JPH0758593B2 - Sense up circuit - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sense amplifier circuit used in a semiconductor memory circuit.

2. Description of the Related Art A conventional sense amplifier circuit and its operation will be described with reference to FIGS.

First, FIG. 5 is a circuit diagram of a conventional P-type sense amplifier. 1 is a P-type flip-flop circuit, 2 is a bit line pair, 3
Is the common source node of the P-type flip-flop circuit 1,
It is a switch element for connecting to the internal power source ▲ V _{′ CC} ▼ 6 which is stepped down from the external power source Vcc5.

Next, the operation will be described with reference to FIG.

First, by reading the memory cell, a potential difference ΔV is generated in the bit line pair 2. Next, in order to amplify the potential difference ΔV, the switch element 3 is turned on and the flip-flop circuit 1
Is activated.

Further, FIG. 7 is a circuit diagram of a conventional N-type sense amplifier, in which 10 is an N-type flip-flop circuit, 2 is a bit line pair, 30 is a common source node of the N-type flip-flop circuit 30, and is an external power source. It is a switch element for connecting to Vss50. Further, the substrate potential of the N-type MOS transistor forming the flip-flop circuit 10 and the switch element 30 is fixed to the potential V ′ _BB output from the substrate bias generation circuit 40.

Next, the operation will be described with reference to FIG.

First, by reading the memory cell, a potential difference ΔV is generated in the bit line pair 2. Next, in order to amplify the potential difference ΔV, the switch element 30 is turned on and the flip-flop circuit is turned on.
Activate 10.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, if the power supply voltage of the memory cell portion is lowered due to the reliability of the oxide film in the memory cell, naturally,
The operating voltage of the flip-flop circuit 1 will drop accordingly. On the other hand, since the threshold value V _th of the transistor forming the flip-flop circuit remains unchanged, the current driving capability of the transistor decreases as understood from the equation (1).

In equation (1), I _bit is the charge / discharge current, W is the gate width of the transistor, L is the gate length of the transistor, μ is the mobility, C _ox is the gate oxide film capacitance of the transistor, and V _bit is the potential of the bit line. , V _s is the potential of the common source node.

The decrease in the current drive capacity of the transistor means that
This means that the charging / discharging current drive capability of the bit line is reduced, which means that the time required for amplification becomes longer and the reading speed of the memory is reduced.

The above problem is a very important problem in the future, as the semiconductor memory becomes finer and higher in density, the power supply voltage tends to decrease due to reliability problems.

In view of the above problems, the present invention is intended to realize a high-speed readable sense amplifier circuit.

Means for Solving the Problems According to the present invention, a common node of a flip-flop type or current mirror type sense amplifier circuit composed of a plurality of transistors is connected to a first power supply voltage supply line via a first switch element. Further, the common node is connected to a supply line of a second power supply voltage having a voltage higher than the first power supply voltage via a second switch element, and a first switch element and a second switch Using the element, temporarily connect the supply line of the power supply voltage connected to the common node to the first node.
The present invention provides a sense amplifier circuit that switches from the power supply voltage to the second power supply voltage and amplifies it.

Function The present invention connects the common node of the flip-flop type or current mirror type sense amplifier circuit composed of a plurality of transistors to the supply line of the first power supply voltage via the first switch element. Activates the sense amplifier circuit, starts amplification of the minute potential difference ΔV of the bit line pair,
Further, after that, via the second switch element, the supply line of the second power supply voltage and the common node are connected so that the operating voltage of the transistor included in the sense amplifier circuit becomes higher than the first power supply voltage. Thus, the current drive capability of the transistor can be increased, and a high-speed sense amplifier circuit that requires a short amplification time can be realized.

Embodiment FIG. 1 shows a circuit example of a sense amplifier circuit of the present invention.

Since the circuit of the first embodiment of the present invention shown in FIG. 1 has basically the same configuration as the conventional circuit shown in FIG. 2, the same components are designated by the same reference numerals. Detailed description is omitted.

First, the configuration of the sense amplifier circuit shown in FIG. 1 will be described. The common source node of the flip-flop circuit 1 composed of two P-type MOS type transistors is replaced by a first switch element composed of a P-type MOS type transistor. 6 to the supply line of the internal power supply voltage ▲ V _{′ CC} ▼ 6. Where ▲
V _{′ CC} ▼ is a power supply voltage obtained by stepping down the external power supply voltage 5 by the down converter 4.

Further, the common source node is connected to the supply line of the external power supply voltage 5 via the second switch element 3 composed of a P-type MOS transistor.

The operation of this sense amplifier circuit will be described with reference to FIG.

By raising the word line, the memory cell is read, and the potential difference ΔV is generated in the bit line pair 2. After that, the sense amplifier control signal 10 is set to low to turn on the first switch element 6 to connect the common source node to the supply line of ∇V _{′ CC} ∇6. Then, the sense amplifier circuit 1 is activated to start amplification. However, as described in the conventional example, since the power supply voltage is lowered, the operating voltage of the transistor forming the P-type flip-flop circuit 1 is low,
The current drive capacity is low. Therefore, there is a problem that the time required for the amplification becomes long, but in the first embodiment, in order to accelerate the amplification, by setting the sense amplifier control signal 10 high and the control signal 20 low, the P Of the transistors forming the P-type flip-flop circuit 1 by replacing the supply line of the internal power supply voltage ▲ V _{′ CC} ▼ 6 connected to the common source node of the P-type flip-flop circuit 1 with the supply line of the external power supply voltage Vcc5. Increase operating voltage and current drive capability. At the timing when the amplification is accelerated and then the bit line pair 2 is amplified to the voltage level of the internal power supply voltage ▲ V _{′ CC} ▼ 6, the sense amplifier control signal 1 is set to low and the control signal 2 is set to high. pair 2, prevented from being amplified higher than the internal power supply voltage ▲ V _'CC ▼ 6 voltage level. Further, since the substrate potential of each transistor is fixed to Vcc5 which is a high voltage, the source and drain regions of each transistor do not have a forward bias relationship with the substrate, so there is no problem of leakage.

As described above, in the first embodiment, P which enables high-speed amplification
Type sense amplifier circuit can be realized.

Next, FIG. 3 shows a circuit example of the second embodiment of the present invention.

Explaining the configuration of the sense amplifier circuit shown in FIG. 3, the common source node of the flip-flop circuit 1 composed of two N-type MOS transistors is connected via the first switch element 70 composed of an N-type MOS transistor. And connect to the supply line of the external power supply Vss50. Further, the common source node is connected to the supply line of the substrate potential V _BB generated from the substrate bias generating circuit 40 via the second switch element 30 composed of an N-type MOS transistor.

The operation of this sense amplifier circuit will be described with reference to FIG.

The memory cell is read by raising the word line, and a potential difference ΔV is generated in the bit line pair 2. After that, the signal 100 after the sense amplifier control is made high to turn on the first switch element 70 to connect the common source node to the supply line of Vss50. Then, the sense amplifier circuit 10 is activated and starts amplification. However, as described in the conventional example, since the power supply voltage is stepped down, the operating voltage of the transistor forming the sense amplifier circuit 10 is low, and the current driving capability is low. Therefore, there is a problem that the time required for amplification becomes long, but in the second embodiment, in order to accelerate the amplification, the sense amplifier control signal 100 is set low and the control signal 2 is set.
By setting 00 to high, it is connected to the common source node of the sense amplifier circuit 10. The supply line of Vss50 is connected to the supply line of the substrate potential V _BB 60 to increase the operating voltage of the transistor forming the N-type flip-flop circuit 10 and enhance the current driving capability. After the amplification is accelerated, the bit line pair 2 is set to the voltage level of Vss50 by setting the sense amplifier control signal 100 to high and the control signal 200 to low at the timing when the bit line pair 2 is amplified to the voltage level of Vss50. Prevent it from getting lower. Also, since the substrate potential of each transistor is fixed at a low voltage V _BB 60, the source and drain regions of each transistor cannot be biased in the forward direction with respect to the substrate, so there is also the problem of leakage. Absent.

As described above, in the second embodiment, N that enables high-speed amplification is used.
Type sense amplifier circuit can be realized.

Further, as can be easily considered, a CMOS sense amplifier circuit in which the first embodiment and the second embodiment of the present invention are combined can be easily realized.

According to the present invention, in view of reliability of the oxide film of the memory cell, the operating voltage of the sense amplifier circuit is lowered and the amplification time is lengthened due to the internal power supply voltage being lowered. The problem is that the operating voltage of the transistor that constitutes the sense amplifier circuit during the amplification period of the sense amplifier circuit is
This can be solved by replacing the supply line of the power supply which is temporarily tangential to the common source node with the supply line of the high voltage power supply so as to be higher, and its practical effect is great.

[Brief description of drawings]

FIG. 1 is a circuit diagram of the first embodiment of the present invention, and FIG.
FIG. 3 is a circuit diagram of a second embodiment of the present invention, FIG. 4 is a circuit operation diagram of a second embodiment of the present invention, and FIGS. Conventional circuit diagrams, FIGS. 6 and 8 are operation explanatory diagrams of a conventional circuit. 1 ... P-type flip-flop circuit, 2 ... bit line pair,
3,6,30,70 …… Switch element, 5,60 …… Second power supply voltage, 6,50 …… First power supply voltage.

Claims (4)

[Claims] 1. A common node of a flip-flop type or current mirror type sense amplifier circuit composed of a plurality of transistors is connected to a supply line of a first power supply voltage via a first switch element, and further, Second common node
Connected to a supply line of a second power supply voltage having a voltage higher than the first power supply voltage via the switch element of, and the common node is temporarily used by using the first switch element and the second switch element. A sense amplifier circuit, characterized in that the supply line of the power supply voltage connected to is switched from the first power supply voltage to the second power supply voltage for amplification. 2. The sense amplifier circuit according to claim 1, wherein the first power supply voltage is generated by a down converter and the second power supply voltage is an external power supply voltage. 3. A common node of a flip-flop type or current mirror type sense amplifier circuit composed of a plurality of transistors is connected to a supply line of a first power supply voltage via a first switch element, and the common node is further provided. Is connected to a supply line of a second power supply voltage having a voltage lower than the first power supply voltage via a second switch element, and the first switch element and the second switch element are used to temporarily A sense amplifier circuit characterized in that a supply line of a power supply voltage that is connected to the common node is switched from the first power supply voltage to a second power supply voltage for amplification. 4. The first power supply voltage is an external current voltage, and the second power supply voltage is
4. The sense amplifier circuit according to claim 3, wherein the power supply voltage is generated by a substrate bias generation circuit.