Patent Publication Number: US-2022224345-A1

Title: Differential signal skew calibration circuit and semiconductor memory

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is continuation of International Application PCT/CN2021/094240, filed on May 18, 2021, which claims priority to Chinese Patent Application No. 202010489144.3, filed with the CNIPA on Jun. 2, 2020, and entitled “Differential Signal Skew Calibration Circuit and Semiconductor Memory”. The contents of International Application PCT/CN2021/094240 and Chinese Patent Application No. 202010489144.3 are hereby incorporated by reference in their entireties. 
    
    
     TECHNICAL FIELD 
     The application relates to the technical field of semiconductor memories, and particularly to a differential signal skew calibration circuit and a semiconductor memory. 
     BACKGROUND 
     A Dynamic Random Access Memory (DRAM) is a semiconductor memory. In the related art, a skew of input differential signals is ensured in a DRAM through specially designed wiring on a Printed Circuit Board (PCB). 
     However, with the increase of the complexity of a DRAM system and a clock frequency, the wiring space of a PCB is becoming narrow, resulting in cost increase of the DRAM system. 
     SUMMARY 
     Based on this, it is necessary to provide a differential signal skew calibration circuit and a semiconductor memory for the problem of cost increase caused by narrowing of a wiring space of a PCB. 
     The application provides a differential signal skew calibration circuit, which may include a phase calibration circuit, a phase detection circuit, and a phase adjustment control circuit. 
     The phase calibration circuit may be configured to calibrate a phase of differential signals. 
     A first end of the phase detection circuit may be connected with an output end of the phase calibration circuit. The phase detection circuit may be configured to perform a preset logical operation on the differential signals to generate a phase difference pulse signal, and acquire a phase relationship of the differential signals according to the differential signals and the phase difference pulse signal. 
     A first end of the phase adjustment control circuit may be connected with a second end of the phase detection circuit, a second end may be connected with a control end of the phase calibration circuit. The phase adjustment control circuit may be configured to receive the phase relationship, generate a phase calibration control instruction according to the phase relationship, and send the instruction to the phase calibration circuit to implement skew calibration of the differential signals. 
     In one embodiment, the phase detection circuit may include a first detection circuit and a second detection circuit. 
     A first end of the first detection circuit may be connected with the output end of the phase calibration circuit. The first detection circuit may be configured to perform the preset logical operation on the differential signals to generate a first phase difference pulse signal and a second phase difference pulse signal. 
     A first end of the second detection circuit may be connected with a second end of the first detection circuit, a second end may be connected with the first end of the phase adjustment control circuit. The second detection circuit may be configured to compare between amplitudes of the first phase difference pulse signal and the second phase difference pulse signal to obtain the phase relationship, and send the phase relationship to the phase adjustment control circuit. 
     In one embodiment, the first detection circuit may include a first logical unit, a phase delay unit, a second logical unit, and a third logical unit. 
     A first end of the first logical unit may be connected with the first end of the phase calibration circuit, a second end may be connected with a second end of the phase calibration circuit. The first logical unit may be configured to perform a first logical operation on a first signal and second signal in the differential signals to generate a phase difference signal. The first end of the phase calibration circuit and the second end of the phase calibration circuit may form the output end of the phase calibration circuit. 
     A first end of the phase delay unit may be connected with a third end of the first logical unit. The phase delay unit may be configured to perform phase delay processing on the phase difference signal to generate a phase delay signal. 
     A first end of the second logical unit may be connected with the first end of the phase calibration circuit, a second end may be connected with a second end of the phase delay unit. The second logical unit may be configured to perform a second logical operation on the phase delay signal and the first signal to generate the first phase difference pulse signal. 
     A first end of the third logical unit may be connected with the second end of the phase calibration circuit, a second end may be connected with the second end of the phase delay unit. The third logical unit may be configured to perform a third logical operation on the phase delay signal and the second signal to generate the second phase difference pulse signal. 
     In one embodiment, the first logical unit may include a NOR gate, and/or the second logical unit may include an AND gate, and/or the third logical unit may include an AND gate. 
     In one embodiment, the phase detection circuit may further include a controllable storage circuit. 
     A first end of the controllable storage circuit may be connected with the output end of the phase calibration circuit, a second end may be connected with the second end of the first detection circuit, and a third end may be connected with the first end of the second detection circuit. The controllable storage circuit may be configured to store the first phase difference pulse signal and the second phase difference pulse signal according to a period of the differential signals. 
     In one embodiment, the controllable storage circuit may include a first controllable storage unit and a second controllable storage unit. 
     A first end of the first controllable storage unit may be connected with the second end of the phase calibration circuit, a second end may be connected with a third end of the second logical unit, and a third end may be connected with the first end of the second detection circuit. The first controllable storage unit may be configured to generate a first storage control signal according to a period of the second signal, and receive and store, according to the first storage control signal, the first phase difference pulse signal or release the stored first phase difference pulse signal. 
     A first end of the second controllable storage unit may be connected with the first end of the phase calibration circuit, a second end may be connected with a third end of the third logical unit, and a third end may be connected with the first end of the second detection circuit. The second controllable storage unit may be configured to generate a second storage control signal according to a period of the first signal, and receive and store, according to the second storage control signal, the second phase difference pulse signal or release the stored first phase difference pulse signal. 
     In one embodiment, the first controllable storage unit may include a first frequency division subunit and a second storage subunit. 
     A first end of the first frequency division subunit may be connected with the second end of the phase calibration circuit. The first frequency division subunit may be configured to generate the first storage control signal according to the period of the second signal. 
     A first end of the first storage subunit may be connected with the third end of the second logical unit, a second end may be connected with a second end of the first frequency division subunit, and a third end may be connected with the first end of the second detection circuit. The first storage subunit may be configured to receive the first storage control signal, and store the first phase difference pulse signal according to the first storage control signal or release the stored first phase difference pulse signal. 
     In one embodiment, the first storage subunit may include a first voltage-controlled switch component, a second voltage-controlled switch component, and a first capacitor. 
     A first end of the first voltage-controlled switch component may be connected with the third end of the second logical unit, a second end may be connected with the second end of the first frequency division subunit. The first voltage-controlled switch component may be configured to receive the first storage control signal, and may be turned on or off according to the first storage control signal. 
     A first end of the second voltage-controlled switch component may be connected with a third end of the first voltage-controlled switch component, a second end may be connected with the second end of the first frequency division subunit. The second voltage-controlled switch component may be configured to receive an inverted signal of the first storage control signal, and may be turned on or off according to the inverted signal of the first storage control signal. 
     A first end of the first capacitor may be connected with the third end of the first voltage-controlled switch component and the first end of the second detection circuit respectively, a second end may be connected with a third end of the second voltage-controlled switch component and a ground respectively. The first capacitor may be configured to store the first phase difference pulse signal or release the stored first phase difference pulse signal. 
     In one embodiment, the first storage subunit may further include a first diode. 
     A first end of the first diode may be connected with the third end of the first voltage-controlled switch component, a second end may be connected with the first end of the second voltage-controlled switch component. 
     In one embodiment, the second controllable storage unit may include a second frequency division subunit and a second storage subunit. 
     A first end of the second frequency division subunit may be connected with the first end of the phase calibration circuit. The second frequency division subunit may be configured to generate the second storage control signal according to the period of the first signal. 
     A first end of the second storage subunit may be connected with the third end of the third logical unit, a second end may be connected with a second end of the second frequency division subunit, and a third end may be connected with the first end of the second detection circuit. The second storage subunit may be configured to receive the second storage control signal, and store the second phase difference pulse signal according to the second storage control signal or release the stored second phase difference pulse signal. 
     In one embodiment, the second storage subunit may include a third voltage-controlled switch component, a fourth voltage-controlled switch component, and a second capacitor. 
     A first end of the third voltage-controlled switch component may be connected with the third end of the third logical unit, a second end may be connected with the second end of the second frequency division subunit. The third voltage-controlled switch component may be configured to receive the second storage control signal, and may be turned on or off according to the second storage control signal. 
     A first end of the fourth voltage-controlled switch component may be connected with a third end of the third voltage-controlled switch component, a second end may be connected with the second end of the second frequency division subunit. The fourth voltage-controlled switch component may be configured to receive an inverted signal of the second storage control signal, and may be turned on or off according to the inverted signal of the second storage control signal. 
     A first end of the second capacitor may be connected with the third end of the third voltage-controlled switch component and the first end of the second detection circuit respectively, a second end may be connected with a third end of the fourth voltage-controlled switch component and the ground respectively. The second capacitor may be configured to store the second phase difference pulse signal or release the stored second phase difference pulse signal. 
     In one embodiment, the second storage subunit may further include a second diode. 
     A first end of the second diode may be connected with the third end of the third voltage-controlled switch component, a second end may be connected with the first end of the fourth voltage-controlled switch component. 
     In one embodiment, the second detection circuit may include a first voltage comparison unit and a second voltage comparison unit. 
     A positive input end of the first voltage comparison unit may be connected with a third end of the first controllable storage unit, a negative input end may be connected with a third end of the second controllable storage unit. The first voltage comparison unit may be configured to compare the first phase difference pulse signal and the second phase difference pulse signal to generate a first comparison result. 
     A positive input end of the second voltage comparison unit may be connected with the third end of the second controllable storage unit, a negative input end may be connected with the third end of the first controllable storage unit. The second voltage comparison unit may be configured to compare the second phase difference pulse signal and the first phase difference pulse signal to generate a second comparison result. 
     The first comparison result and the second comparison result may form the phase relationship. 
     Based on the same inventive concept, the application also provides a semiconductor memory, which may include the differential signal skew calibration circuit as described in any abovementioned embodiment. 
     The differential signal skew calibration circuit may acquire the phase relationship of the differential signals through the phase detection circuit. The phase adjustment control circuit may generate the phase calibration control instruction according to the phase relationship of the differential signals to control the phase calibration circuit to calibrate a phase skew of the input differential signals. The differential signal skew calibration circuit reduces difficulties in wiring in a PCB, namely the phase skew of the input differential signals may be automatically detected and calibrated through a circuit design, so that the quality of the differential signals is improved, and the cost is reduced. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order to describe the embodiments of the application more clearly, the drawings required to be used in descriptions about the embodiments will be simply introduced below. It is apparent that the drawings described below are only some embodiments of the application. Other drawings may further be obtained by those of ordinary skill in the art according to these drawings without creative work. 
         FIG. 1  is a structure diagram of a differential signal skew calibration circuit according to an embodiment of the application. 
         FIG. 2  is a time sequence diagram of a differential signal skew calibration circuit according to an embodiment of the application. 
         FIG. 3  is a time sequence diagram of another differential signal skew calibration circuit according to an embodiment of the application. 
     
    
    
     DESCRIPTIONS ABOUT THE REFERENCE SIGN NUMBERS 
       100 -differential signal skew calibration circuit,  10 -phase calibration circuit,  20 -phase detection circuit,  210 -first detection circuit,  211 -first logical unit,  212 -phase delay unit,  213 -second logical unit,  214 -third logical unit,  220 -second detection circuit,  221 -first voltage comparison unit,  222 -second voltage comparison unit,  230 -controllable storage circuit,  231 -first controllable storage unit,  240 -first frequency division subunit,  250 -first storage subunit,  251 -first voltage-controlled switch component,  252 -second voltage-controlled switch component,  253 -first capacitor,  254 -first diode,  232 -second controllable storage unit,  260 -second frequency division subunit,  270 -second storage subunit,  271 -third voltage-controlled switch component,  272 -fourth voltage-controlled switch component,  273 -second capacitor,  274 -second diode, and  30 -phase adjustment control circuit. 
     DETAILED DESCRIPTION 
     In order to make the objectives, features, and advantages of the application clearer and easier to understand, specific implementation modes of the application will be described below in detail in combination with the drawings. Many specific details are described in the following descriptions to make the application understood adequately. However, the application may be implemented in many other manners different from those described here, those skilled in the art may make similar improvements without departing from the essence of the application, and thus the application is not limited to specific implementations disclosed below. 
     It is to be noted that, when an element is described as “fixed” on another element, it may be directly arranged on the other element or there may be an element therebetween. When a component is considered as “connected” to another component, it may be directly connected to the other component or a component may also exist therebetween. 
     In addition, terms “first” and “second” are only for description and should not be understood to indicate or imply relative importance or implicitly indicate the number of indicated technical features. Therefore, a feature defined by “first” and “second” may explicitly or implicitly indicate inclusion of one or more such features. In the descriptions of the application, “multiple” means two or more than two, unless otherwise limited definitely and specifically. 
     Unless otherwise defined, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art of the application. In the disclosure, terms used in the description of the application are only for a purpose of describing specific embodiments and not intended to limit the application. Term “and/or” used herein includes one or any and all combinations of multiple related items which are listed. 
     Referring to  FIG. 1 , the application provides a differential signal skew calibration circuit  100 . The differential signal skew calibration circuit  100  includes a phase calibration circuit  10 , a phase detection circuit  20 , and a phase adjustment control circuit  30 . 
     The phase calibration circuit  10  is configured to calibrate a phase of a differential signals. 
     A first end of the phase detection circuit  20  is connected with an output end of the phase calibration circuit  10 . The phase detection circuit is configured to perform a preset logical operation on the differential signals to generate a phase difference pulse signal, and acquire a phase relationship of the differential signals according to the differential signals and the phase difference pulse signal. 
     A first end of the phase adjustment control circuit  30  is connected with a second end of the phase detection circuit  20 , a second end is connected with a control end of the phase calibration circuit  10 . The phase adjustment control circuit is configured to receive the phase relationship, generate a phase calibration control instruction according to the phase relationship, and send the instruction to the phase calibration circuit  10  to implement skew calibration of the differential signals. 
     In one embodiment, the differential signals input to the differential signal skew calibration circuit  100  may be, but not limited to, differential clock signals (CK_t, CK_c) or a differential data strobe signal (DQS_t, DQS_c). When the differential signals are input to the differential signal skew calibration circuit  100  for the first time, a phase of the differential signals may be detected through the phase detection circuit  20 . The phase detection circuit  20  may generate the phase difference pulse signal according to a phase skew of the differential signals, and judge the phase relationship of the differential signals according to the differential signals and the phase difference pulse signal, and meanwhile, may convert different phase relationships into different high/low-level signal combinations for output. The phase adjustment control circuit  30  may include an adjustable delay control logical unit. The adjustable delay control logical unit may judge a phase skew condition of the differential signals according to a high/low-level signal combination output by the phase detection circuit  20 , and generate a corresponding phase calibration control instruction for sending to the phase calibration circuit  10 . 
     In one embodiment, the phase calibration circuit  10  may include two adjustable delay units. Each adjustable delay unit controls one signal in the differential signals, namely each adjustable delay unit may adjust a phase delay of the corresponding differential signals according to the phase calibration control instruction sent by the phase adjustment control circuit  30  to implement calibration of the phase skew of the differential signals. 
     It can be understood that the differential signal skew calibration circuit  100  may acquire the phase relationship of the differential signals through the phase detection circuit  20 . The phase adjustment control circuit  30  may generate the phase calibration control instruction according to the phase relationship of the differential signals to control the phase calibration circuit  10  to calibrate the phase skew of the input differential signals. The differential signal skew calibration circuit  100  reduces difficulties in wiring design of a PCB, namely the phase skew of the input differential signals may be automatically detected and calibrated through a circuit design, so that the quality of the differential signals is improved, and the cost is reduced. 
     In one embodiment, the phase detection circuit  20  includes a first detection circuit  210  and a second detection circuit  220 . 
     A first end of the first detection circuit  210  is connected with the output end of the phase calibration circuit  10 . The first detection circuit is configured to perform the preset logical operation on the differential signals to generate a first phase difference pulse signal and a second phase difference pulse signal. In the embodiment, the first end of the first detection circuit  210  may be a signal input end, a second end may be a signal output end. It can be understood that the first phase difference pulse signal and the second phase difference pulse signal include information of a phase difference of the differential signals, and may be configured to judge the phase relationship of the differential signals. 
     A first end of the second detection circuit  220  is connected with a second end of the first detection circuit  210 , a second end is connected with the first end of the phase adjustment control circuit  30 . The second detection circuit is configured to compare amplitudes of the first phase difference pulse signal and the second phase difference pulse signal to acquire the phase relationship, and send the phase relationship to the phase adjustment control circuit  30 . In the embodiment, the first end of the second detection circuit  220  may be a signal input end, the second end may be a signal output end. It can be understood that, since the first phase difference pulse signal and the second phase difference pulse signal may reflect the phase difference of the differential signals, the amplitudes of the first phase difference pulse signal and the second phase difference pulse signal may be compared to obtain the phase relationship of the differential signals, i.e., a phase relationship of lead, lag, or inversion. 
     In one embodiment, the second detection circuit  220  may convert the phase relationship of the differential signals into a combination of high levels and/or low levels, and send it to the phase adjustment control circuit  30 . 
     Referring to  FIG. 2  together, in one embodiment, the first detection circuit  210  includes a first logical unit  211 , a phase delay unit  212 , a second logical unit  213 , and a third logical unit  214 . 
     A first end of the first logical unit  211  is connected with the first end of the phase calibration circuit  10 , a second end is connected with a second end of the phase calibration circuit  10 . The first logical unit is configured to perform a first logical operation on a first signal and second signal in the differential signals to generate a phase difference signal. The first end of the phase calibration circuit  10  and the second end of the phase calibration circuit  10  form the output end of the phase calibration circuit  10 . In the embodiment, the first end and second end of the first logical unit  211  may be signal input ends, while a third end may be a signal output end. 
     In one embodiment, the first logical unit  211  may be a logical NOR unit, and namely includes a NOR gate, so that the first logical operation may be a logical NOR operation. In the embodiment, the logical NOR operation may be performed on the first signal and the second signal to detect a phase delay between the first signal and the second signal, referring to a time sequence diagram of a phase difference signal in  FIG. 2 . 
     A first end of the phase delay unit  212  is connected with a third end of the first logical unit  211 . The phase delay unit is configured to perform phase delay processing on the phase difference signal to generate a phase delay signal. In the embodiment, the first end of the phase delay unit  212  may be a signal input end, a second end may be a signal output end. 
     In one embodiment, the phase delay unit  212  may include, but not limited to, a delay line, to delay the input phase difference signal. The phase delay unit  212  may be arranged to generate the phase delay signal. In the embodiment, the phase delay unit  212  may control the delay of the phase difference signal in a preset range to convert the phase difference signal into the phase difference pulse signal, referring to the time sequence diagram of the phase delay signal in  FIG. 2 . 
     A first end of the second logical unit  213  is connected with the first end of the phase calibration circuit  10 , a second end is connected with a second end of the phase delay unit  212 . The second logical unit is configured to perform a second logical operation on the phase delay signal and the first signal to generate the first phase difference pulse signal. In the embodiment, the first end and second end of the second logical unit  213  may be signal input ends, a third end may be a signal output end. 
     In one embodiment, the second logical unit  213  may be a logical AND unit, and namely includes an AND gate, so that the second logical operation may be a logical AND operation. In the embodiment, the second logical unit  213  may perform the logical AND operation on the first signal and the phase delay signal, referring to a time sequence diagram of the first phase difference pulse signal in  FIG. 2 . 
     A first end of the third logical unit  214  is connected with the second end of the phase calibration circuit  10 , a second end is connected with the second end of the phase delay unit  212 . The third logical unit is configured to perform a third logical operation on the phase delay signal and the second signal to generate the second phase difference pulse signal. In the embodiment, the first end and second end of the third logical unit  214  may be signal input ends, a third end may be a signal output end. 
     In one embodiment, the third logical unit  214  may be a logical AND unit, and namely includes an AND gate, so that the third logical operation may be a logical AND operation. In the embodiment, the third logical unit  214  may perform the logical AND operation on the second signal and the phase delay signal, referring to a time sequence diagram of the second phase difference pulse signal in  FIG. 2 . It can be understood that the first phase difference pulse signal and the second phase difference pulse signal include information of the phase relationship between the first signal and the second signal, and may be used for the judgment of the phase relationship between the first signal and the second signal. 
     In one embodiment, the first logical unit  211  in the first detection circuit  210  may acquire the phase delay of the differential signals, and the phase delay unit  212 , the second logical unit  213  and the third logical unit  214  may acquire the first phase difference pulse signal and the second phase difference pulse signal. The second detection circuit  220  may compare between the amplitudes of the first phase difference pulse signal and the second phase difference pulse signal to acquire the phase relationship of lead, lag or inversion of the differential signals. Therefore, the phase adjustment control circuit  30  may generate the phase calibration control instruction according to the phase delay and the phase relationship, and send the phase calibration control instruction to the phase calibration circuit  10  to implement skew calibration of the differential signals. 
     In one embodiment, the phase detection circuit  20  further includes a controllable storage circuit  230 , of which a first end is connected with the output end of the phase calibration circuit  10 , a second end is connected with the second end of the first detection circuit  210 , and a third end is connected with the first end of the second detection circuit  220 . The controllable storage circuit is configured to store the first phase difference pulse signal and the second phase difference pulse signal according to a period of the differential signals. In the embodiment, the first end and second end of the controllable storage circuit  230  may be signal input ends, the third end may be a signal output end. 
     In one embodiment, since a signal output by the first detection circuit  210  and reflecting the phase difference of the differential signals is a pulse signal, i.e., the first phase difference pulse signal and the second phase difference pulse signal, and a single pulse signal is unfavorable for extraction of the phase relationship of the differential signals, the controllable storage circuit  230  may be arranged to store multiple first phase difference pulse signals and multiple second phase difference pulse signals to improve the accuracy of the phase relationship, acquired by the second detection circuit  220 , of the differential signals and further improve the calibration accuracy of the differential signal skew calibration circuit  100 . 
     In one embodiment, the controllable storage circuit  230  includes a first controllable storage unit  231  and a second controllable storage unit  232 . 
     A first end of the first controllable storage unit  231  is connected with the second end of the phase calibration circuit  10 , a second end is connected with a third end of the second logical unit  213 , and a third end is connected with the first end of the second detection circuit  220 . The first controllable storage unit is configured to generate a first storage control signal according to a period of the second signal, and receive and store, according to the first storage control signal, the first phase difference pulse signal or release the stored first phase difference pulse signal. In the embodiment, the first end and second end of the first controllable storage unit  231  may be signal input ends, the third end may be a signal output end. 
     A first end of the second controllable storage unit  232  is connected with the first end of the phase calibration circuit  10 , a second end is connected with a third end of the third logical unit  214 , and a third end is connected with the first end of the second detection circuit  220 . The second controllable storage unit is configured to generate a second storage control signal according to a period of the first signal, and receive and store, according to the second storage control signal, the second phase difference pulse signal or release the stored first phase difference pulse signal. In the embodiment, the first end and second end of the second controllable storage unit  232  may be signal input ends, the third end may be a signal output end. 
     In one embodiment, the first controllable storage unit  231  includes a first frequency division subunit  240  and a first storage subunit  250 . 
     A first end of the first frequency division subunit  240  is connected with the second end of the phase calibration circuit  10 . The first frequency division subunit is configured to generate the first storage control signal according to the period of the second signal. In the embodiment, the first end of the first frequency division subunit  240  may be a signal input end, a second end may be a signal output end. 
     In one embodiment, the first frequency division subunit  240  may include an adjustable frequency division circuit. The arranged adjustable frequency division circuit may enlarge a frequency range of the differential signal skew calibration circuit. Since the first frequency division subunit  240  generates the first storage control signal according to the period of the second signal, the adjustable frequency division circuit may output a signal of which a frequency is one in integer of a frequency of the second signal as the first storage control unit, referring to a time sequence diagram of the first storage control signal in  FIG. 2 . In other words, the frequency of the second signal may be an integral multiple of the frequency of the signal output by the adjustable frequency division circuit. It can be understood that the specific frequency of the first storage control signal may be set as practically required. For example, for a time sequence of two first storage control signals in  FIG. 2 , the frequency of the one first storage control signal is half of the frequency of the second signal, and the frequency of the other first storage control signal is a quarter of the frequency of the second signal. 
     It can be understood that the frequency of the first storage control signal determines a period of the first storage control signal, and if the period of the first storage control signal is longer, the first storage subunit  250  may store more first phase difference pulse signals, and the calibration accuracy of the differential signal skew calibration circuit is higher. However, if the period of the first storage control signal is too long, the processing speed of the differential signal skew calibration circuit may decrease. Therefore, the processing speed of the differential signal skew calibration circuit and the calibration accuracy of the differential signal skew calibration circuit may be comprehensively considered when the specific frequency of the first storage control signal is selected. 
     A first end of the first storage subunit  250  is connected with the third end of the second logical unit  213 , a second end is connected with a second end of the first frequency division subunit  240 , and a third end is connected with the first end of the second detection circuit  220 . The first storage subunit is configured to receive the first storage control signal, and store the first phase difference pulse signal according to the first storage control signal or release the stored first phase difference pulse signal. In the embodiment, the first end and second end of the first storage subunit  250  are signal input ends, the third end is a signal output end. 
     In one embodiment, the first storage subunit  250  includes a first voltage-controlled switch component  251 , a second voltage-controlled switch component  252 , and a first capacitor  253 . 
     A first end of the first voltage-controlled switch component  251  is connected with the third end of the second logical unit  213 , a second end is connected with the second end of the first frequency division subunit  240 . The first voltage-controlled switch component is configured to receive the first storage control signal, and is turned on or off according to the first storage control signal. In the embodiment, the first end of the first voltage-controlled switch component  251  may be a signal input end, the second end may be a control end, a third end may be a signal output end. 
     A first end of the second voltage-controlled switch component  252  is connected with a third end of the first voltage-controlled switch component  251 , a second end is connected with the second end of the first frequency division subunit  240 . The second voltage-controlled switch component is configured to receive an inverted signal of the first storage control signal, and is turned on or off according to the inverted signal of the first storage control signal. In the embodiment, the first end of the second voltage-controlled switch component  252  may be a signal input end, the second end may be a control end, a third end may be a signal output end. 
     In one embodiment, the second voltage-controlled switch component  252  may include a logical NOT unit, i.e., an NOT gate. After the first storage control signal output by the first frequency division subunit  240  through the second end passes through the NOT gate, the inverted signal of the first storage control signal may be obtained. Therefore, the second voltage-controlled switch component  252  may be turned on or off according to the inverted signal of the first storage control signal. 
     A first end of the first capacitor  253  is connected with the third end of the first voltage-controlled switch component  251  and the first end of the second detection circuit  220  respectively, a second end is connected with a third end of the second voltage-controlled switch component  252  and a ground respectively. The first capacitor is configured to store the first phase difference pulse signal or release the stored first phase difference pulse signal. 
     In one embodiment, the first voltage-controlled switch component  251  may receive the first storage control signal, and may be turned on or off according to the first storage control signal. For example, when the first storage control signal is at a high level, the first voltage-controlled switch component  251  is turned on, the second voltage-controlled switch component  252  is turned off, and the second logical unit  213  outputs the first phase difference pulse signal to the first capacitor through the third end of the second logical unit, namely the first capacitor  253  is charged. When the first storage control signal is at a low level, the first voltage-controlled switch component  251  is turned off, the second voltage-controlled switch component  252  is turned on, and the first capacitor  253  releases the stored first phase difference pulse signal through the first end of the first capacitor. 
     In one embodiment, the first storage subunit  250  further includes a first diode  254 , of which a first end is connected with a third end of the first voltage-controlled switch component  251 , and a second end is connected with the first end of the second voltage-controlled switch component  252 . In the embodiment, the first end of the first diode  254  may be a signal input end, the second end may be a signal output end. It can be understood that the first diode  254  may limit a direction of an electrical signal. Compared with an integrating circuit in the related art, the arranged first diode  254  and second diode  274  may increase a recognition speed of the first phase difference pulse signal and the second phase difference pulse signal, and may also increase a difference between the first phase difference pulse signal and the second phase difference pulse signal to ensure the final calibration accuracy of the differential signal skew calibration circuit. 
     In one embodiment, the second controllable storage unit  232  includes a second frequency division subunit  260  and a second storage subunit  270 . 
     A first end of the second frequency division subunit  260  is connected with the first end of the phase calibration circuit  10 . The second frequency division subunit is configured to generate the second storage control signal according to the period of the first signal. 
     A first end of the second storage subunit  270  is connected with the third end of the third logical unit  214 , a second end is connected with a second end of the second frequency division subunit  260 , and a third end is connected with the first end of the second detection circuit  220 . The second storage subunit is configured to receive the second storage control signal, and store the second phase difference pulse signal according to the second storage control signal or release the stored second phase difference pulse signal. 
     It can be understood that the second frequency division subunit  260  may be the same as the first frequency division subunit  240  in any abovementioned embodiment, and the second storage subunit  270  may be the same as the first storage subunit  250  in any abovementioned embodiment. Elaborations are omitted herein. 
     In one embodiment, the second storage subunit  270  includes a third voltage-controlled switch component  271 , a fourth voltage-controlled switch component  272 , and a second capacitor  273 . 
     A first end of the third voltage-controlled switch component  271  is connected with the third end of the third logical unit  214 , a second end is connected with the second end of the second frequency division subunit  260 . The third voltage-controlled switch component is configured to receive the second storage control signal, and is turned on or off according to the second storage control signal. 
     A first end of the fourth voltage-controlled switch component  272  is connected with a third end of the third voltage-controlled switch component  271 , a second end is connected with the second end of the second frequency division subunit  260 . The fourth voltage-controlled switch component is configured to receive an inverted signal of the second storage control signal, and is turned on or off according to the inverted signal of the second storage control signal. 
     A first end of the second capacitor  273  is connected with the third end of the third voltage-controlled switch component  271  and the first end of the second detection circuit  220  respectively, a second end is connected with a third end of the fourth voltage-controlled switch component  272  and the ground respectively. The second capacitor is configured to store the second phase difference pulse signal or release the stored second phase difference pulse signal. 
     In one embodiment, the second storage subunit  270  further includes a second diode  274  of which a first end is connected with a third end of the third voltage-controlled switch component  271 , and a second end is connected with the first end of the fourth voltage-controlled switch component  272 . 
     It can be understood that the third voltage-controlled switch component  271  may be the same as the first voltage-controlled switch component  251  in any abovementioned embodiment, the fourth voltage-controlled switch component  272  may be the same as the second voltage-controlled switch component  252  in any abovementioned embodiment, the second capacitor  273  may be the same as the first capacitor  253  in any abovementioned embodiment, and the second diode  274  may be the same as the first diode  254  in any abovementioned embodiment. Elaborations are omitted herein. 
     In one embodiment, the second detection circuit  220  includes a first voltage comparison unit  221  and a second voltage comparison unit  222 . 
     A positive input end of the first voltage comparison unit  221  is connected with a third end of the first controllable storage unit  231 , a negative input end is connected with a third end of the second controllable storage unit  232 . The first voltage comparison unit is configured to compare the first phase difference pulse signal and the second phase difference pulse signal to generate a first comparison result. 
     A positive input end of the second voltage comparison unit  222  is connected with the third end of the second controllable storage unit  232 , a negative input end is connected with the third end of the first controllable storage unit  231 . The second voltage comparison unit is configured to compare the second phase difference pulse signal and the first phase difference pulse signal to generate a second comparison result. The first comparison result and the second comparison result form the phase relationship. In one embodiment, each of the first voltage comparison unit  221  and the second voltage comparison unit  222  may be a voltage comparator, and has many advantages such as simple structure, high detection speed, and wide applicable frequency range. 
     In one embodiment, referring to  FIG. 2 , when the output of the first voltage comparison unit  221  is at a high level, and the output of the second voltage comparison unit  222  is at a low level, the second signal is delayed. Referring to  FIG. 3 , when the output of the first voltage comparison unit  221  is at a low level, and the output of the second voltage comparison unit  222  is at a high level, the first signal is delayed. It can be understood that, when both of the outputs of the first voltage comparison units  221  and the second voltage comparison unit  222  are at low levels, the phase relationship between the second signal and the first signal is inversion, namely the two signals are completely inverted, and in such case, phase delay adjustment is not required. 
     Based on the same inventive concept, the application also provides a semiconductor memory. The semiconductor memory includes the differential signal skew calibration circuit as described in any abovementioned embodiment, and elaborations are omitted herein. 
     Each technical feature of the abovementioned embodiments may be combined freely. For simplicity of description, not all possible combinations of the abovementioned embodiments are described. However, any combination of these technical features shall fall within the scope recorded in the specification without conflicting. 
     The abovementioned embodiments only express some implementation modes of the application and are specifically described in detail and not thus understood as limits to the patent scope of the application. It is to be pointed out that those of ordinary skill in the art may further make a plurality of transformations and improvements without departing from the concept of the application and all of these fall within the scope of protection of the application. Therefore, the scope of patent protection of the application should be salient object to the appended claims.