CN100376081C - Delayed locking loop capable of sharing counter and related method - Google Patents
Delayed locking loop capable of sharing counter and related method Download PDFInfo
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- CN100376081C CN100376081C CNB2005101039118A CN200510103911A CN100376081C CN 100376081 C CN100376081 C CN 100376081C CN B2005101039118 A CNB2005101039118 A CN B2005101039118A CN 200510103911 A CN200510103911 A CN 200510103911A CN 100376081 C CN100376081 C CN 100376081C
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Abstract
The present invention relates to a delay locking loop for delaying an input clock to lock a delaying clock. The delay locking loop comprises a frequency divider, a plurality of delayers, a phase detector and a counter, wherein the frequency divider is used for making the frequency of the input clock divided by N to generate a frequency division signal; the delayers are used for delaying the input clock according to a counting value so that each delayer generates a plurality of delaying clocks of different delays, and the delayers are mutually connected in series; the phase detector is coupled with the finally delayer and is used for detecting the phase conversion between the finally delaying clock and the input clock. Besides, the counter is coupled with the phase detector and the frequency divider and is used for generating the counting value according to the phase conversion between the finally delaying clock and the input clock.
Description
Technical field
The present invention relates to a kind of delay-locked loop, particularly relate to a kind of delayed locking loop capable of sharing counter.
Background technology
Delay-locked loop (delay locked loop, DLL) be a kind of circuit structure that is widely used in the computer operation environment, be used for producing required clock, and when the computing clock of computer increases gradually, if will implement the design of high-speed assembly, then the clock of low clock skew (low-skew) distribute and will become more and more important.Comprised in the known computer systems and can carry out the processor that the data literary composition changes with multiple memory and I/O unit.(synchronousdynami crandom access memory SDRAM) is example, and it is applied in pipelined fashion and is sent to data processor, and the transfer rate of data equals the frequency of operation of processor haply at this moment with synchronous RAM.In the application of double message transmission rate (DDR) memory, when a memory clock produced positive edge (risingedge) or negative edge (falling edge), double message transmission rate synchronous RAM (DDR SDRAM) can output to a Memory Controller (memory Controller) with data.And the delay-locked loop that is used in the Memory Controller is designed to produce the sequential of a delayed clock with delay memory controller lock (latch) input clock according to memory clock, positive edge or negative edge that this expression delay-locked loop can provide a retardation to be used for suitably being offset script in (shift) memory clock, last Memory Controller just can be with correct data storing in latch means (latchdevice).
See also Fig. 1, Fig. 1 is known delay locked loop (delay locked loop, DLL) 100 a functional block diagram.Delay-locked loop 100 includes a multiplexer (multiplexer, MUX) 102, one frequency divider (frequency divider), 104, one reverser (inverter) 105, phase detectors (phase detector) 106, one counter (counter) 108 and a delayer (delay component) 110.For instance, delay-locked loop 100 desires locking one falls behind input clock 90 degree (promptly with the input clock quadrature) and frequency is the delayed clock of 500MHz, and detail operations is as follows.
Suppose multiplexer 102 selection clock CLK
1Be used as input clock IN, its frequency is 1GHz, and input clock IN oppositely produces a reference clock REFCLK via reverser 105 again.Delayer 110 is made up of many roads delay chain (delay chain), the input clock of the corresponding different operating frequency band of each road delay chain, and in other words, delayer 110 can provide the input clock of wideband to use, and it is applied as known in the art, is simply described as follows.At this, delayer 110 provides input clock CLK
1One predetermined delay amount dt is to export a delayed clock FBCLK.Use which delay chain then to select signal SEL[1:0 as for this by one] select, be 2 selection signal SEL[1:0 in this length] can select 4 tunnel different delay chains, the input clock of the corresponding different frequency of difference.Phase detectors 106 then compare the phase place of delayed clock FBCLK and reference clock REFCLK, then trigger the signal UP that once rises if the phase place of reference clock REFCLK is ahead of.The edge of rising signal UP enter counter 108 next frequency division signal CNTCLK4 of back treatment (can be rising edge or falling edge triggers) i.e. output adds 1 count value DCNT[7:0].Frequency division signal CNTCLK4 is produced by frequency divider 104, is 4 in this frequency division multiplying power, and promptly the cycle of frequency division signal CNTCLK4 is input clock CLK
14 times, yet the multiplying power of frequency division do not limited, for instance, the frequency division multiplying power also can be 8 or 16 times.Counter 108 can constantly be gone up number, increases its retardation dt gradually with control lag device 110, till the delayed clock of delayer 110 outputs falls behind input clock 180 degree.In case delayed clock falls behind input clock 180 degree, known delay locked loop 100 promptly enters lock-out state, and reduce to 500MHz with the frequency of input clock by 1GHz this moment again, and then delayed clock promptly falls behind input clock 90 degree.The delayed clock of delayer output at this moment is required backward input clock 90 degree (promptly with the input clock quadrature) and frequency is the delayed clock of 500MHz.
Yet, as shown in the above description, when the each desire of known delay locked loop produces required delayed clock, all need the operating frequency (operating frequency) of input clock is heightened 2 times (for example 500MHz becomes 1GHz), when back to be locked output falls behind the delayed clock of 180 degree, re-enter the input clock of practical operation frequency (for example 500MHz) again, to obtain the delayed clock of required backward input clock 90 degree (promptly with the input clock quadrature).Above-mentioned method is complicated and time consumption not only, and when the frequency of operation of input clock behaviour is more and more high, and the operation that input clock is heightened 2 frequencys multiplication is difficulty more and more also.In addition, for the delayer of wideband, owing to have the multipath delay chain, and Counter Design makes the delay chain normal running of low frequency, so when input clock increases, because sum counter does not match, have the risk of upset operation corresponding to the delay chain of high frequency.In other words, the known delay locked loop can't normally be shared a counter and not produce the risk of upset operation.
Summary of the invention
In view of this, one of purpose of the present invention provides and a kind ofly need not the operating frequency frequency multiplication of input clock and can share a counter and do not have the delay-locked loop of upset operation risk.
For achieving the above object, the invention provides a kind of delayed locking loop capable of sharing counter and be used for postponing an input clock to lock a delayed clock.This delay-locked loop includes: a frequency divider, be used for frequency with this input clock divided by N to produce a frequency division signal; A plurality of delayers are used for postponing this input clock to produce the different a plurality of delayed clocks that postpone in each delayer according to a count value, and wherein these a plurality of delayers are connected in series each other; One phase detectors couple a last delayer, are used for detecting the phase transition of a last delayed clock and this input clock; And a counter, be coupled to these phase detectors and this frequency divider, be used for producing this count value according to the phase transition of this last delayed clock and this input clock.
The present invention also provides a kind of delayer of wideband, is used for postponing an input clock to produce a delayed clock according to a count value.The delayer of this wideband includes: a decoder is used for this count value is done to export a decoding signal after the decoding computing; A plurality of code detectors are used for producing a plurality of detection signals according to this count value; A plurality of delay chains are coupled to this decoder and this a plurality of code detectors, are used for postponing this input clock to export a plurality of temporary delay clocks of corresponding different retardations according to these a plurality of detection signals and this decoding signal; One multiplexer is coupled to this decoder and this a plurality of delay chains, is used for according to this delayed clock of selecting corresponding input clock frequency in oneself these a plurality of temporary delay clocks of this decoder; And an output buffer, be coupled to this multiplexer, be used for exporting this delayed clock.
The present invention also provides a kind of delay one input clock to lock the method for a delayed clock, and it includes: with the frequency of this input clock divided by N to produce a frequency division signal; Postpone this input clock to produce the different a plurality of delayed clocks that postpone according to a count value; Detect the phase transition of a last delayed clock and this input clock; And the phase transition of this last delayed clock of foundation and this input clock produces this count value; Wherein, this last delayed clock falls behind this input clock 180 degree during locking.
For above and other objects of the present invention, feature and advantage can be become apparent, a preferred embodiment cited below particularly, and be described with reference to the accompanying drawings as follows.
Description of drawings
Fig. 1 is the functional block diagram of known delay locked loop.
Fig. 2 is the functional block diagram of an embodiment of delayed locking loop capable of sharing counter of the present invention.
Fig. 3 is the circuit diagram of delayer shown in Figure 2.
The reference numeral explanation
100,200 delay-locked loops
102,202 multiplexers
104,204 frequency dividers
105,205 reversers
106,206 phase detectors
108,208 counters
110,210,212 delayers
302 decoders
304,306,308,310 delay chains
312,313,314 code detectors
316 multiplexers
318 output buffers
Embodiment
Fig. 2 is the functional block diagram of an embodiment of delayed locking loop capable of sharing counter 200 of the present invention.Delay-locked loop 200 includes a multiplexer (multiplexer, MUX) 202, one frequency divider (frequency divider), 204, one reverser (inverter) 205, phase detectors (phase detector) 206, one counter (counter) 208 and a plurality of delayer (delaycomponent) 210,212.Via using the improved delayer 210,212 of the present invention, delay-locked loop 200 of the present invention can be under the environment of wideband input clock sharing counter 208 and do not have the risk of upset operation, its details is waited until aftermentioned.For instance, delay-locked loop 200 desires locking one falls behind input clock 90 degree (promptly with the input clock quadrature) and frequency is the delayed clock of 500MHz, and its operation is as follows.
Suppose multiplexer 202 selection clock CLK
1Be used as input clock IN, its frequency is 500MHz, and input clock IN oppositely produces a reference clock REFCLK via reverser 205 again.Delayer 210 and 212 is made up of many roads delay chain (delay chain), the input clock of the corresponding different operating frequency band of each road delay chain, and detailed function circuit is waited until aftermentioned.At this, delayer 210 and 212 provides input clock IN one predetermined delay amount dt altogether, to export a delayed clock FBCLK2.Should use which delay chain then to select signal SEL[1:0 as for delayer 210 and 212 by one] select, be 2 selection signal SEL[1:0 in this length] can select 4 tunnel different delay chains, the input clock of the corresponding different frequency of difference.Phase detectors 206 then compare the phase place of delayed clock FBCLK2 and reference clock REFCLK, then trigger the signal UP that once rises if the phase place of reference clock REFCLK is ahead of.The edge (can be rising edge or falling edge) of rising signal UP enter counter 208 next frequency division signal CNTCLK4 of back treatment is promptly exported and is added 1 count value DCNT[7:0].Frequency division signal CNTCLK4 is produced by frequency divider 204, be 4 in this frequency division multiplying power, yet the multiplying power of frequency division is equally also not limited.Counter 208 can constantly be gone up number, increases gradually with control lag device 210 and the 212 retardation dt that provided, till the delayed clock of delayer 212 outputs falls behind input clock 180 degree.In case delayed clock FBCLK2 falls behind input clock 180 degree, delay-locked loop 200 of the present invention promptly enters lock-out state, and the delayed clock FBCLK2 of delayer 210 outputs this moment promptly falls behind input clock 90 degree.
When delay-locked loop 200 each desires of the present invention as shown in the above description produce required delayed clock, needn't still need the operating frequency of input clock is heightened 2 times (for example 500MHz becomes 1GHz) as the known delay locked loop, and can be directly the input clock of corresponding operating frequency be inputed to delay-locked loop of the present invention, take out the delayed clocks that output falls behind 90 degree from first delayer (delayer 210) again after to be locked get final product (this moment second delayer fall behind input clock 180 spend).
Below describe the delayer 210,212 of the present invention's improvement in detail, its can be under the environment of wideband input clock the sharing counter 208 and principle of the risk of upset operation can not take place.Component delays device 210 of the same name and 212 circuit configurations are identical, are example at this with delayer 210.
Fig. 3 is the circuit diagram of delayer 210 shown in Figure 2.Delayer 210 includes a decoder (decoder) 302, a plurality of delay chain 304,306,308 and 310, a plurality of code detectors (codedetector) 312,313 and 314, one multiplexer 316 and an output buffer (outputbuffer) 318.The input clock of the corresponding different operating frequency band of each road delay chain disposes as follows: 128 delay cells are arranged in the delay chain 304,64 delay cells are arranged in the delay chain 306,32 delay cells are arranged in the delay chain 308,16 delay cells are arranged in the delay chain 310.In other words, delay chain 304 is to the operational frequency bands of delay chain 310 correspondences by the low frequency tremendously high frequency.Note that the pairing operational frequency bands of each road delay chain is different from other road delay chain and gets final product, this from low to high frequently arrangement mode only for convenience of description.In addition, then by its corresponding operational frequency bands decision, operational frequency bands is higher for the delay cell number in the delay chain, and the number of delay cell is fewer, otherwise operational frequency bands is lower, and the number of delay cell the more.
Decoder 302 is with the count value DCNT[7:0 of input] make after the decoding computing output one decoding signal and control each road delay chain input clock IN is done to postpone exporting the temporary delay clock of corresponding different retardations, and control multiplexer 316 is selected the temporary delay clock of an optimal corresponding input clock operating frequency again via the real required delayed clock of output buffer 318 outputs in each road delay chain.
Because the count value DCNT[7:0 of counter] and the delay chain 304 of lowest frequency (in 128 delay cells are arranged) mate, so its count range is 0 to 127 (with 8 bit representations).Yet other delay chain (delay chain 306, delay chain 308, delay chain 310) is the count value DCNT[7:0 of sum counter not] coupling, therefore have the possibility of upset operation, for instance, for delay chain 306, owing in it 64 delay cells are only arranged, so as count value DCNT[7:0] when surpassing 63, corresponding decoding signal is when control lag chain 306 output delay signals, and the problem that has overflow takes place.In like manner, have the problem of overflow too for delay chain 308 and delay chain 310.Be promptly to add a plurality of code detectors 312,313 and 314, be used for assisting Xie Jue Xie Code that the problem of overflow can take place when the delay chain of control higher-frequency with the delayer that the present invention improves.For instance, for delay chain 306, as count value DCNT[7:0] when surpassing 63, code detectors 312 is promptly exported one and is detected signal so that corresponding count value DCNT[7:0] when constantly increasing, the retardation of the delayed clock of delay chain 306 reduces on the contrary gradually, to solve the problem of overflow.In like manner, code detectors 313 and 314 with the problem that solves when the counting overflows take place delay chain 308 and 310, still can correctly control each road delay chain with auxiliary decoder 302 respectively under the situation of multipath delay chain.
When delay-locked loop desire of the present invention produces required delayed clock, needn't earlier the operating frequency of input clock be heightened 2 times, can be directly with the input clock of handling under this operating frequency.In addition, for the wideband delayer with multipath delay chain, delay-locked loop of the present invention also can be under the situation that does not increase the counter number, shares a counter and keeps the normal running of higher-frequency delay chain.
Though the present invention discloses as above with preferred embodiment; right its is not in order to limit the present invention; those skilled in the art can do some changes and retouching under the premise without departing from the spirit and scope of the present invention, so protection scope of the present invention is as the criterion with claim of the present invention.
Claims (8)
1. a delay-locked loop is used for postponing an input clock to lock a delayed clock, and this delay-locked loop includes:
One frequency divider, be used for frequency with this input clock divided by N to produce a frequency division signal;
A plurality of delayers are used for postponing this input clock to produce the different a plurality of delayed clocks that postpone in each delayer according to a count value, and wherein these a plurality of delayers are connected in series each other;
One phase detectors are coupled to a last last delayer that is connected in series in these a plurality of delayers, are used for detecting the phase transition of a last delayed clock and this input clock; And
One counter is coupled to these phase detectors and this frequency divider, is used for producing this count value according to the phase transition of this last delayed clock and this input clock;
Wherein, this last delayer produces during locking should last delayed clock falls behind this input clock 180 and spends.
2. delay-locked loop as claimed in claim 1, it also includes one first multiplexer, is coupled to this frequency divider, these phase detectors and this a plurality of delayers, uses to select one from the clock of a plurality of different frequencies and be used as this input clock.
3. delay-locked loop as claimed in claim 1, wherein these a plurality of delayers include one first delayer and one second delayer, one first delayed clock that this first delayer produces falls behind this input clock 90 degree, and this last delayed clock that this second delayer produces falls behind this input clock 180 degree; This first delayed clock is the output of this delay-locked loop.
4. delay-locked loop as claimed in claim 1, wherein this delayer includes:
One decoder is used for doing to export a decoding signal after the decoding computing according to this count value;
A plurality of code detectors are used for producing a plurality of detection signals according to this count value;
A plurality of delay chains are coupled to this decoder and this a plurality of code detectors respectively, are used for postponing this input clock to export a plurality of temporary delay clocks of corresponding different retardations according to these a plurality of detection signals and this decoding signal;
One second multiplexer is coupled to this decoder and this a plurality of delay chains, is used for according to this delayed clock of selecting corresponding input clock frequency in oneself these a plurality of temporary delay clocks of this decoding signal; And
One output buffer is coupled to this second multiplexer, is used for exporting this delayed clock;
Wherein the lowest frequency delay chain in these a plurality of delay chains is controlled the retardation of this input clock to export a lowest frequency temporary delay clock according to this decoding signal, other delay chain is controlled the retardation of this input clock according to this decoding signal and corresponding a plurality of detection signals, wherein when the decoding signal will make indivedual delay chain generation overflow, corresponding detection signal promptly influenced this decoding signal and controls.
5. one kind postpones an input clock to lock the method for a delayed clock, and it includes:
With the frequency of this input clock divided by N to produce a frequency division signal;
Postpone this input clock to produce the different a plurality of delayed clocks that postpone according to a count value;
Detect the phase transition of a last delayed clock and this input clock; And
Phase transition according to this last delayed clock and this input clock produces this count value;
Wherein, this last delayed clock falls behind this input clock 180 degree during locking.
6. method as claimed in claim 5, it also comprises selects one from the clock of a plurality of different frequencies and is used as this input clock.
7. method as claimed in claim 5, wherein these a plurality of delayed clocks include one first delayed clock and a last delayed clock, when locking, this first delayed clock falls behind this input clock 90 degree, this last delayed clock falls behind this input clock 180 degree, and wherein this first delayed clock is the output of this delay-locked loop.
8. method as claimed in claim 5 wherein postpones this input clock and also includes with the step that produces arbitrary delayed clock:
This count value is done to export a decoding signal after the decoding computing;
Produce a plurality of detection signals according to this count value;
Postpone this input clock to export a plurality of temporary delay clocks of corresponding different retardations according to these a plurality of detection signals and this decoding signal;
In these a plurality of temporary delay clocks, select this delayed clock of corresponding input clock frequency according to this decoding signal; And
Export this delayed clock;
Wherein a lowest frequency temporary delay clock is exported control the retardation of this input clock according to this decoding signal after, and other temporary delay clock is exported control the retardation of this input clock according to this decoding signal and corresponding a plurality of detection signals after.
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| CNB2005101039118A CN100376081C (en) | 2005-09-15 | 2005-09-15 | Delayed locking loop capable of sharing counter and related method |
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| CN100376081C true CN100376081C (en) | 2008-03-19 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101018049B (en) * | 2007-02-14 | 2011-04-13 | 威盛电子股份有限公司 | Delay phase locked loop |
| CN108551342B (en) * | 2018-03-20 | 2022-04-01 | 上海集成电路研发中心有限公司 | Delay phase-locked loop with wide frequency input range |
| KR102534241B1 (en) * | 2018-11-05 | 2023-05-22 | 에스케이하이닉스 주식회사 | Phase detection circuit, clock generation circuit and semiconductor apparatus including the phase detection circuit |
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| CN1237831A (en) * | 1998-05-12 | 1999-12-08 | 三菱电机株式会社 | Clock generator and clock generating method capable of varying clock frequency without increasing nuber of delay elements |
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