KR19990003965A - SDRAM Interface on PDP-TV - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor memory device for storing image information displayed on a screen in a PDP-TV. In particular, the present invention relates to a PDP- using synchronous dynamic RAM (SDRAM) without using static RAM (SRAM) or dynamic RAM (DRAM). An SDRAM interface device of a PDP-TV for storing and reading frame data of a TV is disclosed.

In order to store and read the frame data of PDP-TV, SDRAM of 1M × 8bit × 2bank is used.The memory array of SDRAM is composed of 2048 rows and 512 columns. It is synchronous to, so if you apply a row address and a column address once, the data is continuously output. Since this output data can be written for 1066 clock intervals, it is possible to convert the row address, thus reducing the amount of memory required. It has the effect of speeding up access.

Description

A SDRAM interface of PDP-TV

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor memory device for storing image information displayed on a screen in a PDP-TV. In particular, the present invention relates to synchronous dynamic RAM (hereinafter referred to as 'SDRAM') without using a static RAM (SRAM) or a dynamic RAM (DRAM). The present invention relates to an SDRAM interface device of a PDP-TV for storing and reading data of a PDP-TV by using a.

In general, a random access memory such as DRAM or SRAM has been used as a conventional memory for processing image signals.

FIG. 1 is a block diagram showing an example of a conventional DRAM, and FIG. 2 is a block diagram specifically showing a configuration of main parts of the DRAM shown in FIG.

As shown in FIG. 2, the memory array 1 shown in FIG. 1 includes a plurality of word lines WL, bit line pairs and word lines that intersect a plurality of bit line pairs BL1 to BL8 and bit line pairs. It includes a plurality of memory cells (MC) provided at the intersection of. The plurality of bit line pairs are also divided into a plurality of bit line groups BG1 and BG2 each including four bit line pairs. In FIG. 2, the bit line pair BL1-BL4 constitutes the bit line group BG1, and the bit line pair BL5-BL8 constitutes the bit line group BG2. The plurality of word lines are connected to the row decoder 2 shown in FIG. The row decoder selects any of a plurality of word lines and activates the selected word lines. As a result, the row decoder makes the potential of the selected word line high and the potential of the unselected word line low.

The Sense Amplifier group 3 shown in FIG. 1 includes a plurality of sense amplifiers connected to each bit line pair in FIG. 2, each sense amplifier detecting a potential difference on a corresponding bit line pair. Amplify. Further, the column selector circuit group 4 shown in FIG. 1 includes a plurality of column selector circuits each provided corresponding to the bit line group. In FIG. 2, the column selection circuit SL1 provided in correspondence with the bit line group BG1 and the column selection circuit SL2 selected in correspondence with the bit line group BG2 are indicated. Each column select circuit includes four sets of transfer gates (TGs) corresponding to four pairs of bit lines in each bit line group, so four sets of transfer gates corresponding to four pairs of bit lines in each bit line group Four input / output line pairs I01 to I04 are respectively connected.

In addition, the column decoder 5 selects any one of the bit line groups, and simultaneously sets four transfer gates in the corresponding column selection circuit to conduction state. In FIG. 2, the column select signal CSL1 generated at the column decoder 5 is given to four sets of transfer gates in the column select circuit SL1, while the column select signal CSL2 is given to four sets of transfer gates in the column select signal SL2. .

In FIG. 1, the memory block B1 includes an input buffer 6, a 4-bit serial / parallel conversion circuit 7, a write buffer 8, a preamplifier 9, and a 4-bit parallel / serial conversion circuit. (10) and the output buffer (11).

The input buffer 6, the serial-parallel conversion circuit 7, and the write buffer 8 operate in the data write operation, and the preamplifier 9, the parallel-serial conversion circuit 10, and the output buffer 11 are operated. Operates in the data read operation. On the semiconductor chip CH, a row address buffer 12, a column address buffer 13, a control signal buffer 14, a clock buffer 15, an address counter 16 and a timing generating circuit 17 are provided. The row address buffer 12 applies an externally given address signal ADD to the row decoder 2 as a row address signal in the timing generation circuit. The column address buffer 13 also applies an externally given address signal as a column address signal to the address counter at a predetermined timing. Meanwhile, the control signal buffer 14 inputs an external row address strobe signal (/ RAS), an external column address strobe signal (/ CAS), an external write enable signal (/ WE), and an external output enable signal (/ OE). After that, it is applied to the timing generating circuit 17 with a constant signal.

In addition, the clock buffer 15 receives a given clock signal from the outside and applies the same signal to each circuit inside the chip, and the address counter 16 receives the column address signal given by the column address buffer 13 as a start address. Change in response to a clock signal.

The address counter 16 generates a column address signal comprising two bits A0 and A1, which are given to the serial-parallel conversion circuit 7 and the parallel-serial conversion circuit 10. The other bits A2-An in this column address signal are given to the column decoder 5, and the timing generating circuit 17 generates various control signals for controlling each circuit in the chip.

The operation of the random access mode of the DRAM shown in FIG. 1 and FIG. 2 will be described in detail.

The row decoder 2 selects one of the word lines in the memory array 1 in response to the row address signal, sets its potential high, and selects a corresponding bit line from the memory cell connected to the selected word line. The data is read into The read data is sensed by the sense amplifier included in the sense amplifier group 3 and then amplified and maintained. The column decoder 5 also selects one of the bit line groups to activate the corresponding column selection circuit in response to bits A2-An of the given column address signal via the address counter 16. The four bit line pairs in the bit line group selected above are connected to the four input / output line pairs I01 to I04 through the column selection circuit, respectively.

On the other hand, in the data read operation, 4-bit data on the four bit line pairs in the selected bit line group is applied to the preamplifier 9 for later amplification through the four input / output line pairs I01-I04. After the applied signal is amplified by the preamplifier 9, four bits of data are respectively applied to the read data buses RDB1-RDB4. The parallel-serial conversion circuit 10 applies one of four bits of data on the read data buses RDB1-RDB4 to the output buffer 11 in response to two bits A0 and A1 of the column address signal. As a result, data is provided from the output buffer 11 to the input / output terminal I / O.

In addition, during the data writing operation, data is externally sequentially given to the input / output terminals, and the data is sequentially applied to the serial-parallel conversion circuit 7 through the input buffer 6, and the serial-parallel conversion circuit is the data. Is converted into parallel data and the same is given to the recording buffer 8. As a result, data can be read into four input / output line pairs I01 to I04.

The mode in which the column selection circuit is randomly activated according to an externally applied address signal is called a page mode. Only the address signal specifying the start address is set in the address counter 16, and then the address signal generated from the address counter. The mode in which the column selection circuits are activated sequentially is called a serial mode. On the other hand, since the sense amplifier group 3 generally holds thousands of bits of data, the page mode and the serial mode can be accessed at high speed. In particular, a plurality of data obtained by activation of one column selection circuit in serial mode further increases the speed of serial access by performing parallel / serial conversion or by performing time division operation (pipeline control).

FIG. 3 shows the main parts of the DRAM shown in FIGS. 1 and 2.

2, bit line group BG1 includes bit line pair BL1-BL4, bit line group BG2 includes bit line pair BL5-BL8, bit line group BG3 represents bit line pair BL9-BL12 and bit line group BG4 represents bit line pair. BL5-BL16. On the other hand, the column addresses assigned to the bit line pair BL1-BL16 are each designated by Y1-Y16, and the bit line pair BL1-BL4 in the bit line group BG1 is connected to the input / output line pairs I01-I04 through the column select circuit SL1, respectively. . The bit line pair BL5-BL8 in the bit line group BG2 is connected to the input / output line pairs I01-I04 through the column select circuit SL2, respectively, and the bit line pair BL13-BL16 in the bit line group BG4 is connected to the input / output line pair I01 through the column select circuit SL4. Are respectively connected to -I04. As described above, the input / output line pairs I01 to I04 are common to all bit line groups. Therefore, simultaneous activation of multiple column selection circuits is impossible, and in the serial mode, the start address is set in the address counter 16 and one column selection circuit corresponding to the start address is activated.

As shown in Fig. 4, when the start address is set to Y1-Y4, the column selection circuit SL1 is activated first. Column addresses Y1, Y2, Y3, Y4 are sequentially accessed when the start address Y1 and column selection circuit SL1 are activated, and column addresses Y2, Y3, Y4 are sequentially accessed when the start address Y2 and column selection circuit SL1 are activated. When start addresses Y3 and SL1 are activated, they are set to Y3, Y4 and start addresses Y4. When column selection circuit SL1 is activated, only column address Y4 is accessed. Thus, the range that can be accessed without requiring activation of other column selection circuits depends on the start address. In particular, if the start address is set to Y4, for example, it is necessary to activate another column selection circuit to access the next column address. This has the problem that the time from activation of the column selector circuit to preamplifier operation determines the bitrate. This problem will be explained below with reference to FIGS. 5 and 6.

Fig. 5 is a timing chart indicating operation when the start address is set to Y1 in the serial mode, and Fig. 6 is a timing chart indicating operation when the start address is set to Y4 in the serial mode. 5 and 6, D1-D12 represent the data read in the bit line pair BL1-BL12 (FIGS. 2 and 3), respectively.

When the external row address strobe signal / RAS falls to low, an externally given address signal ADD is given to the row decoder 2 in the row address signal AX. Thereby, one word line is activated. Thereafter, when the external column address strobe signal / CAS falls to low, an externally given address signal ADD is given to the address counter 16 as the column address signal AY. The address counter 16 gives two bits A0 and A1 in the column address signal AY to the parallel-serial converting circuit 10 and the other bits A2-An to the column decoder 5.

In Fig. 5, if column address signal AY designates column address Y1, the start address is set at Y1. First, the column decoder 5 raises the column select signal CSL1 to high and activates the column select circuit SL1. As a result, the data D1-D4 on the bit line pair BL1-BL4 are respectively read into the input / output line pairs I01-I04. The data D1-D4 are given to the read data buses RDB1-RDB4 via the preamplifier 9. The address counter 16 sequentially counts up the column address signal AY in response to the clock signal given by the clock buffer 15. The parallel-serial conversion circuit 10 sequentially selects data D1-D4 and applies the same to the output buffer 11 in response to two bits A0 and A1 in the column address signal AY. Thereby, the data D1-D4 are supplied in series from the input / output terminal I / O as the output data Dout. When the column decoder 5 raises the column select signal CSL2 high, data D5-D8 are read into the input / output line pairs I01-I04 in the same manner. The data D5-D8 are given to the read data buses RDB1-RDB4 via the preamplifier 9, respectively. The address counter 16 sequentially counts up the column address signal AY in response to the clock signal given by the clock buffer 15.

The parallel-serial conversion circuit 10 sequentially selects the data D5-D8 and applies the same to the output buffer 11 in response to two bits A0 and A1 in the ear address signal AY. Thereby, the data D5-D8 are supplied in series from the input / output terminal as the output data Dout, and in this method, the data is read in series to the input / output terminal.

As shown in Fig. 6, if the column address signal AY opens and designates the dress Y4, the start address is set to Y4. Also in this case, the column decoder 5 first raises the column select signal CLS1 to high and activates the column select circuit SL1. Thereby, the data D1-D4 on the bit line pair BL1-BL4 are read into the input / output line pairs I01-I04, respectively, and the data D1-D4 respond to the two bits A0 and A1 in the column address signal. The preamplifier 9 is applied to the data RDB1-RDB4.

The parallel-serial conversion circuit 10 selects the data D4 in response to two bits A0 and A1 in the column address signal AY and applies the same to the output buffer 11. The data D4 is output from the input / output terminal as the output data Dout. Next, when the column decoder raises the column select signal CSL2 high, the data D5-D8 are read into the input / output line pairs I01-I04 in the same manner. Data D5-D8 are each given to the read data buses RDB1-RDB4 via the preamplifier. The address counter 16 sequentially counts up the column address signal AY in response to the clock signal CLK given by the clock buffer 15.

The parallel-serial conversion circuit 10 sequentially selects the data D5-D8 in response to two bits A0 and A1 in the column address signal AY and applies the same to the output buffer. The data D5-D8 are called output data Dout and are output in series at the input / output terminal. In this case, the column select signal CSL2 may rise high only after the column select signal CSL1 falls low. In addition, a gap is required between the falling of the column selection signal CSL1 and the rising of the column selection signal CSL2 in order to avoid the two column selection signals from changing to the on state at the same time.

As shown in Fig. 5, if the column address signal AY designates the column address Y1, no gap occurs between the output data and thus the bit rate is not lowered. However, as shown in FIG. 6, if the column address signal AY designates the column address Y4, a gap is generated between the data D4 and D5 output from the input / output terminal.

As such, when one bit line pair in a bit line group and one bit line pair in another bit line group are continuously selected, a data gap occurs, which causes a problem of deterioration in access speed and bit rate.

Accordingly, an object of the present invention is to solve the above problem, and an object of the present invention is to provide image information having an image resolution of 853 × 480 in an PDP-TV using SDRAM composed of 1M × 8 bit × 2 banks. It is designed to reduce the amount of memory while saving and reading data, while providing high speed.

1 is a block diagram showing the overall configuration of a DRAM in the prior art;

FIG. 2 is a diagram showing a detailed configuration of main parts of a DRAM in FIG. 1; FIG.

3 is a view schematically showing only main parts of the configuration shown in FIG. 2;

FIG. 4 shows a range that can be accessed in the DRAMs shown in FIGS. 1 and 2 without having to activate another column selection circuit.

5 is a timing chart showing operation in the serial mode of the DRAM in FIGS. 1 and 2;

FIG. 6 is a timing chart showing disadvantages relating to operation of the DRAM in the serial mode in FIGS. 1 and 2;

7 is a block diagram schematically showing the configuration of a CMOS SDRAM;

8 is a block diagram of an interface of an SDRAM in the PDP-TV of the present invention.

9 illustrates an electrode structure of a PDP-TV.

10 is a diagram showing a clock for data recording and reading.

11 is a block diagram schematically illustrating a memory map.

* Explanation of symbols for the main parts of the drawings

10: video decoder unit 20: mode switching unit

30: memory section 32: line memory section

34: frame memory section 40: PISO section

50: address section 60: data selection section

70: PDP part

According to an aspect of the present invention, a video decoder unit connected to a tuner circuit and outputting a constant resolution for image information of a screen, and an image signal connected to the video decoder unit and output from a video decoder unit, namely, interlaced mode A mode switching unit for converting a signal into a sequential mode signal, a line memory unit connected to the mode switching unit, a line memory unit for recording and reading image information output from the mode switching unit, and a line memory unit PISO (Parallel Input Serial Output) unit for converting signals output in parallel to the serial signal, the frame memory A is connected to the PISO unit, and writes and reads the serial signals output from the PISO unit in units of frames. Connected to the frame memory section consisting of frame memory B, the mode switching section and the line memory section, and the recording signal and reading of the frame memory section An address unit for providing the address according to the call, and

A PDP-TV connected to the frame memory section, comprising a data selection section for selecting image data output in the read mode from frame memory A and frame memory B and providing the PDP section to the PDP section; Provides an SDRAM interface device.

First, the embodiment of the SDRAM will be briefly described in order to help the understanding of the present invention.

Fig. 7 is a block diagram schematically showing the configuration of a CMOS type SDRAM.

The SDRAM used in the present invention has a memory array consisting of 2 banks of 1,048,576 words x 8 bits. On the other hand, in bank selection 78, program key A ₁₁ is latched by the / RAS and / CAS signals, bank A is selected when A ₁₁ is low, and bank B is selected when A ₁₁ is high.

In addition, the memory cell array 70 includes memory cells (not shown) arranged in a matrix in the row and column directions, a word line (not shown) provided in one row for each row, and a pair for each column. Contains bit line pairs (not shown). Each of the memory cells is connected to a word line of a corresponding row and a bit line pair of a corresponding column. Further, the word line is selected by the row decoder 77, and the bit line pair is selected by the column decoder 72. The word line selection in the row decoder 77 and the bit line pair selection in the column decoder are performed after the signal is applied to the column buffer 76 and the row buffer 80 by the address register 79, respectively. This is done in response to an address signal output from the decoder.

On the other hand, the / RAS (row address strobe signal) and / CAS (column address strobe signal) input to the timing register 75 again apply a clock to the row address register and the column address register. Initially, / RAS and / CAS are high, but after the setup time for the row address register elapses, the / RAS input goes low. When a row address is applied to the row buffer unit 80, the corresponding address is represented as a row decoder input. That is, in / RAS, the row enables the decoder to decode the row address and selects one row array. At the time when the row address ends and the column address starts, the corresponding column address is applied to the address input, and the / CAS input goes low to apply the column address to the column address register. The / CAS can also enable the column decoder to decode the column address and select the corresponding column array.

In addition, the refresh counter 80 of the row buffer 80 allows all cells in the same row to be refreshed every time a read operation occurs in one cell, and the sense amplifier 71 reads the data in the memory cell array. Amplify the data (read data) appearing in each bit line pair in the block.

The input / output controller 82 transmits a bit line pair in the memory cell array 80 to the data input register 81 and the output buffer 83 so as to correspond to each of the bit line pairs. And a data input register 81 and an output buffer 83 based on the most significant bit signal and the / WE signal in each of the address signals output from the row and column buffers.

An embodiment of the present invention will be described in detail with reference to the block diagram of the SDRAM.

8 is a schematic block diagram showing a data interface device using the SDRAM of the PDP-TV according to the present invention.

Referring to FIG. 8, the video signal and the audio signal transmitted from the broadcasting station are received by the tuner circuit unit and then applied to the video decoder unit 10 through a predetermined process. The signals applied to the video decoder 10 are output to the mode switching unit 20 as signals having a constant resolution.

Since the signal applied from the video decoder is an interlaced mode signal, the signal is converted into a sequential mode signal. The reason is that, unlike the cathode ray tube driving pixel by pixel, the PDP-TV's three primary color light components of red, green, and blue (RGB) produced by the target image are broken by line for a certain period of time. This is because it is a line sequential method that is converted into an electrical signal and transmitted and received. In addition, the signals converted into the sequential signals are applied to the line memory unit by 8 bits for each RGB, and are simultaneously applied to the address unit 50 as well.

Fig. 9 shows the electrode structure of the PDP, Fig. 10 is a clock diagram of data writing and reading, and Fig. 11 schematically shows a memory map.

A line memory is connected to the rear end of the mode switching section 20 to interface with the PDP-TV having the electrode structure of FIG. Since the data in this line memory is synchronized with the clock, once a row address and a column address are applied, data is automatically output without applying an address thereafter. In order to alternately read and write the data, the data need only be read for 1H cycles.

As shown in FIG. 10, since the present invention relates to a PDP-TV having a resolution of 853x480, 853 valid data are recorded for 853 clock sections, and 853 data for 1066 clock sections in a horizontal sync clock. You only have to read because you can afford to. Since the 1066 clocks generally generate 800 clocks when recording 640 valid data, 866 clocks infer 1066 clocks based on the 800 clocks. That is, since the SDRAM requires a clock cycle of 3 clocks or more when the row address is changed, 853 output data can be read while changing rows with a margin of 1066 clock periods.

In addition, in selecting the memory of the SDRAM, the PDP-TV displays data generated by 853 × 8 data per line by weight, so that when 853 is divided into 8, 106.625, that is, 107 addresses are required. That is, as shown in Fig. 11, one line of data is stored per two row addresses. In total, six 1M × 8bit × 2bank memories are required, with 1M consisting of 2048-bit rows and 512-bit columns. At 853 x 480 resolutions, the 853 can store 427 addresses in two row addresses.

Based on the above description, the upper 4 bits of the R 8 bits applied by the mode switching unit 20 are stored in the RA of the line memory unit, the lower 4 bits are stored in the RB, and the upper 4 bits of the G 8 bits are stored in the GA. The lower 4 bits are stored in GB, and the upper 4 bits in B 8 bits are stored in BA, and the lower 4 bits are stored in BB, respectively. Data stored in the line memory section is applied to the PISO section in accordance with the read and write signals.

The image data provided in parallel (MSB to LSB) in the line memory unit 32 is rearranged to be stored as bits having the same weight at one address of the frame memory. That is, while the first shift resister loads eight samples of image data, in the second shift resister, eight samples of previously loaded image data are sequentially ordered from the most significant bit (8 bits) to the least significant bit (8 bits). It is output while shifting to. Therefore, in order to continuously rearrange the image data provided by the line memory section 32, two first and second shift resist sections are provided, and they alternately repeat the load and shift operations. In addition, two frame memory units 34 capable of storing a single piece of image data are also provided so that they can be written and read in units of frames alternately, so that image data can be continuously stored and displayed.

The present system converts and displays video data input by interlacing in a sequential manner, so that the order of write addressing and read addressing is different. That is, the image data of one frame stored in the memory reads one line of odd line data and then repeats reading of even line data. Further, in the PDP gradation processing, one field is divided into several subfields, and image data corresponding to each subfield must be read and provided in turn, so that the reading order is structurally very different from the recording order. Therefore, a write generator 56, a read generator 54, and an address generator are required, and serve to provide a corresponding address according to each operation mode (write and read mode) of the frame memories A and B. FIG.

The serial signals output from the PISO unit are applied to the frame memory unit in frame units, and the data stored in the frame memory unit outputs data in accordance with an operation signal for data selection, and the address drive IC unit of the PDP unit (not shown). If the data required by is output from the data selector with upper 12 bits and lower 12 bits, one PDP screen is displayed.

As can be seen from the above description, in order to store and read the frame data of the PDP-TV, an SDRAM consisting of 1M × 8bit × 2 banks is used, and since the SDRA M is synchronized with a clock, it is continuously output from the SDRAM. Since data can be read only during the 853 clock period during the 1066 clock period, the data can be written in a relaxed manner, and also by accurate counting in converting the row address, thereby reducing the amount of memory required and increasing the access speed. It works.

Claims (4)

In the SDRAM interface device of the PDP-TV composed of the input part of the composite video signal, the video decoder part, the mode switching part, the memory part, the PISO part, the address part, and the data selection part and the PDP part, the image signals of the tuner circuit part are converted into RGB signals. A video decoder 10 for converting to a format having a constant resolution, A mode switching unit 20 for converting the interlaced mode signal applied from the video decoder into a sequential mode signal and outputting 8-bit RGB signals respectively; In the RGB signal applied by the mode switching unit, the upper 4 bits and the lower 4 bits of R are respectively stored in the line memory unit of RA and RB, and the upper 4 bits and the lower 4 bits of G are stored in GA and GB, A line memory section 32 for storing the upper 4 and lower 4 bits of B in the line memories of BA and BB, respectively, A PISO unit 40 for serially outputting data on image information applied in parallel from the line memory unit 32; A frame memory unit 34 for storing a serial signal of image information output from the PISO unit in units of frames, Data selection for selecting and outputting image data output in the read mode among the address unit 50 for providing an address in response to the read and write signals of the memory unit 30 and the frame memories 34 A and B. An SDRAM interface device of a PDP-TV, comprising: a unit (60) and a PDP unit. The line memory unit 32 is configured to convert the line memory RA, RB, GA, GB, BA, 8 bit into upper 4 bits and lower 4 bits, respectively, according to the electrode structure of the RGB signal shown in FIG. 10. The SDRAM interface device of the PDP-TV characterized by having a structure in which valid data of the 853 clock shown in Fig. 10 is read during the 1066 clock period after being stored in the BB. 3. The memory map of the line memory section 32 is a PDP-TV having a resolution of 853x480 because the memory array of the SDRAM is composed of 2048 rows and 512 columns as shown in FIG. An SDRAM interface device of a PDP-TV, characterized by dividing image information for 853 rows into two rows of memory. 2. The SDRAM interface device of claim 1, wherein the PISO unit (40) outputs data applied in parallel from the line memory unit in series.