Circuit and method for recovering clock data in highly integrated semiconductor memory apparatus

The present patent application is a Divisional application claiming the benefit of application Ser. No. 12/157,287, filed Jun. 9, 2008 now U.S. Pat. No. 7,965,582.

The present invention claims priority of Korean patent application number 10-2007-0111482, filed on Nov. 2, 2007, which is incorporated by reference in its entirety.

The present invention relates to a highly integrated semiconductor device, and more particularly, to a semiconductor memory device including a clock data recovery (CDR) circuit for recovering signals and data distorted during high-speed processing.

Semiconductor memory devices are used for storing data in various systems such as a system composed of a plurality of semiconductor devices. When a data processing device, such as a central processing unit (CPU), requests or sends data, a semiconductor memory device outputs or stores the data based on address information received from the data processing device.

As the operating speed of a semiconductor device system increases owing to the advance of semiconductor integrated circuit technology, the semiconductor device system requires high-speed semiconductor memory devices capable of rapidly outputting and storing data. For high-speed and stable operations of a semiconductor memory device, circuits of the semiconductor memory device need to be operated at a high speed. That is, the circuits of the semiconductor memory device need to process signals or data rapidly and transfer the signals or data at a high speed.

As the operating speed of semiconductor memory devices need to be high for being used in high-speed systems, the signal/data transmission speed of interfaces is also required to be high. A clock data recovery (CDR) method has been developed to prevent malfunctions or instable operations of a semiconductor memory device caused by noises, interferences, and distortions of signals and data.

That is, a recent semiconductor memory device includes a CDR circuit for reliably transferring signals and data at a high speed. CDR technology is used in most high-speed systems for recovering original data and clock signals from data and clock signals distorted or changed during transmission.

In a semiconductor memory device, transmission of data and clock signals can be delayed due to various reasons. In this case, the semiconductor memory device cannot normally operate according to the data and clock signals, and thus the possibility of malfunction of the semiconductor memory device increases. To solve these problems, circuits of the semiconductor memory device can be operated according to an inner clock produced corresponding to an external reference clock. When the inner clock is not in phase with the external reference clock, the phase difference is detected and reported to the circuits so as to allow the circuits to change the phase of the inner clock in response to the reported phase difference or operate in consideration of the phase difference.

The above-described operation can be performed using a CDR circuit. For this, the CDR circuit includes a phase comparator and a filter. The phase comparator detects a difference between the external reference clock and the inner clock, and the detection result is output through the filter.

FIG. 1 is a block diagram illustrating a conventional semiconductor memory device including CDR circuits.

Referring to FIG. 1 , for example, the semiconductor memory device includes first to thirty second data pads DQ 0 to D 31 , and first to thirty second CDR circuits 120 _ 0 to 120 _ 31 respectively connected to the first to thirty second data pads DQ 0 to D 31 . The first CDR circuit 120 _ 0 includes a receiver 122 _ 0 , a sampling unit 124 _ 0 , a delay unit 128 _ 0 , and a phase detection unit 126 _ 0 . The other CDR circuits 120 _ 1 to 120 _ 31 have the same elements. Thus, descriptions of the other CDR circuits 120 _ 1 to 120 _ 31 will be omitted.

Each of the first to thirty second CDR circuits 120 _ 0 to 120 _ 31 connected to the first to thirty second data pads DQ 0 to D 31 can recover clock data with no aid from other devices. This will now be described using the first CDR circuit 120 _ 0 as an example. The receiver 122 _ 0 receives a signal through the first data pad DQ 0 and transfers the signal to the sampling unit 124 _ 0 . First, the sampling unit 124 _ 0 transfers the signal to the phase detection unit 126 _ 0 according to a receiving reference clock RX_CLK. The phase detection unit 126 _ 0 detects transition time points of signals transferred from the sampling unit 124 _ 0 (that is, time points at which successively transferred signals change from a logic high level to a logic low level, or from a logic low level to a logic high level). Then, the phase detection unit 126 _ 0 calculates a delay value so as to place the transition time points on the centers of rising and falling edges of the receiving reference clock RX_CLK. The delay unit 128 _ 0 delays the receiving reference clock RX_CLK according to the delay value so as to adjust the phase of the receiving reference clock RX_CLK. Then, the sampling unit 124 _ 0 transfers signals transferred from the receiver 122 _ 0 to an inner unit of the semiconductor memory device according to the phase-adjusted receiving reference clock RX_CLK. Since the phase of the receiving reference clock RX_CLK can be adjusted as described above, signal input/output errors can be prevented when the semiconductor memory device receives and transfers signals at a high speed.

Each of the first to thirty second CDR circuits 120 _ 0 to 120 _ 31 connected to the first to thirty second data pads DQ 0 to D 31 includes a clock generator (not shown). The clock generator generates a receiving reference clock RX_CLK that is used for determining the time for recognizing input signals.

Since the first to thirty second data pads DQ 0 to D 31 can have different data transmission delay levels, the first to thirty second CDR circuits 120 _ 0 to 120 _ 31 are connected to the first to thirty second data pads DQ 0 to D 31 , respectively. However, the first to thirty second CDR circuits 120 _ 0 to 120 _ 31 occupy a large area of the semiconductor memory device. Therefore, the number of data transmission channels of the semiconductor memory device may be limited, or the power consumption of the semiconductor memory device may be increased due to the CDR operation.

Embodiments of the present invention are directed to providing an apparatus and method for improving a clock data recover (CDR) circuit of a highly integrated semiconductor memory apparatus so as to be usefully used in a highly integrated semiconductor apparatus, an electronic device, and an electronic system, the apparatus and method being configured to recover clock data using a small space and power by grouping signal input/output pads and allowing each of the groups to share a clock data recovery (CDR) circuit.

In accordance with an aspect of the present invention, there is provided a plurality of signal receiving units configured to receive signals through a plurality of input/output pads and transfer the signals according to a receiving reference clock, the signal receiving units being divided into groups, a plurality of phase detection units configured to detect phases of signals output from the groups of the signal receiving units, a plurality of phase detection control units configured to control the phase detection units so that the phase detection units sequentially detect the phases of the signals output from each of the groups of the signal receiving units and a notification unit configured to output signals output from the phase detection units. In accordance with another aspect of the present invention, there is provided a semiconductor memory apparatus configured to detect phases of parallel signals received according to a receiving reference clock and convert the detection result into a serial signal; and a data processing apparatus configured to detect a signal transmission state using the serial signal received from the semiconductor memory apparatus and adjust output times of new signals to be transferred to the semiconductor memory apparatus. In accordance with an aspect of the present invention, there is provided a method for recovering clock data that includes a step of generating a first serial signal by combining first signals received through even numbered input/output pads after detecting phases of the first signals, a step of generating a second serial signal by combining second signals received through odd numbered input/output pads after detecting phases of the second signals, a step of transferring a serialized signal produced by combining the first and second serial signals and adjusting output times of new signals based on a signal transmission state detected using the serialized signal.

FIG. 1 is a block diagram illustrating a conventional semiconductor memory device including clock data recovery (CDR) circuits.

FIG. 2A is a block diagram illustrating a semiconductor memory apparatus and a data processing apparatus in accordance with an embodiment of the present invention.

FIG. 2B is a flowchart for explaining operations of the semiconductor memory apparatus and the data processing apparatus of FIG. 2A , in accordance with an embodiment of the present invention.

FIG. 3A is a block diagram illustrating a semiconductor memory apparatus and a data processing apparatus in accordance with another embodiment of the present invention.

FIG. 3B is a flowchart for explaining operations of the semiconductor memory apparatus and the data processing apparatus of FIG. 3A , in accordance with an embodiment of the present invention.

FIG. 4 is a circuit diagram illustrating a phase detection control unit of the semiconductor memory apparatus of FIG. 3A , in accordance with an embodiment of the present invention.

FIG. 5 is a circuit diagram illustrating a serialization unit of the semiconductor memory apparatus of FIG. 3A , in accordance with an embodiment of the present invention.

Hereinafter, circuit and method for recovering clock data in highly integrated semiconductor memory apparatus in accordance with the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2A is a block diagram illustrating a semiconductor memory apparatus and a data processing apparatus in accordance with an embodiment of the present invention.

Referring to FIG. 2A , the semiconductor memory apparatus may be a dynamic random access memory (DRAM). The semiconductor memory apparatus receives a plurality of parallel signals according to a receiving reference clock signal and detects phases of the signals. Then, the semiconductor memory apparatus converts the detection result into a serial signal. The data processing apparatus may be a general processing unit (GPU). The data processing apparatus detects a signal transmission state using the serial signal received from the semiconductor memory apparatus. Then, the data processing apparatus controls output times of new signals to be transferred to the semiconductor memory apparatus. The semiconductor memory apparatus and the data processing apparatus can form a system capable of clock data recovery.

In the semiconductor memory device of FIG. 1 , each of the CDR circuits 120 _ 0 to 120 _ 31 connected to the data pads DQ 0 to DQ 31 can adjust a receiving time of input data. However, in the current embodiment shown in FIG. 2A , the semiconductor memory apparatus receives signals (or data) and informs the data processing apparatus of a transmission state of the signals, and then the data processing apparatus adjusts times for transferring the next signals to the semiconductor memory apparatus.

In detail, referring to FIG. 2A , the semiconductor memory apparatus includes first to thirty second signal phase detection units 220 _ 0 to 220 _ 31 and a notification unit. The signal phase detection units 220 _ 0 to 220 _ 31 receive signals from the data processing apparatus through first to thirty second input/output pads DQ 0 to DQ 31 and transfer the signals. In addition, the signal phase detection units 220 _ 0 to 220 _ 31 detect the phases of the received signals. The notification unit transfers output signals of the signal phase detection units 220 _ 0 to 220 _ 31 to the data processing apparatus for informing the data processing apparatus of a signal transmission state of the signals. The notification unit includes a serialization unit 280 and a transmission unit 290 . The serialization unit 280 serializes signals received from the signal phase detection units 220 _ 0 to 220 _ 31 , and the serialized signals are transferred to the data processing apparatus through the transmission unit 290 .

The first to thirty second signal phase detection units 220 _ 0 to 220 _ 31 have the same structure. Thus, only the first signal phase detection unit 220 _U will now be described, and descriptions of the second to thirty second signal phase detection units 220 _ 1 to 220 _ 31 will be omitted for conciseness. The first signal phase detection units 220 _ 0 include a receiver 222 _ 0 , a sampling unit 224 _ 0 , and a phase detection unit 226 _ 0 . The receiver 222 _ 0 receives signals input through the first input/output pad DQ 0 . The sampling unit 224 _ 0 transfers the signals received from the receiver 222 _ 0 to the phase detection unit 226 _ 0 according to a receiving reference clock RX_CLK. The phase detection unit 226 _ 0 detects phases of the signals received from the sampling unit 224 _ 0 .

In operation, the receiver 222 _ 0 receives signals through the first input/output pad DQ 0 and transfers the signals to the sampling unit 224 _ 0 . The sampling unit 224 _ 0 transfers the signals received from the receiver 222 _ 0 to the phase detection unit 226 _ 0 according to a receiving reference clock RX_CLK. The phase detection unit 226 _ 0 detects transition time points of the signals received from the sampling unit 224 _ 0 (that is, time points at which successively transferred signals change from a logic high level to a logic low level, or from a logic low level to a logic high level). Then, the phase detection unit 226 _ 0 transfers the signals to the serialization unit 280 . In this way, signals are transferred to the serialization unit 280 from the first signal phase detection unit 220 _ 0 and the other second to thirty second signal phase detection units 220 _ 1 to 220 _ 31 . Then, the serialization unit 280 serializes the signals and transfers the serialized signals to the data processing apparatus through the transmission unit 290 . The data processing apparatus detects a signal transmission state from the serialized signals received through the transmission unit 290 . Then, the data processing apparatus adjusts signal output times based on the detected signal transmission state.

The data processing apparatus includes a receiving unit 540 and first to thirty second signal transmission determination units 520 _ 0 to 520 _ 31 . The receiving unit 540 receives serialized signals transferred through the transmission unit 290 . The signal transmission determination units 520 _ 0 to 520 _ 31 analyze signals output from the receiving unit 540 for detecting a signal transmission state and determining a delay value according to the detection result. Each of the signal transmission determination units 520 _ 0 to 520 _ 31 includes a delay unit and an output unit Tx. The delay unit is configured to delay output of new signals, and the output unit Tx outputs delayed new signals under control of the delay unit. That is, unlike a conventional semiconductor memory device, the data processing apparatus adjusts output times of new signals according to serialized signals received from the semiconductor memory apparatus so that high-speed signals and data transmission can be stabilized.

FIG. 2B is a flowchart for explaining operations of the semiconductor memory apparatus and the data processing apparatus of FIG. 2A , in accordance with an embodiment of the present invention.

Referring to FIG. 2B , clock data can be recovered as follows. In operation S 202 , the semiconductor memory apparatus detects phases of input signals. In operation S 203 , the signals are combined. In operation S 204 , the combined signals are sent to the data processing apparatus. In operation S 205 , the data processing apparatus detects a signal transmission state of the signal and decreases or increases a delay value for adjusting output times of new signals.

FIG. 3A is a block diagram illustrating a semiconductor memory apparatus and a data processing apparatus in accordance with another embodiment of the present invention.

Referring to FIG. 3A , the data processing apparatus has the same structure as the data processing apparatus depicted in FIG. 2A . However, in the semiconductor memory apparatus of 3 A, a plurality of phase detection units 340 _ 0 to 340 _ 15 are shared by neighboring signal phase detection units 320 _ 0 to 320 _ 31 .

In detail, the semiconductor memory apparatus includes a plurality of signal receiving units 320 _ 0 to 320 _ 31 , the plurality of phase detection units 340 _ 0 to 340 _ 15 , a plurality of phase detection control units 360 _ 0 to 360 _ 15 , and a notification unit. The signal receiving units 320 _ 0 to 320 _ 31 receive signals from the data processing apparatus through a plurality of input/output pads DQ 0 to DQ 31 and transfer the signals according to a receiving reference clock RX_CLK. The signal receiving units 320 _ 0 to 320 _ 31 are divided into groups. The phase detection units 340 _ 0 to 340 _ 15 receive outputs of the groups of the signal receiving units 320 _ 0 to 320 _ 31 for detecting phases of the outputs. The phase detection control units 360 _ 0 to 360 _ 15 control the phase detection units 340 _ 0 to 340 _ 15 to sequentially detect the phases of the outputs of the groups of the signal receiving units 320 _ 0 to 320 _ 31 . The notification unit transfers outputs of the phase detection units 340 _ 0 to 340 _ 15 to the data processing apparatus so as to allow the data processing apparatus to detect a signal transmission state. The notification unit includes a serialization unit 380 and a transmission unit 390 . The serialization unit 380 serializes signals received from the phase detection units 340 _ 0 to 340 _ 15 , and the serialized signals are transferred to the data processing apparatus through the transmission unit 390 .

The signal receiving units 320 _ 0 to 320 _ 31 have the same structure. Thus, only the first signal receiving unit 320 _ 0 will now be described, and descriptions of the second to thirty second signal receiving units 320 _ 1 to 320 _ 31 will be omitted. The first signal receiving unit 320 _ 0 includes a receiver 322 _ 0 and a sampling unit 324 _ 0 . The receiver 322 _ 0 receives signals input through the first input/output pad DQ 0 . The sampling unit 324 _ 0 transfers signals according to a receiving reference clock RX_CLK.

Signals input through the input/output pads DQ 0 to DQ 31 are recognized and transferred by the plurality of signal receiving units 320 _ 0 to 320 _ 31 corresponding to the input/output pads DQ 0 to DQ 31 . Signals output from the neighboring two of the signal receiving units 320 _U to 320 _ 31 are transferred to a corresponding one of the phase detection units 340 _ 0 to 340 _ 15 that are controlled by the phase detection control units 360 _ 0 to 360 _ 15 . That is, two input/output pads share one phase detection unit. The phase detection control units 360 _ 0 to 360 _ 15 control the phase detection units 340 _ 0 to 340 _ 15 to detect the phases of signals output from the even or odd numbered signal receiving units 320 _ 0 to 320 _ 31 . Therefore, in accordance with the current embodiment, the semiconductor memory apparatus can have a reduced CDR circuit area as compared with the semiconductor memory apparatus of FIG. 2A .

FIG. 3B is a flowchart for explaining operations of the semiconductor memory apparatus and the data processing apparatus of FIG. 3A , in accordance with an embodiment of the present invention.

Referring to FIG. 3B , clock data can be recovered as follows. In operation S 302 , the semiconductor memory apparatus detects the phases of signals input through even numbered input/output pads. In operation S 303 , the signals input through the even numbered input/output pads are combined. In operation S 304 , the semiconductor memory apparatus detects the phases of signals input through odd numbered input/output pads. In operation S 305 , the signals input through the odd numbered input/output pads are combined. In operation S 306 , the signals combined in operations S 303 and S 305 are serialized and transferred to the data processing apparatus. In operation S 307 , the data processing apparatus detects a signal transmission state and decreases or increases a delay value for controlling output times of new signals.

FIG. 4 is a circuit diagram illustrating the phase detection control unit 360 _ 0 of FIG. 3A , in accordance with an embodiment of the present invention. The phase detection control units 360 _ 0 to 360 _ 15 of the semiconductor memory apparatus of FIG. 3A have the same structure. Thus, only the first phase detection control unit 360 _ 0 will now be described.

Referring to FIG. 4 , the phase detection control unit 360 _ 0 includes a flip-flop 362 _ 0 and an inverter 364 _ 0 . The flip-flop 362 _ 0 receives a signal and outputs the signal according to a first clock CLK/N produced by dividing a system clock by a predetermined value. The inverter 364 _ 0 inverts the signal output from the flip-flop 362 _ 0 and returns the inverted signal to an input of the flip-flop 362 _ 0 to generate a pulse signal having a width corresponding to a rising edge of the first clock CLK/N for controlling the phase detection unit 340 _ 0 . The phase detection unit 340 _ 0 detects the phase of a signal output from the first signal receiving unit 320 _ 0 or the second signal receiving unit 320 _ 1 and sends the signal to the serialization unit 380 . In FIG. 4 , N is a natural number selected for recognizing signals output from two input/output pads.

FIG. 5 is a circuit diagram illustrating the serialization unit 380 of FIG. 3A , in accordance with an embodiment of the present invention.

Referring to FIG. 5 , the serialization unit 380 includes a plurality of flip-flops 382 _ 0 to 382 _ 7 , 384 _ 0 to 384 _ 7 , 386 _ 0 , and 386 _ 1 , and a plurality of multiplexers 383 _ 0 to 383 _ 7 , 385 _ 0 , 385 _ 1 , and 387 . The flip-flops 382 _ 0 to 382 _ 7 , 384 _ 0 to 384 _ 7 , 386 _ 0 , and 386 _ 1 receive signals from the phase detection units 340 _ 0 to 340 _ 15 and transfer the signals according to division clocks produced by dividing a reference clock by a predetermined value. The multiplexers 383 _ 0 to 383 _ 7 , 385 _ 0 , 385 _ 1 , and 387 receive signals output from the flip-flops 382 _ 0 to 382 _ 7 , 384 _ 0 to 384 _ 7 , 386 _ 0 , and 386 _ 1 and transfer the signals sequentially.

In detail, the flip-flops 382 _ 0 to 382 _ 7 , 384 _ 0 to 384 _ 7 , 386 _ 0 , and 386 _ 1 of the serialization unit 380 can be grouped into first flip-flops 382 _ 0 to 382 _ 7 , second flip-flops 384 _ 0 to 384 _ 7 , and third flip-flops 386 _U and 386 _ 1 . The multiplexers 383 _ 0 to 383 _ 7 , 385 _ 0 , 385 _ 1 , and 387 of the serialization unit 380 can be grouped into first multiplexers 383 _ 0 to 383 _ 7 , second multiplexers 385 _ 0 and 385 _ 1 , and a third multiplexer 387 . The first flip-flops 382 _ 0 to 382 _ 7 receive data from input/output pads DQ 0 to DQ 3 , DQ 4 to DQ 7 , . . . , and DQ 28 to DQ 31 , respectively, and transfer the signals according to a first division clock CLK/32 produced by dividing a system clock by 32. The first multiplexers 383 _ 0 to 383 _ 7 receive signals from the first flip-flops 382 _ 0 to 382 _ 7 and output the signals sequentially. Here, each of the first multiplexers 383 _ 0 to 33 _ 7 receive four signals from each of the first flip-flops 382 _ 0 to 382 _ 7 . The second flip-flops 384 _ 0 to 384 _ 7 receive signals output from the first multiplexers 383 _ 0 to 383 _ 7 and transfer the signals according to a second division clock CLK/8 produced by dividing the system clock by 8. The second multiplexers 385 _ 0 and 385 _ 1 receive signals output from the second flip-flops 384 _ 0 to 384 _ 7 and output the signals sequentially. Here, each of the second multiplexers 385 _ 0 and 385 _ 1 receive four signals. The third flip-flops 386 _ 0 and 386 _ 1 receive signals output from the second multiplexers 385 _ 0 to 385 _ 1 and transfer the signals according to a third division clock CLK/2 produced by dividing the system clock by 2. The third multiplexer 387 receives signals output from the third flip-flops 386 _ 0 and 386 _ 1 and outputs the signals sequentially.

As described above, the serialization unit 380 can serialize signals output from the first to thirty second input/output pads DQ 0 to DQ 31 using the flip-flops 382 _ 0 to 382 _ 7 , 384 _ 0 to 384 _ 7 , and 386 _ 0 and 386 _ 1 , and the multiplexers 383 _ 0 to 383 _ 7 , 385 _ 0 , 385 _ 1 , and 387 . In addition, according to the number of input/output pads, the structure of the serialization unit 380 can be varied, and the division clocks can be varied.

In accordance with the present invention, signal input/output channels of the semiconductor memory apparatus are grouped, and each of the groups shares a CRD circuit. Therefore, the area of the semiconductor memory apparatus occupied by the CRD circuits can be reduced, and thus the semiconductor memory apparatus can be highly integrated.

Moreover, in accordance with the present invention, the CDR circuit can be usefully used in a semiconductor memory apparatus, an electronic device, or an electronic system for reducing the number of components and power consumption.

While the present invention has been described with respect to the specific embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims.