TW201027552A - Sense amplifier, memory device and sensing method - Google Patents

Abstract

A sense amplifier for a read only memory (ROM) is provided. The sense amplifier includes a comparator and a selecting unit. The comparator compares a bit-line voltage and a reference voltage to obtain an output data. The selecting unit selects either a first voltage or a second voltage as the reference voltage according to the output data.

Description

201027552 VI. Description of invention:

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a sense amplifier, and more particularly to a sense amplifier for a read only memory (ROM).

Read-only memory is a common semiconductor storage device that is a type of memory that can only read data. Therefore, once the data is stored in the vocabulary memory, the data cannot be easily changed or deleted. In general, read-only memory is often used in electronic devices or computer systems to avoid the loss of stored data due to power off.

Figure 1 shows a read-only memory, one, , · ^ ^ ^ Pp 丄丫, . The hidden cell MG and the memory cell Ml are located on the same _ bit line = this is the word line WL0 Controlled, and the memory unit M; is controlled by the sub-element WL1. When a .^ _ data is used, it must be detected that the state of the memory unit in the read-only memory is open state (such as the display, in addition to the memory unit The number of memory cells of the display device will also be increased with the addition of 'additional' to the bit-coded two-review == body for reading, and the sensed amplification system can be used to display a conventionally obtained voltage ~. The second comparator 210 and The pin amplifier 200. The sense amplifier 200 includes a VBL and a reference voltage source latdl) 22G. The comparator 210 can compare the voltage and then the phase locker 220 and obtain a comparison result A. The comparison result Dc is locked according to the signal slateh; cmp 97023/0516-A41906twf cmp 201027552 and the output data D corresponding to the comparison result Dcmp is provided. 〇ut to the output buffer. However, when the number of memory cells on the bit line BL increases, the parasitic capacitance on the bit line BL also increases. Therefore, for the bit line bl, it is susceptible to interference from noise at the power supply or ground, such as a power/ground bounce problem. For read-only memory with low operating voltage capability, the problem of noise interference is significantly more severe. Referring to FIG. 3, when reading the read-only memory, the sense amplifier 200 may obtain a bounce voltage Vbl from the bit line BL of the read-only memory due to interference of the noise on the power supply terminal or the ground terminal. . Next, the comparator 210 compares the voltage Vbl with the reference voltage Vref. Then, the phase locker 220 locks the erroneous comparison result according to the signal slatch and provides the erroneous output data Dout to the output buffer. Therefore, once the wrong data is locked, the sense amplifier 2 cannot return the error data to the correct data' and provide it to the output buffer. SUMMARY OF THE INVENTION The present invention provides a sense amplifier suitable for use in a read only memory. The above-mentioned sense amplifier includes: a comparator for comparing a bit line voltage and a reference voltage to obtain an output data; and a selection unit for selecting a first voltage according to the rounded data and One of the second voltages is used as the above reference voltage. Furthermore, the present invention provides a memory device comprising: a read-only memory having a plurality of memory cells arranged on a single bit line; and, a sense amplifier. The sense amplifier includes: a conversion unit for converting a current of one of the bit lines into a one-bit line voltage; and a comparator for the reference of the above-mentioned bit line and a reference for the 97023/0516-A41906twf 4 201027552 a voltage for obtaining an output data, and a selecting unit for selecting one of a first voltage and a second voltage as the reference voltage according to the output data, wherein the first voltage is greater than the second voltage . Furthermore, the present invention provides a sensing method for sensing an output data from a bit line of a read-only memory. The sensing method includes: converting one of the bit lines into a bit line voltage; selecting one of the first voltage and the second voltage as a reference voltage according to the output data; and, the bit The line voltage and the above reference voltage are compared to obtain the above output data. The above and other objects, features and advantages of the present invention will become more apparent and understood from The figure shows a sense amplifier 400 in accordance with an embodiment of the present invention. The sense amplifier 400 includes a conversion unit 41A, a comparator 420, and a selection unit 430. When the read-only memory is read, the conversion unit 41〇 converts the current & on the bit line in the read-only memory into the bit line pad VBL. The comparator 420 can compare the bit line voltage Vbl and the reference voltage & to produce an output data Dw. In this embodiment, when the bit line voltage VBL is greater than the reference voltage 1, the output data D(10) is at a high voltage level. On the other hand, when the reference voltage vref is greater than the bit line voltage Vbl, the output 97023/0516-A41906twf 201027552 indicates that the data Dout is a low voltage level. The selection unit 43A can be coupled to the voltage VL or the voltage Vh according to the negative input end of the output data U comparator 420, wherein the voltage vH is greater than the voltage V1. Therefore, the voltage VH can be selected as the reference voltage vref according to the output data D^, and = the second voltage VL is taken as the reference voltage Vref. In this implementation, when the output data 〇_ is a high voltage level, the selection unit 430 couples the negative input terminal of the comparator 42A to the voltage vL to use the voltage V1 as the reference voltage Vref. When the output data D〇m is a low voltage level, the selection unit 43〇 couples the negative input terminal of the comparator 420 to the voltage νΗ to use the voltage Vh as the reference voltage \^ef. w Refer to Figure 5, which shows the waveform of the internal signal of the sense amplifier in Figure 4. During the period T1 and the period Τ2, the bit line BL is interfered by the noise on the power supply terminal or the ground terminal (for example, the noise generated when the output buffer operates), thereby causing the current Ibl to bounce (b〇unce) or The phenomenon of shock appears. Via the conversion unit 41, the current Ib1 is converted into the bit line voltage vBL. At the same time, the bounce phenomenon on the current Ibl is also amplified, so that the bounce phenomenon on the bit line voltage Vbl is more pronounced. During the period τ , , since the output data Dout is at a low voltage level, the selection unit 43 当 takes the voltage VH as the reference voltage Vref. Therefore, the comparator 42 比较 compares the bit line voltage VBL with the voltage 乂 11 instead of the voltage V1. Since the bounce voltage on the bit line voltage vBL is not higher than the voltage Vh, the output data D〇ut provided by the sense amplifier is not interfered by the noise on the bit line BL, that is, the output data D〇 Ut does not become a high voltage level during the period τΐ. Similarly, during the period of period T2, since the output data Dout is at a high voltage level, the selection unit 43() regards the voltage V1 as the reference voltage Vref of 97023/0516-A41906twf 201027552. Therefore, the comparator 420 compares the bit line voltage Vbl with the voltage vL instead of the voltage vH. Since the bounce voltage on the bit line voltage vBL is not lower than the voltage vL, the input and output data Dout& provided by the sense amplifier will not be disturbed by the bit line BL, that is, the wheel data DQUt will not It becomes a low voltage level during the period of period T2. In one embodiment, the sense amplifier of the present invention can be placed in an integrated circuit. As for the integrated circuit, as the size of the chip and the complexity of the application increase, the noise interference at the power supply terminal and the ground terminal also increases. ❹ Therefore, in an integrated circuit, a memory device including the sense amplifier of the present invention and a read-only memory (for example, a mask-type read-only memory (MaskROM)) can reduce noise interference to read-only memory. The impact of the output data. In addition, if the initial value of the output data is incorrect, the memory device can also correct the error output data to the correct output data. Figure 6 is a diagram showing a sensing method according to an embodiment of the present invention for sensing output data D〇ut from a bit line BL of a read-only memory. First, in step S602, the current IBL on the bit line BL is converted into the bit line voltage Vbl. Next, in step S604, one of the voltage vH and the voltage V1 may be selected as the reference voltage vref according to the output data Dcut. For example, when the output data is high voltage level, the voltage vl can be regarded as the reference voltage Vref. Conversely, when the output data is at a low voltage level, the voltage vH can be taken as the reference voltage Vref. Next, in step S6, the bit line voltage VBL is compared with the reference voltage Vref to obtain the correct output data Dout. For example, when the bit line voltage vBL is greater than the reference voltage v ^ , the output data Dout can be obtained as a high voltage level, and when the reference voltage is ^

When Vref is greater than the bit line voltage VBL, the output data can be obtained as low power. 97023/0516-A41906twf 7 201027552 .. Pressure level. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic diagram showing a read only memory; Fig. 2 is a conventional sense amplifier; i Fig. 3 is a waveform diagram showing the internal signal of the sense amplifier in Fig. 2; 4 is a view showing a sense amplifier according to an embodiment of the present invention; FIG. 5 is a view showing a waveform of a signal inside the sense amplifier in FIG. 4; and FIG. 6 is a view showing an embodiment according to an embodiment of the present invention. The sensing method described. [Major component symbol description] 210, 420~ comparator; 410~ conversion unit; BL~bit line; MM2~ memory unit; Dcmp~ comparison result; SLateh~ signal; Vh, Vl~ voltage, WL0, WL1~ Word line. 200, 400~ sense amplifier; 220~ phase locker; 430~ select unit;

Dout~ output data;

Ibl~ current; S602-S606~ step; VBL~bit line voltage;

Vref~reference voltage; and 97023/0516-A41906twf 8

Claims (1)

201027552 VII. Patent Application Range: » 1. A sense amplifier for a read-only memory, comprising: a comparator for comparing a bit line voltage and a reference voltage to obtain an output data; And a selecting unit, configured to select one of the first voltage and the second voltage as the reference voltage according to the output data. 2. The sense amplifier of claim 1, further comprising: a conversion unit for converting a current of φ on a bit line of the read-only memory to the bit line voltage. 3. The sense amplifier of claim 1, wherein the first voltage system is greater than the second voltage. 4. The sense amplifier of claim 3, wherein when the output data is a high voltage level, the selection unit selects the second voltage as the reference voltage, and when the output data is a low voltage level On time, the selection unit selects the first voltage as the reference voltage. 5. The sense amplifier of claim 4, wherein the comparator has a positive input for receiving the bit line voltage and a negative input for receiving the reference voltage. 6. The sense amplifier of claim 1, wherein the above-mentioned read-only memory system is disposed in an integrated circuit. 7. The sense amplifier of claim 1, wherein the above-mentioned read-only memory system is a reticle type read only memory. 8. A memory device comprising: a read only memory having a plurality of memory cells disposed on a bit line 97023/0516-A41906twf 9 201027552; and a sense amplifier comprising: a conversion unit for Converting a current of one of the bit lines into a bit line voltage; a comparator for comparing the bit line voltage and a reference voltage to obtain an output data; and a selecting unit for outputting the data according to the output And selecting one of the first voltage and the second voltage as the reference voltage, wherein the first voltage is greater than the second voltage. 9. The memory device of claim 8, wherein the selection unit selects the second voltage as the reference voltage when the output data is at a high voltage level, and when the output data is a low voltage level On time, the selection unit selects the first voltage as the reference voltage. 10. The memory device of claim 9, wherein the comparator has a positive input for receiving the bit line voltage and a negative input for receiving the reference voltage. 11. The memory device of claim 8, wherein the readable memory system is a reticle type read only memory. 12. A sensing method for sensing an output data from a bit line of a read-only memory, comprising: converting a current of one of the bit lines into a bit line voltage; and according to the output data, Selecting one of a first voltage and a second voltage as a reference voltage; and comparing the bit line voltage and the reference voltage to obtain 97023/0516-A41906twf 10 201027552 to the above output data. 13. The sensing method of claim 12, wherein the first voltage system is greater than the second voltage. 14. The sensing method of claim 13, wherein the selecting step comprises: selecting the second voltage as the reference voltage when the output data is at a high voltage level; and when the output data is At the low voltage level, the above first voltage is selected as the above reference voltage. 15. The sensing method according to claim 14, wherein when the bit line voltage is greater than the reference voltage, the output data is a high voltage level, and when the reference voltage is greater than the bit line voltage The above output data is a low voltage level. 16. The sensing method of claim 12, wherein the read-only memory system is disposed in an integrated circuit. 17. The sensing method according to claim 12, wherein the above-mentioned ® read-only memory system is a reticle type read only memory. 97023/0516-A41906twf 11