CN117579039A

CN117579039A - Ring oscillator circuit and electronic apparatus

Info

Publication number: CN117579039A
Application number: CN202311542406.8A
Authority: CN
Inventors: 孙志亮; 朱永成; 黄金煌
Original assignee: Beijing Unigroup Tsingteng Microsystems Co Ltd
Current assignee: Beijing Unigroup Tsingteng Microsystems Co Ltd
Priority date: 2023-11-17
Filing date: 2023-11-17
Publication date: 2024-02-20

Abstract

The application relates to the technical field of oscillators and discloses a ring oscillator circuit, which comprises: the oscillating circuit comprises a signal input end and a signal output end, and the signal output end is used for outputting an oscillating signal; the signal selection circuit comprises a reference signal input end for receiving a reference signal, an oscillation signal input end for receiving an oscillation signal and an oscillation signal output end; the oscillation signal output end is connected with the signal input end of the oscillation circuit, and the oscillation signal output end outputs an injection signal or an oscillation signal under the selection action of the control signal. In the embodiment of the disclosure, the control signal may select the oscillation signal output end to output the oscillation signal or the injection signal. In the case where the output signal is an oscillation signal, the oscillation circuit forms a loop. Under the condition of outputting the injection signal, the signal selection circuit firstly breaks the original oscillation loop, and does not need the injection signal to destroy the oscillation of the loop, thereby reducing the requirement on the driving force of the injection signal. The application also discloses electronic equipment.

Description

Ring oscillator circuit and electronic apparatus

Technical Field

The present application relates to the field of oscillator technology, for example, to a ring oscillator circuit and an electronic device.

Background

Currently, a low jitter clock is the basis for ensuring a low bit error rate for communications. Based on a phase locked loop (phase locked loop, PLL) structure, the clock generation circuit feeds back an error of a clock generated by an oscillator (Voltage Controlled Oscillator, VCO) with a reference clock to the VCO through a phase frequency detector so that the clock of the VCO follows the reference clock. The VCO in the PLL architecture typically has two structures, including an LC oscillator and a ring oscillator. The LC oscillator has high Q value and good phase noise performance, but has large inductance area, small tuning range and is unfavorable for integration. The ring oscillator has a simple structure and a small area, but the noise performance is poorer than that of the LC oscillator. To achieve the same noise performance as an LC oscillator, the power consumption of a ring oscillator is about 100 times that of an LC oscillator. Filtering the VCO noise through the PLL loop requires a large bandwidth and the wideband phase locked loop has poor stability. And the oscillator based on injection locking can complete noise elimination instantaneously, and has no error detection and controlled part, thus saving the time of the PLL re-locking.

As shown in fig. 1, in the related art, by adding an interference signal to an oscillator, the output of the oscillator is pulled to other frequencies according to the magnitude of the interference signal due to the frequency pulling principle. In case the amplitude of the noise signal is large, the output of the oscillator will be pulled to the noise frequency. Therefore, by reasonably adding the reference signal into the oscillator, the phase noise accumulated by the oscillator can be eliminated in each period, and the instantaneous oscillation of the ring oscillator can be completed in nanosecond-level time.

In the process of implementing the embodiments of the present disclosure, it is found that at least the following problems exist in the related art:

in the related art, in order to destroy the oscillation of the loop itself and make the equivalent filtering bandwidth reach the ideal value, the injection signal needs to have a large driving force to destroy the oscillation of the loop, so that the injection signal has a large current and has large power consumption.

It should be noted that the information disclosed in the foregoing background section is only for enhancing understanding of the background of the present application and thus may include information that does not form the prior art that is already known to those of ordinary skill in the art.

Disclosure of Invention

The following presents a simplified summary in order to provide a basic understanding of some aspects of the disclosed embodiments. This summary is not an extensive overview, and is intended to neither identify key/critical elements nor delineate the scope of such embodiments, but is intended as a prelude to the more detailed description that follows.

Embodiments of the present disclosure provide a ring oscillator circuit and electronic apparatus to reduce the requirement for injection signal driving force.

In some embodiments, the ring oscillator circuit includes: the oscillating circuit comprises a signal input end and a signal output end, and the signal output end is used for outputting an oscillating signal; the signal selection circuit comprises a reference signal input end for receiving a reference signal, an oscillation signal input end for receiving an oscillation signal and an oscillation signal output end; the oscillation signal output end is connected with the signal input end of the oscillation circuit, and the oscillation signal output end outputs an injection signal or an oscillation signal under the selection action of the control signal.

Optionally, the reference signal input comprises a forward reference signal input and a reverse reference signal input; the forward reference signal input is for receiving a forward reference signal and the reverse reference signal input is for receiving a reverse reference signal.

Optionally, the signal selection circuit includes: a first multiplexer including a first input, a second input, and a first output; the first input end is used as a forward reference signal input end; the second input end is used as a reverse reference signal input end; the first output end outputs a forward reference signal or a reverse reference signal under the selection action of the control signal, and takes the signal output by the first output end as an injection signal; a second multiplexer including a third input, a fourth input, and a second output; the third input end is connected with the first output end; the fourth input end is used as an oscillating signal input end; the second output end is used as an oscillating signal output end; the second output end outputs an injection signal or an oscillation signal under the selection action of the control signal.

Optionally, the oscillating circuit comprises an odd number of inverters connected in series; the input end of the first inverter is used as a signal input end, the output end of the last inverter is used as a signal output end, and the power ends of all the inverters are connected in parallel to be used as the power end of the oscillating circuit.

Optionally, the oscillating circuit comprises three inverters connected in series.

Optionally, the ring oscillator circuit further comprises: the current control circuit comprises a first digital input end for receiving a first digital signal, a second digital input end for receiving a second digital signal and a current output end, wherein the current output end is connected with a power end of the oscillating circuit; the current control circuit controls the current of the current output terminal according to the first digital signal and the second digital signal.

Optionally, the current control circuit comprises: the current output circuit comprises a control end and a third output end for outputting current; the third output end is used as a current output end; the digital control circuit comprises a fifth input end, a sixth input end and a control signal output end for outputting control signals; the fifth input end is used as a first digital input end; the sixth input end is used as a second digital input end; the control signal output end is connected with the control end of the current output circuit and controls the current output by the current output circuit.

Optionally, the current output circuit comprises a plurality of branches connected in parallel, and the output ends of all the branches are connected in parallel to serve as current output ends; each branch is provided with a switch for controlling the current on the branch; all switches are connected with the control end.

Optionally, the digital control circuit includes: the discrete modulator is connected with the fifth input end and is used for outputting a modulation signal according to the received first digital signal; the adder is connected with the discrete modulator and the sixth input end and is used for adding the received second digital signal and the modulation signal and outputting a third digital signal; the thermometer encoder is connected with the adder and the control end of the current output circuit, and is used for converting the third digital signal into thermometer codes and sending the thermometer codes to the control end of the current output circuit, and the control end respectively controls the switch on each branch according to the thermometer codes.

In some embodiments, the electronic device includes a ring oscillator circuit as described above.

The ring oscillation circuit and the electronic device provided by the embodiment of the disclosure can realize the following technical effects:

in the embodiment of the disclosure, a signal output end of the oscillating circuit is connected with an oscillating signal input end of the signal selecting circuit, and the oscillating signal output end of the signal selecting circuit is connected with the signal input end of the oscillating circuit. Under the selection action of the control signal, the oscillation signal output end can output an oscillation signal, and at the moment, the oscillation signal output by the signal output end of the oscillation circuit acts on the signal input end through the signal selection circuit, and the oscillation circuit forms a loop. When the reference signal is required to be injected, the oscillation signal output end outputs the injection signal under the selection action of the control signal, and the injection signal acts on the signal input end of the oscillation circuit, and at the moment, the original oscillation loop is disconnected. Thus, in the disclosed embodiments, the signal selection circuit is used to destroy the oscillation of the loop itself, and the reference signal with larger driving force is not needed to destroy the oscillation of the loop, so that the requirement for the driving force of the injected signal is reduced.

The foregoing general description and the following description are exemplary and explanatory only and are not restrictive of the application.

Drawings

One or more embodiments are illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like references indicate similar elements, and in which like reference numerals refer to similar elements, and in which:

FIG. 1 is a circuit diagram of an injection locked oscillator circuit;

FIG. 2 is a block diagram of a ring oscillator circuit provided in an embodiment of the present disclosure;

FIG. 3 is a circuit diagram of a ring oscillator circuit provided by an embodiment of the present disclosure;

FIG. 4 is a timing diagram of signals at a portion of the input and output terminals of a ring oscillator circuit provided in an embodiment of the present disclosure;

FIG. 5 is a block diagram of another ring oscillator circuit provided by an embodiment of the present disclosure;

fig. 6 is a circuit diagram of another ring oscillator circuit provided by an embodiment of the present disclosure.

Detailed Description

So that the manner in which the features and techniques of the disclosed embodiments can be understood in more detail, a more particular description of the embodiments of the disclosure, briefly summarized below, may be had by reference to the appended drawings, which are not intended to be limiting of the embodiments of the disclosure. In the following description of the technology, for purposes of explanation, numerous details are set forth in order to provide a thorough understanding of the disclosed embodiments. However, one or more embodiments may still be practiced without these details. In other instances, well-known structures and devices may be shown simplified in order to simplify the drawing.

The terms first, second and the like in the description and in the claims of the embodiments of the disclosure and in the above-described figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate in order to describe embodiments of the present disclosure. Furthermore, the terms "comprise" and "have," as well as any variations thereof, are intended to cover a non-exclusive inclusion.

The term "plurality" means two or more, unless otherwise indicated.

In the embodiment of the present disclosure, the character "/" indicates that the front and rear objects are an or relationship. For example, A/B represents: a or B.

The term "corresponding" may refer to an association or binding relationship, and the correspondence between a and B refers to an association or binding relationship between a and B.

In connection with the injection locked oscillator circuit shown in fig. 1, if the oscillation frequency of the oscillation loop is F0 when there is no disturbance, a disturbance current Iinj with a frequency Finj is added to the oscillation loop, and at this time, the current in the loop becomes the vector sum of Iosc and Iinj. A new phase shift is introduced in the loop, and according to the barkhausen criterion, the oscillating loop oscillates to another frequency F1 in order to maintain stability, and the phase difference contributed by the frequency difference F1-F0 is used to cancel the phase shift caused by the interference signal. However, in this method, a large driving force is required for the injection signal to break the oscillation of the loop itself so that the equivalent filter bandwidth reaches an ideal value. At this time, the current of the injected signal is also large, thereby generating large power consumption.

In embodiments of the present disclosure, a ring oscillator circuit is provided that may reduce the requirement for injection signal driving force.

As shown in connection with fig. 2, the ring oscillator circuit provided by the embodiment of the present disclosure includes an oscillating circuit DCO and a signal selecting circuit SC. The oscillating circuit DCO comprises a signal input and a signal output for outputting an oscillating signal Sout. The signal selection circuit SC comprises a reference signal input for receiving a reference signal, an oscillating signal input for receiving an oscillating signal Sout and an oscillating signal output. The oscillating signal output end is connected with the signal input end of the oscillating circuit, and outputs an injection signal Sinj or an oscillating signal Sout under the selection action of the control signal.

By adopting the ring oscillator circuit provided by the embodiment of the disclosure, the signal output end of the oscillating circuit DCO is connected with the oscillating signal input end of the signal selection circuit SC, and the oscillating signal output end of the signal selection circuit SC is connected with the signal input end of the oscillating circuit DCO. Under the selection action of the control signal, the oscillating signal output end can output the oscillating signal Sout, and at this time, the oscillating signal Sout output by the signal output end of the oscillating circuit DCO acts on the signal input end through the signal selection circuit SC, so that the oscillating circuit DCO forms a loop. And under the condition that the reference signal needs to be injected, the oscillation signal output end outputs an injection signal Sinj under the selection action of the control signal and acts on the signal input end of the oscillation circuit DCO. At this time, the original oscillation loop of the oscillation circuit is disconnected. Thus, in the presently disclosed embodiments, the signal selection circuit SC is used to disrupt the oscillation of the loop itself, rather than the need to inject a larger driving force reference signal to disrupt the oscillation of the loop, thereby reducing the driving force requirements for the injected signal. At this time, injection locking can be realized by selecting an injection signal with smaller current, and the power consumption of the injection locking oscillator is reduced.

Alternatively, as shown in connection with fig. 2, the reference signal input comprises a forward reference signal input and a reverse reference signal input; the forward reference signal input is for receiving a forward reference signal Fref and the reverse reference signal input is for receiving a reverse reference signal NFref.

In this embodiment, after the reference signal is inverted and delayed, the forward reference signal Fref and the inverted reference signal NFref with opposite phases can be obtained. The falling edge in the forward reference signal Fref becomes the rising edge in the backward reference signal NFref. In the case of injecting the reference signal into the oscillating circuit, the oscillating circuit needs to be controlled by the rising edge of the reference signal, so as to eliminate the phase error of the oscillating circuit. Therefore, by combining the forward reference signal Fref and the backward reference signal NFref and outputting the injection signal Sinj at the oscillation signal output end of the signal selection circuit, the oscillation circuit can be commonly controlled by using the rising edge and the falling edge of the reference signal, so that the elimination of the phase error twice in one period of the reference signal is realized, and the noise performance of the ring oscillator is further improved. In addition, the ring oscillator circuit provided by the embodiment of the disclosure has the advantages of low power consumption, low jitter, easiness in integration and the like.

Optionally, as shown in connection with fig. 3, the signal selection circuit SC comprises a first multiplexer Mux0 and a second multiplexer Mux1. The first multiplexer Mux0 includes a first input, a second input, and a first output. The first input end is used as a forward reference signal input end; the second input end is used as a reverse reference signal input end; the first output end outputs a forward reference signal Fref or a reverse reference signal NFref under the selection action of the control signal, and the signal output by the first output end is used as an injection signal Sinj. The second multiplexer Mux1 comprises a third input, a fourth input and a second output. The third input end is connected with the first output end; the fourth input end is used as an oscillating signal input end; the second output end is used as an oscillating signal output end; the second output terminal outputs the injection signal Sinj or the oscillation signal Sout under the selection of the control signal.

In this embodiment, the first multiplexer connects the first input to the first output in case of the first control signal s0=1; in the case of the first control signal s0=0, the second input is connected to the first output. The second multiplexer connects the third input terminal with the second output terminal in case of the second control signal s1=1; in the case of the second control signal s1=0, the fourth input is connected to the second output.

Referring to fig. 4, the first multiplexer Mux0 may connect the first output terminal with the first input terminal or the second input terminal under the action of the first control signal S0, output the forward reference signal Fref or the backward reference signal NFref at the first output terminal, and use the signal output by the first output terminal as the injection signal Sinj. Therefore, under the action of the first control signal S0, the injection signal Sinj output by the first output terminal changes the falling edge of the forward reference signal Fref into the rising edge compared with the original forward reference signal Fref. And the second multiplexer Mux1 is controlled by the second control signal S1, and in the original oscillating circuit DCO, the fourth input end of the second multiplexer Mux1 is controlled to be connected with the second output end, and at the moment, the signal output end of the oscillating circuit DCO is connected with the signal output end through the second multiplexer Mux1 to form an oscillating loop.

When the oscillation loop is disturbed, the oscillation signal Sout output by the oscillation loop may deviate from the original phase, and at this time, a reference signal needs to be injected to eliminate the phase error of the oscillation loop. The second multiplexer Mux1 controls the third input terminal to be connected with the second output terminal, and takes the injection signal Sinj received by the third input terminal as the output signal of the second output terminal, so that the rising edge of the injection signal Sinj acts on the oscillating circuit DCO. At this time, since the original oscillation loop is disconnected and the oscillation of the loop itself is already destroyed, the injection signal Sinj of large driving force is no longer required to destroy the oscillation of the loop. In addition, when the injection signal Sinj is injected into the oscillating circuit DCO, since the loop itself has no driving force, the edge of the input point is completely aligned with the edge of the injection signal Sinj, so that the noise of the ring oscillator can be further reduced.

Optionally, the oscillating circuit DCO comprises an odd number of inverters connected in series. The input end of the first inverter is used as a signal input end, the output end of the last inverter is used as a signal output end, and the power ends of all the inverters are connected in parallel to be used as the power end of the oscillating circuit DCO.

In this embodiment, the oscillating circuit DCO comprises an odd number of inverters connected in series. The input ends of the odd number of inverters are connected end to end, so that the input signal of the input end of the first inverter can be subjected to odd number of inversions, and finally a signal inversed with the input signal is output at the output end of the last inverter. The oscillation loop formed by the odd number of inverters has simple circuit, easy starting oscillation and convenient integration.

Optionally, the oscillating circuit DCO comprises three inverters connected in series.

In the embodiment of the present disclosure, three inverters connected in series are taken as an example. Since the output signals of the inverters may have a delay compared to the input signals, in a ring oscillator the number of inverters and the delay time of the individual inverters determine the oscillation period of the ring oscillator output signal. By using different numbers and types of inverters, the ring oscillator can generate oscillating signals with various frequencies, and has the advantages of stable frequency, strong anti-interference capability and the like.

Optionally, as shown in connection with fig. 5, the ring oscillator circuit further comprises a current control circuit IC. The current control circuit IC comprises a first digital input receiving the first digital signal D1, a second digital input receiving the second digital signal D2 and a current output. The current output end is connected with the power end of the oscillating circuit; the current control circuit controls the current I at the current output terminal according to the first digital signal D1 and the second digital signal D2.

In this embodiment, the ring oscillator circuit further includes a current control circuit IC. The current control circuit IC may control the magnitude of the current flowing into the inverter in the oscillating circuit DCO according to the first digital signal D1 and the second digital signal D2. The output frequency of the oscillating circuit DCO is controlled by controlling the current flowing into the oscillating circuit DCO.

Optionally, the current control circuit IC comprises a current output circuit IO and a digital control circuit DC. The current output circuit IO comprises a control terminal and a third output terminal for outputting a current I. The third output terminal serves as a current output terminal. The digital control circuit DC comprises a fifth input, a sixth input and a control signal output for outputting a control signal. The fifth input end is used as a first digital input end; the sixth input end is used as a second digital input end; the control signal output end is connected with the control end of the current output circuit IO and controls the current output by the current output circuit IO.

In the current control circuit IC, a digital control circuit DC outputs a control signal at a control signal output terminal according to the first digital signal D1 and the second digital signal D2, and the control signal acts on a control terminal of the current output circuit IO, thereby controlling the current output by the current output circuit IO. In addition, the digital control mode can enable the ring oscillator to still work under the condition that no clock signal is injected, and the low-power-consumption and low-noise oscillator circuit is realized.

Optionally, the current output circuit IO includes a plurality of branches connected in parallel, and output ends of all the branches are connected in parallel and serve as current output ends; each branch is provided with a switch for controlling the current on the branch; all switches are connected with the control end.

The current output circuit IO includes a plurality of branches connected in parallel. In connection with fig. 6, taking three branches as an example, each branch can output a branch current, the output ends of all branches are connected in parallel as current output ends, and the output current I is the sum of the currents of all branches. Each branch is provided with a switch, and the control end of the current output circuit IO can respectively control the opening or closing of each switch. Under the condition that a switch is opened, a corresponding branch circuit is opened, and no current is output; with the switch closed, the corresponding branch may output a corresponding current.

Optionally, the digital control circuit DC comprises a discrete modulator SDM, an adder S and a thermometer encoder TE. The discrete modulator SDM is connected to the fifth input. The discrete modulator SDM is arranged to output a modulated signal in dependence of the received first digital signal D1. The adder S is connected to both the discrete modulator SDM and the sixth input. The adder S is configured to add the received second digital signal D2 to the modulated signal, and output a third digital signal. The thermometer encoder TE is connected with the adder S and the control end of the current output circuit IO. The thermometer encoder TE is configured to convert the third digital signal into a thermometer code, and send the thermometer code to a control end of the current output circuit IO, where the control end controls the switch on each branch according to the thermometer code.

In this embodiment, the first digital signal D1 is a binary 4-bit fraction and the second digital signal D2 is a binary 7-bit integer. Thus, the first digital signal D1 is subjected to fractional conversion by the discrete modulator SDM, and the signal output by the discrete modulator SDM is output as a modulated signal. And then the modulating signal and the second digital signal D2 are added through an adder S, and a third digital signal is output. The thermometer encoder TE may convert the third digital signal into a thermometer code, and send the thermometer code to the control end of the current output circuit IO, where the control end controls the switch on each branch according to the thermometer code.

In some specific embodiments, taking three switches as an example, in the case of thermometer encoder TE output 000, all switches are controlled to be turned off, and at this time, there is no current in oscillating circuit DCO, and the ring oscillator is turned off; one switch is controlled to be closed in the case of thermometer encoder TE output 001, or two switches are controlled to be closed in the case of thermometer encoder TE output 011. At this time, the branch in the current output circuit IO will have a current output, which acts on the power supply terminal of the oscillating circuit DCO. The oscillation circuit DCO starts oscillation under the condition that a signal input end is provided with a signal input end, and outputs an oscillation signal Sout; in the case of thermometer encoder TE output 111, three switches are controlled to be closed, and the currents of three branches are applied to oscillating circuit DCO, at which time the oscillating signal Sout output by the ring oscillator is at its maximum frequency. Thus, changing the closed state of the switch, the input current of the oscillating circuit DCO can be controlled, thereby controlling the frequency of the output signal of the oscillating circuit DCO. In addition, in the case where the reference signal needs to be injected, the oscillating circuit DCO may be turned off in advance by turning off the switch in the current output circuit IO in advance by the digital control circuit DC.

The embodiment of the disclosure provides an electronic device, which comprises the ring oscillator circuit. The electronic device may be used to generate a low jitter clock signal to reduce the bit error rate during communication.

The above description and the drawings illustrate embodiments of the disclosure sufficiently to enable those skilled in the art to practice them. Other embodiments may include structural and other modifications. The embodiments represent only possible variations. Individual components and functions are optional unless explicitly required, and the sequence of operations may vary. Portions and features of some embodiments may be included in, or substituted for, those of others. The embodiments of the present disclosure are not limited to the structures that have been described above and shown in the drawings, and various modifications and changes may be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.

Claims

1. A ring oscillator circuit, comprising:

the oscillating circuit comprises a signal input end and a signal output end, and the signal output end is used for outputting an oscillating signal;

the signal selection circuit comprises a reference signal input end for receiving a reference signal, an oscillation signal input end for receiving an oscillation signal and an oscillation signal output end; the oscillation signal output end is connected with the signal input end of the oscillation circuit, and the oscillation signal output end outputs an injection signal or an oscillation signal under the selection action of the control signal.

2. The ring oscillator circuit of claim 1, wherein the reference signal input comprises a forward reference signal input and a reverse reference signal input; the forward reference signal input is for receiving a forward reference signal and the reverse reference signal input is for receiving a reverse reference signal.

3. The ring oscillator circuit of claim 2, wherein the signal selection circuit comprises:

a first multiplexer including a first input, a second input, and a first output; the first input end is used as a forward reference signal input end; the second input end is used as a reverse reference signal input end; the first output end outputs a forward reference signal or a reverse reference signal under the selection action of the control signal, and takes the signal output by the first output end as an injection signal;

a second multiplexer including a third input, a fourth input, and a second output; the third input end is connected with the first output end; the fourth input end is used as an oscillating signal input end; the second output end is used as an oscillating signal output end; the second output end outputs an injection signal or an oscillation signal under the selection action of the control signal.

4. A ring oscillator circuit as claimed in any one of claims 1 to 3, wherein the oscillating circuit comprises an odd number of inverters connected in series; the input end of the first inverter is used as a signal input end, the output end of the last inverter is used as a signal output end, and the power ends of all the inverters are connected in parallel to be used as the power end of the oscillating circuit.

5. The ring oscillator circuit of claim 4 wherein the oscillating circuit comprises three inverters in series.

6. The ring oscillator circuit of claim 4, further comprising:

the current control circuit comprises a first digital input end for receiving a first digital signal, a second digital input end for receiving a second digital signal and a current output end, wherein the current output end is connected with a power end of the oscillating circuit; the current control circuit controls the current of the current output terminal according to the first digital signal and the second digital signal.

7. The ring oscillator circuit of claim 6, wherein the current control circuit comprises:

the current output circuit comprises a control end and a third output end for outputting current; the third output end is used as a current output end;

the digital control circuit comprises a fifth input end, a sixth input end and a control signal output end for outputting control signals; the fifth input end is used as a first digital input end; the sixth input end is used as a second digital input end; the control signal output end is connected with the control end of the current output circuit and controls the current output by the current output circuit.

8. The ring oscillator circuit of claim 7, wherein the current output circuit comprises a plurality of branches connected in parallel, the outputs of all branches being connected in parallel as current outputs; each branch is provided with a switch for controlling the current on the branch; all switches are connected with the control end.

9. The ring oscillator circuit of claim 8, wherein the digital control circuit comprises:

the discrete modulator is connected with the fifth input end and is used for outputting a modulation signal according to the received first digital signal;

the adder is connected with the discrete modulator and the sixth input end and is used for adding the received second digital signal and the modulation signal and outputting a third digital signal;

the thermometer encoder is connected with the adder and the control end of the current output circuit, and is used for converting the third digital signal into thermometer codes and sending the thermometer codes to the control end of the current output circuit, and the control end respectively controls the switch on each branch according to the thermometer codes.

10. An electronic device comprising a ring oscillator circuit as claimed in any one of claims 1 to 9.