Oscillator and chip
By increasing the voltage unit in the oscillator circuit, the capacitor charging time is shortened, the problem of delaying the existing oscillator under the short cycle setting causes the clock signal deviation, realized the output of high -precision oscillating signal, and reduced the cost of chip costs. And area occupation.
Patent Information
- Application Number
- CN202421202469.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-29
- Publication Date
- 2025-01-28
- Estimated Expiration
- 2034-05-29
AI Technical Summary
The existing oscillators have a large deviation from the preset value due to delay in the short-period setting, and the clock signal cycle is high and the area is occupied when integrated in the chip, making it difficult to achieve high-precision oscillation signal output.
A oscillator circuit is designed. By increasing the voltage unit, the first voltage is higher than the voltage of the first end of the capacitor, thereby reducing the voltage value required when the comparator output is switched, shortening the charging time of the capacitor, and offset the delay time of the circuit.
Achieve the reduction of delay under short cycle settings, improve the accuracy of oscillator, and reduce chip cost and area occupation by simplifying the circuit structure and removing complex control circuits.
Smart Images
Figure CN222423635U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of integrated circuits, and in particular relates to an oscillator and a chip. Background Art
[0002] With the development of semiconductor technology and electronic technology, the integration of digital-analog hybrid electronic systems is getting higher and higher. In order to ensure the reliable operation of the electronic system, it is necessary to set the oscillator to output a stable oscillation signal as a clock signal to coordinate the working timing of various components in the electronic system. Whether the frequency of the oscillation signal output by the oscillator is accurate has a vital impact on the reliable operation of the electronic system.
[0003] Commonly used oscillator circuits at present include crystal oscillators, ring oscillators, LC oscillators, etc. Among them, crystal oscillators have high precision and are less affected by temperature and voltage, but the required quartz crystal volume and cost are high, making it difficult to integrate into the chip; ring oscillator circuits are simple and easy to integrate, with very low area costs, but are easily affected by temperature and power supply voltage, and have poor frequency stability; LC oscillators have relatively good temperature and voltage characteristics, but in the chip, the inductor L and capacitor C occupy a large area, the chip cost is high, and it is not easy to integrate. In addition, the above oscillator circuits are prone to certain delays due to the nature of their own devices. Under long-cycle settings, the impact of the delay time is not significant, but in short cycles, the proportion of delay is relatively large, which will cause the clock signal period to deviate significantly from the preset value.
[0004] Therefore, in view of the above technical problems, it is necessary to provide a new oscillator and chip.
[0005] The information disclosed in this background technology section is only intended to increase the understanding of the overall background of the present invention, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art already known to a person skilled in the art. Utility Model Content
[0006] The utility model aims to provide an oscillator and a chip, which can avoid the influence of device delay and generate a high-precision oscillation signal.
[0007] In order to achieve the above-mentioned purpose, a specific embodiment of the utility model provides an oscillator, including a reference voltage unit, a first current source, a capacitor, a voltage divider unit, a discharge unit and a comparator. The reference voltage unit is connected to a first input terminal of the comparator to generate a reference voltage, a first terminal of the first current source is connected to a power supply voltage, a second terminal of the first current source and a first terminal of the voltage divider unit are connected to a discharge unit and a second input terminal of the comparator, a second terminal of the voltage divider unit is connected to a first terminal of the capacitor, and a second terminal of the capacitor is connected to a ground voltage, the discharge unit discharges the first terminal of the capacitor through the voltage divider unit based on the control of a control signal and generates a first voltage, and the comparator is used to compare the reference voltage with the first voltage and generate an oscillation signal.
[0008] In one or more embodiments of the present utility model, the reference voltage unit includes a second current source and a first resistance unit, the first end of the second current source is connected to the power supply voltage, the second end of the second current source and the first end of the first resistance unit are connected to the first input end of the comparator, and the second end of the first resistance unit is connected to the ground voltage.
[0009] In one or more embodiments of the present invention, the first resistance unit includes an adjustable resistor.
[0010] In one or more embodiments of the present invention, the voltage divider unit includes a second resistor unit, a first end of the second resistor unit is used to form a first end of the voltage divider unit, and a second end of the second resistor unit is used to form a second end of the voltage divider unit.
[0011] In one or more embodiments of the present invention, the second resistance unit includes one or more resistors, and the multiple resistors are connected in series, in parallel, or in mixed connection.
[0012] In one or more embodiments of the present invention, the discharge unit includes a switch, a first end of the switch is connected to the first end of the voltage divider unit, a second end of the switch is connected to the ground voltage, a control end of the switch is used to receive a control signal, and the switch controls the on and off between the first end of the voltage divider unit and the ground voltage based on the control signal.
[0013] In one or more embodiments of the present invention, the switch includes a MOS tube.
[0014] In one or more embodiments of the present invention, the oscillator further includes a control module, the control module is connected to the output end of the comparator, and the control module is used to generate a control signal based on the oscillation signal.
[0015] A specific embodiment of the utility model further provides an oscillator chip, comprising the above-mentioned oscillator.
[0016] Compared with the prior art, the oscillator and chip of the utility model increase the voltage dividing unit to make the first voltage higher than the voltage of the first end of the capacitor, thereby reducing the voltage value that the capacitor needs to be charged to when the output of the comparator is switched, and indirectly shortening the charging time to offset the circuit delay time. The entire circuit structure is simple, and there is no need to set up a complex control circuit to control the charging and discharging time through logical operations, which can automatically eliminate most of the delay effects, greatly reduce the impact of circuit delay on the oscillation period, and improve the accuracy of the oscillator. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the utility model, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.
[0018] Figure 1 1 is a circuit diagram of an oscillator in one embodiment of the present invention. DETAILED DESCRIPTION
[0019] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.
[0020] The words "coupled" or "connected" or "connected" in the specification include both direct connection and indirect connection. Indirect connection is a connection through an intermediate medium, such as a connection through an electrically conductive medium, which may have parasitic inductance or parasitic capacitance; indirect connection may also include connection through other active or passive devices on the basis of achieving the same or similar functional purposes, such as connection through circuits or components such as switches and follower circuits. In addition, in the present utility model, words such as "first" and "second" are mainly used to distinguish one technical feature from another technical feature, and do not necessarily require or imply that there is a certain actual relationship, quantity or order between these technical features.
[0021] like Figure 1 As shown, the oscillator in an embodiment of the present invention includes a reference voltage unit 10 , a first current source I1 , a capacitor C, a voltage dividing unit 20 , a discharge unit 30 , a comparator CMP and a control module 40 .
[0022] The reference voltage unit 10 is connected to the first input terminal of the comparator CMP to generate a reference voltage Vref. The first terminal of the first current source I1 is connected to the power supply voltage VDD, the second terminal of the first current source I1 and the first terminal of the voltage divider unit 20 are connected to the discharge unit 30 and the second input terminal of the comparator CMP, the second terminal of the voltage divider unit 20 is connected to the first terminal of the capacitor C, and the second terminal of the capacitor C is connected to the ground voltage GND. The discharge unit 30 discharges the first terminal of the capacitor C through the voltage divider unit based on the control of the control signal CTRL and generates a first voltage V1.
[0023] The comparator CMP is used to compare the reference voltage Vref with the first voltage V1 and generate an oscillation signal Clk. The control module 40 is connected to the output terminal of the comparator CMP and the discharge unit 30. The control module 40 is used to generate a control signal CTRL based on the oscillation signal Clk.
[0024] Specifically, the reference voltage unit 10 includes a second current source I2 and a first resistor unit. A first end of the second current source I2 is connected to the power supply voltage VDD, a second end of the second current source I2 and a first end of the first resistor unit are connected to a first input end of the comparator CMP, and a second end of the first resistor unit is connected to a ground voltage GND.
[0025] In one embodiment, the first resistor unit includes an adjustable resistor R1, whose resistance is set to R1, and the current value generated by the second current source I2 is I2, then the reference voltage Vref = I2*R1. By adjusting the resistance of the adjustable resistor R1, the voltage value of the reference voltage Vref can be freely set.
[0026] like Figure 1 As shown, the voltage dividing unit 20 includes a second resistor unit. In one embodiment, the second resistor unit includes a second resistor R2, a first end of the second resistor R2 is connected to the second end of the first current source I1 and the second input end of the comparator CMP, and a second end of the second resistor R2 is connected to the first end of the capacitor C.
[0027] The discharge unit 30 includes a switch M1, a first end of the switch M1 is connected to a first end of a second resistor R2, a second end of the switch M1 is connected to a ground voltage GND, a control end of the switch M1 is connected to a control module 40, and the switch M1 controls the on / off between the first end of the second resistor R2 and the ground voltage GND based on a control signal CTRL.
[0028] Specifically, the switch M1 includes a MOS tube. In one embodiment, the MOS tube is an N-channel transistor, whose first end is a source, the second end is a drain, and the control end is a gate. When the control signal CTRL is at a low level, the switch M1 is closed, and the first current source I1 charges the capacitor C through the second resistor R2. When the control signal CTRL is at a high level, the switch M1 is turned on, and the voltage at the first end of the second resistor R2 is pulled down to the ground voltage GND, and the voltage at the first end of the capacitor C is further pulled down to the ground voltage, and the capacitor C is discharged. In other embodiments, the switch M1 can be a P-channel transistor or other types of switching devices, and its connection method and control method are adaptively adjusted.
[0029] In one embodiment, the first input terminal of the comparator CMP is a negative input terminal, the second input terminal of the comparator CMP is a positive input terminal, when the first voltage V1 is greater than or equal to the reference voltage Vref, the oscillation signal Clk generated by the comparator CMP is a high level, when the first voltage V1 is less than the reference voltage Vref, the oscillation signal Clk generated by the comparator CMP is a low level. In other embodiments, the first input terminal and the second input terminal of the comparator CMP can be interchanged to generate an oscillation signal Clk of opposite levels.
[0030] In the actual working process, the control module 40 first generates a low-level control signal CTRL, the capacitor C is charged, and the first voltage V1 is:
[0031]
[0032] Wherein, I1 is the current value generated by the first current source I1, R2 is the resistance value of the second resistor R2, C is the capacitance value of the capacitor C, and t is the charging time.
[0033] When the first voltage V1 gradually increases to be equal to the reference voltage Vref, the comparator CMP outputs an oscillation signal Clk that turns high, completing the charging process of one oscillation cycle. At this time:
[0034] V1=Vref=I2*R1
[0035] Then the charging time t is:
[0036]
[0037] Among them, R2*C is inversely proportional to the charging time t, which can be regarded as accelerating the reverse time of the charging process.
[0038] After receiving the high-level oscillation signal Clk, the control module 40 generates a high-level control signal CTRL, the switch M1 is turned on, the capacitor C is discharged, the first voltage V1 is pulled down to the ground voltage, and the comparator CMP outputs the oscillation signal Clk low. Then the control module 40 regenerates the low-level control signal CTRL and starts a new oscillation cycle.
[0039] Under non-ideal conditions, the oscillator charging time t is increased by a delay time td due to the inevitable delay of the comparator CMP or other components in the circuit during operation. This delay time td is generally determined by the properties of the comparator CMP and is relatively fixed. The delay time td has little effect in the long cycle setting, but the delay ratio is too large in the short cycle, which will cause the oscillation signal Clk period to deviate significantly from the preset value.
[0040] At this time, the resistance value of the second resistor R2 can be selected so that the value of R2*C is equal to or close to the organic delay time td of the circuit, thereby offsetting the delay time td, and the charging time t is:
[0041]
[0042] The final charging time t is proportional to R1*C, which allows the user to adjust the charging time and thus the oscillator period directly by adjusting the resistance of the adjustable resistor R1.
[0043] In addition, under different temperature conditions, the delay time td of the circuit may also be different. In this case, the second resistor R2 with an appropriate temperature coefficient can be selected so that R2*C can offset the delay time td as much as possible under different temperatures.
[0044] By adding a voltage divider unit, the charging time of capacitor C is shortened, thereby offsetting the oscillator delay. The entire circuit structure is simple, and there is no need to set up a complex control circuit to control the charging and discharging time through logical operations, which can automatically eliminate most of the delay effects.
[0045] In other embodiments, the second resistor unit may further include a plurality of resistors, and the plurality of resistors are connected to each other in series, in parallel or in a mixed manner. In this case, R2 in the above formula should be the overall resistance value of the entire second resistor unit. The plurality of resistors may have different temperature coefficients. In this case, setting a plurality of resistors is conducive to flexibly changing the overall temperature coefficient of the second resistor unit, thereby maximally offsetting the delay time td.
[0046] In other embodiments, the voltage divider unit 20 may also be other structures capable of dividing the voltage of the capacitor C during the charging process of the capacitor C, as long as the first voltage V1 can be made higher than the voltage at the first end of the capacitor C, thereby reducing the voltage value to which the capacitor C needs to be charged when the output of the comparator CMP is switched, and indirectly shortening the charging time t to offset the circuit delay time td.
[0047] In other embodiments, the control module 40 may not be provided, and the switch M1 may be controlled to be turned on and off by a control signal provided outside the oscillator.
[0048] An oscillator chip is also provided in one embodiment of the utility model, including the above-mentioned oscillator.
[0049] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be regarded as exemplary and non-restrictive from any point of view, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention. Any reference numeral in a claim should not be regarded as limiting the claim to which it relates.
[0050] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.
Claims
1. An oscillator, characterized in that: It includes a reference voltage unit, a first current source, a capacitor, a voltage dividing unit, a discharge unit and a comparator; The reference voltage unit is connected to the first input terminal of the comparator to generate a reference voltage, the first terminal of the first current source is connected to the power supply voltage, the second terminal of the first current source and the first terminal of the voltage divider unit are connected to the discharge unit and the second input terminal of the comparator, the second terminal of the voltage divider unit is connected to the first terminal of the capacitor, and the second terminal of the capacitor is connected to the ground voltage, the discharge unit discharges the first terminal of the capacitor through the voltage divider unit based on the control of the control signal and generates a first voltage, and the comparator is used to compare the reference voltage and the first voltage and generate an oscillation signal.
2. The oscillator according to claim 1, characterized in that The reference voltage unit includes a second current source and a first resistance unit, the first end of the second current source is connected to the power supply voltage, the second end of the second current source and the first end of the first resistance unit are connected to the first input end of the comparator, and the second end of the first resistance unit is connected to the ground voltage.
3. The oscillator according to claim 2, characterized in that The first resistance unit includes an adjustable resistor.
4. The oscillator according to claim 1, characterized in that The voltage dividing unit includes a second resistance unit, a first end of the second resistance unit is used to form a first end of the voltage dividing unit, and a second end of the second resistance unit is used to form a second end of the voltage dividing unit.
5. The oscillator according to claim 4, characterized in that The second resistance unit includes one or more resistors, and the multiple resistors are connected in series, in parallel, or in mixed connection.
6. The oscillator according to claim 1, characterized in that The discharge unit includes a switch, a first end of the switch is connected to the first end of the voltage divider unit, a second end of the switch is connected to the ground voltage, a control end of the switch is used to receive a control signal, and the switch controls the connection between the first end of the voltage divider unit and the ground voltage based on the control signal.
7. The oscillator according to claim 6, characterized in that The switch includes a MOS tube.
8. The oscillator according to claim 1, characterized in that The oscillator further comprises a control module, wherein the control module is connected to the output end of the comparator, and the control module is used to generate a control signal based on the oscillation signal.
9. A chip, characterized in that: The invention comprises an oscillator as claimed in any one of claims 1 to 8.