KR101052699B1 - Method and circuit of measuring a time interval between events - Google Patents

Abstract

PURPOSE: A method and circuit for measuring an event time is provided to exactly measure a time range of minute interval by measuring time ranges about time interval between events by using frequency signals. CONSTITUTION: Time ranges about time interval between events are measured by using frequency signals. A common range of time ranges is determines as an event time(S270). At least one frequency among frequencies of frequency signals is different with other frequency. An oscillation frequency of frequency signals within time interval is measured(S220). Time ranges are measured by using oscillation frequency and frequencies of frequency signals(S230).

Description

Method and circuit of measuring a time interval between events

The present invention relates to a method and circuit for measuring a range of time intervals between events.

Event time measurement using a TDC (Time to Digital Converter) or the like, particularly the measurement of time intervals between events, is used in various technical fields. For example, the event time measurement method can be used to measure the time interval between the start and the end of a chemical reaction, and to determine the time of flight (TOF) for measuring the distance to a specific object using a laser. Used to measure the interval between the occurrence of the first event and the occurrence of the second event, such as the measurement of the time interval between when the laser beam reflected from the object is received, the measurement of the delay time occurring in the semiconductor device, and the like. Can be.

Hereinafter, the TOF system will be described with reference to the accompanying drawings.

1 is a view for explaining the concept of a conventional time interval measuring method.

Referring to FIG. 1, the TOF system measures a time interval between when a laser is output (first event) and when a laser reflected from an object is received (second event), and the measured time interval and the speed of the laser are measured. Measure the distance to the object by multiplying by. At this time, the time interval between the laser output point and the laser reception point is measured by using a clock signal and a counter output through the ring oscillator.

Specifically, as shown in FIG. 1, the clock signal is output from the time point at which the laser is output, and the counter is used to more accurately determine the number of oscillations of the clock signal measured within the time interval between the time point at which the laser is output and the time point at which the laser is received. , The number of occurrences of the rising edge) is measured (= 4). At this time, the time interval between the laser output point and the laser reception point is measured by multiplying the number of occurrences of the rising edge (= 4) by the period of the clock signal (= T _P ).

However, when measuring the time interval between events using this event time measurement method, it is difficult to measure the exact time interval because the interval between the occurrence of the first event and the occurrence of the second event is very narrow. And measured as an approximation.

On the other hand, if there is a small error in the measured time interval, a large error may occur in the result value (measuring distance, etc.). As a result, a large error can be generated by using the conventional event time measuring method.

For example, the actual time interval T _R between the point at which the laser is output and the point at which the laser is received does not exactly match the time interval T _M measured by multiplying the number of occurrences of the rising edge by the period of the clock signal. Error may occur as much as the error time T _E. In this case, when the frequency of the clock signal is 100 MHz, the error time T _E becomes about ± 10 nS, whereby a large error of about 1.5 m occurs between the measured distance and the actual distance.

That is, the conventional TDC-based event time measuring method using the clock signal to measure the time interval cannot accurately measure the time interval due to asynchronous synchronization of the edge of the clock signal with the timing of occurrence of the second event. There was this.

In order to solve the problems of the prior art as described above, the present invention is to propose a method and circuit for measuring the event time that can be measured more precisely the range of the fine time interval through the iterative measuring method.

In order to achieve the above object, according to an embodiment of the present invention, measuring the time ranges for the time interval between events using N (an integer of 2 or more) frequency signals; And determining a common range of the time ranges as an event time, wherein at least one of the frequencies of the frequency signals is different from another frequency. .

The measuring of the time ranges may include measuring the number of oscillations of the frequency signals within the time interval, and measuring the time ranges using the number of oscillations of the measured frequency signals and the frequencies.

The frequency signals are clock signals, and the number of oscillations of the frequency signals may be equal to the number of occurrences of a rising edge of the clocks within the time interval.

The lower limit of the i-th time range measured using an i-th frequency signal among the frequency signals is a value smaller than 1 by the number of oscillations of the i-th frequency signal divided by the frequency of the i-th frequency signal, and i The upper limit value of the ith time range may be a value obtained by dividing the number of oscillations of the i th frequency signal by the frequency of the i th frequency signal.

Measuring the time ranges may be performed sequentially or simultaneously on one or more devices.

An occurrence time point of a first event corresponding to a start point of a time range means an output time point of a signal for distance measurement, a start time of a chemical reaction, or a start time of measurement of a delay time occurring in a semiconductor device, and an end point of the time range. The occurrence time point of the second event corresponding to may mean the arrival time of the response signal transmitted in response to the signal for distance measurement, the end time of the chemical reaction, or the end time of measurement of the delay time occurring in the semiconductor device. Can be.

Further, according to another embodiment of the present invention, measuring the number of oscillation of the frequency signals in time between events using N (an integer of 2 or more) frequency signals; And determining a common range of time ranges generated by using the number of oscillations of the measured frequency signals and the frequency of the frequency signals as an event time, wherein at least one of the frequencies of the frequency signals is different from another frequency. Another event time measuring method is provided.

According to still another embodiment of the present invention, there is provided a circuit used for an event time measuring method, comprising: M first integer delay elements; And N (integer of 2 or more) second delay elements, wherein an output terminal of at least one of the first delay elements is connected to an input terminal of a corresponding second delay element. A measurement circuit is provided.

An output terminal of the first delay element is connected to an input terminal of a corresponding second delay element and is also connected to an input terminal of a first delay element of a next stage, and an output terminal of one of the second delay elements is a corresponding first delay element. It may be connected to the input terminal of and the input terminal of the second delay element of the next stage.

The first input of one of the first delay elements is connected to the output of the first delay element of the previous stage, and the other second input is connected to the output of the corresponding second delay element. May select and operate only one of the input terminals according to a control signal.

The first input terminal of the second delay element is connected to the output terminal of the corresponding first delay element, and the other second input terminal is connected to the output end of the second delay element of the next stage, wherein the second delay element is in accordance with a control signal. Only one of the input terminals may be selected and operated.

The first delay element and the second delay element may operate as either a buffer or an inverter according to a control signal.

According to the present invention, it is possible to measure the range of minute time intervals more accurately through an iterative measuring method.

In addition, according to the present invention, there is an advantage in that a range of time intervals can be measured in a simple method without requiring any internal / external equipment other than the oscillation circuit and the counter.

In addition, according to the present invention, there is an advantage of measuring a range of time intervals with a high resolution of about picoseconds.

1 is a view for explaining the concept of a conventional time interval measuring method.
2 is a flow chart showing the overall flow of the event time measurement method according to an embodiment of the present invention.
3 is a diagram for describing a concept of setting a lower limit value and an upper limit value of an event time according to an embodiment of the present invention.
4 is a flowchart illustrating the overall flow of a method for repeatedly measuring an event time according to an embodiment of the present invention.
FIG. 5 is a diagram illustrating examples of signals output in the process of performing an event time measuring method according to an exemplary embodiment of the present invention.
6 is a circuit diagram illustrating a detailed configuration of an event time measuring circuit according to an embodiment of the present invention.
7 is a circuit diagram illustrating a detailed configuration of delay elements 610 and 620 according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited or limited by the embodiments. Like reference numerals in the drawings denote like elements.

2 is a flowchart illustrating an overall flow of a method for measuring an event time according to an embodiment of the present invention, and FIG. 3 is a view for explaining a concept of setting a lower limit value and an upper limit value of an event time according to an embodiment of the present invention. to be.

The event time measuring method according to an embodiment of the present invention includes a time interval between a first event (starting point of a time range) and a second event (end point of a time range) occurring at a slight interval difference (hereinafter, “between events”). The possible time range of the "time interval" is measured with high resolution. Here, the occurrence time of the first event refers to the start of the start time of the specific event, such as the start time of the chemical reaction, the output time of the laser for the distance measurement, the start time of the measurement of the delay time occurring in the semiconductor device, etc. 2 The point of occurrence of an event may be a specific starting point, such as the end of a chemical reaction, the reception of a transmitted (i.e. reflected) laser in response to a signal output for distance measurement, or the end of a measurement of a delay occurring in a semiconductor device. It means the end of the event.

Hereinafter, a process performed for each step will be described in detail with reference to FIG. 2.

First, in step S210, a first frequency signal having a first frequency is output through an oscillator circuit (eg, a ring oscillator) at the time of occurrence of the first event. In this case, the first frequency signal may be a signal in the form of a clock pulse. In addition, the first frequency may be lower than the frequency of the frequency signal used in the conventional event time method.

In operation S220, the number of oscillations of the first frequency signal in the time interval between the events is measured.

In this case, the measurement of the number of oscillations of the first frequency signal may be performed through a counter. That is, the counter starts measuring the number of oscillations of the first frequency signal at the time when the first event occurs and ends the measurement of the number of oscillations of the first frequency signal at the time when the second event occurs. The number of oscillations of the first frequency signal within the interval may be measured.

If the first frequency signal is a clock signal, in step S220, the number of oscillations of the first frequency signal may be measured by measuring the number of occurrences of rising edges of the clocks within a time interval between events. Can be. In other words, the number of oscillations of the first frequency signal may be equal to the number of occurrences of the rising edge of the clocks within the time interval between the events. Of course, in step S220, the number of oscillations of the first frequency signal may be measured by measuring a falling edge according to the method of constructing the invention.

In operation S230, the first time range is measured by setting a first lower limit value and a first upper limit value of a time range for a time interval between events based on the measured number of oscillations of the first frequency signal and the first frequency. . The first time range is determined as an event time until steps S230 to S270 described below are performed.

If the first frequency signal is a clock signal and the number of oscillations of the first frequency signal is the number of occurrences of the rising edges of the clocks, in step S230, the first frequency signal is smaller than the number of oscillations of the first frequency signal by one. The value divided by the frequency may be set as the first lower limit, and the value obtained by multiplying the oscillation number of the first frequency signal by the inverse of the first frequency may be set as the first upper limit. As an example, the measurement of the first time range in step S230 may be performed as shown in FIG. 3A (number of oscillations of the first frequency signal: 4, first lower limit: 3 × T). _P1 first upper limit: 4 × T _P1 )

Next, in step S240, the second frequency signal having the second frequency is output through the oscillation circuit at the time of occurrence of the first event. Here, the second frequency may be lower than the frequency of the frequency signal used in the conventional event time method.

In this case, the second frequency may be larger or smaller than the first frequency, but it is assumed that the second frequency is a large frequency for convenience of description. In addition, the second frequency signal may also be a signal in the form of a clock pulse.

In operation S250, the number of oscillations of the second frequency signal in the time interval between the events is measured. Measurement of the number of oscillations of the second frequency signal may also be performed through a counter. In addition, when the second frequency signal is a clock signal, in step S250, as in step S220, the number of oscillations of the second frequency signal is measured by measuring the number of occurrences of the rising edge of the clocks within the time interval of the events. It can be measured.

If the second frequency signal is a clock signal and the number of oscillations of the second frequency signal is the number of occurrences of rising edges of the clocks, the number of oscillations of the second frequency signal is determined as shown in FIG. It may be equal to the number of oscillations of the first frequency signal (number of oscillations of the second frequency signal: 4), or as shown in (c) of FIG. 3, a value increased by one from the number of oscillations of the first frequency signal. (The number of oscillations of the second frequency signal: 5).

In operation S260, the second time range is measured by setting a second lower limit value and a second upper limit value of a time range for a time interval between events based on the measured number of oscillations of the second frequency signal and the second frequency. .

If the second frequency signal is a clock signal and the number of oscillations of the second frequency signal is the number of occurrences of the rising edges of the clocks, in step S260, a value smaller by one than the number of oscillations of the second frequency signal is increased to the second frequency. The value obtained by dividing by may be set as the second lower limit value, and the value obtained by dividing the number of oscillations of the second frequency signal by the second frequency may be set as the second upper limit value. As an example, the measurement of the second time range in step S260 may be performed as shown in FIGS. 3B and 3C (in the case of FIG. Oscillation number: 4, 2nd lower limit value: 3xT _P2 , 2nd upper limit value: 4xT _P2 , In the case of (c) of FIG. 3, 2nd frequency signal oscillation number: 5, 2nd lower limit value: 4x T _P2 , second upper limit value: 5 x T _P2 ).

In step S270, a common range of the first time range and the second time range is determined (updated) as the event time. In other words, in step S270, the event time is determined by setting a larger value among the first lower limit value and the second lower limit value as the lower limit value of the event time, and setting a smaller value among the first upper limit value and the second upper limit value as the upper limit value of the event time ( Update). Accordingly, in step S270, an event time narrower than the event time set through steps S210 to S230 may be set to increase the resolution of a range of time intervals between measured events. It becomes possible.

At this time, as described above, the number of oscillations of the second frequency signal may be the same as the number of oscillations of the first frequency signal, or may have a value increased by one than the number of oscillations of the first frequency signal. In each case, the common range setting operation in step S270 will be described in more detail. Here, it is assumed that the first frequency signal and the second frequency signal are clock signals, the number of oscillations of each frequency signal is equal to the number of rising edges of the clocks, and the second frequency is greater than the first frequency.

1) of the first frequency signal Oscillation  Number of times and the second frequency signal Oscillation  If the number is the same

First, when the first lower limit value and the first upper limit value described above are expressed by Equation 1, Equation 1 below.

Here, LB ₁ is a first lower limit value, HB ₁ is a first upper limit value, N _C is an oscillation number of a first frequency signal, and f ₁ is a first frequency.

Meanwhile, since the number of oscillations of the first frequency signal and the number of oscillations of the second frequency signal are the same, the second lower limit value and the second upper limit value may be expressed by Equation 2 below.

Here, LB ₂ is the second lower limit, HB ₂ is the second upper limit, and f ₂ is the second frequency.

Here, the ratio of the first lower limit value and the second lower limit value and the ratio of the first upper limit value and the second upper limit value are calculated by Equation 3 below.

In this case, since the second frequency is greater than the first frequency, referring to Equation 3, the second lower limit value is smaller than the first lower limit value, the second upper limit value is smaller than the first upper limit value, and the ratio is the same. .

Therefore, in the case of this example, in step S270, in order to narrow the range of event time, the first lower limit value, which is a large lower limit value, is set (updated) as the lower limit value of the event time, and the second upper limit value, which is a small upper limit value, is set as the upper limit value of the event time ( The common time range of the first time range and the second time range is determined as the event time.

2) of the first frequency signal Oscillation  Number of times of the second frequency signal Oscillation  Is less than 1

Since the number of oscillations of the second frequency signal is one greater than the number of oscillations of the first frequency signal, the second lower limit value and the second upper limit value are expressed by Equation 4 below.

In this case, since the first lower limit value and the first lower limit value are expressed as in Equation 1, the following equation is calculated when the ratio of the first lower limit value and the second lower limit value and the ratio of the first upper limit value and the second upper limit value are calculated. Same as 5.

가 1보다 크면(즉, 제2 하한값이 제1 하한값 보다 크면), 단계(S270)에서는 제2 하한값을 이벤트 시간의 하한값으로 설정하고, 반대로

가 1보다 작으면(즉, 제1 하한값이 제2 하한값 보다 크면), 단계(S270)에서는 제1 하한값을 이벤트 시간의 하한값으로 설정한다. Where

Is greater than 1 (i.e., the second lower limit is greater than the first lower limit), in step S270, the second lower limit is set as the lower limit of the event time, and vice versa.

If is less than 1 (that is, if the first lower limit is greater than the second lower limit), then at step S270 the first lower limit is set as the lower limit of the event time.

)이 제1 주파수 신호의 오실레이션 횟수보다 1만큼 작은 값 및 제1 주파수 신호의 오실레이션 횟수의 비율(

)보다 크면 제2 하한값을 이벤트 시간의 하한값으로 설정하고, 제1 주파수 및 제2 주파수의 비율(

)이 제1 주파수 신호의 오실레이션 횟수보다 1만큼 작은 값 및 제1 주파수 신호의 오실레이션 횟수의 비율(

)보다 작으면 제1 하한값을 이벤트 시간의 하한값으로 설정한다. That is, in step S270, the ratio of the first frequency and the second frequency (

) Is a value of 1 less than the number of oscillations of the first frequency signal and the ratio of the number of oscillations of the first frequency signal (

If greater than), the second lower limit value is set as the lower limit value of the event time, and the ratio of the first frequency and the second frequency (

) Is a value of 1 less than the number of oscillations of the first frequency signal and the ratio of the number of oscillations of the first frequency signal (

If lower than), the first lower limit value is set as the lower limit value of the event time.

가 1보다 크면(즉, 제2 상한값이 제1 상한값 보다 크면), 단계(S270)에서는 제1 상한값을 이벤트 시간의 상한값으로 설정하고, 반대로

가 1보다 작으면(즉, 제1 상한값이 제2 상한값 보다 크면), 단계(S270)에서는 제2 상한값을 이벤트 시간의 하한값으로 설정한다. Similarly, if

Is greater than 1 (that is, if the second upper limit value is greater than the first upper limit value), in step S270, the first upper limit value is set as the upper limit value of the event time, and vice versa.

If is less than 1 (ie, the first upper limit value is greater than the second upper limit value), then in step S270, the second upper limit value is set as the lower limit value of the event time.

)이 제1 주파수 신호의 오실레이션 횟수 및 제2 주파수 신호의 오실레이션 횟수(즉, 제1 주파수 신호의 오실레이션 횟수보다 1만큼 큰 값)의 비율(

)보다 크면 제1 상한값을 이벤트의 시간의 상한값으로 설정하고, 제1 주파수 및 제2 주파수의 비율(

)이 제1 주파수 신호의 오실레이션 횟수 및 제2 주파수 신호의 오실레이션 횟수의 비율(

)보다 작으면 제2 상한값을 이벤트 시간의 상한값으로 설정한다. That is, in step S270, the ratio of the first frequency and the second frequency (

) Is the ratio of the number of oscillations of the first frequency signal and the number of oscillations of the second frequency signal (that is, a value that is one greater than the number of oscillations of the first frequency signal)

If greater than), the first upper limit value is set as the upper limit value of the time of the event, and the ratio of the first frequency and the second frequency (

Is the ratio of the number of oscillations of the first frequency signal and the number of oscillations of the second frequency signal (

If smaller than), the second upper limit value is set as an upper limit value of the event time.

The event time, which is a common range of the first time range and the second time range, is determined according to the lower limit value and the upper limit value of the time interval between the events set as described above.

On the other hand, the performing of the step (S210) to step (S230) and the performing of the step (S240) to (S260) may be performed sequentially in one event time measuring apparatus, or simultaneously in two event time measuring apparatus It may also be performed.

Such an event time measuring method may be repeatedly performed using different N frequency signals, thereby narrowing the range of time intervals between the measured events (that is, the time intervals between the events). Can increase the resolution in the range of more).

That is, the event time measuring method according to an embodiment of the present invention performs the same steps as previously measured in the first time range and the second time range by repeatedly performing N (integer or greater) frequency signals between the events. The N time ranges for the time interval of may be measured, and a common range of the N time ranges may be calculated to determine the event time. At this time, at least one of the frequencies of the N frequency signals is different from the other frequency, preferably the frequencies of the N frequency signals are different from each other.

In this case, the measurement of the time range that is repeatedly performed may be sequentially performed in one event time measuring apparatus, or may be simultaneously performed in a plurality of event measuring apparatuses.

Hereinafter, an example of a method for measuring a time interval that is repeatedly performed will be described with reference to FIG. 4.

FIG. 4 is a flowchart illustrating an overall flow of a method for repeatedly measuring an event time according to an embodiment of the present invention, and FIG. 5 is a diagram illustrating signals outputted during the execution of an event time measuring method according to an embodiment of the present invention. It is a figure which shows an example.

For convenience of description, FIGS. 4 and 5 will be described with reference to an example of measuring the number of occurrences of rising edges of clocks by using a frequency signal in the form of a clock signal to measure the number of oscillations of each frequency signal. Of course, the oscillation number of the frequency signal may be measured by specifying the number of falling edges of the clocks according to the configuration of the present invention.

4 and 5 illustrate that the frequency of the frequency signal is incrementally increased by a predetermined value, this is for convenience of description, and the repeated event time measuring method according to an embodiment of the present invention has a frequency. It may be performed while increasing the frequency of the signal irregularly by an arbitrary value.

Hereinafter, a process performed for each step will be described in detail with reference to FIGS. 4 and 5.

First, in step S410, a frequency signal having a predetermined frequency is output at the time when the first event occurs. Hereinafter, a predetermined frequency will be referred to as a "reference frequency (f _ref )".

In step S420, the number of oscillations (that is, the number of occurrences of the rising edge) of the frequency signal in the time interval between the events is measured.

In operation S430, the range of time intervals between the events is measured based on the measured number of oscillations and the frequency f _ref of the frequency signal, and the range of the measured time intervals is determined as the event time.

In this case, step S410 to step S430 may be performed in the same method as step S210 to step S230 of FIG. 2.

In step S440, a frequency signal whose frequency is changed (i.e. increased) by a predetermined value G is output at the time of occurrence of the first event, and in step S450, the frequency signal in the time interval between the events. The number of oscillations is remeasured, and in step S460, the time range of the time interval between events is remeasured based on the number of remeasured oscillations and the changed frequency of the frequency signal. In this case, steps S440 to S460 may also be performed according to the same method as steps S240 to S260 described above with reference to FIG. 2 (in this case, the first frequency has a value of f _ref . , The second frequency is f _ref + G).

In step S470, a common range of an event time determined at a previous time point (that is, step S430) and a time range remeasured in step S460 is calculated, and the calculated common range is determined as a new event time (update). do. Step S470 may also be performed according to the same method as step S270 described above with reference to FIG. 2.

In step S480, it is determined whether the measurement of the event time is finished.

If it is determined in step S480 that the measurement of the event time has ended, the last updated event time is determined as the final event time. On the contrary, if it is determined in step S480 that the measurement of the event time is not finished, steps S440 to S470 are repeatedly performed, and accordingly the event time is updated repeatedly so that the event time has a narrower range. This is measured.

FIG. 5 shows an example in the case where steps S440 to S470 are repeatedly performed four times. Here, the gray-filled part is a time range of time intervals between events measured using each frequency signal.

Referring to FIG. 5, the frequency of the frequency signal is f _ref + G, f _ref + 2G, f _ref In the case of + 3G, the number of oscillations is constant as "2", and the frequency of the frequency signal is f _ref In the case of + 4G, it can be seen that the oscillation number is changed (increased) to "3".

At this time, as described above through Equation 3, if the number of oscillations does not change, the lower limit and the upper limit of the range (parts shown in gray) of the time interval between the events set by the respective frequency signals are constant ratios. When the event time is measured in the first to third times, the lower limit value of the event time set in the previous execution step is maintained as is through the step S470, and the upper limit value of the time range measured in the next execution step is It is set to the upper limit and the event time is updated.

However, when the oscillation number is changed to "3", as shown in FIG. 5, the time point at which the oscillation number is changed (f _ref) The lower limit in + 4G or f _A ) becomes the largest lower limit, and the previous time point (f _ref adjacent to the point where the oscillation number changes) The upper limit in + 3G or f _B ) (ie, the upper limit of the event time set in the previous execution step) becomes the smallest upper limit.

Therefore, when measuring the fourth event time, the lower limit value at the time when the oscillation number is changed through the step S470 is set as the lower limit value of the event time, and the upper limit value at the previous time point adjacent to the time when the oscillation number is changed is the event time. The upper limit of the event time set in the previous execution step is kept as the upper limit of the event time.

In other words, if the number of oscillations measured again in step S450 is changed, in step S470, the upper limit value of the event time determined in the previous execution step is maintained, and the lower limit value of the time range measured in the current execution step is changed to the event. Updated to the lower limit of time.

Hereinafter, referring to the example illustrated in FIG. 5, when a change in oscillation number occurs in the process of performing steps S440 to S470 repeatedly, a lower limit value of an event time determined at the time when the change occurs, and It is proved that the upper limit value corresponds to the "lower limit value of the time range measured at the time when the change occurred" and the "upper limit value of the time range measured at the time immediately before the change occurred", so that the narrowest range ( It will be described that the event time of the highest resolution range can be determined.

a) the lower limit of the maximum among the lower limits derived at each stage of performance;

As described in Equation 3 above, if the number of oscillations does not change (increase) even if the frequency increases, the lower limit value in each execution step decreases at a constant rate, so that the lower limit value (ie, LB at f _ref ) measured _initially is It becomes the lower limit with the maximum magnitude. Therefore, "LB at f _ref " becomes the maximum lower limit until the oscillation number is changed.

However, if the number of oscillations is changed (ie, increased by 1), Equation 3 cannot be applied, and the ratio of "LB at f _ref " and "LB at f _A " is determined as in Equation 6 below.

Here, N _C means the number of oscillations before the change.

가 1보다 크다면, "LB at f_A"는 이전 최대 하한값인 "LB at f_ref"보다 큰 값을 가지게 된다. 다시 말해,

의 관계가 성립하는 경우, "LB at f_A"가 최대의 하한값이 된다.
therefore,

If is greater than 1, "LB at f _A " has a value larger than the previous maximum lower limit "LB at f _ref ". In other words,

If the relation is true, "LB at f _A " is the maximum lower limit.

b) the minimum of the upper bounds derived for each performance step

As described in Equation 3 above, if the number of oscillations does not change (increase) even when the frequency increases, the upper limit value in each execution step decreases at a constant rate, and thus the upper limit value measured last (that is, HB at f _B ) This is the upper limit of this minimum size. Therefore, "HB at f _B " becomes the minimum upper limit until the oscillation number is changed.

However, if the number of oscillations is changed (ie, increased by 1), Equation 3 cannot be applied, and the ratio of "HB at f _B " and "HB at f _A " is determined as in Equation 7 below.

Here, N _C means the number of oscillations before the change.

가 1보다 작다면, "HB at f_B"는 "HB at f_A"보다 작은 값을 가지게 된다. 다시 말해,

의 관계가 성립하는 경우, "HB at f_B"가 최소의 상한값이 된다.
therefore,

If is less than 1, "HB at f _B " is smaller than "HB at f _A ". In other words,

When the relation is satisfied, "HB at f _B " becomes the minimum upper limit.

c) comparison of the magnitude of the maximum and minimum values

The ratio of the maximum lower limit and the minimum upper limit is expressed by Equation 8 below.

Since f _A is larger than f _B , "HB at f _B " becomes larger than "LB at f _A ". Therefore, when setting the lower limit value and the upper limit value of the fine time range through step S460, an error in which the upper limit value is smaller than the lower limit value does not occur.

Meanwhile, the performing of the steps S410 to S430 and the performing of the steps S440 to S460 may be sequentially performed in one event time measuring apparatus, or simultaneously in a plurality of event time measuring apparatuses. It may also be performed. For example, in the example of FIG. 5, five signal outputs and oscillation number measurement are performed, which may be repeatedly performed five times sequentially through one event time measuring apparatus, and five event times. It may also be carried out at one time via the measuring device.

As such, the event time measuring method according to an embodiment of the present invention does not require any internal / external equipment other than the oscillation circuit and the counter, and has a high resolution of about picoseconds by a simple method. There is an advantage to measuring the range.

Hereinafter, an example of a circuit for outputting a signal having a changeable frequency (programmable frequency) as described above will be described in detail with reference to FIG. 6.

6 is a circuit diagram illustrating a detailed configuration of an event time measuring circuit according to an embodiment of the present invention.

Referring to FIG. 6, the event time measuring circuit 600 according to an exemplary embodiment of the present invention may include first delay elements 610 of M (an integer of 2 or more) and second delay elements of N (an integer of 2 or more). 620 and internal counter 630.

In this case, the number M of the first delay elements 610 may be the same as the number N of the second delay elements 620. Hereinafter, for convenience of description, the event time measuring circuit 600 including the same number N of first delay elements 610 and second delay elements 620 will be described.

The event time specifying circuit 600 according to an embodiment of the present invention is a circuit for outputting a programmable frequency signal. Referring to the preliminary circuit configuration, the output terminals of the first delay elements 610 may be corresponding to each other. It is connected to the input terminal of the second delay element 620 and is also connected to the input terminal of the first delay element 610 of the next stage, the output terminal of the second delay elements 620 is the input terminal of the corresponding first delay element 610 It is connected to the input terminal of the second delay element 620 of the next stage.

In more detail, the N first delay elements 610 are disposed in a first row in the event time measuring circuit 600, and the N second delay elements 620 are included in the event time measuring circuit. Disposed in a second row within 620. The first delay element and the second delay element included in the same column correspond to each other and constitute one delay element pair.

In this case, the first delay elements 610 and the second delay elements 620 may have the same structure, and the input terminals of the delay elements 610 and 620 may include two input terminals F and P, One output terminal O and three control signal input terminals SA, SB, and INV may be included.

In this case, the first input terminal F of the i-th second delay element 620 is connected to the output terminal O of the i-th first delay element 610 and the second of the i-th second delay element 620. The input terminal P is connected to the output terminal O of the i + 1th second delay element 620.

In addition, the first input terminal F of the i-th first delay element 610 is connected to the output terminal O of the i-th second delay element 620 and the second input terminal of the i-th first delay element 610. P is connected to the output terminal O of the i-1 th first delay element 610.

The delay elements 610 and 620 connected as described above operate by selecting only one of the two input terminals F and P according to the control signal input through the first control signal input terminal SA. Receive).

For example, when the first control signals SAU_i and SAD_i having the high logic 1 are received through the first control signal input terminal SA, the delay elements 610 and 620 may receive the first input terminal F. Receives an input signal through the first control signal input terminal (SA), when receiving the first control signal (SAU_i, SAD_i) having a low logic (0) through the second input terminal (P) can do.

In addition, each of the delay elements 610 and 620 may operate as either a buffer or an inverter. In this case, the operation modes of the delay elements 610 and 620 may be determined based on the second control signals INVU_i and INVD_i input through the second control signal input terminal INV.

For example, when the second control signals INVU_i and INVD_i having the high logic 1 are received through the second control signal input terminal INV, the corresponding delay elements 610 and 620 operate as an inverter and control the second control signal. When the second control signals INVU_i and INVD_i having the low logic 0 are received through the signal input terminal INV, the corresponding delay elements 610 and 620 may operate as buffers.

Hereinafter, the configuration and operation of the delay elements 610 and 620 will be described in more detail with reference to FIG. 7.

7 is a circuit diagram illustrating a detailed configuration of delay elements 610 and 620 according to an embodiment of the present invention.

As shown in FIG. 7, the delay elements 610, 620 include two selectors 640, 650, one XOR gate 660, and two buffers 670, 680.

The first selector 640 selects one of the first input terminal F and the second input terminal P based on the first control signals SAU_i and SAD_i received through the first control signal input terminal SA. Select to receive the signal. That is, as described above, when the first control signals SAU_i and SAD_i have the high logic 1, the first input terminal F is selected, and when the first control signals SAU_i and SAD_i have the low logic 0, the second input terminal P is Is selected.

The XOR gate 660 performs an exclusive OR operation on the output signal of the first selector 640 and the second control signals INVU_i and INVD_i received through the second control signal input terminal INV.

Therefore, when the second control signals INVU_i and INVD_i have the high logic 1, the output signals of the first selector 660 are inverted and output so that the delay elements 610 and 620 operate as inverters. When the two control signals INVU_i and INVD_i have a low logic (0), since the output signal of the first selector 660 is output as it is, the delay elements 610 and 620 operate as a buffer.

The second selector 650 is output from the XOR gate 660 and the signal output from the XOR gate 660 based on the third control signals SBU_i and SBD_i received through the third control signal input terminal SB. One of the signals passed through the two buffers 670 and 680 (time delayed) is transmitted to the output terminal O. That is, when the third control signals SBU_i and SBD_i have the high logic 1, the output signal of the XOR gate 650 is transferred to the output terminal O as it is, and when the third control signals SBU_i and SBD_i have the low logic 0, the time-delayed XOR gate The output signal of 660 is transmitted to the output terminal (O).

Hereinafter, the event time measuring circuit 600 according to an exemplary embodiment of the present invention will be described with reference to FIG. 7 again.

The internal counter 630 measures the number of oscillations of the output signal Clk_Osc of the first second delay element 620.

The event time measuring circuit 600 configured as described above may be adjusted by appropriately adjusting the levels of the first control signals SAU_i and SAD_i and the second control signals INVU_i and INVD_i input to the respective delay elements 610 and 620. It is possible to form a ring oscillator including a number of delay elements to output a signal having a programmable frequency.

For example, when a ring oscillator including six delay elements is to be implemented, a user may include a first control signal having a high logic 1 as the first control signal input terminal SA of the third second delay element 620. And the first control signals SAU_i and SAD_i having the low logic (0) to the first control signal input terminal SA of the remaining delay elements 610 and 620, thereby providing three first delay elements 610. ) And a ring oscillator consisting of three second delay elements 620. In addition, as described above, since the ring oscillator must include an odd number of inverters, the user can appropriately adjust the levels of the second control signals INVU_i and INVD_i of the six delay elements 610 and 620 constituting the ring oscillator. Therefore, the ring oscillator may be implemented such that only the odd delay elements 610 and 620 operate as an inverter.

At this time, the frequency of the output signal is inversely proportional to the number of delay elements forming the ring oscillator. In other words, the larger the number of delay elements forming the ring oscillator, the longer the period of the output signal is, the frequency of the output signal is reduced. In contrast, the smaller the number of delay elements forming the ring oscillator, the shorter the period of the output signal, so that the frequency of the output signal increases.

As such, the event time measuring circuit 600 according to an embodiment of the present invention may adjust the frequency of the output frequency signal by appropriately adjusting the number of delay elements forming the ring oscillator. At this time, the frequency of the output frequency signal can be expressed as shown in Equation 9 below.

Here, f is the frequency of the signal output from the event time measuring circuit 600, N _B is the number of delay elements forming the ring oscillator, T _D means the delay time in the delay element, respectively.

On the other hand, as shown in FIG. 6, since the power supply voltage VDD is applied to the first input terminal F of the first second delay element 620, the first second delay element 620 is the first control signal input terminal ( The oscillation signal having a specific frequency is output only when the first control signal SAD_1 having the low logic 0 is input through SA. That is, the first second delay element 620 may output the oscillation signal only in the time interval in which the first control signal SAD_1 has the low logic (0).

Therefore, when the first event occurs, the user may output a signal having a predetermined frequency by changing the first control signal SAD_1 from the high logic 1 to the low logic 0. In addition, when the second event occurs, the output of the signal may be stopped by changing the first control signal SAD_1 from the low logic 0 to the high logic 1.

As such, the event time measuring circuit 600 according to an embodiment of the present invention may adjust the frequency (oscillation number) of the output signal by appropriately changing the levels of the first control signals SAU_i and SAD_i. do. Accordingly, the time interval measuring method described above with reference to FIGS. 2 and 4 can be performed using the event time measuring circuit 600.

As described above, the present invention has been described with reference to particular embodiments, such as specific elements, and limited embodiments and drawings. However, it should be understood that the present invention is not limited to the above- Various modifications and variations may be made thereto by those skilled in the art to which the present invention pertains. Therefore, the spirit of the present invention should not be limited to the described embodiments, and all of the equivalents or equivalents of the claims as well as the claims to be described later will belong to the scope of the present invention. .

Claims (14)

Measuring time ranges for a time interval between events using N (an integer greater than or equal to 2) frequency signals; And
Determining a common range of the time ranges as an event time
Including,
At least one of the frequencies of the frequency signals is different from another frequency. The method of claim 1,
Measuring the time ranges
Measuring the number of oscillations of the frequency signals in the time interval, and measuring the time ranges using the number of oscillations of the measured frequency signals and the frequencies. The method of claim 2,
The frequency signals are clock signals, and the number of oscillations of the frequency signals is equal to the number of occurrences of a rising edge of the clocks within the time interval. The method of claim 3,
The lower limit of the i th time range measured using an i th frequency signal among the frequency signals is a value obtained by dividing a value smaller than 1 by the number of oscillations of the i th frequency signal by the frequency of the i th frequency signal,
And an upper limit value of the i th time range is a value obtained by dividing the number of oscillations of the i th frequency signal by the frequency of the i th frequency signal. The method of claim 1,
Measuring the time ranges is performed sequentially or simultaneously in one or more devices. The method of claim 1,
An occurrence time point of the first event corresponding to the start point of the time range refers to an output time point of a signal for distance measurement, a start time of a chemical reaction, or a start time of measurement of a delay time occurring in a semiconductor device.
A time point of occurrence of a second event corresponding to an end point of the time range may include a time point of arrival of a response signal transmitted in response to the signal for distance measurement, an end point of the chemical reaction, or a measurement of a delay time occurring in the semiconductor device. Event time measurement method, characterized in that the end time. Measuring the number of oscillations of said frequency signals in time between events using N (an integer greater than or equal to 2) frequency signals; And
Determining a common range of time ranges generated by using the number of oscillations of the measured frequency signals and the frequency of the frequency signals as an event time.
Including,
At least one of the frequencies of the frequency signals is different from another frequency. The method of claim 7, wherein
The frequency signals are clock signals, and the number of oscillations of the frequency signals is equal to the number of occurrences of the rising edge of the clocks within the time interval. The method of claim 8,
The lower limit value of the i th time range of the generated time ranges is a value that is smaller than the oscillation number of the i th frequency signal of the frequency signals by 1 by the frequency of the i th frequency signal,
And an upper limit value of the i th time range is a value obtained by dividing the number of oscillations of the i th frequency signal by the frequency of the i th signal. In the circuit used for the event time measurement method,
M (integer or greater) two first delay elements; And
N second integer elements
Including,
And an output terminal of at least one of the first delay elements is connected to an input of a corresponding second delay element. The method of claim 10,
The output terminal of the first delay element is connected to the input terminal of the corresponding second delay element and is also connected to the input terminal of the first delay element of the next stage.
And an output terminal of one of the second delay elements is connected to an input terminal of a corresponding first delay element and an input terminal of a second delay element of a next stage. The method of claim 10,
The first input terminal of one of the first delay elements is connected to the output terminal of the first delay element of the previous stage, the other second input terminal is connected to the output terminal of the corresponding second delay element,
And the first delay element selects and operates only one of the input terminals according to a control signal. The method of claim 10,
The first input terminal of the second delay element is connected to the output terminal of the corresponding first delay element, the other second input terminal is connected to the output terminal of the second delay element of the next stage,
And the second delay element selects and operates only one of the input terminals according to a control signal. The method of claim 10,
The first delay element and the second delay element operate as either a buffer or an inverter according to a control signal.

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