signal, the first oscillation signal is in a proportional relationship with a voltage value of the capacitor, when the capacitor is charged, the second oscillation signal is at a third level, when the capacitor is discharged, the second oscillation signal is at a fourth level, and the fourth level is opposite to the third level.

Optionally, the charge-discharge module is further configured to output the first oscillation signal, and the charge-discharge module includes an eleventh triode, a twelfth triode, a thirteenth triode, and a fourteenth triode; wherein the content of the first and second substances,

the first end of the capacitor is configured as the constant current input end, the first end of the capacitor is further used for outputting the first constant current, the first end of the capacitor is further used for outputting the first oscillation signal, and the second end of the capacitor is used for grounding;

the eleventh triode is an NPN triode, a collector of the eleventh triode is connected with the first end of the capacitor, an emitter of the eleventh triode is used for grounding, a collector of the eleventh triode is used for acquiring the third constant current, and the eleventh triode is configured to be the discharge branch circuit;

the twelfth triode is an NPN type triode, a collector of the twelfth triode is used for being connected with a power supply, and an emitter of the twelfth triode is connected with a base of the eleventh triode;

the thirteenth triode is an NPN type triode, a collector of the thirteenth triode is used for obtaining the reference current, the collector of the thirteenth triode is connected with a base of the twelfth triode, the base of the thirteenth triode is connected with an emitter of the twelfth triode, and the emitter of the thirteenth triode is used for grounding;

the fourteenth triode is an NPN triode, the base of the fourteenth triode is connected with the collector of the thirteenth triode, the base of the fourteenth triode is used for acquiring a conducting signal, and the emitter of the fourteenth triode is used for grounding;

the conducting signal is generated based on an output signal of the voltage comparison module, when the output signal of the voltage comparison module is at the first level, the conducting signal is at a high level, and when the output signal of the voltage comparison module is at the second level, the conducting signal is at a low level.

Optionally, the oscillator circuit further includes a signal conversion module, where the signal conversion module is configured to output a conducting signal based on an output signal of the voltage comparison module, where the conducting signal is used to control the conduction and the shutdown of the discharging branch, and the signal conversion module is further configured to output the second oscillation signal, and the signal conversion module includes a fifteenth triode, a sixteenth triode, a seventeenth triode, an eighteenth triode, a nineteenth triode, a twentieth triode, a twenty-first triode, a twenty-second triode, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, and a ninth resistor; wherein the content of the first and second substances,

the fifteenth triode is a PNP type triode, an emitter of the fifteenth triode is used for acquiring the reference current, a base of the fifteenth triode is used for acquiring the reference voltage, and a collector of the fifteenth triode is used for grounding;

the sixteenth triode is an NPN triode, a collector of the sixteenth triode is used for being connected with a power supply, and a base of the sixteenth triode is connected with a collector of the fifteenth triode;

the seventeenth triode is an NPN triode, a collector of the seventeenth triode is used for outputting the conducting signal, an emitter of the seventeenth triode is used for being grounded, and a base of the seventeenth triode is used for being grounded through the sixth resistor;

the eighteenth triode is a PNP triode, an emitting electrode of the eighteenth triode is connected with an emitting electrode of the sixteenth triode, a base electrode of the eighteenth triode is connected with a collector electrode of the seventeenth triode through the fifth resistor, and the collector electrode of the eighteenth triode is connected with a base electrode of the seventeenth triode;

the nineteenth triode is a PNP type triode, an emitting electrode of the nineteenth triode is connected with an emitting electrode of the sixteenth triode, a base electrode of the nineteenth triode is connected with a base electrode of the eighteenth triode, a collector electrode of the nineteenth triode is used for outputting the second oscillation signal, the third level is a low level, and the fourth level is a high level;

the twenty-third triode is an NPN type triode, a collector of the twentieth triode is connected with a collector of the nineteenth triode, a base of the twentieth triode is connected with a collector of the seventeenth triode, and an emitter of the twentieth triode is used for being grounded;

the twenty-first triode is a PNP triode, a collector electrode of the twenty-first triode is connected with an emitting electrode of the sixteenth triode, a base electrode of the twenty-first triode is connected with a base electrode of the eighteenth triode, and a collector electrode of the twenty-first triode is connected with a base electrode of the twenty-first triode;

the second triode is an NPN type triode, a collector of the second triode is connected with a collector of the first triode through the seventh resistor, a base of the second triode is used for acquiring an output signal of the voltage comparison module, and an emitter of the second triode is used for grounding;

a first end of the eighth resistor is connected to the emitter of the sixteenth transistor, a second end of the eighth resistor is connected to the first end of the ninth resistor, a second end of the ninth resistor is connected to the collector of the twenty-second transistor, and a second end of the eighth resistor is configured as the variable voltage detecting point.

Optionally, the voltage comparison module includes a twenty-third triode, a twenty-fourth triode and a tenth resistor; wherein the content of the first and second substances,

the twenty-third triode is a PNP-type triode, an emitter of the twenty-third triode is used for obtaining the reference current, a base of the twenty-third triode is configured as the second comparison terminal, a collector of the twenty-third triode is configured as the output terminal of the voltage comparison module, and the collector of the twenty-third triode is used for being grounded through the tenth resistor;

the twenty-fourth triode is a PNP type triode, an emitter of the twenty-fourth triode is connected with an emitter of the twenty-third triode, a base of the twenty-fourth triode is configured as the first comparison end, and a collector of the twenty-fourth triode is used for being grounded;

the first level is a low level and the second level is a high level.

In order to solve the technical problem, the invention further provides a chip, which includes the oscillator circuit.

Compared with the prior art, in the oscillator circuit and the chip provided by the invention, the oscillator circuit outputs the oscillation signal based on the voltage of the capacitor, and the capacitor is charged and discharged in a mode of combining three constant currents, so that the cycle precision of the oscillation signal is improved; the current value of one of the three constant currents can be changed according to the frequency adjusting signal, so that the frequency of the oscillating signal is changed. Meanwhile, the charging and discharging states of the capacitor are switched by combining the variable voltage detection point and the voltage comparison module, so that the circuit structure is simplified. The configuration solves the problems that the frequency of the oscillator circuit in the prior art is difficult to adjust and the precision is difficult to ensure, and simplifies the circuit structure.

Drawings

It will be appreciated by those skilled in the art that the drawings are provided for a better understanding of the invention and do not constitute any limitation to the scope of the invention. Wherein:

FIG. 1 is a schematic circuit diagram of an oscillator circuit of the present invention;

fig. 2 is a waveform diagram of the oscillator circuit of the present invention under one operating condition.

In the drawings:

100-a reference current module; 200-a frequency adjustment module; 300-a charge-discharge module; 400-a signal conversion module; 500-voltage comparison module.

Detailed Description

To further clarify the objects, advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. It is to be noted that the drawings are in greatly simplified form and are not to scale, but are merely intended to facilitate and clarify the explanation of the embodiments of the present invention. Further, the structures illustrated in the drawings are often part of actual structures. In particular, the drawings may have different emphasis points and may sometimes be scaled differently.

As used in this application, the singular forms "a", "an" and "the" include plural referents, the term "or" is generally employed in a sense including "and/or," the terms "a" and "an" are generally employed in a sense including "at least one," the terms "at least two" are generally employed in a sense including "two or more," and the terms "first", "second" and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicit to the number of technical features indicated. Thus, features defined as "first", "second" and "third" may explicitly or implicitly include one or at least two of the features, "one end" and "the other end" and "proximal end" and "distal end" generally refer to the corresponding two parts, which include not only the end points, but also the terms "mounted", "connected" and "connected" should be understood broadly, e.g., as a fixed connection, as a detachable connection, or as an integral part; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. Furthermore, as used in the present invention, the disposition of an element with another element generally only means that there is a connection, coupling, fit or driving relationship between the two elements, and the connection, coupling, fit or driving relationship between the two elements may be direct or indirect through intermediate elements, and cannot be understood as indicating or implying any spatial positional relationship between the two elements, i.e., an element may be in any orientation inside, outside, above, below or to one side of another element, unless the content clearly indicates otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

The core idea of the invention is to provide an oscillator circuit and a chip to solve the problems that the frequency adjustment of the oscillator circuit in the prior art is difficult and the accuracy is difficult to ensure.

The following description refers to the accompanying drawings.

Referring to fig. 1 to 2, fig. 1 is a schematic circuit diagram of an oscillator circuit according to the present invention; fig. 2 is a waveform diagram of the oscillator circuit of the present invention under one operating condition.

Fig. 1 shows an oscillator circuit comprising a frequency adjustment module 200, a charge and discharge module 300, a voltage comparison module 500 and a variable voltage detection point; wherein the content of the first and second substances,

the charge-discharge module 300 is configured to output a first constant current I1 to the frequency adjustment module 200; in fig. 1, the first constant current I1 is the current I1 flowing into the device Q10.

The frequency adjusting module 200 is configured to limit a current value of the first constant current I1 to at least two preset values based on a frequency adjusting signal; the preset value may be 0, in the embodiment shown in fig. 1, the preset values are two, in other embodiments, the number of the preset values may also be multiple, the frequency adjustment signal may be set according to actual needs, for example, the frequency adjustment signal is two paths of independent high and low level signals, which may be 4 possibilities in total, and the frequency adjustment module 200 changes the conduction condition of an internal circuit according to the specific conditions of the two paths of signals, so as to change the magnitude of the current value of the first constant current I1. The frequency adjustment signal may also be a set of one path, and the frequency adjustment module 200 limits the current value of the first constant current I1 to at least three preset values according to the waveform of the frequency adjustment signal, for example, the frequency adjustment signal includes three pulse width modulation signals with different duty ratios.

The charge and discharge module 300 comprises a constant current input end, a capacitor C1 and a discharge branch; the constant current input end is used for acquiring a second constant current I2; when the discharging branch is turned off, the difference value of the second constant current I2 and the first constant current I1 charges the capacitor; when the discharge branch circuit is switched on, the capacitor outputs a third constant current I3 to the discharge branch circuit, and the difference value between the sum of the first constant current I1 and the third constant current I3 and the second constant current I2 discharges the capacitor;

the voltage comparison module 500 comprises a first comparison terminal and a second comparison terminal; when the voltage of the first comparing terminal is less than or equal to the voltage of the second comparing terminal, the voltage comparing module 500 outputs a first level and drives the discharging branch to be turned off; otherwise, the voltage comparison module 500 outputs a second level and drives the discharging branch to be turned on, where the second level is opposite to the first level; in the circuit diagram shown in fig. 1, the first level is a low level, and the second level is a high level, but in other embodiments, the first level may be a high level, and the second level may be a low level. The first comparison end is used for obtaining the voltage of the capacitor, and the second comparison end is used for obtaining the voltage of the variable voltage detection point;

the variable voltage monitoring point is configured to output a first reference voltage VTH when the voltage comparison module 500 outputs the first level, and otherwise, output a second reference voltage VTL; the first reference voltage VTH is greater than the second reference voltage VTL; that is, after the voltage of the first comparing terminal exceeds the voltage of the second comparing terminal, the voltage of the first comparing terminal needs to be decreased by a larger voltage difference, so that the voltage comparing module outputs the first level, where the voltage difference is the difference between the first reference voltage VTH and the first reference voltage VTL.

The oscillator circuit outputs an oscillation signal based on the voltage value of the capacitor C1.

Based on the above description, the capacitor C1 is charged first by (I2-I1), then when the voltage reaches the first reference voltage VTH, it is discharged by (I3 + I1-I2), and then when it drops to the second reference voltage VTL, it starts to be charged again, forming a cycle. The oscillator circuit converts the voltage value of the capacitor C1 by arranging other modules or elements, thereby outputting the oscillation signal. The specific conversion process can be understood by referring to the subsequent part of the description, but is not limited to the conversion scheme described in the description. Meanwhile, I1 in the scheme is a variable constant current. Obviously, I2-I1 is greater than 0, I3+ I1-I2 is greater than 0, and the above numerical relationship can be realized by adjusting relevant parameters of the circuit.

In the prior art, the frequency of the oscillator circuit is difficult to adjust and the precision is difficult to ensure, and the capacitor C1 is charged and discharged by setting a plurality of constant currents and combining the constant currents, so that the precision of the circulation process is ensured. On the other hand, the charging time of the capacitor C1 is adjusted by setting the variable constant current I1, so that the period time of the oscillating signal can be conveniently adjusted. Meanwhile, in order to enable the charging and discharging processes of the capacitor C1 to be adaptive to charging and discharging currents of different magnitudes, the variable voltage detection point is arranged, so that the charging and discharging processes can be smoothly switched. It should be understood that the variable voltage monitoring point may be selected as a desired point in an existing circuit, or may be constructed based on an existing circuit, and may not need to be implemented using a completely separate module. Of course, in some embodiments, a completely independent module may be used to implement the variable voltage monitoring point.

That is to say, through above-mentioned setting, can solve the oscillator circuit frequency adjustment among the prior art and make great and be difficult to the problem of guaranteeing the precision.

Optionally, the oscillator circuit further includes a reference current module 100, where the reference current module 100 is configured to output the reference current based on a reference voltage VREF, and the reference current includes the second constant current I2, that is, the reference current further includes other currents, and the other currents are used as reference currents (bias currents) of other modules. The reference current module 100 includes a variable resistance module, the variable resistance module includes at least two external resistance ports and at least one fusible conductive wire, and the variable resistance module adjusts the reference current based on a resistance value connected to the external resistance ports and an on-off state of the fusible conductive wire. With the configuration, the reference current can be accurately adjusted by externally connecting a resistor to the oscillator circuit and fusing the fusible conductive wire, so that the influence on the circuit precision caused by process errors in different embodiments is reduced or eliminated, and the precision of the oscillator circuit is further improved.

The variable resistance module may be configured according to actual situations, and in the embodiment shown in fig. 1, the variable resistance module includes a first resistor R1, a second resistor R2, a third resistor R3 and a fourth resistor R4; wherein the content of the first and second substances,

a first end of the first resistor R1 is used for connecting other elements of the reference current module 100, a first end of the second resistor R2 is connected to a second end of the first resistor R1, a first end of the third resistor R3 is connected to a second end of the second resistor R2, a first end of the fourth resistor R4 is connected to a second end of the third resistor R3, and a second end of the fourth resistor R4 is used for grounding;

a second end of the first resistor R1 is configured as an external resistor port PAD1, a second end of the second resistor R1 is configured as an external resistor port PAD2, a second end of the third resistor R3 is configured as an external resistor port PAD3, a second end of the first resistor R1 and a second end of the second resistor R2 are connected by the fusible wire F1, a second end of the second resistor R2 and a second end of the third resistor R3 are connected by the fusible wire F2, and a second end of the third resistor R3 and a second end of the fourth resistor R4 are connected by the fusible wire F3.

With such a configuration, regardless of the resistance value of the external resistor, the variable resistor module has dozens of different actual connection relationships, and can conveniently obtain an accurate current value I4 by adjusting the circuit structure thereof, and output the expected reference current based on the current value.

Further, the reference current module 100 further includes a first transistor Q1, a second transistor Q2, a third transistor Q3, a fourth transistor Q4, a fifth transistor Q5, a sixth transistor Q6, and a seventh transistor Q7; wherein the content of the first and second substances,

the first triode Q1 is a PNP type triode, the emitter of the first triode Q1 is used for connecting a power supply, and the base of the first triode Q1 is connected with the collector of the first triode Q1;

the second triode Q2 is an NPN type triode, the base of the second triode Q2 is used for obtaining the reference voltage VREF, and the collector of the second triode Q2 is connected with the collector of the first triode Q1;

a first end of the first resistor R1 is connected with an emitter of the second triode Q2;

the third triode Q3, the fourth triode Q4, the fifth triode Q5, the sixth triode Q6 and the seventh triode Q7 are all PNP type triodes, emitters of the third triode Q3, the fourth triode Q4, the fifth triode Q5, the sixth triode Q6 and the seventh triode Q7 are all used for connecting a power supply, bases of the third triode Q3, the fourth triode Q4, the fifth triode Q5, the sixth triode Q6 and the seventh triode Q7 are all connected with a base of the first triode Q1, and collectors of the third triode Q3, the fourth triode Q4, the fifth triode Q5, the sixth triode Q6 and the seventh triode Q7 are all used for outputting the reference current.

So configured, the reference current module 100 generates a reference current I4 and outputs the expected reference current based on the reference current I4 and a plurality of current mirrors. It should be understood that the current copy ratio of the current mirrors may be configured according to actual requirements, and is not described herein.

In the embodiment shown in fig. 1, the frequency adjustment module 200 is configured to limit the current value of the first constant current I1 to two preset values based on a frequency adjustment signal CF, where the frequency adjustment signal CF includes a high level signal and a low level signal; the frequency adjusting module comprises an eighth triode Q8, a ninth triode Q9 and a thirteenth triode Q10; wherein the content of the first and second substances,

the eighth transistor Q8 is an NPN transistor, a collector of the eighth transistor Q8 is configured to obtain the reference current, a base of the eighth transistor Q8 is configured to obtain the frequency adjustment signal CF, and an emitter of the eighth transistor Q8 is configured to be grounded;

the ninth triode Q9 is an NPN type triode, a collector of the ninth triode Q9 is connected to a collector of the eighth triode Q8, a base of the ninth triode Q9 is connected to a collector of the ninth triode Q9, and an emitter of the ninth triode Q9 is grounded;

the thirteenth pole tube Q10 is an NPN type triode, a collector of the thirteenth pole tube Q10 is used for obtaining the first constant current I1, a base of the thirteenth pole tube Q10 is connected with a base of the ninth pole tube Q9, and an emitter of the thirteenth pole tube Q10 is used for grounding.

Based on the above structure, when the frequency adjustment signal CF is at a high level, Q8 is turned on, Q9 and Q10 are turned off, and I1 = 0 is a current (i.e., the first constant current) flowing through the collector of Q10. When the frequency adjustment signal CF is at a low level, Q8 is turned off, Q9 and Q10 are turned on, and a current (i.e., the first constant current) I1 = K1 × K2 × I4 flows through a collector of Q10, where K1 is a current conversion ratio of a current mirror formed by Q1 and Q3, and K2 is a current conversion ratio of a current mirror formed by Q9 and Q10, and the current conversion ratio of the current mirror can be calculated according to a ratio of emitter areas of two triodes forming the current mirror, and will not be described in this specification. It is understood that the collector current and the emitter current are not exactly equal for the triode, but the formula calculation in this specification is only for explaining the principle of circuit operation, not for precise calculation, and thus the difference between the collector current and the emitter current is not distinguished here and is considered equal. In the following, it can be understood according to this idea.

The frequency adjustment module 200 may further include at least one resistor, and the at least one resistor is used for adjusting the current, and in different embodiments, the resistor may be disposed at different positions of the frequency adjustment module 200, and may be disposed according to common knowledge by a person skilled in the art, and will not be described in this specification.

It should be understood that the frequency adjustment module 200 shown in fig. 1 only provides two preset values, and one of the preset values is zero. In other embodiments, the frequency adjustment module 200 may be configured according to actual situations, and provide more than two preset values.

The oscillation signal includes a first oscillation signal SAW and a second oscillation signal OSC, the first oscillation signal SAW is in a proportional relationship with a voltage value of the capacitor, the second oscillation signal OSC is a third level when the capacitor is charged, the second oscillation signal OSC is a fourth level when the capacitor is discharged, and the fourth level is opposite to the third level. That is, the first oscillation signal is a triangular wave, and the second oscillation signal OSC is a square wave.

The charge-discharge module 300 is further configured to output the first oscillation signal SAW, and the charge-discharge module 300 includes an eleventh triode Q11, a twelfth triode Q12, a thirteenth triode Q13, and a fourteenth triode Q14; wherein the content of the first and second substances,

a first end of the capacitor C1 is configured as the constant current input end, a first end of the capacitor C1 is further used for outputting the first constant current I1, a first end of the capacitor C1 is further used for outputting the first oscillation signal SAW, and a second end of the capacitor C1 is used for grounding; when the capacitor C1 outputs the first oscillation signal SAW, the first oscillation signal SAW may be directly output, or may be output through a blocking unit or a blocking element. The latter is a preferable scheme, so that the interference of an external circuit on the charging and discharging states of the capacitor C1 can be avoided. It should be understood that the first oscillating signal SAW is proportional to the voltage value of the capacitor C1, in this embodiment, the voltage value of the first oscillating signal SAW is equal to the voltage value of the capacitor C1, and in other embodiments, the voltage value of the capacitor C1 may be amplified, reduced, shunted, divided, inverted, and superimposed before being output. Thus, the voltage values of the first oscillation signal SAW and the capacitor C1 are not necessarily equal.

The eleventh triode Q11 is an NPN type triode, a collector of the eleventh triode Q11 is connected to the first end of the capacitor C1, an emitter of the eleventh triode Q11 is grounded, a collector of the eleventh triode Q11 is used for obtaining the third constant current I3, and the eleventh triode Q11 is configured as the discharging branch;

the twelfth triode Q12 is an NPN type triode, the collector of the twelfth triode Q12 is used for connecting a power supply, and the emitter of the twelfth triode Q12 is connected with the base of the eleventh triode Q11;

the thirteenth triode Q13 is an NPN type triode, a collector of the thirteenth triode Q13 is used for obtaining the reference current, a collector of the thirteenth triode Q13 is connected with a base of the twelfth triode Q12, a base of the thirteenth triode Q13 is connected with an emitter of the twelfth triode Q12, and an emitter of the thirteenth triode Q13 is used for grounding;

the fourteenth triode Q14 is an NPN type triode, a base of the fourteenth triode Q14 is connected to a collector of the thirteenth triode Q13, a base of the fourteenth triode Q14 is used for obtaining a conducting signal, and an emitter of the fourteenth triode Q14 is used for grounding;

the conducting signal is generated based on the output signal of the voltage comparing module 500, when the output signal of the voltage comparing module 500 is at the first level, the conducting signal is at a high level, and when the output signal of the voltage comparing module is at the second level, the conducting signal is at a low level.

Based on the circuit structure, when the on signal is at a high level, Q14 is turned on, Q11 and Q13 are turned off, that is, the discharging branch is turned off; when the on signal is at a low level, Q13 is turned off, Q11 and Q13 are turned on, and at this time, the value of the third constant current I3 is K3 × K4 × I4, where K3 is a current conversion ratio of a current mirror composed of Q1 and Q5, and K4 is a current conversion ratio of a current mirror composed of Q11 and Q13.

In this embodiment, the oscillator circuit further includes a signal conversion module 400, where the signal conversion module 400 is configured to output a conducting signal based on an output signal of the voltage comparison module 500, where the conducting signal is used to control the conduction and the disconnection of the discharging branch, and the signal conversion module is further configured to output the second oscillation signal OSC, and the signal conversion module includes a fifteenth triode Q15, a sixteenth triode Q16, a seventeenth triode Q17, an eighteenth triode Q8, a nineteenth triode Q19, a twentieth triode Q20, a twenty-first triode Q21, a twenty-second triode Q22, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, and a ninth resistor R9; wherein the content of the first and second substances,

the fifteenth triode Q15 is a PNP-type triode, the emitter of the fifteenth triode Q15 is used for obtaining the reference current, the base of the fifteenth triode Q15 is used for obtaining the reference voltage, and the collector of the fifteenth triode Q15 is used for grounding;

the sixteenth triode Q16 is an NPN type triode, the collector of the sixteenth triode Q16 is used for connecting a power supply, and the base of the sixteenth triode Q16 is connected with the collector of the fifteenth triode Q15;

the seventeenth triode Q17 is an NPN type triode, a collector of the seventeenth triode Q17 is used for outputting the turn-on signal, an emitter of the seventeenth triode Q17 is used for grounding, and a base of the seventeenth triode Q17 is used for grounding through the sixth resistor R6;

the eighteenth triode Q18 is a PNP triode, the emitter of the eighteenth triode Q18 is connected to the emitter of the sixteenth triode Q16, the base of the eighteenth triode Q18 is connected to the collector of the seventeenth triode Q17 through the fifth resistor R5, and the collector of the eighteenth triode Q18 is connected to the base of the seventeenth triode Q17;

the nineteenth triode Q19 is a PNP triode, an emitter of the nineteenth triode Q19 is connected to an emitter of the sixteenth triode Q16, a base of the nineteenth triode Q19 is connected to a base of the eighteenth triode Q18, a collector of the nineteenth triode Q19 is used for outputting the second oscillation signal OSC, the third level is a low level, and the fourth level is a high level;

the twentieth triode Q20 is an NPN-type triode, a collector of the twentieth triode Q29 is connected to a collector of the nineteenth triode Q19, a base of the twentieth triode Q20 is connected to a collector of the seventeenth triode Q17, and an emitter of the twentieth triode Q20 is grounded;

the twenty-first triode Q21 is a PNP type triode, the emitter of the twenty-first triode Q21 is connected with the emitter of the sixteenth triode Q16, the base of the twenty-first triode Q21 is connected with the base of the eighteenth triode Q18, and the collector of the twenty-first triode Q21 is connected with the base of the twenty-first triode Q21;

the twenty-second triode Q22 is an NPN-type triode, a collector of the twenty-second triode Q22 is connected to a collector of the twenty-first triode Q21 through the seventh resistor R7, a base of the twenty-second triode Q22 is used for acquiring the output signal of the voltage comparison module 500, and an emitter of the twenty-second triode Q22 is used for grounding;

a first end of the eighth resistor R8 is connected to the emitter of the sixteenth transistor Q16, a second end of the eighth resistor R8 is connected to a first end of the ninth resistor R9, a second end of the ninth resistor R9 is connected to the collector of the twenty-second transistor Q22, and a second end of the eighth resistor R8 is configured as the variable voltage detecting point.

Based on the above circuit structure, the operation principle of the signal conversion module 400 is explained as follows. The a-point voltage in fig. 1 is VREF + VbeQ15-VbeQ16= VREF (VbeQ 15, VbeQ16 are absolute values of base emitter voltages of Q15, Q16, respectively), i.e., the a-point voltage is always VREF. When the base of Q22 is at a low level, i.e., the first level, Q22 is turned off, and the voltage at the second end of the eighth resistor R8 is also at this value, i.e., the first reference voltage VTH = VREF. So configured, it is advantageous to directly adjust the first reference voltage VTH by adjusting the magnitude of the reference voltage. Meanwhile, collector currents of the Q21, the Q19 and the Q18 are zero, a base of the Q20 is at a high level (an absolute value of a voltage of a point a minus a base emitter voltage of the Q18), the Q20 and the Q14 are turned on, and the second oscillation signal OSC and the turn-on signal are both at a low level. When the base of Q22 is at a high level, that is, the second level, Q22 is turned on, and the voltage at the second end of the eighth resistor R8 becomes VREF × R9/(R8 + R9), that is, the second reference voltage VTL = VREF × R9/(R8 + R9). Meanwhile, the collector current of the Q18 raises the voltage across the R6, the Q17 is turned on, the Q20 and the Q14 are turned off, and the second oscillation signal OSC and the on signal are both at a high level.

It should be understood that the signal conversion module 400 is used to provide the on signal, the second oscillation signal OSC, and the variable voltage detecting point simultaneously through one module. Therefore, the device can be solved and the circuit structure can be simplified.

Finally, the voltage comparison module 500 includes a twenty-third transistor Q23, a twenty-fourth transistor Q24, and a tenth resistor R10; wherein the content of the first and second substances,

the twenty-third transistor Q23 is a PNP-type transistor, an emitter of the twenty-third transistor Q23 is used for obtaining the reference current, a base of the twenty-third transistor Q23 is configured as the second comparison terminal, a collector of the twenty-third transistor Q23 is configured as the output terminal of the voltage comparison module, and a collector of the twenty-third transistor Q23 is used for being grounded through the tenth resistor R10;

the twenty-fourth transistor Q24 is a PNP-type transistor, an emitter of the twenty-fourth transistor Q24 is connected to an emitter of the twenty-third transistor Q23, a base of the twenty-fourth transistor Q24 is configured as the first comparison terminal, and a collector of the twenty-fourth transistor Q24 is configured to be grounded;

the first level is a low level and the second level is a high level.

Based on the above circuit structure, the voltage comparison module 500 may implement that "when the voltage of the first comparison terminal is less than or equal to the voltage of the second comparison terminal, the voltage comparison module 500 outputs a first level; otherwise, the voltage comparison module 500 outputs the effect of the second level ".

In this embodiment, the calculation formula of the key parameter is as follows:

the formula I is as follows:

I4=(VREF-VbeQ2)/(R1+R2+R3+R4)

the above formula is used for calculating the reference current I4 when the resistors F1-F3 are all disconnected, otherwise, the denominator of the above formula is converted according to the actual resistance value of the variable resistor module, VREF is the reference voltage, and VbeQ2 is the base-emitter junction voltage drop of Q2.

The formula II is as follows:

t10=(VTH-VTL)*C1/I2

t10 represents the charging time of C1 when CF is high, and also the rise time of the triangular wave SAW, VTH = VREF, VTL = VREF × R9/(R8 + R9).

The formula III is as follows:

t11=(VTH-VTL)*C1/(I3-I2)

t11 represents the discharge time of C1 when CF is high, and also represents the fall time of the triangular wave SAW.

The formula four is as follows:

T1=t10+t11

t1 is the oscillation period of the oscillator circuit when CF is high.

The formula five is as follows:

t20=(VTH-VTL)*C1/（I2-I1）

t20 represents the charging time of C1 when CF is low, and is also the rise time of the triangular wave SAW; i1 takes the value K1 by K2 by I4.

Formula six:

t21=(VTH-VTL)*C1/(I4+I2-I3)

t21 represents the discharge time of C1 when CF is low, and also represents the fall time of the triangular wave SAW.

The formula seven:

T2=t20+t21

t2 is the oscillation period of the oscillator circuit when CF is low.

Based on the above formula, those skilled in the art can set reasonable component parameters according to actual requirements.

The waveform diagram of the oscillator circuit under a working condition is shown in fig. 2, and as can be seen from fig. 2, the oscillator circuit can work according to design expectation and output appropriate triangular waves and square waves.

The embodiment also provides a chip, and the chip comprises the oscillator circuit. The specific details of the chip can be understood with reference to the foregoing content of the present specification, and the chip also has the advantages of frequency adjustability and high precision.

Compared with the prior art, in the oscillator circuit and the chip provided by the invention, the oscillator circuit outputs the oscillation signal based on the voltage of the capacitor C1, and the capacitor C1 is charged and discharged in a mode of combining three constant currents, so that the cycle precision of the oscillation signal is improved; the current value of one of the three constant currents can be changed according to the frequency adjusting signal, so that the frequency of the oscillating signal is changed. Meanwhile, the charging and discharging states of the capacitor C1 are switched by combining the variable voltage detection point and the voltage comparison module 500, so that the circuit structure is simplified. The configuration solves the problems that the frequency of the oscillator circuit in the prior art is difficult to adjust and the precision is difficult to ensure, and simplifies the circuit structure.

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 according to the above disclosure are within the scope of the present invention.

Claims (6)

1. The oscillator circuit is characterized by comprising a frequency adjusting module, a charging and discharging module, a voltage comparing module and a variable voltage detecting point; wherein the content of the first and second substances,

the charge-discharge module is used for outputting a first constant current to the frequency adjustment module;

the frequency adjusting module is used for limiting the current value of the first constant current to at least two preset values based on a frequency adjusting signal;

the charging and discharging module comprises a constant current input end, a capacitor and a discharging branch circuit; the constant current input end is used for acquiring a second constant current; when the discharge branch is switched off, the difference value between the second constant current and the first constant current charges the capacitor; when the discharge branch circuit is conducted, the capacitor outputs a third constant current to the discharge branch circuit, and the difference value between the sum of the first constant current and the third constant current and the second constant current discharges the capacitor;

the voltage comparison module comprises a first comparison end and a second comparison end; when the voltage of the first comparison end is less than or equal to the voltage of the second comparison end, the voltage comparison module outputs a first level and drives the discharge branch circuit to be switched off; otherwise, the voltage comparison module outputs a second level and drives the discharging branch to be conducted, wherein the second level is opposite to the first level; the first comparison end is used for obtaining the voltage of the capacitor, and the second comparison end is used for obtaining the voltage of the variable voltage detection point;

the variable voltage detection point is configured to output a first reference voltage when the voltage comparison module outputs the first level, and otherwise, output a second reference voltage; the first reference voltage is greater than the second reference voltage;

the oscillator circuit outputs an oscillation signal based on a voltage value of the capacitor;

the frequency adjusting module is used for limiting the current value of the first constant current to two preset values based on a frequency adjusting signal, wherein the frequency adjusting signal comprises a high level signal and a low level signal; the frequency adjusting module comprises an eighth triode, a ninth triode and a thirteenth triode; wherein the content of the first and second substances,

the eighth triode is an NPN triode, a collector of the eighth triode is used for acquiring reference current, a base of the eighth triode is used for acquiring the frequency adjustment signal, and an emitter of the eighth triode is used for grounding;

the ninth triode is an NPN type triode, a collector of the ninth triode is connected with a collector of the eighth triode, a base of the ninth triode is connected with a collector of the ninth triode, and an emitter of the ninth triode is used for being grounded;

the thirteenth polar tube is an NPN type polar tube, a collector electrode of the thirteenth polar tube is used for obtaining the first constant current, a base electrode of the thirteenth polar tube is connected with a base electrode of the ninth polar tube, and an emitter electrode of the thirteenth polar tube is used for grounding;

the oscillation signal comprises a first oscillation signal and a second oscillation signal, the first oscillation signal is in a proportional relation with the voltage value of the capacitor, the second oscillation signal is at a third level when the capacitor is charged, the second oscillation signal is at a fourth level when the capacitor is discharged, and the fourth level is opposite to the third level;

the charge-discharge module is further used for outputting the first oscillation signal, and the charge-discharge module comprises an eleventh triode, a twelfth triode, a thirteenth triode and a fourteenth triode; wherein the content of the first and second substances,

the first end of the capacitor is configured as the constant current input end, the first end of the capacitor is further used for outputting the first constant current, the first end of the capacitor is further used for outputting the first oscillation signal, and the second end of the capacitor is used for grounding;

the eleventh triode is an NPN triode, a collector of the eleventh triode is connected with the first end of the capacitor, an emitter of the eleventh triode is used for grounding, a collector of the eleventh triode is used for acquiring the third constant current, and the eleventh triode is configured to be the discharge branch circuit;

the twelfth triode is an NPN type triode, a collector of the twelfth triode is used for being connected with a power supply, and an emitter of the twelfth triode is connected with a base of the eleventh triode;

the thirteenth triode is an NPN type triode, a collector of the thirteenth triode is used for obtaining the reference current, the collector of the thirteenth triode is connected with a base of the twelfth triode, the base of the thirteenth triode is connected with an emitter of the twelfth triode, and the emitter of the thirteenth triode is used for grounding;

the fourteenth triode is an NPN triode, the base of the fourteenth triode is connected with the collector of the thirteenth triode, the base of the fourteenth triode is used for acquiring a conducting signal, and the emitter of the fourteenth triode is used for grounding;

the conducting signal is generated based on an output signal of the voltage comparison module, when the output signal of the voltage comparison module is at the first level, the conducting signal is at a high level, and when the output signal of the voltage comparison module is at the second level, the conducting signal is at a low level;

the oscillator circuit further comprises a signal conversion module, the signal conversion module is used for outputting a conducting signal based on an output signal of the voltage comparison module, the conducting signal is used for controlling the conduction and the disconnection of the discharging branch, the signal conversion module is also used for outputting a second oscillating signal, and the signal conversion module comprises a fifteenth triode, a sixteenth triode, a seventeenth triode, an eighteenth triode, a nineteenth triode, a twentieth triode, a twenty-first triode, a twenty-second triode, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor and a ninth resistor; wherein the content of the first and second substances,

the fifteenth triode is a PNP type triode, an emitter of the fifteenth triode is used for acquiring the reference current, a base of the fifteenth triode is used for acquiring the reference voltage, and a collector of the fifteenth triode is used for grounding;

the sixteenth triode is an NPN triode, a collector of the sixteenth triode is used for being connected with a power supply, and a base of the sixteenth triode is connected with a collector of the fifteenth triode;

the seventeenth triode is an NPN triode, a collector of the seventeenth triode is used for outputting the conducting signal, an emitter of the seventeenth triode is used for being grounded, and a base of the seventeenth triode is used for being grounded through the sixth resistor;

the eighteenth triode is a PNP triode, an emitting electrode of the eighteenth triode is connected with an emitting electrode of the sixteenth triode, a base electrode of the eighteenth triode is connected with a collector electrode of the seventeenth triode through the fifth resistor, and the collector electrode of the eighteenth triode is connected with a base electrode of the seventeenth triode;

the nineteenth triode is a PNP type triode, an emitting electrode of the nineteenth triode is connected with an emitting electrode of the sixteenth triode, a base electrode of the nineteenth triode is connected with a base electrode of the eighteenth triode, a collector electrode of the nineteenth triode is used for outputting the second oscillation signal, the third level is a low level, and the fourth level is a high level;

the twenty-third triode is an NPN type triode, a collector of the twentieth triode is connected with a collector of the nineteenth triode, a base of the twentieth triode is connected with a collector of the seventeenth triode, and an emitter of the twentieth triode is used for being grounded;

the twenty-first triode is a PNP triode, a collector electrode of the twenty-first triode is connected with an emitting electrode of the sixteenth triode, a base electrode of the twenty-first triode is connected with a base electrode of the eighteenth triode, and a collector electrode of the twenty-first triode is connected with a base electrode of the twenty-first triode;

the second triode is an NPN type triode, a collector of the second triode is connected with a collector of the first triode through the seventh resistor, a base of the second triode is used for acquiring an output signal of the voltage comparison module, and an emitter of the second triode is used for grounding;

a first end of the eighth resistor is connected to the emitter of the sixteenth transistor, a second end of the eighth resistor is connected to the first end of the ninth resistor, a second end of the ninth resistor is connected to the collector of the twenty-second transistor, and a second end of the eighth resistor is configured as the variable voltage detecting point.

2. The oscillator circuit according to claim 1, further comprising a reference current module, wherein the reference current module is configured to output the reference current based on a reference voltage, the reference current comprises the second constant current, the reference current module comprises a variable resistance module, the variable resistance module comprises at least two external resistance ports and at least one fusible conductive wire, and the variable resistance module adjusts a magnitude of the reference current based on a resistance value connected to the external resistance ports and an on-off state of the fusible conductive wire.

3. The oscillator circuit of claim 2, wherein the variable resistance module comprises a first resistance, a second resistance, a third resistance, and a fourth resistance; wherein the content of the first and second substances,

the first end of the first resistor is used for connecting other elements of the reference current module, the first end of the second resistor is connected with the second end of the first resistor, the first end of the third resistor is connected with the second end of the second resistor, the first end of the fourth resistor is connected with the second end of the third resistor, and the second end of the fourth resistor is used for grounding;

the second end of the first resistor is configured as an external resistor port, the second end of the second resistor is configured as an external resistor port, the second end of the third resistor is configured as an external resistor port, the second end of the first resistor and the second end of the second resistor are connected through the fusible wire, the second end of the second resistor and the second end of the third resistor are connected through the fusible wire, and the second end of the third resistor and the second end of the fourth resistor are connected through the fusible wire.

4. The oscillator circuit of claim 3, wherein the reference current module further comprises a first transistor, a second transistor, a third transistor, a fourth transistor, a fifth transistor, a sixth transistor, and a seventh transistor; wherein the content of the first and second substances,

the first triode is a PNP triode, an emitting electrode of the first triode is used for being connected with a power supply, and a base electrode of the first triode is connected with a collector electrode of the first triode;

the second triode is an NPN triode, the base of the second triode is used for acquiring the reference voltage, and the collector of the second triode is connected with the collector of the first triode;

the first end of the first resistor is connected with the emitting electrode of the second triode;

the third triode, the fourth triode, the fifth triode, the sixth triode and the seventh triode are PNP type triodes, emitting electrodes of the third triode, the fourth triode, the fifth triode, the sixth triode and the seventh triode are all used for connecting a power supply, bases of the third triode, the fourth triode, the fifth triode, the sixth triode and the seventh triode are all connected with a base electrode of the first triode, and collecting electrodes of the third triode, the fourth triode, the fifth triode, the sixth triode and the seventh triode are all used for outputting the reference current.

5. The oscillator circuit of claim 1, wherein the voltage comparison module comprises a twenty-third transistor, a twenty-fourth transistor, and a tenth resistor; wherein the content of the first and second substances,

the twenty-third triode is a PNP-type triode, an emitter of the twenty-third triode is used for obtaining the reference current, a base of the twenty-third triode is configured as the second comparison terminal, a collector of the twenty-third triode is configured as the output terminal of the voltage comparison module, and the collector of the twenty-third triode is used for being grounded through the tenth resistor;

the twenty-fourth triode is a PNP type triode, an emitter of the twenty-fourth triode is connected with an emitter of the twenty-third triode, a base of the twenty-fourth triode is configured as the first comparison end, and a collector of the twenty-fourth triode is used for being grounded;

the first level is a low level and the second level is a high level.

6. A chip comprising an oscillator circuit as claimed in any one of claims 1 to 5.

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