Circuit operating speed detecting circuit
Disclosed is a circuit operating speed detecting circuit configured to detect an operating speed of a target circuit during a monitor mode. The circuit operating speed detecting circuit includes a signal generator, an adjustable delay circuit, and a signal detector. During the monitor mode, the signal generator generates a predetermined signal in a current operating condition, the adjustable delay circuit generates a delay signal according to the predetermined signal in the current operating condition, and the signal detector detects the degree of delay of the delay signal in the current operating condition so as to generate a first result if the degree of delay is not greater than a predetermined threshold and generate a second result if the degree of delay is greater than the predetermined threshold, in which the first and the second results are related to the operating speed of the target circuit.
The present invention relates to a detecting circuit, especially to a circuit operating speed detecting circuit.
2. Description of Related ArtThe operating speed of an integrated circuit (IC) is dependent on the length of a critical path of the IC; in other words, it is dependent on the degree of signal transmission delay caused by the critical path. The critical path is subject to the manufacturing process, voltage, temperature, aging status, and the like of the IC, in which the manufacturing process of the IC is known and invariable, the voltage is affected by the environmental condition (e.g., an unstable external power source) and the usage/condition of the IC (e.g., the IC or a device including the IC executing a specific application program; or the IR drop of the IC) and thereby varies with time, the temperature is affected by the environmental condition (e.g., the weather) and the usage/condition of the IC (e.g., the IC or a device including the IC executing a specific application program; or the IC power) and thereby varies with time, and the aging status is dependent upon the remaining life of the IC.
In light of the above, the operating speed of the IC varies with time due to the composite influence of the manufacturing process, voltage, temperature, and aging status (PVTA). The optimum performance of the IC may be achieved if the variation of the operating speed of the IC is well monitored and used for adjusting the IC. Since the operating speed of the IC is related to the upper limit of the operating clock allowing the IC to operate normally, the higher the operating speed, the higher the upper limit.
Several techniques capable of measuring the operating speed of an IC are listed below:
- (1) Ring oscillator. This technique can estimate the operating speed of an IC by monitoring the operating speed of a ring oscillator, but the problems are: slow response; and impossible to measure the voltage variation within a short period of time.
- (2) Voltage meter/temperature meter. This technique measures the voltage/temperature of the internal part of an IC to estimate the operating speed of the IC, but the problems are: consuming a lot of circuit area; requiring conversion of the result of measurement to obtain the operating speed of the IC; and slow response.
- (3) Critical path monitoring. This technique measures the signal delay caused by the critical path of an IC to estimate the operating speed of the IC, but the problems are: complicated design flow because the critical path is usually uncertain till the late stage of the design of the IC; hard to find out the dominant critical path because different critical paths of the IC are dominant in different environmental conditions respectively; and impossible to monitor all of the critical paths.
- (4) Pre-error detecting. This technique connects the critical path of an IC with an additional delay circuit in parallel and detects the output of the delay circuit; when the output of the delay circuit indicates that the signal delay gets longer and longer, it shows that the operating speed of the IC trends down and the IC may operate abnormally with the current operating clock in no time. This technique has the following problems: consuming a lot of circuit area; and the delay caused by the critical path becoming longer due to the extra loading of the additional delay circuit.
An object of the present invention is to provide a circuit operating speed detecting circuit capable of preventing the problems of the prior arts.
The circuit operating speed detecting circuit of the present invention is configured to detect an operating speed of a target circuit during a monitor mode while the target circuit is configured to operate according to a reference clock. An embodiment of the circuit operating speed detecting circuit includes a signal generator, an adjustable delay circuit, and a signal detector. The signal generator is configured to generate a predetermined signal in a current operating condition during the monitor mode, in which the current operating condition relates to at least one of a manufacturing process of the target circuit, a current operating voltage of the target circuit, a current temperature of the target circuit, and a current aging status of the target circuit and thus the current operating condition varies with time. The adjustable delay circuit is coupled between the signal generator and the signal detector, and configured to generate a delay signal according to the predetermined signal in the current operating condition during the monitor mode. The signal detector is configured to detect the degree of delay of the delay signal in the current operating condition during the monitor mode, and thereby generate a first result in response to the degree of delay being equal to or less than a predetermined threshold and generate a second result in response to the degree of delay being greater than the predetermined threshold, wherein each of the first and second results is related to the operating speed of the target circuit; for instance, the first result indicates that the target circuit can operate normally in the current operating condition and the second result indicates that the target circuit may not operate normally in the current operating condition, and thus the maximum operating speed of the target circuit in connection with the first result is higher than the maximum operating speed of the target circuit in connection with the second result. In an exemplary implementation, when the target circuit operates in the current operating condition, if the signal detector generates the first result, it indicates that the frequency of the reference clock should be maintained or increased for better performance, and if the signal detector generates the second result, it indicates that the frequency of the reference clock should be decreased for safe operation.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiments that are illustrated in the various figures and drawings.
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- step S810: In a first operating condition such as the lowest voltage condition allowing the target circuit to operate normally, outputting a calibration signal SCAL to the adjustable delay circuit 120 to adjust the adjustable delay circuit 120 and have the delay contribution of the adjustable delay circuit 120 be equal to a predetermined delay (e.g., the cycle of the aforementioned reference clock), in which when the delay contribution is equal to the predetermined delay, the value of the calibration signal SCAL is a first value, and a first number of delay component(s) among the adjustable delay circuit 120, which could be composed of the aforementioned N delay units 210/520, is enabled to delay the predetermined signal w1. An instance of the aforementioned lowest voltage condition is that the switching speed of the NMOS and PMOS transistors of the target circuit is typical, the operating voltage is 0.9V, the temperature is 25□, and the aging status has not reached a predetermined aging status.
It should be noted that during the monitor mode, the first operating condition is treated as a warning operating condition of the target circuit, and the adjustable delay circuit 120 is set in accordance with the first value of the calibration signal SCAL that is dependent upon the first operating condition. In addition, during the calibration mode, in a second operating condition such as a normal voltage condition (e.g., a condition that the switching speed of the NMOS and PMOS transistors of the target circuit is typical, the operating voltage is 1V, the temperature is 25° C., and the aging status has not reached a predetermined aging status) allowing the target circuit to operate normally, the calibration signal SCAL is outputted to the adjustable delay circuit 120 to adjust the adjustable delay circuit 120 and thereby have the delay contribution of the adjustable delay circuit 120 be equal to the predetermined delay (e.g., the cycle of the aforementioned reference clock), in which when the delay contribution is equal to the predetermined delay, the value of the calibration signal SCAL is a second value, and a second number of delay components of the adjustable delay circuit 120, which could be composed of the aforementioned N delay units 210/520, is enabled to delay the predetermined signal w1. The second number of delay components is greater than the aforementioned first number of delay component(s) because a delay caused by an enabled delay component in the second operating condition is less than the delay caused by an enabled delay component in the first operating condition. The difference between the second number and the first number indicates the change of transmission delay from the normal voltage condition to the lowest voltage condition.
In light of the above, during the monitor mode, the delay contribution of the adjustable delay circuit 120, which is set in accordance with the first value of the calibration signal SCAL, won't reach the predetermined delay in a normal operating condition (i.e., the second operating condition). When the current operating condition of the target circuit is getting worse and reaches the warning operating condition (i.e., the first operating condition), the delay contribution of the adjustable delay circuit 120 will reach the predetermined delay (while the degree of delay of the delay signal w2 reaches the aforementioned predetermined threshold). If the current operating condition keeps getting worse (e.g., the aforementioned operating voltage keeps going down), the target circuit may not operate normally. Therefore, when the signal detector 130 finds that the degree of delay of the delay signal w2 reaches/exceeds the predetermined threshold, the signal detector 130 can issue a warning signal according to the demand for implementation so that a circuit or user receiving the warning signal can lower the frequency of the aforementioned reference clock to ensure that the target circuit can operate normally in accordance with the lower frequency. It should be noted that during the calibration mode, the calibrating circuit 710 can output the calibration signal SCAL to the adjustable delay circuit 120 according to the detection result generated by the signal detector 130 every round in a specific operating condition and thereby use the increasing/decreasing values of the calibration signal SCAL to gradually increase/decrease the delay contribution of the adjustable delay circuit 120 until the detection result changes from the first/second result to the second/first result; consequently the setting of the adjustable delay circuit 120 corresponding to the change of the detection result stands for the relation between the specific operating condition and the value of the calibration signal SCAL. When outputting the calibration signal SCAL, the calibrating circuit 710 may output an enabling signal EN simultaneously to enable the signal generator 110 so that the signal generator 100 generates the predetermined signal w1 for the next round of detection.
It should be noted that people of ordinary skill in the art can implement the present invention by selectively using some or all of the features of any embodiment in this specification or selectively using some or all of the features of multiple embodiments in this specification as long as such implementation is practicable, which implies that the present invention can be carried out flexibly.
To sum up, the present invention can rapidly detect and respond to the operating speed of the target circuit without considering and/or connecting any critical path of the target circuit. Accordingly, the present invention has the advantages of simplified design, quick response, and practicable applications.
The aforementioned descriptions represent merely the preferred embodiments of the present invention, without any intention to limit the scope of the present invention thereto. Various equivalent changes, alterations, or modifications based on the claims of present invention are all consequently viewed as being embraced by the scope of the present invention.
Claims
1. A circuit operating speed detecting circuit, the circuit operating speed detecting circuit configured to detect an operating speed of a target circuit during a monitor mode, the target circuit operating according to a reference clock, the circuit operating speed detecting circuit comprising:
- a signal generator configured to generate a predetermined signal in a current operating condition during the monitor mode, in which the current operating condition relates to at least one of a manufacturing process of the target circuit, a current operating voltage of the target circuit, a current temperature of the target circuit, and a current aging status of the target circuit;
- an adjustable delay circuit coupled between the signal generator and a signal detector and configured to generate a delay signal according to the predetermined signal in the current operating condition during the monitor mode;
- the signal detector configured to detect a degree of delay of the delay signal in the current operating condition during the monitor mode, and thereby generate a first result on condition that the degree of delay of the delay signal is equal to or less than a predetermined threshold and generate a second result on condition that the degree of delay of the delay signal is greater than the predetermined threshold, wherein each of the first result and the second result is related to the operating speed of the target circuit; and
- a calibrating circuit configured to execute a following step during a calibration mode: outputting a calibration signal to the adjustable delay circuit according to one of the first result and the second result in a warning operating condition and thereby gradually adjusting the adjustable delay circuit with the calibration signal until a delay contribution of the adjustable delay circuit reaches a predetermined delay in the warning operating condition,
- wherein when the delay contribution of the adjustable delay circuit reaches the predetermined delay in the warning operating condition during the calibration mode, a value of the calibration signal is treated as a threshold value of the warning operating condition; the adjustable delay circuit is set according to the threshold value of the calibration signal in the monitor mode; and if the current operating condition reaches the warning operating condition during the monitor mode, the delay contribution of the adjustable delay circuit reaches the predetermined delay and the degree of delay of the delay signal reaches the predetermined threshold.
2. The circuit operating speed detecting circuit of claim 1, wherein the circuit operating speed detecting circuit is a digital circuit.
3. The circuit operating speed detecting circuit of claim 1, wherein both a transmission delay characteristic of the adjustable delay circuit and a transmission delay characteristic of the target circuit vary with the current operating condition, and a trend of the transmission delay characteristic of the adjustable delay circuit is proportional to a trend of the transmission delay characteristic of the target circuit.
4. The circuit operating speed detecting circuit of claim 1, wherein each of the first result and the second result is used for determining whether to adjust a frequency of the reference clock.
5. The circuit operating speed detecting circuit of claim 4, wherein when the target circuit operates in the current operating condition, the first result is used for maintaining or increasing the frequency of the reference clock, and the second result is used for decreasing the frequency of the reference clock.
6. The circuit operating speed detecting circuit of claim 4, wherein the predetermined threshold is related to a cycle of the reference clock.
7. The circuit operating speed detecting circuit of claim 6, wherein the predetermined threshold is equal to the cycle of the reference clock.
8. The circuit operating speed detecting circuit of claim 1, wherein the predetermined threshold is dependent upon a cycle of the reference clock.
9. The circuit operating speed detecting circuit of claim 8, wherein the predetermined threshold is equal to a cycle of the reference clock.
10. The circuit operating speed detecting circuit of claim 1, wherein the circuit operating speed detecting circuit is included in an integrated circuit including the target circuit.
11. The circuit operating speed detecting circuit of claim 1, wherein the adjustable delay circuit includes N delay units that are connected in series, and the adjustable delay circuit uses M delay unit(s) among the N delay units according to N control signals to generate the delay signal, in which the N is an integer greater than one and the M is a positive integer not greater than the N.
12. The circuit operating speed detecting circuit of claim 11, wherein each of the N delay units includes:
- an input terminal configured to receive an input signal that is the predetermined signal or a delay version of the predetermined signal;
- at least one delay component configured to generate an output signal by delaying the input signal; and
- a multiplexer configured to output one of the input signal and the output signal according to the N control signals.
13. The circuit operating speed detecting circuit of claim 12, wherein the N delay units include a first delay unit and a second delay unit, and a maximum delay caused by the first delay unit is different from a maximum delay caused by the second delay unit in the current operating condition.
14. The circuit operating speed detecting circuit of claim 13, wherein a number of delay component(s) included in the first delay unit is different from a number of delay component(s) included in the second delay unit.
15. The circuit operating speed detecting circuit of claim 12, wherein the signal detector is used for sampling the predetermined signal and the delay signal and thereby generating two sample results, and further used for determining whether the degree of delay of the delay signal is greater than the predetermined threshold in accordance with a relation between the two sample results.
16. The circuit operating speed detecting circuit of claim 1, wherein the adjustable delay circuit includes N delay units and a multiplexer, the N delay units are connected in series, and the multiplexer is configured to receive an output signal of each of the N delay units and thereby output one of the N output signals of the N delay units according to a control signal.
17. The circuit operating speed detecting circuit of claim 16, wherein each of the N delay units includes:
- an input terminal configured to receive an input signal that is the predetermined signal or a delay version of the predetermined signal;
- at least one delay component configured to generate the output signal by delaying the input signal; and
- an AND gate configured to generate a logical conjunction result of the input signal and the output signal.
18. The circuit operating speed detecting circuit of claim 16, wherein the signal detector is configured to detect a pulse width of the delay signal and thereby determine whether the degree of delay of the delay signal is greater than the predetermined threshold.
19. A circuit operating speed detecting circuit, the circuit operating speed detecting circuit configured to detect an operating speed of a target circuit during a monitor mode, the target circuit operating according to a reference clock, the circuit operating speed detecting circuit comprising:
- a signal generator configured to generate a predetermined signal in a current operating condition during the monitor mode, in which the current operating condition relates to at least one of a manufacturing process of the target circuit, a current operating voltage of the target circuit, a current temperature of the target circuit, and a current aging status of the target circuit;
- an adjustable delay circuit coupled between the signal generator and a signal detector and configured to generate a delay signal according to the predetermined signal in the current operating condition during the monitor mode; and
- the signal detector including a counter configured to measure a pulse width of the delay signal so that the signal detector detects a degree of delay of the delay signal according to the pulse width in the current operating condition during the monitor mode, then generates a first result on condition that the degree of delay of the delay signal is equal to or less than a predetermined threshold, and generates a second result on condition that the degree of delay of the delay signal is greater than the predetermined threshold,
- wherein each of the first result and the second result is related to the operating speed of the target circuit.
20. The circuit operating speed detecting circuit of claim 19, wherein the adjustable delay circuit includes N delay units and a multiplexer, the N delay units are connected in series, and the multiplexer is configured to receive an output signal of each of the N delay units and thereby output one of the N output signals of the N delay units according to a control signal.
Type: Application
Filed: Sep 17, 2019
Publication Date: Jul 2, 2020
Inventors: CHUN-YI KUO (Hsinchu County), WEN-HSUAN HSU (Changhua County), YING-YEN CHEN (Chiayi County)
Application Number: 16/573,136