Oscillation circuit and circuit system using same

Abstract

The invention provides an oscillation circuit and a circuit system using the same. The oscillation circuit comprises a current mirror circuit, a charging and discharging circuit, an output stage circuit, a first resistor, a second resistor and a diode circuit. The current mirror circuit outputs a reference current. The charging and discharging circuit charges the first charge storage component by using a reference current or discharges the first charge storage component, and generates a first control voltage according to the first charge storage component. The output stage circuit comprises a first switch transistor, and the first switch transistor is controlled by a first control voltage and outputs a first oscillation signal. The first resistor and the second resistor have the same temperature drift, the first resistance value of the first resistor is larger than the second resistance value of the second resistor, and the resistance drift amount of the first resistor changing along with the temperature is smaller than the resistance drift amount of the second resistor changing along with the temperature, so that the frequency accuracy influenced by the temperature change is reduced.

Description

Technical Field

[0001] The present invention relates to an oscillating circuit and a circuit system using the oscillating circuit, and in particular to an oscillating circuit and a circuit system using the oscillating circuit, which can reduce the influence of temperature change on the frequency accuracy. Background Art

[0002] Existing oscillator circuits are required to achieve frequency drift accuracy in their applications, and the frequency of the output signal of most oscillator circuits is related to passive components (e.g., resistors and capacitors), so the frequency accuracy problem is limited by passive components such as resistors and capacitors. However, in some processes, the temperature drift of resistors is large, and there are no passive components with two different temperature directions that can be used. For example, all resistors have positive or negative temperature drift, that is, resistors with positive temperature drift and resistors with negative temperature drift do not exist in the process at the same time.

[0003] Common polysilicon resistors may have negative temperature drift in older processes, and resistors of other materials may have positive temperature drift. Therefore, resistors with different temperature drifts can be connected in series to achieve zero temperature drift, so that the frequency of the output signal generated by the oscillation circuit will not have temperature drift. However, in more advanced processes, polysilicon resistors have positive temperature drift, and resistors of other materials also have positive temperature drift, making it impossible to use resistors in series to achieve zero temperature drift. In view of this, a new oscillation circuit architecture needs to be proposed, so that even if the passive components are in the same temperature direction, the temperature compensation effect can be achieved, thereby meeting the demand for accurate frequency drift. Summary of the invention

[0004] It can be understood from the above description that the present invention is to provide a new oscillation circuit architecture, which can achieve the effect of temperature compensation even if the passive components are in the same temperature direction, thereby meeting the demand for accurate frequency drift, and in some embodiments, even achieve the effect of zero temperature drift.

[0005] In order to solve the above-mentioned known technical problems, an embodiment of the present invention provides an oscillating circuit, which includes a current mirror circuit, a charge and discharge circuit, an output stage circuit, a first resistor, a second resistor and a diode circuit. The current mirror circuit has a plurality of current output terminals, and a part of the plurality of current output terminals is used to output a plurality of reference currents. The charge and discharge circuit is electrically connected to a first current output terminal of the plurality of current output terminals, and includes a first charge storage component, wherein the charge and discharge circuit is controlled by a control signal to charge the first charge storage component with a reference current, or to discharge the first charge storage component, and thereby generate a first control voltage. The output stage circuit includes a first switching transistor, wherein the first switching transistor is electrically connected to a second current output terminal of the plurality of current output terminals and the charge and discharge circuit, and the first switching transistor is controlled by a first control voltage to output a first oscillation signal. The two ends of the first resistor are electrically connected to a third current output terminal of the plurality of current output terminals and a low voltage, respectively. One end of the second resistor is electrically connected to a fourth current output terminal of the plurality of current output terminals. The two ends of the diode circuit are electrically connected to the other end of the second resistor and a low voltage, respectively. The first resistor and the second resistor have the same temperature drift, the first resistance value of the first resistor is greater than the second resistance value of the second resistor, and the resistance drift of the first resistor with temperature change is less than the resistance drift of the second resistor with temperature change.

[0006] Based on the above purpose, the present invention further provides a circuit system, which includes the aforementioned oscillating circuit and a functional circuit. The functional circuit is electrically connected to the oscillating circuit and is used to perform a corresponding function according to a first oscillating signal of the oscillating circuit.

[0007] In summary, according to the oscillation circuit provided above, the technical problem of reduced frequency accuracy of the oscillation circuit due to temperature drift can be reduced, and the circuit system using the oscillation circuit provided above can also significantly reduce the probability of malfunction of the circuit system due to temperature drift because the frequency accuracy of the oscillation circuit is effectively improved, thereby improving the operating accuracy and stability of the circuit system. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] In order to make the above and other objects, features, advantages and embodiments of the present invention more clearly understood, the accompanying drawings are described as follows:

[0009] Figure 1 is a schematic circuit diagram of an oscillator circuit according to an embodiment of the present invention;

[0010] Figure 2 is a schematic circuit diagram of an oscillator circuit according to another embodiment of the present invention; and

[0011] Figure 3 is a schematic block diagram of a circuit system according to an embodiment of the present invention.

[0012] Reference Numbers

[0013] 1: Oscillator circuit

[0014] 11: Current mirror circuit

[0015] 12: Charging and discharging circuit

[0016] 13: Output stage circuit

[0017] 14:SRM

[0018] Iref: reference current

[0019] R+: First resistor

[0020] R++: Second resistor

[0021] Vx, Vy: voltage

[0022] Vci: first control voltage

[0023] vC2: Second control voltage

[0024] C1: First capacitor

[0025] C2: Second capacitor

[0026] S1: First switch

[0027] S2: Second switch

[0028] S3: The third switch

[0029] S4: The fourth switch

[0030] MN1: First N-type transistor

[0031] MN2: Second N-type transistor

[0032] MN3: The third N-type transistor

[0033] VTHN: On-state voltage

[0034] MP1: First P-type transistor

[0035] MP2: Second P-type transistor

[0036] MP3: The third P-type transistor

[0037] MP4: The fourth P-type transistor

[0038] MP5: The fifth P-type transistor

[0039] OP: Operational Amplifier

[0040] 2: Functional circuit DETAILED DESCRIPTION

[0041] In order to solve the technical problems of the background technology, the embodiment of the present invention mainly provides an oscillating circuit, which includes a current mirror circuit, a charging and discharging circuit, an output stage circuit, a first resistor, a second resistor and a diode circuit. The current mirror circuit outputs a reference current. The charging and discharging circuit uses the reference current to charge the first charge storage component, or discharges the first charge storage component, and generates a first control voltage accordingly. The output stage circuit includes a first switching transistor, which is controlled by the first control voltage and outputs a first oscillation signal. When the first resistor and the second resistor have the same temperature drift (for example, the first resistor and the second resistor are both resistors with positive temperature coefficients, or the first resistor and the second resistor are both resistors with negative temperature coefficients), in order to reduce the frequency accuracy affected by temperature changes, the first resistance value of the first resistor is designed to be greater than the second resistance value of the second resistor, and the resistance drift amount of the first resistor that changes with temperature is designed to be less than the resistance drift amount of the second resistor that changes with temperature. In addition, the embodiment of the present invention also provides a circuit system, which uses the above-mentioned oscillating circuit to reduce the probability of malfunction of the circuit system caused by temperature drift.

[0042] First, please refer to Figure 1 , Figure 1 1 is a schematic circuit diagram of an oscillation circuit of an embodiment of the present invention. The oscillation circuit includes a current mirror circuit 11, a charge and discharge circuit 12, an output stage circuit 13, a first resistor R+, a second resistor R++, a diode circuit (implemented by a first N-type transistor MN1) and a buffer output circuit (implemented by an SR latch 14). The current mirror circuit 11 has a plurality of current output terminals, and a portion of the plurality of current output terminals is used to output a plurality of reference currents Iref. The charge and discharge circuit 12 is electrically connected to a first current output terminal of the plurality of current output terminals of the current mirror circuit 11, and includes a first charge storage component (implemented by a first capacitor C1), wherein the charge and discharge circuit 12 is controlled by a control signal (a plurality of signals for controlling the first switch S1 to the fourth switch S4) to charge the first charge storage component with the reference current Iref, or to discharge the first charge storage component, and thereby generate a first control voltage VC1.

[0043] The output stage circuit 13 includes a first switch transistor (implemented by a second N-type transistor MN2), wherein the first switch transistor is electrically connected to the second current output terminal of the multiple current output terminals of the current mirror circuit 11 and the charge and discharge circuit 12, and the first switch transistor is controlled by the first control voltage VC1 to output a first oscillation signal. The two ends of the first resistor R+ are electrically connected to the third current output terminal of the multiple current output terminals of the current mirror circuit 11 and a low voltage (for example, a ground voltage). One end of the second resistor R++ is electrically connected to the fourth current output terminal of the multiple current output terminals of the current mirror circuit 11. The two ends of the diode circuit are electrically connected to the other end of the second resistor R++ and a low voltage. The first resistor R+ and the second resistor R++ have the same temperature drift, for example, the first resistor R+ and the second resistor R++ are both positive temperature drift (i.e., resistors with positive temperature coefficients), or both are negative temperature drift (i.e., resistors with negative temperature coefficients). In addition, the first resistor R+ and the second resistor R++ can be polysilicon resistors, or resistors with different materials from each other, and the present invention is not limited thereto. In addition, the buffer output circuit is electrically connected to the output stage circuit 13 for receiving the first oscillation signal and the second oscillation signal and outputting a frequency signal. It should be noted that the buffer output circuit may be a non-essential component of the oscillation circuit and can be removed.

[0044] In this embodiment, the current mirror circuit 11 is designed so that the voltage Vx at the fourth current output terminal is equal to the voltage Vy at the third current output terminal, Vx=Vy, and the conduction voltage of the diode circuit is designed to be VTHN. Therefore, the reference current Iref can be expressed as The voltage Vx on the third current output terminal can be expressed as When the sizes of the first N-type transistor MN1 and the second N-type transistor MN2 are the same, the frequency of the first oscillation signal can be expressed as Wherein C is the capacitance value of the first charge storage component, VC is the voltage value of the first control voltage, and td is the delay time caused by the resistance and the capacitance. Therefore, in order to reduce the frequency accuracy affected by temperature changes, the first resistance value of the first resistor R+ needs to be designed to be greater than the second resistance value of the second resistor R++, and the resistance drift of the first resistor R+ with temperature changes needs to be designed to be less than the resistance drift of the second resistor R++ with temperature changes. Further, in order to achieve zero temperature drift, the resistance value ratio of the first resistor to the second resistor can be designed to be equal to the resistance drift ratio of the resistance drift of the second resistor to the resistance drift of the first resistor, that is, assuming that R+:R++=X:1, and the resistance drift of the second resistor and the resistance drift of the first resistor are ±Z and ±Y respectively, then R+:R++=X:1=Z:Y.

[0045] Further, in this embodiment, the charge and discharge circuit 12 may further include a second charge storage element (implemented by a second capacitor C2), and the output stage circuit 13 may further include a second switch transistor (implemented by a third N-type transistor MN3), wherein the charge and discharge circuit 12 is further controlled by a control signal to charge the second charge storage element with a reference current Iref, or to discharge the second charge storage element, and thereby generate a second control voltage VC2, the second switch transistor is electrically connected to the fifth current output terminal of the plurality of current output terminals of the current mirror circuit 11 and the charge and discharge circuit 12, and the second switch transistor is controlled by the second control voltage VC2 to output a second oscillation signal, wherein the control signal includes a first control signal and a second control signal that are inverted to each other. In this embodiment, the first control voltage VC1 is equal to the second control voltage VC2, that is, VC=VC1=VC2, the capacitance value of the second charge storage element is equal to the capacitance value of the first charge storage element, that is, C1=C2=C, and the sizes of the first N-type transistor MN1, the second N-type transistor MN2, and the third N-type transistor MN3 are the same.

[0046] In addition, the charging and discharging control method in the charging and discharging circuit can be provided by setting a plurality of switches, and the plurality of switches can include a first switch S1 to a fourth switch S4. The two ends of the first switch S1 are electrically connected to the first current output end and the first end of the first charge storage component, respectively, wherein the second end of the first charge storage component is electrically connected to a low voltage. The two ends of the second switch S2 are electrically connected to the first end of the first charge storage component and the low voltage, respectively. The two ends of the third switch S3 are electrically connected to the first current output end and the first end of the second charge storage component, respectively, wherein the second end of the second charge storage component is electrically connected to a low voltage. The two ends of the fourth switch S4 are electrically connected to the first end of the second charge storage component and the low voltage, respectively. The control signal includes a first control signal and a second control signal, wherein the first switch S1 and the fourth switch S4 are controlled by the first control signal, and the second switch S2 and the third switch S3 are controlled by the second control signal.

[0047] In addition, the diode circuit is implemented by the first N-type transistor MN1, the first switch transistor is implemented by the second N-type transistor MN2, and the second switch transistor is implemented by the third N-type transistor MN3. The drain of the first N-type transistor MN1 is electrically connected to the other end of the second resistor R++ and the gate of the first N-type transistor MN1, and the source of the first N-type transistor MN1 is electrically connected to a low voltage. The drain of the second N-type transistor MN2 is electrically connected to the second current output terminal, the gate of the second N-type transistor MN2 receives the first control voltage VC1, and the source of the second N-type transistor MN2 is electrically connected to the low voltage. The drain of the third N-type transistor MN3 is electrically connected to the fifth current output terminal, the gate of the third N-type transistor MN3 receives the second control voltage VC2, and the source of the third N-type transistor MN3 is electrically connected to the low voltage.

[0048] For further information, please refer to Figure 2 , Figure 2 1 is a schematic circuit diagram of an oscillator circuit of another embodiment of the present invention. In this embodiment, the current mirror circuit 11 includes a first P-type transistor MP1 to a fifth P-type transistor MP5 and an operational amplifier OP. The source of the first P-type transistor MP1, the source of the second P-type transistor MP2, the source of the third P-type transistor MP3, the source of the fourth P-type transistor MP4 and the source of the fifth P-type transistor MP5 receive the system voltage, the gate of the first P-type transistor MP1, the gate of the second P-type transistor MP2, the gate of the third P-type transistor MP3, the gate of the fourth P-type transistor MP4 and the gate of the fifth P-type transistor MP5 are electrically connected to each other, and the source of the first P-type transistor MP1, a source of the second P-type transistor MP2, the source of the third P-type transistor MP3, the source of the fourth P-type transistor MP4 and the source of the fifth P-type transistor MP5 serve as the fourth current output terminal, the third current output terminal, the first current output terminal, the second current output terminal and the fifth current output terminal, respectively. The output terminal of the operational amplifier OP is electrically connected to the gate of the first P-type transistor MP1 and the gate of the second P-type transistor MP2. The inverting input terminal and the non-inverting input terminal of the operational amplifier OP are electrically connected to one end of the first resistor R+ and one end of the second resistor R++ respectively.

[0049] Please refer to Figure 3 , Figure 3 : is a schematic block diagram of a circuit system of an embodiment of the present invention. The circuit system includes an oscillating circuit 1 and a functional circuit 2. The oscillating circuit 1 can be the oscillating circuit of the above embodiment. The functional circuit 2 is electrically connected to the oscillating circuit 1 and is used to perform corresponding functions according to the first oscillating signal, the second oscillating signal and / or the frequency signal of the oscillating circuit.

[0050] In summary, compared with the background technology, the technical solution of the present invention solves the technical problem that when the passive components are at the same temperature offset, the influence of temperature drift on frequency accuracy cannot be effectively eliminated, and the technical solution of the present invention can even achieve zero temperature offset.

[0051] The present invention is disclosed herein only by preferred embodiments, but those skilled in the art should understand that the above embodiments are only used to describe the present invention and are not used to limit the scope of the patent rights claimed by the present invention. Any changes or substitutions that are equal or equivalent to the above embodiments should be interpreted as being included in the spirit or scope of the present invention. Therefore, the protection scope of the present invention should be based on the definition of the above claims.

Claims

1. An oscillator circuit, characterized in that: include: A current mirror circuit having a plurality of current output terminals, a portion of which is used to output a plurality of reference currents; a charge-discharge circuit electrically connected to a first current output terminal of the plurality of current output terminals, comprising a first charge storage component, wherein the charge-discharge circuit is controlled by a control signal to charge the first charge storage component with the reference current, or to discharge the first charge storage component, and to generate a first control voltage accordingly; an output stage circuit, comprising a first switch transistor, wherein the first switch transistor is electrically connected to a second current output terminal of the plurality of current output terminals and the charge-discharge circuit, and the first switch transistor is controlled by the first control voltage to output a first oscillation signal; a first resistor, two ends of which are electrically connected to a third current output terminal of the plurality of current output terminals and a low voltage respectively; a second resistor, one end of which is electrically connected to a fourth current output end of the plurality of current output ends; as well as A diode circuit has two ends electrically connected to the other end of the second resistor and the low voltage respectively, wherein the first resistor and the second resistor have the same temperature drift, a first resistance value of the first resistor is greater than a second resistance value of the second resistor, and a resistance drift amount of the first resistor that changes with a temperature is less than a resistance drift amount of the second resistor that changes with the temperature.

2. The oscillation circuit according to claim 1, characterized in that: The first resistor and the second resistor both have positive temperature drift.

3. The oscillation circuit according to claim 1, characterized in that: The first resistor and the second resistor both have negative temperature drift.

4. The oscillation circuit according to claim 1, characterized in that: A resistance ratio of the first resistor to the second resistor is equal to a resistance drift ratio of the resistance drift of the second resistor to the resistance drift of the first resistor.

5. The oscillation circuit according to claim 1, characterized in that: The charge and discharge circuit also includes a second charge storage component, and the output stage circuit further includes a second switching transistor, wherein the charge and discharge circuit is further controlled by the control signal to use the reference current to charge the second charge storage component, or to discharge the second charge storage component, and thereby generate a second control voltage. The second switching transistor electrically connects a fifth current output terminal of the multiple current output terminals and the charge and discharge circuit, and the second switching transistor is controlled by the second control voltage to output a second oscillation signal, wherein the control signal includes a first control signal and a second control signal that are inverted to each other.

6. The oscillation circuit according to claim 5, characterized in that: The charging and discharging circuit also includes: a first switch, two ends of which are electrically connected to the first current output end and the first end of the first charge storage component, respectively, wherein a second end of the first charge storage component is electrically connected to the low voltage; a second switch, two ends of which are electrically connected to the first end of the first charge storage component and the low voltage respectively; a third switch, two ends of which are electrically connected to the first current output end and the first end of the second charge storage component, respectively, wherein a second end of the second charge storage component is electrically connected to the low voltage; and a fourth switch, two ends of which are electrically connected to the first end of the second charge storage component and the low voltage respectively; The first charge storage component and the second charge storage component are respectively a first capacitor and a second capacitor, the first switch and the fourth switch are controlled by the first control signal, and the second switch and the third switch are controlled by the second control signal.

7. The oscillation circuit according to claim 5, characterized in that: The current mirror circuit includes: a first P-type transistor, a second P-type transistor, a third P-type transistor, a fourth P-type transistor and a fifth P-type transistor, wherein a source of the first P-type transistor, a source of the second P-type transistor, a source of the third P-type transistor, a source of the fourth P-type transistor and a source of the fifth P-type transistor receive a system voltage, a gate of the first P-type transistor, a gate of the second P-type transistor, a gate of the third P-type transistor, a gate of the fourth P-type transistor and a gate of the fifth P-type transistor are electrically connected to each other, and a source of the first P-type transistor, a source of the second P-type transistor, a source of the third P-type transistor, a source of the fourth P-type transistor and a source of the fifth P-type transistor serve as the fourth current output terminal, the third current output terminal, the first current output terminal, the second current output terminal and the fifth current output terminal respectively; and An operational amplifier has an output terminal electrically connected to the gate of the first P-type transistor and the gate of the second P-type transistor, and an inverting input terminal and a non-inverting input terminal electrically connected to one end of the first resistor and one end of the second resistor respectively.

8. The oscillation circuit according to claim 5, characterized in that: Also includes: An SR latch is electrically connected to the output stage circuit and is used for receiving the first oscillation signal and the second oscillation signal to output a frequency signal.

9. The oscillation circuit according to claim 5, characterized in that: The diode circuit is a first N-type transistor, a drain of the first N-type transistor is electrically connected to the other end of the second resistor and a gate of the first N-type transistor, and a source of the first N-type transistor is electrically connected to the low voltage; the first switch transistor is a second N-type transistor, a drain of the second N-type transistor is electrically connected to the second current output end, a gate of the second N-type transistor receives the first control voltage, and a source of the second N-type transistor is electrically connected to the low voltage; and the second switch transistor is a third N-type transistor, a drain of the third N-type transistor is electrically connected to the fifth current output end, a gate of the third N-type transistor receives the second control voltage, and a source of the third N-type transistor is electrically connected to the low voltage.

10. A circuit system, characterized in that: include: The oscillator circuit according to any one of claims 1 to 9; as well as A functional circuit is electrically connected to the oscillation circuit and is used for performing a corresponding function according to the first oscillation signal of the oscillation circuit.

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