US20010022522A1 - Clock generating circuit for compensation of delay difference using closed loop analog synchronous mirror delay structure - Google Patents
Clock generating circuit for compensation of delay difference using closed loop analog synchronous mirror delay structure Download PDFInfo
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- US20010022522A1 US20010022522A1 US09/730,634 US73063400A US2001022522A1 US 20010022522 A1 US20010022522 A1 US 20010022522A1 US 73063400 A US73063400 A US 73063400A US 2001022522 A1 US2001022522 A1 US 2001022522A1
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- 230000001360 synchronised effect Effects 0.000 title abstract description 10
- 238000005086 pumping Methods 0.000 claims description 99
- 230000004044 response Effects 0.000 claims description 32
- 230000000630 rising effect Effects 0.000 claims description 12
- 230000007704 transition Effects 0.000 claims 4
- 238000010586 diagram Methods 0.000 description 17
- 230000000694 effects Effects 0.000 description 10
- 238000000034 method Methods 0.000 description 10
- 239000003990 capacitor Substances 0.000 description 4
- 230000003111 delayed effect Effects 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 230000001105 regulatory effect Effects 0.000 description 3
- 230000008859 change Effects 0.000 description 2
- 230000001934 delay Effects 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 238000013139 quantization Methods 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C11/00—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor
- G11C11/21—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using electric elements
- G11C11/34—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using electric elements using semiconductor devices
- G11C11/40—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using electric elements using semiconductor devices using transistors
- G11C11/401—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using electric elements using semiconductor devices using transistors forming cells needing refreshing or charge regeneration, i.e. dynamic cells
- G11C11/4063—Auxiliary circuits, e.g. for addressing, decoding, driving, writing, sensing or timing
- G11C11/407—Auxiliary circuits, e.g. for addressing, decoding, driving, writing, sensing or timing for memory cells of the field-effect type
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C7/00—Arrangements for writing information into, or reading information out from, a digital store
- G11C7/22—Read-write [R-W] timing or clocking circuits; Read-write [R-W] control signal generators or management
- G11C7/222—Clock generating, synchronizing or distributing circuits within memory device
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C7/00—Arrangements for writing information into, or reading information out from, a digital store
- G11C7/10—Input/output [I/O] data interface arrangements, e.g. I/O data control circuits, I/O data buffers
- G11C7/1072—Input/output [I/O] data interface arrangements, e.g. I/O data control circuits, I/O data buffers for memories with random access ports synchronised on clock signal pulse trains, e.g. synchronous memories, self timed memories
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K5/00—Manipulating of pulses not covered by one of the other main groups of this subclass
- H03K5/00006—Changing the frequency
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K5/00—Manipulating of pulses not covered by one of the other main groups of this subclass
- H03K5/13—Arrangements having a single output and transforming input signals into pulses delivered at desired time intervals
- H03K5/135—Arrangements having a single output and transforming input signals into pulses delivered at desired time intervals by the use of time reference signals, e.g. clock signals
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03L—AUTOMATIC CONTROL, STARTING, SYNCHRONISATION OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES
- H03L7/00—Automatic control of frequency or phase; Synchronisation
Definitions
- the present invention relates to an integrated circuit device, and more particularly, to a clock generating circuit for generating a clock signal synchronizing with a reference signal.
- a synchronous dynamic random access memory includes a clock generating circuit for generating an internal clock signal synchronizing with an external clock signal. Since many operations of an SDRAM including data input/output are with reference to the internal clock signal, the clock signal generating circuit which generates the internal clock signal is an important circuit to SDRAM.
- a phase-locked loop (PLL) or a delay-locked loop (DLL) is used in SDRAMs to synchronize an internal clock signal with an external clock signal.
- PLL or DLL uses a feedback circuit within SDRAM and generates an internal clock signal which derives from and synchronizes with an external clock signal.
- SDRAM employs a mode for minimizing the power consumption by reducing the supply of power when an input/output operation is not performed.
- a state in which the supply of power is reduced is referred to as a power down mode or a sleep mode, and a mode in which an input/output operation is performed is referred to as an activated mode.
- an SDRAM commences after the PLL or DLL reaches stabilization, when changing from a power down mode to an activated mode.
- An internal clock signal generated by the stabilized PLL or DLL is used to clock and synchronize internal circuits. Since PLL or DLL includes a feedback circuit, it usually takes from several hundreds of cycles through several thousands of cycles to stabilize the PLL or DLL. The time required for stabilizing PLL or DLL greatly affects the operating speed of an entire system.
- circuit designers have sought effective clock synchronization methods which change from a power down mode to an activated mode rapidly and consume a small amount of power, especially in power down mode.
- One of these methods is a synchronous mirror delay method, which duplicates internal electrostatic capacity of an SDRAM and delay time with respect to the characteristics of an input/output multiplexer within SDRAM by using an internal mirror delay circuit. With the copied capacity and delay time, the synchronous mirror delay method controls the input/output signal of SDRAM.
- a synchronous mirror delay method is disclosed by Saeki et al. in “A 2.5 ns Clock Access 250 MHz 256 Mb SDRAM With a Synchronous Mirror Delay”, IEEE J. Solid State Circuits, vol. 31, pp. 1656-1664, November 1996. According to this synchronous mirror delay method, the time required for the DLL of a clock generator to be stabilized is reduced to two cycles.
- the synchronous mirror delay method disclosed by Saeki et al. is implemented by a digital circuit, which digitizes and duplicates the internal electrostatic capacity of SDRAM and a delay time based on characteristics of an input/output multiplexer within an SDRAM. However, during a digitizing process, quantization errors may occur.
- a method to solve the above described problem is disclosed in the commonly assigned Korean Patent Application No. 98-34882, entitled “Internal Clock Generating Circuit with Analog Pumping Structure.”
- the disclosure in its entirety of Korean Patent Application No. 34882 is incorporated by reference herein.
- the invention disclosed in Korean Patent Application No. 34882 eliminates the delay error of an output clock due to a quantization error.
- the mirror delay circuit disclosed in the Korea Patent Application No. 34882 may not accurately mirror a desired delay time when there are changes in fabrication conditions such as temperature and pressure.
- the difference between the delay time of a mirror delay circuit and the delay time of an actual circuit may cause synchronization error of an internal clock signal against an external clock signal, and may further decrease the operating speed of the SDRAM.
- a clock generating circuit which generates an internal clock signal synchronizing with an external clock signal within a short time, wherein the clock generating circuit rapidly eliminates the error between the internal clock signal and the external clock signal which may occur between the delay time of a mirror delay circuit and the delay time of an actual circuit.
- a clock generating circuit for generating an internal clock signal synchronizing with an external clock signal.
- the clock generating circuit includes a controller for receiving the internal clock signal and the reference clock signal and generating first and second divided signals, wherein the first and the second divided signals have different phases and a 1/(2N) (N is a natural number) frequency of the reference clock signal; a linear current pump for generating first and second pumping signals in response to the first and the second divided signals, wherein each of the first and the second pumping signals has a level-up time rate and a level-down time rate which are the same; and a fast comparator for providing a pre-clock signal for generating the internal clock signal, in response to the first and the second pumping signals, wherein the pre-clock signal responds to a voltage level based on at least one of the first and the second pumping signals with respect to a predetermined reference voltage.
- a clock generating circuit for generating an internal clock signal synchronizing with a reference clock signal.
- the clock generating circuit includes a controller for receiving the internal clock signal and the reference clock signal and generating first and second divided signals, wherein the first and the second divided signals have different phases and a 1/(2N) (N is a natural number) frequency of the reference clock signal; a linear current pump for generating first and second pumping signals in response to the first and the second divided signals, wherein each of the first and the second pumping signals has a level-up time rate and a level-down time rate which are the same; a fast comparator for providing a pre-clock signal in response to the first and the second pumping signals, wherein the pre-clock signal responds to a voltage level based on at least one of the first and the second pumping signals with respect to a reference voltage; a selection delay unit for delaying the pre-clock signal by a predetermined variable delay time to generate the internal clock signal; and a delay regulator for providing
- FIG. 1 is a block diagram of a clock generating circuit according to an embodiment of the present invention
- FIG. 2 is a block diagram of the controller of FIG. 1;
- FIG. 3 is a diagram of a linear current pump of FIG. 1;
- FIG. 4 is a detailed circuit diagram of the first pumping unit of FIG. 3;
- FIG. 5 is a detailed circuit diagram of the second pumping unit of FIG. 3;
- FIG. 6 is a detailed circuit diagram of the fast comparator of FIG. 1;
- FIG. 7 is a timing chart of main terminals of the clock generating circuit of FIG. 1;
- FIG. 8 is a block diagram of a clock generating circuit according to another embodiment of the present invention.
- FIG. 9 is a block diagram of the duty controller of FIG. 8.
- FIG. 10 is a detailed circuit diagram of the duty fast comparator of FIG. 8.
- a clock generating circuit 10 includes a controller 11 , a linear current pump 13 , a fast comparator 15 and a driver 17 .
- the controller 11 receives an internal clock signal KCLK and an external clock signal ECLK and generates first and second divided signals VDIV 1 and VDIV 2 and first and second inverted divided signals VDIV 1 B and VDIV 2 B.
- the first and second inverted divided signal VDIV 1 B and VDIV 2 B are the inverted signals of the first and second divided signals VDIV 1 and VDIV 2 .
- the first and second divided signals VDIV 1 and VDIV 2 have different phases but have the same frequency.
- the frequency of the first and second divided signals VDIV 1 and VDIV 2 is half the frequency of the external clock signal ECLK.
- the linear current pump 13 generates first and second pumping signals VPUMPL and VPUMPR in response to the first and second divided signals VDIV 1 and VDIV 2 .
- the first and second pumping signals VPUMPL and VPUMPR have the same level-up time rate and the same level-down time rate.
- the level-up time rate indicates a rate at which a voltage level rises
- the level-down time rate indicates a rate at which a voltage level drops.
- the fast comparator 15 provides a pre-clock signal JCLK in response to the first and second pumping signals VPUMPL and VPUMPR.
- a reference voltage VREF not shown
- the pre-clock signal JCLK is activated to a “high” level.
- the pre-clock signal JCLK is inputted to and driven by the driver 17 before outputting from the driver 17 as the internal clock signal KCLK.
- the internal clock signal KCLK outputted from the drive 17 is delayed from the pre-clock signal JCLK by a predetermined driving delay time dtd (see FIG. 7).
- a toggle control signal TOG_CNT will be described below with reference to FIG. 2.
- FIG. 2 is a detailed diagram of the controller 11 of FIG. 1.
- the controller 11 includes a buffer 21 , a mirror delay circuit 23 , a multiplexer (MUX) 25 , a first divider 27 and a second divider 29 .
- MUX multiplexer
- the external clock signal ECLK inputted from the outside is buffered by the buffer 21 and generated as a reference clock signal ICLK.
- the external clock signal ECLK may directly be the reference clock signal ICLK without the buffer 21 .
- the mirror delay circuit 23 delays the reference clock signal ICLK by a predetermined mirror delay time dtm (see FIG. 7) to generate a delay clock signal IDCLK.
- the mirror delay time dtm is equal to the driving delay time dtd.
- the driving delay time dtd and the mirror delay time dtm may be different due to variations in fabrication conditions such as temperature and pressure. Accordingly, it is assumed that the driving delay time dtd is different from the mirror delay time dtm in this specification.
- the MUX 25 selects one of the delay clock signal IDCLK and the internal clock signal KCLK in response to the toggle control signal TOG_CNT and outputs the selected signal to the first divider 27 .
- the toggle control signal TOG_CNT is maintained at a “low” level, the MUX 25 selects and outputs the delay clock signal IDCLK when TOG_CNT is low.
- the toggle control signal TOG_CNT changes into a “high” level, the MUX 25 selects and outputs the internal clock signal KCLK when TOG_CONT is high.
- the first divider 27 divides the frequency of the delay clock signal IDCLK or the frequency of the internal clock signal KCLK by 2 to generate the first divided signal VDIV 1 and the first inverted divided signal VDIV 1 B.
- the first divider 27 is a T flip-flop (TFF) which has the delay clock signal IDCLK or the internal clock signal KCLK as an input and generates the first divided signal VDIV 1 and the first inverted divided signal VDIV 1 B as output signals.
- TFF T flip-flop
- the second divider 29 divides the frequency of the reference clock signal ICLK by 2 to generate the second divided signal VDIV 2 and the second inverted divided signal VDIV 2 B.
- the second divider 29 is a T flip-flop (TFF) which has the reference clock signal ICLK as an input and generates the second divided signal VDIV 2 and the second inverted divided signal VDIV 2 B as output signals.
- TFF T flip-flop
- FIG. 3 is a diagram of the linear current pump 13 of FIG. 1.
- the linear current pump 13 includes first and second pumping units 31 and 33 .
- the first pumping unit 31 provides the first pumping signal VPUMPL and a first auxiliary signal VAUXL in response to the first and second divided signals VDIV 1 and VDIV 2 .
- the second pumping unit 33 provides the second pumping signal VPUMPR and a second auxiliary signal VAUXR in response to the first and second divided signals VDIV 1 and VDIV 2 .
- FIG. 4 is a detailed circuit diagram of the first pumping unit 31 of FIG. 3.
- the first pumping unit 31 includes a pumping signal terminal N 46 , switching transistors 43 , 45 and 47 , a current source 41 , a current sink 49 and a capacitor C 1 .
- the pumping signal terminal N 46 provides the first pumping signal VPUMPL.
- the first pumping signal VPUMPL is pre-charged to a voltage level equal to a reference voltage VREF in a section in which the second divided signal VDIV 2 is activated to a “high” level and the first divided signal VDIV 1 is deactivated to a “low” level (the first inverted divided signal VDIV 1 B is “high”).
- the switching transistor 45 is turned on so that the pumping signal terminal N 46 is connected to the reference voltage VREF. Accordingly, the voltage level of the first pumping signal VPUMPL becomes equal to the reference voltage VREF. In this case, the first auxiliary signal VAUXL becomes “high”.
- the current source 41 supplies current from supply voltage VCC to the pumping signal terminal N 46 .
- the switching transistor 43 is turned on so that the pumping signal terminal N 46 is connected to the current source 43 . Accordingly, the voltage level of the first pumping signal VPUMPL rises. In this case, the voltage level of the first pumping signal VPUMPL rises at a first time changing rate.
- the current sink 49 discharges the current from the pumping signal terminal N 46 to ground voltage VSS.
- the switching transistor 47 is turned on so that the pumping signal terminal N 46 is coupled to the current sink 49 .
- the discharge rate of the current sink 49 is equal to the supply rate of the current source 41 . Accordingly, the voltage level of the first pumping signal VPUMPL falls at the first time changing rate.
- the capacitor C 1 is provided between the pumping signal terminal N 46 and the ground voltage VSS to prevent the voltage level of the first pumping signal VPUMPL from rapidly rising or falling.
- FIG. 5 is a detailed circuit diagram of the second pumping unit 33 of FIG. 3.
- the second pumping unit 33 includes a pumping signal terminal N 56 , switching transistors 53 , 55 and 57 , a current source 51 , a current sink 59 and a capacitor C 2 .
- the pumping signal terminal N 56 provides the second pumping signal VPUMPR.
- the second pumping signal VPUMPR is pre-charged to a voltage level equal to a reference voltage VREF in a section in which the first divided signal VDIV 1 is activated to a “high” level and the second divided signal VDIV 2 is deactivated to a “low” level (the second inverted divided signal VDIV 2 B is “high”).
- the switching transistor 55 is turned on so that the pumping signal terminal N 56 is coupled to the reference voltage VREF. Accordingly, the voltage level of the second pumping signal VPUMPR becomes equal to the reference voltage VREF. In this case, the second auxiliary signal VAUXR goes to “high”.
- the current source 51 supplies current from supply voltage VCC to the pumping signal terminal N 56 .
- the switching transistor 53 is turned on so that the pumping signal terminal N 56 is coupled to the current source 51 . Accordingly, the voltage level of the second pumping signal VPUMPR rises. In this case, the voltage level of the second pumping signal VPUMPR rises at a second time changing rate.
- the current sink 59 discharges the current from the pumping signal terminal N 56 to ground voltage VSS.
- the switching transistor 57 is turned on so that the pumping signal terminal N 56 is coupled to the current sink 59 .
- the discharge rate of the current sink 59 is equal to the supply rate of the current source 51 . Accordingly, the voltage level of the second pumping signal VPUMPR falls at the second time changing rate.
- the first time changing rate is identical to the second time changing rate.
- the capacitor C 2 is provided between the pumping signal terminal N 56 and the ground voltage VSS to prevent the voltage level of the second pumping signal VPUMPR from rapidly rising or falling.
- FIG. 6 is a detailed circuit diagram of the fast comparator 15 of FIG. 1.
- the fast comparator 15 includes a first comparator 61 , second comparator 63 and a logic operation unit 65 .
- the first comparator 61 compares the voltage level of the first pumping signal VPUMPL with the reference voltage VREF to generate a first comparison signal VCOML.
- the first comparison signal VCOML goes to a high voltage level.
- the first comparison signal VCOML goes to a low voltage level.
- the first auxiliary signal VAUXL is “high” while the first pumping signal VPUMPL is being pre-charged to the reference voltage VREF. Accordingly, while the voltage level of the first pumping signal VPUMPL is being the reference voltage VREF, an NMOS transistor 61 a is turned on and the voltage level of the first comparison signal VCOML is prevented from being unstable.
- the second comparator 63 has similar configuration and operational effect to the first comparator 61 . Thus, the description of the configuration and operational effect of the second comparator 63 is omitted.
- the difference between the first and second comparators 61 and 63 is that the second comparator 63 compares the voltage level of the second pumping signal VPUMPR with the reference voltage VREF to generate a second comparison signal VCOMR.
- the logic operation unit 65 compares the first comparison signal VCOML with the second comparison signal VCOMR to generate the pre-clock signal JCLK.
- the logic operation unit 65 can be implemented by a NAND gate. Therefore, when the voltage level of the first or second pumping signal VPUMPL or VPUMPR is lower than the reference voltage VREF, the pre-clock signal JCLK is activated to a “high” level.
- FIG. 7 is a timing chart of main terminals of the clock generating circuit of FIG. 1. And the operational effect of the clock generating circuit 10 of FIG. 1 is described.
- the delay clock signal IDCLK and the reference clock signal ICLK are divided by 2, respectively. And thus, the first divided signal VDIV 1 and the second divided signal VDIV 2 are generated.
- the pre-clock signal JCLK maintains a “high” level while the voltage level of the first or second pumping signal VPUMPL or VPUMPR is being lower than the reference voltage VREF. Accordingly, the width of a section in which the pre-clock signal JCLK maintains the “high” level is identical to the width of the mirror delay time dtm of the mirror delay circuit 23 of FIG. 2. Hence, as shown in FIG. 7, the falling edge of the pre-clock signal JCLK is locked to the rising edge of the reference clock signal ICLK. The locking occurs about every two cycle.
- the pre-clock signal JCLK is delayed by the driving delay time dtd by the driver 17 and then generated as the internal clock signal KCLK.
- the driving delay time dtd is the same as the mirror delay time dtm, the rising edge of the internal clock signal KCLK can be accurately coincident with the rising edge of the reference clock signal ICLK.
- the driving delay time dtd is different from the mirror delay time dtm, the rising edge of the internal clock signal KCLK cannot be coincident with the rising edge of the reference clock signal ICLK.
- the toggle control signal TOG_CNT is activated to a “high” level.
- the operational effect of the clock generating circuit 10 in a section T 2 (the second stage of operation) in which the toggle control signal TOG_CNT is being activated to the “high” level is described below.
- the first divider 27 divides the internal clock signal KCLK instead the delay clock signal IDCLK by 2 to generate the first divided signal VDIV 1 . Then, a section in which the first or second pumping signal VPUMPL or VPUMPR is pre-charged to the reference voltage VREF corresponding to the driving delay time dtd. A section in which voltage level of the first or second pumping signal VPUMPL or VPUMPR is lower than the reference voltage VREF also corresponds to the driving delay time dtd.
- the pre-clock signal JCLK is “high” prior to the reference clock signal ICLK by the driving delay time dtd and goes to “low” at the rising edge of the reference clock signal ICLK. Therefore, the rising edge of the internal clock signal KCLK which is delayed by the driving delay time dtd from the pre-clock signal JCLK can be accurately coincident with the rising edge of the reference clock signal ICLK.
- the width of a section in which the internal clock signal KCLK is activated to a “high” level is the same as the driving delay time dtd by the driver 17 of FIG. 1. Accordingly, a duty cycle of the internal clock signal KCLK is determined in accordance with the driving delay time dtd by the driver 17 .
- the driving delay time dtd may vary according to the change in fabrication conditions such as temperature and pressure. Therefore, to generate the internal clock signal KCLK having an accurate duty, a circuit for regulating the driving delay time dtd is required.
- An example including the circuit for regulating the driving delay time dtd is shown in FIG. 8.
- FIG. 8 is a schematic diagram of a clock generating circuit according to another embodiment of the present invention.
- the clock generating circuit 80 includes a selection delay unit 86 for regulating a delay time from a pre-clock signal JCLK to an internal clock signal KCLK and a delay regulator 84 in addition to a controller 81 , a linear current pump 83 , a fast comparator 85 and a driver 87 .
- the controller 81 , the linear current pump 83 , the fast comparator 85 and the driver 87 have the similar configuration and operational effects as those of the corresponding elements of the clock generating circuit 10 in FIG. 1. Thus, the description of the configuration and operational effects of these same elements is omitted.
- the same reference characters in the embodiment in FIG. 1 also shown in FIG. 8 include an external clock signal ECLK, an internal clock signal KCLK and a pre-clock signal JCLK.
- FIG. 8 differs from the embodiment of FIG. 1 by further including the duty reference signal generator 82 , the delay regulator 84 and the selection delay unit 86 .
- the selection delay unit 86 delays the pre-clock signal JCLK by a variable delay time dtv and provides the delay to the driver 87 .
- the variable delay time dtv is controlled by a duty control signal DUTY_CNT.
- the delay regulator 84 receives a duty reference signal HCLK and the pre-clock signal JCLK and generates the duty control signal DUTY_CNT.
- the delay regulator 84 provides the duty control signal DUTY_CNT to the selection delay unit 86 to regulate the variable delay time dtv such that the duty ratio of the internal clock signal KCLK is identical to the duty ratio of the duty reference signal HCLK.
- the selection delay unit 86 and the delay regulator 84 can be easily implemented by those skilled in the art. Therefore, the description of their configurations is omitted.
- the duty reference signal generator 82 receives the external clock signal ECLK and generates the duty reference signal HCLK.
- the duty reference signal generator 82 includes a duty controller 82 a , a duty linear current pump 82 b and a duty fast comparator 82 c.
- the duty controller 82 a and the duty linear current pump 82 b have similar configuration and operational effect as the controller 11 and the linear current pump 13 of FIG. 1, respectively.
- the duty controller 82 a and the duty linear current pump 82 b will be described focusing on the differences.
- the duty controller 82 a receives the external clock signal ECLK and generates first and second duty divided signals DVDIV 1 and DVDIV 2 .
- the duty controller 82 a will be described in more detail with reference to FIG. 9.
- FIG. 9 is a detailed diagram of the duty controller 82 a of FIG. 8.
- the duty controller 82 a is similar to the controller 11 of FIG. 2.
- the first divider 27 of the controller 1 divides one signal, which is selected from the delay clock signal IDCLK and the internal clock signal KCLK in response to the toggle control signal TOG_CNT, by 2
- a first divider 97 of the duty controller 82 a divides only a delay clock signal DIDCLK by 2.
- the duty linear current pump 82 b generates first and second duty pump signals DVPUMPL and DVPUMPR in response to the first and second duty divided signals DVDIV 1 and DVDIV 2 .
- the duty linear current pump 82 b has similar configuration and operational effect as the linear current pump 13 depicted in FIGS. 3 through 5 and thus the description of configuration and operational effect of the duty linear current pump 82 b is omitted.
- the duty fast comparator 82 c generates the duty reference signal HCLK in response to the first and second pumping signals DVPUMPL and DVPUMPR.
- the configuration of the duty fast comparator 82 c will be described in more detail with reference to FIG. 10.
- FIG. 10 is a detailed circuit diagram of the duty fast comparator 82 c of FIG. 8.
- the duty fast comparator 82 c includes a first comparator 1001 , a second comparator 1003 and a logic operation unit 1005 .
- the first comparator 1001 receives the first duty pumping signal DVPUMPL via the negative input terminal and the second duty pumping signal DVPUMPR via the positive input terminal and compares the voltage levels of them to generate a first duty comparison signal DVCOM 1 .
- the second comparator 1003 receives the first duty pumping signal DVPUMPL via the positive input terminal and the second duty pumping signal DVPUMPR via the negative input terminal and compares the voltage levels of them to generate a second duty comparison signal DVCOM 2 .
- the logic operation unit 1005 is enabled when the delay clock signal DIDCLK is “low”.
- the logic operation unit 1005 performs an OR operation on the first and second duty-comparison signals DVCOM 1 and DVCOM 2 to provide the duty reference signal HCLK.
- the logic operation unit 1005 includes two AND gates 1005 a and 1005 b and an OR gate 1005 c .
- the duty reference signal HCLK has the same duty ratio as the external clock signal ECLK.
- the duty ratio of the duty reference signal HCLK is 50%.
- the delay regulator 84 compares the duty ratio of the duty reference signal HCLK and the duty ratio of the pre-clock signal JCLK thereto provide the duty control signal DUTY_CNT to the selection delay unit 86 .
- the duty control signal DUTY_CNT controls the selection delay unit 86 so as to decrease the delay time.
- the duty control signal DUTY_CNT controls the selection delay unit 86 so as to increase the delay time.
- the duty ratio of the internal clock signal KCLK can be identical to the duty ratio of the external clock signal ECLK.
- an internal clock signal synchronizing with an external clock signal or a reference clock signal within a short time can be provided.
- the error can be rapidly removed.
- the duty ratio of the internal clock signal can be identical to the duty ratio of the external clock signal or the reference clock signal.
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Abstract
Description
- 1. Field of the Invention
- The present invention relates to an integrated circuit device, and more particularly, to a clock generating circuit for generating a clock signal synchronizing with a reference signal.
- 2. Description of the Related Art
- Usually, a synchronous dynamic random access memory (SDRAM) includes a clock generating circuit for generating an internal clock signal synchronizing with an external clock signal. Since many operations of an SDRAM including data input/output are with reference to the internal clock signal, the clock signal generating circuit which generates the internal clock signal is an important circuit to SDRAM.
- Conventionally, a phase-locked loop (PLL) or a delay-locked loop (DLL) is used in SDRAMs to synchronize an internal clock signal with an external clock signal. PLL or DLL uses a feedback circuit within SDRAM and generates an internal clock signal which derives from and synchronizes with an external clock signal.
- Recently, SDRAM employs a mode for minimizing the power consumption by reducing the supply of power when an input/output operation is not performed. A state in which the supply of power is reduced is referred to as a power down mode or a sleep mode, and a mode in which an input/output operation is performed is referred to as an activated mode.
- Typically, the operation of an SDRAM commence after the PLL or DLL reaches stabilization, when changing from a power down mode to an activated mode. An internal clock signal generated by the stabilized PLL or DLL is used to clock and synchronize internal circuits. Since PLL or DLL includes a feedback circuit, it usually takes from several hundreds of cycles through several thousands of cycles to stabilize the PLL or DLL. The time required for stabilizing PLL or DLL greatly affects the operating speed of an entire system.
- Hence, circuit designers have sought effective clock synchronization methods which change from a power down mode to an activated mode rapidly and consume a small amount of power, especially in power down mode. One of these methods is a synchronous mirror delay method, which duplicates internal electrostatic capacity of an SDRAM and delay time with respect to the characteristics of an input/output multiplexer within SDRAM by using an internal mirror delay circuit. With the copied capacity and delay time, the synchronous mirror delay method controls the input/output signal of SDRAM.
- A synchronous mirror delay method is disclosed by Saeki et al. in “A 2.5 ns Clock Access 250 MHz 256 Mb SDRAM With a Synchronous Mirror Delay”, IEEE J. Solid State Circuits, vol. 31, pp. 1656-1664, November 1996. According to this synchronous mirror delay method, the time required for the DLL of a clock generator to be stabilized is reduced to two cycles.
- The synchronous mirror delay method disclosed by Saeki et al. is implemented by a digital circuit, which digitizes and duplicates the internal electrostatic capacity of SDRAM and a delay time based on characteristics of an input/output multiplexer within an SDRAM. However, during a digitizing process, quantization errors may occur.
- A method to solve the above described problem is disclosed in the commonly assigned Korean Patent Application No. 98-34882, entitled “Internal Clock Generating Circuit with Analog Pumping Structure.” The disclosure in its entirety of Korean Patent Application No. 34882 is incorporated by reference herein. The invention disclosed in Korean Patent Application No. 34882 eliminates the delay error of an output clock due to a quantization error.
- However, even the mirror delay circuit disclosed in the Korea Patent Application No. 34882 may not accurately mirror a desired delay time when there are changes in fabrication conditions such as temperature and pressure. The difference between the delay time of a mirror delay circuit and the delay time of an actual circuit may cause synchronization error of an internal clock signal against an external clock signal, and may further decrease the operating speed of the SDRAM.
- To solve the above problems, it is an objective of the present invention to provide a clock generating circuit which generates an internal clock signal synchronizing with an external clock signal within a short time, wherein the clock generating circuit rapidly eliminates the error between the internal clock signal and the external clock signal which may occur between the delay time of a mirror delay circuit and the delay time of an actual circuit.
- Accordingly, to achieve the above objective, there is provided a clock generating circuit for generating an internal clock signal synchronizing with an external clock signal. The clock generating circuit includes a controller for receiving the internal clock signal and the reference clock signal and generating first and second divided signals, wherein the first and the second divided signals have different phases and a 1/(2N) (N is a natural number) frequency of the reference clock signal; a linear current pump for generating first and second pumping signals in response to the first and the second divided signals, wherein each of the first and the second pumping signals has a level-up time rate and a level-down time rate which are the same; and a fast comparator for providing a pre-clock signal for generating the internal clock signal, in response to the first and the second pumping signals, wherein the pre-clock signal responds to a voltage level based on at least one of the first and the second pumping signals with respect to a predetermined reference voltage.
- In another embodiment, there is provided a clock generating circuit for generating an internal clock signal synchronizing with a reference clock signal. The clock generating circuit includes a controller for receiving the internal clock signal and the reference clock signal and generating first and second divided signals, wherein the first and the second divided signals have different phases and a 1/(2N) (N is a natural number) frequency of the reference clock signal; a linear current pump for generating first and second pumping signals in response to the first and the second divided signals, wherein each of the first and the second pumping signals has a level-up time rate and a level-down time rate which are the same; a fast comparator for providing a pre-clock signal in response to the first and the second pumping signals, wherein the pre-clock signal responds to a voltage level based on at least one of the first and the second pumping signals with respect to a reference voltage; a selection delay unit for delaying the pre-clock signal by a predetermined variable delay time to generate the internal clock signal; and a delay regulator for providing a duty control signal for controlling the duty ratio of the internal clock signal to the selection delay unit.
- The above objective and advantages of the present invention will become more apparent by describing in detail a preferred embodiment thereof with reference to the attached drawings in which:
- FIG. 1 is a block diagram of a clock generating circuit according to an embodiment of the present invention;
- FIG. 2 is a block diagram of the controller of FIG. 1;
- FIG. 3 is a diagram of a linear current pump of FIG. 1;
- FIG. 4 is a detailed circuit diagram of the first pumping unit of FIG. 3;
- FIG. 5 is a detailed circuit diagram of the second pumping unit of FIG. 3;
- FIG. 6 is a detailed circuit diagram of the fast comparator of FIG. 1;
- FIG. 7 is a timing chart of main terminals of the clock generating circuit of FIG. 1;
- FIG. 8 is a block diagram of a clock generating circuit according to another embodiment of the present invention;
- FIG. 9 is a block diagram of the duty controller of FIG. 8; and
- FIG. 10 is a detailed circuit diagram of the duty fast comparator of FIG. 8.
- Referring to FIG. 1, a
clock generating circuit 10 according to an embodiment of the present invention includes acontroller 11, a linearcurrent pump 13, afast comparator 15 and adriver 17. - The
controller 11 receives an internal clock signal KCLK and an external clock signal ECLK and generates first and second divided signals VDIV1 and VDIV2 and first and second inverted divided signals VDIV1B and VDIV2B. The first and second inverted divided signal VDIV1B and VDIV2B are the inverted signals of the first and second divided signals VDIV1 and VDIV2. The first and second divided signals VDIV1 and VDIV2 have different phases but have the same frequency. The frequency of the first and second divided signals VDIV1 and VDIV2 is half the frequency of the external clock signal ECLK. - The linear
current pump 13 generates first and second pumping signals VPUMPL and VPUMPR in response to the first and second divided signals VDIV1 and VDIV2. The first and second pumping signals VPUMPL and VPUMPR have the same level-up time rate and the same level-down time rate. The level-up time rate indicates a rate at which a voltage level rises, and the level-down time rate indicates a rate at which a voltage level drops. - The
fast comparator 15 provides a pre-clock signal JCLK in response to the first and second pumping signals VPUMPL and VPUMPR. When the voltage level of the first or second pumping signal VPUMPL or VPUMPR is lower than a reference voltage VREF (not shown), the pre-clock signal JCLK is activated to a “high” level. - According to the embodiment, the pre-clock signal JCLK is inputted to and driven by the
driver 17 before outputting from thedriver 17 as the internal clock signal KCLK. The internal clock signal KCLK outputted from thedrive 17 is delayed from the pre-clock signal JCLK by a predetermined driving delay time dtd (see FIG. 7). A toggle control signal TOG_CNT will be described below with reference to FIG. 2. - FIG. 2 is a detailed diagram of the
controller 11 of FIG. 1. Referring to FIG. 2, thecontroller 11 includes abuffer 21, amirror delay circuit 23, a multiplexer (MUX) 25, afirst divider 27 and asecond divider 29. - The external clock signal ECLK inputted from the outside is buffered by the
buffer 21 and generated as a reference clock signal ICLK. Alternatively, the external clock signal ECLK may directly be the reference clock signal ICLK without thebuffer 21. - The
mirror delay circuit 23 delays the reference clock signal ICLK by a predetermined mirror delay time dtm (see FIG. 7) to generate a delay clock signal IDCLK. Preferably, the mirror delay time dtm is equal to the driving delay time dtd. However, the driving delay time dtd and the mirror delay time dtm may be different due to variations in fabrication conditions such as temperature and pressure. Accordingly, it is assumed that the driving delay time dtd is different from the mirror delay time dtm in this specification. - The
MUX 25 selects one of the delay clock signal IDCLK and the internal clock signal KCLK in response to the toggle control signal TOG_CNT and outputs the selected signal to thefirst divider 27. At the initial stage of operation, the toggle control signal TOG_CNT is maintained at a “low” level, theMUX 25 selects and outputs the delay clock signal IDCLK when TOG_CNT is low. After predetermined clock cycles (for example, 4 clock cycles) from the beginning of the first stage of operation, the toggle control signal TOG_CNT changes into a “high” level, theMUX 25 selects and outputs the internal clock signal KCLK when TOG_CONT is high. - The
first divider 27 divides the frequency of the delay clock signal IDCLK or the frequency of the internal clock signal KCLK by 2 to generate the first divided signal VDIV1 and the first inverted divided signal VDIV1B. Preferably, thefirst divider 27 is a T flip-flop (TFF) which has the delay clock signal IDCLK or the internal clock signal KCLK as an input and generates the first divided signal VDIV1 and the first inverted divided signal VDIV1B as output signals. - The
second divider 29 divides the frequency of the reference clock signal ICLK by 2 to generate the second divided signal VDIV2 and the second inverted divided signal VDIV2B. Preferably, thesecond divider 29 is a T flip-flop (TFF) which has the reference clock signal ICLK as an input and generates the second divided signal VDIV2 and the second inverted divided signal VDIV2B as output signals. - FIG. 3 is a diagram of the linear
current pump 13 of FIG. 1. Referring to FIG. 3, the linearcurrent pump 13 includes first andsecond pumping units first pumping unit 31 provides the first pumping signal VPUMPL and a first auxiliary signal VAUXL in response to the first and second divided signals VDIV1 and VDIV2. Thesecond pumping unit 33 provides the second pumping signal VPUMPR and a second auxiliary signal VAUXR in response to the first and second divided signals VDIV1 and VDIV2. - FIG. 4 is a detailed circuit diagram of the
first pumping unit 31 of FIG. 3. Referring to FIG. 4, thefirst pumping unit 31 includes a pumping signal terminal N46, switchingtransistors current source 41, acurrent sink 49 and a capacitor C1. - The pumping signal terminal N46 provides the first pumping signal VPUMPL. The first pumping signal VPUMPL is pre-charged to a voltage level equal to a reference voltage VREF in a section in which the second divided signal VDIV2 is activated to a “high” level and the first divided signal VDIV1 is deactivated to a “low” level (the first inverted divided signal VDIV1B is “high”). In the section in which the second divided signal VDIV2 is “high” and the first divided signal VDIV1 is “low”, the switching
transistor 45 is turned on so that the pumping signal terminal N46 is connected to the reference voltage VREF. Accordingly, the voltage level of the first pumping signal VPUMPL becomes equal to the reference voltage VREF. In this case, the first auxiliary signal VAUXL becomes “high”. - The
current source 41 supplies current from supply voltage VCC to the pumping signal terminal N46. When the first and second divided signals VDIV1 and VDIV2 all become “high”, the switchingtransistor 43 is turned on so that the pumping signal terminal N46 is connected to thecurrent source 43. Accordingly, the voltage level of the first pumping signal VPUMPL rises. In this case, the voltage level of the first pumping signal VPUMPL rises at a first time changing rate. - The
current sink 49 discharges the current from the pumping signal terminal N46 to ground voltage VSS. When the second inverted divided signal VDIV2B becomes “high”, the switchingtransistor 47 is turned on so that the pumping signal terminal N46 is coupled to thecurrent sink 49. The discharge rate of thecurrent sink 49 is equal to the supply rate of thecurrent source 41. Accordingly, the voltage level of the first pumping signal VPUMPL falls at the first time changing rate. - The capacitor C1 is provided between the pumping signal terminal N46 and the ground voltage VSS to prevent the voltage level of the first pumping signal VPUMPL from rapidly rising or falling.
- FIG. 5 is a detailed circuit diagram of the
second pumping unit 33 of FIG. 3. Referring to FIG. 5, thesecond pumping unit 33 includes a pumping signal terminal N56, switchingtransistors current source 51, acurrent sink 59 and a capacitor C2. - The pumping signal terminal N56 provides the second pumping signal VPUMPR. The second pumping signal VPUMPR is pre-charged to a voltage level equal to a reference voltage VREF in a section in which the first divided signal VDIV1 is activated to a “high” level and the second divided signal VDIV2 is deactivated to a “low” level (the second inverted divided signal VDIV2B is “high”). In the section in which the first divided signal VDIV1 is “high” and the second divided signal VDIV2 is “low”, the switching
transistor 55 is turned on so that the pumping signal terminal N56 is coupled to the reference voltage VREF. Accordingly, the voltage level of the second pumping signal VPUMPR becomes equal to the reference voltage VREF. In this case, the second auxiliary signal VAUXR goes to “high”. - The
current source 51 supplies current from supply voltage VCC to the pumping signal terminal N56. When the first and second divided signals VDIV1 and VDIV2 all go to “low” (the first and second inverted divided signals VDIV1B and VDIV2B all go to “high”), the switchingtransistor 53 is turned on so that the pumping signal terminal N56 is coupled to thecurrent source 51. Accordingly, the voltage level of the second pumping signal VPUMPR rises. In this case, the voltage level of the second pumping signal VPUMPR rises at a second time changing rate. - The
current sink 59 discharges the current from the pumping signal terminal N56 to ground voltage VSS. When the second divided signal VDIV2 goes to “high”, the switchingtransistor 57 is turned on so that the pumping signal terminal N56 is coupled to thecurrent sink 59. The discharge rate of thecurrent sink 59 is equal to the supply rate of thecurrent source 51. Accordingly, the voltage level of the second pumping signal VPUMPR falls at the second time changing rate. - According to the preferred embodiment, the first time changing rate is identical to the second time changing rate. The capacitor C2 is provided between the pumping signal terminal N56 and the ground voltage VSS to prevent the voltage level of the second pumping signal VPUMPR from rapidly rising or falling.
- FIG. 6 is a detailed circuit diagram of the
fast comparator 15 of FIG. 1. Referring to FIG. 6, thefast comparator 15 includes afirst comparator 61,second comparator 63 and alogic operation unit 65. - The
first comparator 61 compares the voltage level of the first pumping signal VPUMPL with the reference voltage VREF to generate a first comparison signal VCOML. When the voltage level of the first pumping signal VPUMPL is higher than the reference voltage VREF, the first comparison signal VCOML goes to a high voltage level. On the other hand, when voltage level of the first pumping signal VPUMPL is lower than the reference voltage VREF, the first comparison signal VCOML goes to a low voltage level. - The first auxiliary signal VAUXL is “high” while the first pumping signal VPUMPL is being pre-charged to the reference voltage VREF. Accordingly, while the voltage level of the first pumping signal VPUMPL is being the reference voltage VREF, an
NMOS transistor 61 a is turned on and the voltage level of the first comparison signal VCOML is prevented from being unstable. - The
second comparator 63 has similar configuration and operational effect to thefirst comparator 61. Thus, the description of the configuration and operational effect of thesecond comparator 63 is omitted. The difference between the first andsecond comparators second comparator 63 compares the voltage level of the second pumping signal VPUMPR with the reference voltage VREF to generate a second comparison signal VCOMR. - The
logic operation unit 65 compares the first comparison signal VCOML with the second comparison signal VCOMR to generate the pre-clock signal JCLK. Thelogic operation unit 65 can be implemented by a NAND gate. Therefore, when the voltage level of the first or second pumping signal VPUMPL or VPUMPR is lower than the reference voltage VREF, the pre-clock signal JCLK is activated to a “high” level. - FIG. 7 is a timing chart of main terminals of the clock generating circuit of FIG. 1. And the operational effect of the
clock generating circuit 10 of FIG. 1 is described. - With regard to the operational effect of the
clock generating circuit 10 in a section T1 (the initial stage of the operation), the delay clock signal IDCLK and the reference clock signal ICLK are divided by 2, respectively. And thus, the first divided signal VDIV1 and the second divided signal VDIV2 are generated. The pre-clock signal JCLK maintains a “high” level while the voltage level of the first or second pumping signal VPUMPL or VPUMPR is being lower than the reference voltage VREF. Accordingly, the width of a section in which the pre-clock signal JCLK maintains the “high” level is identical to the width of the mirror delay time dtm of themirror delay circuit 23 of FIG. 2. Hence, as shown in FIG. 7, the falling edge of the pre-clock signal JCLK is locked to the rising edge of the reference clock signal ICLK. The locking occurs about every two cycle. - The pre-clock signal JCLK is delayed by the driving delay time dtd by the
driver 17 and then generated as the internal clock signal KCLK. When the driving delay time dtd is the same as the mirror delay time dtm, the rising edge of the internal clock signal KCLK can be accurately coincident with the rising edge of the reference clock signal ICLK. On the other hand, when the driving delay time dtd is different from the mirror delay time dtm, the rising edge of the internal clock signal KCLK cannot be coincident with the rising edge of the reference clock signal ICLK. - To eliminate the difference between the internal clock signal KCLK and the reference clock signal ICLK which may occur when the driving delay time dtd is not the same as the mirror delay time dtm, the toggle control signal TOG_CNT is activated to a “high” level. The operational effect of the
clock generating circuit 10 in a section T2 (the second stage of operation) in which the toggle control signal TOG_CNT is being activated to the “high” level is described below. - When the toggle control signal TOG_CNT goes to “high”, the
first divider 27 divides the internal clock signal KCLK instead the delay clock signal IDCLK by 2 to generate the first divided signal VDIV1. Then, a section in which the first or second pumping signal VPUMPL or VPUMPR is pre-charged to the reference voltage VREF corresponding to the driving delay time dtd. A section in which voltage level of the first or second pumping signal VPUMPL or VPUMPR is lower than the reference voltage VREF also corresponds to the driving delay time dtd. Accordingly, the pre-clock signal JCLK is “high” prior to the reference clock signal ICLK by the driving delay time dtd and goes to “low” at the rising edge of the reference clock signal ICLK. Therefore, the rising edge of the internal clock signal KCLK which is delayed by the driving delay time dtd from the pre-clock signal JCLK can be accurately coincident with the rising edge of the reference clock signal ICLK. - As described previously, the width of a section in which the internal clock signal KCLK is activated to a “high” level is the same as the driving delay time dtd by the
driver 17 of FIG. 1. Accordingly, a duty cycle of the internal clock signal KCLK is determined in accordance with the driving delay time dtd by thedriver 17. - The driving delay time dtd may vary according to the change in fabrication conditions such as temperature and pressure. Therefore, to generate the internal clock signal KCLK having an accurate duty, a circuit for regulating the driving delay time dtd is required. An example including the circuit for regulating the driving delay time dtd is shown in FIG. 8.
- FIG. 8 is a schematic diagram of a clock generating circuit according to another embodiment of the present invention. Referring to FIG. 8, the
clock generating circuit 80 includes aselection delay unit 86 for regulating a delay time from a pre-clock signal JCLK to an internal clock signal KCLK and adelay regulator 84 in addition to acontroller 81, a linearcurrent pump 83, afast comparator 85 and adriver 87. - In FIG. 8, the
controller 81, the linearcurrent pump 83, thefast comparator 85 and thedriver 87 have the similar configuration and operational effects as those of the corresponding elements of theclock generating circuit 10 in FIG. 1. Thus, the description of the configuration and operational effects of these same elements is omitted. The same reference characters in the embodiment in FIG. 1 also shown in FIG. 8 include an external clock signal ECLK, an internal clock signal KCLK and a pre-clock signal JCLK. - The embodiment of FIG. 8 differs from the embodiment of FIG. 1 by further including the duty
reference signal generator 82, thedelay regulator 84 and theselection delay unit 86. - The
selection delay unit 86 delays the pre-clock signal JCLK by a variable delay time dtv and provides the delay to thedriver 87. The variable delay time dtv is controlled by a duty control signal DUTY_CNT. - The
delay regulator 84 receives a duty reference signal HCLK and the pre-clock signal JCLK and generates the duty control signal DUTY_CNT. Thedelay regulator 84 provides the duty control signal DUTY_CNT to theselection delay unit 86 to regulate the variable delay time dtv such that the duty ratio of the internal clock signal KCLK is identical to the duty ratio of the duty reference signal HCLK. - The
selection delay unit 86 and thedelay regulator 84 can be easily implemented by those skilled in the art. Therefore, the description of their configurations is omitted. - The duty
reference signal generator 82 receives the external clock signal ECLK and generates the duty reference signal HCLK. The dutyreference signal generator 82 includes aduty controller 82 a, a duty linearcurrent pump 82 b and a dutyfast comparator 82 c. - According to the preferred embodiment, the
duty controller 82 a and the duty linearcurrent pump 82 b have similar configuration and operational effect as thecontroller 11 and the linearcurrent pump 13 of FIG. 1, respectively. Thus, theduty controller 82 a and the duty linearcurrent pump 82 b will be described focusing on the differences. - The
duty controller 82 a receives the external clock signal ECLK and generates first and second duty divided signals DVDIV1 and DVDIV2. Theduty controller 82 a will be described in more detail with reference to FIG. 9. - FIG. 9 is a detailed diagram of the
duty controller 82 a of FIG. 8. Referring to FIG. 9, theduty controller 82 a is similar to thecontroller 11 of FIG. 2. However, while thefirst divider 27 of thecontroller 1 divides one signal, which is selected from the delay clock signal IDCLK and the internal clock signal KCLK in response to the toggle control signal TOG_CNT, by 2, a first divider 97 of theduty controller 82 a divides only a delay clock signal DIDCLK by 2. - Referring back to FIG. 8, the duty linear
current pump 82 b generates first and second duty pump signals DVPUMPL and DVPUMPR in response to the first and second duty divided signals DVDIV1 and DVDIV2. The duty linearcurrent pump 82 b has similar configuration and operational effect as the linearcurrent pump 13 depicted in FIGS. 3 through 5 and thus the description of configuration and operational effect of the duty linearcurrent pump 82 b is omitted. - The duty
fast comparator 82 c generates the duty reference signal HCLK in response to the first and second pumping signals DVPUMPL and DVPUMPR. The configuration of the dutyfast comparator 82 c will be described in more detail with reference to FIG. 10. - FIG. 10 is a detailed circuit diagram of the duty
fast comparator 82 c of FIG. 8. Referring to FIG. 10, the dutyfast comparator 82 c includes a first comparator 1001, a second comparator 1003 and a logic operation unit 1005. The first comparator 1001 receives the first duty pumping signal DVPUMPL via the negative input terminal and the second duty pumping signal DVPUMPR via the positive input terminal and compares the voltage levels of them to generate a first duty comparison signal DVCOM1. The second comparator 1003 receives the first duty pumping signal DVPUMPL via the positive input terminal and the second duty pumping signal DVPUMPR via the negative input terminal and compares the voltage levels of them to generate a second duty comparison signal DVCOM2. - The logic operation unit1005 is enabled when the delay clock signal DIDCLK is “low”. The logic operation unit 1005 performs an OR operation on the first and second duty-comparison signals DVCOM1 and DVCOM2 to provide the duty reference signal HCLK. Preferably, the logic operation unit 1005 includes two AND gates 1005 a and 1005 b and an OR gate 1005 c. Accordingly, the duty reference signal HCLK has the same duty ratio as the external clock signal ECLK. Preferably, the duty ratio of the duty reference signal HCLK is 50%.
- Referring back to FIG. 8, the
delay regulator 84 compares the duty ratio of the duty reference signal HCLK and the duty ratio of the pre-clock signal JCLK thereto provide the duty control signal DUTY_CNT to theselection delay unit 86. When the duty ratio of the internal clock signal KCLK is larger than the duty ratio of the external clock signal ECLK, the duty control signal DUTY_CNT controls theselection delay unit 86 so as to decrease the delay time. On the other hand, when the duty ratio of the internal clock signal KCLK is smaller than the duty ratio of the external clock signal ECLK, the duty control signal DUTY_CNT controls theselection delay unit 86 so as to increase the delay time. In such processes, the duty ratio of the internal clock signal KCLK can be identical to the duty ratio of the external clock signal ECLK. - While this invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various modifications in form and details may be realized therein. For example, in this specification, a clock generating circuit for synchronizing the internal clock signal KCLK with the reference clock signal ICLK is disclosed. However, it is obvious to those skilled in the art that the internal clock signal KCLK can be synchronized with the external clock signal ECLK when, instead of the reference clock signal ICLK, the external clock signal ECLK is inputted to the
second divider 29 in thecontroller 11 of FIG. 2. Accordingly, the technical scope of the present invention should be defined by the spirit of the scope of the appended claims. - According to a clock generating circuit of the present invention, an internal clock signal synchronizing with an external clock signal or a reference clock signal within a short time can be provided. In addition, even though an error occurs between the delay time of a mirror delay circuit and the delay time of an actual circuit, the error can be rapidly removed. Moreover, the duty ratio of the internal clock signal can be identical to the duty ratio of the external clock signal or the reference clock signal.
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KR1019990066015A KR100335499B1 (en) | 1999-12-30 | 1999-12-30 | Clock generating circuit for compensating a delay difference using a closed loop synchronous mirror delay structure |
KR99-66015 | 1999-12-30 |
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US20010022522A1 true US20010022522A1 (en) | 2001-09-20 |
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US09/730,634 Expired - Lifetime US6437613B2 (en) | 1999-12-30 | 2000-12-06 | Clock generating circuit for compensation of delay difference using closed loop analog synchronous mirror delay structure |
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US20150177769A1 (en) * | 2013-12-19 | 2015-06-25 | SK Hynix Inc. | Voltage generation circuits and semiconductor devices including the same |
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KR100505636B1 (en) * | 2002-06-11 | 2005-08-04 | 삼성전자주식회사 | Analog synchronous mirror delay with duty cycle correction scheme and internal clock generator using the same |
US6839301B2 (en) * | 2003-04-28 | 2005-01-04 | Micron Technology, Inc. | Method and apparatus for improving stability and lock time for synchronous circuits |
US7362144B2 (en) * | 2003-07-31 | 2008-04-22 | Etron Technology, Inc. | Low jitter input buffer with small input signal swing |
US7095261B2 (en) * | 2004-05-05 | 2006-08-22 | Micron Technology, Inc. | Clock capture in clock synchronization circuitry |
US7078950B2 (en) * | 2004-07-20 | 2006-07-18 | Micron Technology, Inc. | Delay-locked loop with feedback compensation |
KR100632368B1 (en) * | 2004-11-23 | 2006-10-09 | 삼성전자주식회사 | Internal Clock Generation Circuit with Improved Locking Speed and Included Analog Synchronous Mirror Delay |
US7375558B2 (en) * | 2005-12-21 | 2008-05-20 | Integrated Device Technology, Inc. | Method and apparatus for pre-clocking |
US7277357B1 (en) * | 2006-06-05 | 2007-10-02 | Micron Technology, Inc. | Method and apparatus for reducing oscillation in synchronous circuits |
KR20170136304A (en) | 2016-06-01 | 2017-12-11 | 삼성전자주식회사 | Stacked semiconductor device and system including the same |
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US5359727A (en) * | 1987-04-27 | 1994-10-25 | Hitachi, Ltd. | Clock generator using PLL and information processing system using the clock generator |
JP2954773B2 (en) * | 1992-01-17 | 1999-09-27 | 株式会社日立製作所 | System clock phase control method |
US5233314A (en) * | 1992-03-27 | 1993-08-03 | Cyrix Corporation | Integrated charge-pump phase-locked loop circuit |
JP3415304B2 (en) * | 1994-11-11 | 2003-06-09 | 株式会社日立製作所 | Clock generation circuit and processor |
KR0138220B1 (en) * | 1994-12-30 | 1998-05-15 | 김주용 | Clock delay compensation and duty control apparatus |
JP3710845B2 (en) * | 1995-06-21 | 2005-10-26 | 株式会社ルネサステクノロジ | Semiconductor memory device |
JP3487532B2 (en) * | 1996-07-08 | 2004-01-19 | 株式会社東芝 | Data processing device, semiconductor storage device, and data processing method |
US5777498A (en) * | 1996-12-02 | 1998-07-07 | Sgs-Thomson Microelectronics, Inc. | Data compensation/resynchronization circuit for phase lock loops |
US6173432B1 (en) * | 1997-06-20 | 2001-01-09 | Micron Technology, Inc. | Method and apparatus for generating a sequence of clock signals |
US5926047A (en) * | 1997-08-29 | 1999-07-20 | Micron Technology, Inc. | Synchronous clock generator including a delay-locked loop signal loss detector |
US6081143A (en) * | 1997-09-26 | 2000-06-27 | Sun Microsystems, Inc. | Frequency comparison and generation in an integrated processor |
KR100303921B1 (en) * | 1997-11-21 | 2001-11-22 | 박종섭 | Dll circuit of semiconductor memory element |
KR100273279B1 (en) * | 1998-02-14 | 2000-12-15 | 김영환 | Clock signal generation circuit for synchronous memory |
JPH11353878A (en) * | 1998-04-07 | 1999-12-24 | Fujitsu Ltd | Semiconductor device |
KR100278658B1 (en) * | 1998-08-27 | 2001-01-15 | 윤종용 | Internal Clock Generation Circuit with Analog Pumping Structure |
JP2000163961A (en) * | 1998-11-26 | 2000-06-16 | Mitsubishi Electric Corp | Synchronous semiconductor integrated circuit device |
JP2000187981A (en) * | 1998-12-22 | 2000-07-04 | Mitsubishi Electric Corp | Synchronous semiconductor memory |
-
1999
- 1999-12-30 KR KR1019990066015A patent/KR100335499B1/en not_active IP Right Cessation
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US20150177769A1 (en) * | 2013-12-19 | 2015-06-25 | SK Hynix Inc. | Voltage generation circuits and semiconductor devices including the same |
US9335777B2 (en) * | 2013-12-19 | 2016-05-10 | SK Hynix Inc. | Voltage generation circuits and semiconductor devices including the same |
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US6437613B2 (en) | 2002-08-20 |
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