US20120294090A1 - Current-Sense Amplifier With Low-Offset Adjustment and Method of Low-Offset Adjustment Thereof - Google Patents
Current-Sense Amplifier With Low-Offset Adjustment and Method of Low-Offset Adjustment Thereof Download PDFInfo
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- US20120294090A1 US20120294090A1 US13/108,550 US201113108550A US2012294090A1 US 20120294090 A1 US20120294090 A1 US 20120294090A1 US 201113108550 A US201113108550 A US 201113108550A US 2012294090 A1 US2012294090 A1 US 2012294090A1
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C16/00—Erasable programmable read-only memories
- G11C16/02—Erasable programmable read-only memories electrically programmable
- G11C16/06—Auxiliary circuits, e.g. for writing into memory
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C16/00—Erasable programmable read-only memories
- G11C16/02—Erasable programmable read-only memories electrically programmable
- G11C16/06—Auxiliary circuits, e.g. for writing into memory
- G11C16/26—Sensing or reading circuits; Data output circuits
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C7/00—Arrangements for writing information into, or reading information out from, a digital store
- G11C7/06—Sense amplifiers; Associated circuits, e.g. timing or triggering circuits
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- the present invention relates to a current-sense amplifier, and more particularly to a current-sense amplifier with low-offset adjustment and a low-offset adjustment method thereof for compensating an input offset voltage of the current-sense amplifier and increasing the data read speed and accuracy of a flash memory.
- Non-volatile memory has been widely applied in memory cards and USB flash drives. Since consumers demand for memory having higher access speed and accuracy but lower power consumption, it has now become an important issue as how to develop a memory with increased data access speed and accuracy to satisfy the market demands.
- electronic engineers try to obtain increased memory access speed and accuracy by reducing the offset voltage of a current-sense amplifier for the memory.
- the offset voltage would adversely affect the quality of a circuit system.
- an input offset voltage thereof would cause unstable current detection accuracy to thereby reduce the memory data read speed and accordingly, result in incorrect data reading.
- the offset voltage of the current-sense amplifier is compensated in order to obtain increased current detection accuracy.
- FIG. 1 is a circuit diagram of a conventional automatic offset compensation scheme with ping-pong control for complementary metal-oxide-semiconductor (CMOS) operational amplifier (data source: IEEE Journal of Solid-state Circuits, Vol. 29, No. 5, May 1994).
- the amplifier is electrically connected to a compensation circuit, which includes a current mirror and an adjustable transistor.
- the adjustable transistor controls the current gain of the current mirror, so as to adjust the offset compensation voltage.
- a control voltage VC is input to a gate of the adjustable transistor to control the working property of the adjustable transistor and accordingly, affect the current gain of the current mirror.
- the control voltage VC is obtained by converting an output voltage of the amplifier using a digital-to-analog converter (DAC).
- DAC digital-to-analog converter
- a computing circuit analyzes the effect of a previous offset compensation, in order to adjust the next compensation voltage.
- the control voltage VC is not a fixed voltage.
- the conventional offset compensation circuit is mainly composed of transistors and capacitors, and feeds back the output voltage of the amplifier to compensate the offset voltage of the current-sense amplifier.
- the compensation effect is adversely affected and fails to achieve ideal compensation, which in turn hinders the memory from providing increased data read speed and accuracy. It is therefore tried by the inventor to work out a way for effectively reducing the input offset voltage of the current-sense amplifier in order to enable increased memory data access speed and accuracy.
- a primary object of the present invention is to provide a current-sense amplifier with low-offset adjustment and a low-offset adjustment method thereof, so as to overcome the problem of slow memory data read speed due to reduced current detection accuracy caused by the offset voltage of the current-sense amplifier for the memory.
- the current-sense amplifier with low-offset adjustment includes a sensing unit, an equalizing unit and a bias compensation unit.
- the sensing unit has a sense amplifier, a latch circuit, a first precharged bit line, and a second precharged bit line.
- the equalizing unit is electrically connected to the first and the second precharged bit line for regulating a voltage of the first precharged bit line and a voltage of the second precharged bit line to the same electric potential, so as to reduce an input offset voltage of the current-sense amplifier and accordingly enable increased memory data read speed.
- the bias compensation unit is electrically connected to the sense amplifier for compensating an offset voltage of the current-sense amplifier, so as to enable increased current detection accuracy and memory data read accuracy.
- the low-offset adjustment method is applicable to the compensation of an offset voltage of a current-sense amplifier.
- the current-sense amplifier includes a sensing unit, an equalizing unit, and a bias compensation unit; and the sensing unit further includes a sense amplifier, a latch circuit, a first precharged bit line, and a second precharged bit line.
- the low-offset adjustment method includes the following steps: the equalizing unit regulates a voltage of the first precharged bit line and a voltage of the second precharged bit line to the same electric potential, so as to reduce the clock-skew sensitivity of the current-sense amplifier; and the bias compensation unit outputs a compensation voltage to the sense amplifier for compensating an offset voltage of the current-sense amplifier.
- the current-sense amplifier with low-offset adjustment and the low-offset adjustment method thereof according to the present invention provide one or more of the following advantages:
- FIG. 1 is a circuit diagram of a conventional automatic offset compensation scheme with ping-pong control for CMOS operational amplifier
- FIG. 2 is a block diagram of a current-sense amplifier with low-offset adjustment according to an embodiment of the present invention
- FIG. 3 is a circuit diagram of the current-sense amplifier with low-offset adjustment according to an embodiment of the present invention
- FIG. 4 is a time-domain graph of the current-sense amplifier with low-offset adjustment according to an embodiment of the present invention.
- FIG. 5 is a flowchart showing the steps included in a low-offset adjustment method according to the present invention.
- FIG. 2 is a block diagram of a current-sense amplifier with low-offset adjustment according to an embodiment of the present invention.
- the current-sense amplifier with low-offset adjustment includes an equalizing unit 1 , a bias compensation unit 2 , and a sensing unit 3 .
- the sensing unit 3 includes a sense amplifier 30 , a latch circuit 31 , a first precharged bit line 32 , and a second precharged bit line 33 .
- the first precharged bit line 32 is coupled to a cell current source I C and is electrically connected to the sense amplifier 30 to generate a first current In 1 .
- the second precharged bit line 33 is coupled to a reference current source I R and is electrically connected to the sense amplifier 30 to generate a second current In 2 .
- the equalizing unit 1 is electrically connected to the first precharged bit line 32 and the second precharged bit line 33 .
- the equalizing unit 1 is coupled at one of two opposite ends to the cell current source I C and at the other end to the reference current source I R .
- the equalizing unit 1 is able to regulate a voltage of the first precharged bit line 32 and a voltage of the second precharged bit line 33 to the same electric potential.
- the cell current source I C is electrically connected at an end to the first precharged bit line 32 and the equalizing unit 1 , and at another end to ground; and the reference current source I R is electrically connected at an end to the second precharged bit line 33 and the equalizing unit 1 , and at another end to ground.
- the sense amplifier 30 is electrically connected to the latch circuit 31 and the bias compensation unit 2 , so that the bias compensation unit 2 can output a compensation voltage to the sense amplifier 30 and the latch circuit 31 for adjusting and compensating an offset voltage of the current-sense amplifier.
- FIG. 3 is a circuit diagram of the current-sense amplifier with low-offset adjustment according to an embodiment of the present invention.
- the current-sense amplifier with low-offset adjustment includes an equalizing unit 1 , a first compensation circuit 21 , a second compensation circuit 22 , a sense amplifier 30 , a latch circuit 31 , a first precharged bit line 32 , a second precharged bit line 33 , a cell current source I C , and a reference current source I R .
- the equalizing unit 1 has a first transistor M 1 , which is a p-type metal-oxide-semiconductor field-effect transistor (MOSFET) and is briefly referred to as a PMOS herein;
- the latch circuit 31 has a second transistor M 2 , which is an n-type MOSFET and is briefly referred to as an NMOS herein, and a third transistor M 3 , which is also an NMOS;
- the first precharged bit line 32 has a fourth transistor M 4 , which is a PMOS;
- the second precharged bit line 33 has a fifth transistor M 5 , which is a PMOS;
- the sense amplifier 30 has a sixth transistor M 6 , which is a PMOS, a seventh transistor M 7 , which is a PMOS, and an eighth transistor M 8 , which is a PMOS.
- the first compensation circuit 21 has a first transmission gate T 1 and a first voltage source V 1 ;
- the second compensation circuit 22 has a second transmission gate
- the fourth transistor M 4 has a source connected to V DD , and a drain coupled to a drain of the first transistor M 1 and an end of the cell current source I C , while another end of the cell current source I C is connected to ground.
- the fourth transistor M 4 has a gate coupled to a gate of the sixth transistor M 6 to generate a first current In 1 ; and the drain of the fourth transistor M 4 can be coupled to the gate thereof to form a short circuit.
- the fifth transistor M 5 has a source connected to V DD , and a drain coupled to a source of the first transistor M 1 and to an end of the reference current source I R , while another end of the reference current source I R is connected to ground.
- the fifth transistor M 5 has a gate coupled to a gate of the seventh transistor M 7 to generate a second current In 2 ; and the drain of the fifth transistor M 5 can be coupled to the gate thereof to form a short circuit. Further, the first transistor M 1 has a gate, at where an EQ signal is input for controlling the first transistor M 1 to turn on or cut off.
- the eighth transistor M 8 has a source connected to V DD , a gate inputting an SED signal for controlling the eighth transistor M 8 to turn on or cut off, and a drain coupled to a source of the sixth transistor M 6 and a source of the seventh transistor M 7 .
- the second transistor M 2 has a drain coupled to a drain of the sixth transistor M 6 and an output of the first transmission gate T 1 ; and the drain of the sixth transistor M 6 outputs a first signal of sense amplifier 30 and is deemed as a first output O 1 of the sense amplifier 30 .
- the second transistor M 2 has a gate coupled to a drain of the third transistor M 3 and an output of the second transmission gate T 2 , and has a source connected to ground.
- the drain of the third transistor M 3 is coupled to a drain of the seventh transistor M 7 and the output of the second transmission gate T 2 ; and the drain of the seventh transistor M 7 outputs a second signal of the sense amplifier 30 and is deemed as second output O 2 of the sense amplifier 30 .
- the third transistor M 3 has a gate coupled to the drain of the second transistor M 2 and the output of the first transmission gate T 1 , and a source connected to ground.
- the first voltage source V 1 is coupled at one of two opposite ends to an input of the first transmission gate T 1 , and connected at the other end to ground.
- the second voltage source V 2 is coupled at one of two opposite ends to an input of the second transmission gate T 2 , and connected at the other end to ground.
- the first and the second transmission gate T 1 , T 2 are both controlled by an SE signal and an SEB signal to turn on or cut off
- FIG. 4 is a time-domain graph of the current-sense amplifier with low-offset adjustment according to an embodiment of the present invention.
- the first transistor M 1 is turned on to pull the first current In 1 and the second current In 2 to the same potential, so as to reduce the clock-skew sensitivity of the current-sense amplifier and enable increased memory data read speed.
- the first transmission gate T 1 outputs the first voltage source V 1 to the first output O 1
- the second transmission gate T 2 outputs the second voltage source V 2 to the second output O 2 .
- the eighth transistor M 8 Since the eighth transistor M 8 is cut off, no current will flow to the first output O 1 and the second output O 2 ; and since the first voltage source V 1 and the second voltage source V 2 are smaller than a threshold voltage of the fourth transistor M 4 and of the fifth transistor M 5 , respectively, the fourth and the fifth transistor M 4 , M 5 would not be brought to turn on, and the first and the second voltage source V 1 , V 2 are present at the first and the second output O 1 , O 2 , respectively.
- first and the second voltage source V 1 , V 2 have voltage values determined according to the offset voltage of the current-sense amplifier, the first voltage source V 1 and the second voltage source V 2 are not necessarily the same in electric potential thereof.
- a main purpose of the voltage difference between the first and the second voltage source V 1 , V 2 is to compensate the offset voltage, so that the offset voltage is reduced and approaches to an ideal value of 0V.
- the current-sense amplifier goes into a development phase.
- the EQ signal changes from low to high
- the first transistor M 1 is cut off
- the first current In 1 and the second current In 2 generate different voltages due to different current values of the cell current source I C and the reference current source I R .
- the current-sense amplifier goes into a sense phase, in which the first transmission gate T 1 and the second transmission gate T 2 are cut off, the EQ signal keeps at high
- the SED signal changes from high to low
- the eighth transistor M 8 is turned on, and the first output O 1 and the second output O 2 produce electric potentials.
- the fourth and the fifth transistor M 4 , M 5 When the voltages reach the threshold voltages of the fourth transistor M 4 and the fifth transistor M 5 , respectively, the fourth and the fifth transistor M 4 , M 5 will be turned on, and the potential at one of the first output O 1 and the second output O 2 will be pulled to ground. From the first output O 1 and the second output O 2 , it is able to know the digital data read out by the memory is 0 or 1.
- MOSFETs are used as circuit elements in the illustrated embodiment of the present invention, it is obvious to one of ordinary skill in the art these circuit elements can be otherwise bipolar transistors or combinations of bipolar transistors and field-effect transistors without departing from the spirit and the scope of the present invention. It is understood the above embodiment is illustrated only as an exemplary and is not intended to limit the present invention in any way.
- FIG. 5 is a flowchart showing the steps included in a low-offset adjustment method according to the present invention.
- the low-offset adjustment method is applicable to the compensation of the offset voltage of the above-described current-sense amplifier.
- the current-sense amplifier includes a sensing unit, an equalizing unit, and a bias compensation unit; and the sensing unit further includes a sense amplifier, a latch circuit, a first precharged bit line, and a second precharged bit line.
- the low-offset adjustment method includes the following steps:
- the equalizing unit regulates the voltages of the first and the second precharged bit line to the same electric potential
- the bias compensation unit outputs a compensation voltage to the sense amplifier to compensate an offset voltage of the sense amplifier
- the equalizing unit reduces the input offset voltage of the current-sense amplifier to enable increased current detection accuracy and accordingly, increased memory data read speed. Further, the compensation circuit supplies compensation voltage to reduce the offset voltage of the current-sense amplifier to ensure good current detection quality and increased memory data read accuracy.
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Abstract
Description
- The present invention relates to a current-sense amplifier, and more particularly to a current-sense amplifier with low-offset adjustment and a low-offset adjustment method thereof for compensating an input offset voltage of the current-sense amplifier and increasing the data read speed and accuracy of a flash memory.
- Non-volatile memory has been widely applied in memory cards and USB flash drives. Since consumers demand for memory having higher access speed and accuracy but lower power consumption, it has now become an important issue as how to develop a memory with increased data access speed and accuracy to satisfy the market demands. Presently, in most cases, electronic engineers try to obtain increased memory access speed and accuracy by reducing the offset voltage of a current-sense amplifier for the memory. The offset voltage would adversely affect the quality of a circuit system. In a current-sense amplifier for memory, an input offset voltage thereof would cause unstable current detection accuracy to thereby reduce the memory data read speed and accordingly, result in incorrect data reading. In conventional solutions, the offset voltage of the current-sense amplifier is compensated in order to obtain increased current detection accuracy.
-
FIG. 1 is a circuit diagram of a conventional automatic offset compensation scheme with ping-pong control for complementary metal-oxide-semiconductor (CMOS) operational amplifier (data source: IEEE Journal of Solid-state Circuits, Vol. 29, No. 5, May 1994). As shown, the amplifier is electrically connected to a compensation circuit, which includes a current mirror and an adjustable transistor. The adjustable transistor controls the current gain of the current mirror, so as to adjust the offset compensation voltage. In the conventional automatic offset compensation scheme shown inFIG. 1 , a control voltage VC is input to a gate of the adjustable transistor to control the working property of the adjustable transistor and accordingly, affect the current gain of the current mirror. The control voltage VC is obtained by converting an output voltage of the amplifier using a digital-to-analog converter (DAC). A computing circuit analyzes the effect of a previous offset compensation, in order to adjust the next compensation voltage. Thus, the control voltage VC is not a fixed voltage. - The conventional offset compensation circuit is mainly composed of transistors and capacitors, and feeds back the output voltage of the amplifier to compensate the offset voltage of the current-sense amplifier. However, due to the amplifier's circuit structure, the compensation effect is adversely affected and fails to achieve ideal compensation, which in turn hinders the memory from providing increased data read speed and accuracy. It is therefore tried by the inventor to work out a way for effectively reducing the input offset voltage of the current-sense amplifier in order to enable increased memory data access speed and accuracy.
- A primary object of the present invention is to provide a current-sense amplifier with low-offset adjustment and a low-offset adjustment method thereof, so as to overcome the problem of slow memory data read speed due to reduced current detection accuracy caused by the offset voltage of the current-sense amplifier for the memory.
- To achieve the above and other objects, the current-sense amplifier with low-offset adjustment according to the present invention includes a sensing unit, an equalizing unit and a bias compensation unit. The sensing unit has a sense amplifier, a latch circuit, a first precharged bit line, and a second precharged bit line. The equalizing unit is electrically connected to the first and the second precharged bit line for regulating a voltage of the first precharged bit line and a voltage of the second precharged bit line to the same electric potential, so as to reduce an input offset voltage of the current-sense amplifier and accordingly enable increased memory data read speed. The bias compensation unit is electrically connected to the sense amplifier for compensating an offset voltage of the current-sense amplifier, so as to enable increased current detection accuracy and memory data read accuracy.
- To achieve the above and other objects, the low-offset adjustment method according to the present invention is applicable to the compensation of an offset voltage of a current-sense amplifier. The current-sense amplifier includes a sensing unit, an equalizing unit, and a bias compensation unit; and the sensing unit further includes a sense amplifier, a latch circuit, a first precharged bit line, and a second precharged bit line. The low-offset adjustment method includes the following steps: the equalizing unit regulates a voltage of the first precharged bit line and a voltage of the second precharged bit line to the same electric potential, so as to reduce the clock-skew sensitivity of the current-sense amplifier; and the bias compensation unit outputs a compensation voltage to the sense amplifier for compensating an offset voltage of the current-sense amplifier.
- According to the above description, the current-sense amplifier with low-offset adjustment and the low-offset adjustment method thereof according to the present invention provide one or more of the following advantages:
- (1) By using the equalizing unit to regulate the voltages of the first and the second precharged bit line to the same electric potential, it is possible to reduce the clock-skew sensitivity of the current-sense amplifier;
- (2) By using the equalizing unit to regulate the voltages of the first and the second precharged bit line to the same potential, it is possible to reduce the clock-skew sensitivity of the current-sense amplifier and accordingly, enable increased memory data read speed.
- (3) By using the bias compensation unit to supply the compensation voltage to the current-sense amplifier, it is possible to increase the current detection accuracy of the current-sense amplifier.
- The structure and the technical means adopted by the present invention to achieve the above and other objects can be best understood by referring to the following detailed description of the preferred embodiments and the accompanying drawings, wherein
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FIG. 1 is a circuit diagram of a conventional automatic offset compensation scheme with ping-pong control for CMOS operational amplifier; -
FIG. 2 is a block diagram of a current-sense amplifier with low-offset adjustment according to an embodiment of the present invention; -
FIG. 3 is a circuit diagram of the current-sense amplifier with low-offset adjustment according to an embodiment of the present invention; -
FIG. 4 is a time-domain graph of the current-sense amplifier with low-offset adjustment according to an embodiment of the present invention; and -
FIG. 5 is a flowchart showing the steps included in a low-offset adjustment method according to the present invention. - The present invention will now be described with some preferred embodiments thereof and with reference to the accompanying drawings. For the purpose of easy to understand, elements that are the same in the preferred embodiments are denoted by the same reference numerals.
- Please refer to
FIG. 2 that is a block diagram of a current-sense amplifier with low-offset adjustment according to an embodiment of the present invention. As shown, the current-sense amplifier with low-offset adjustment includes an equalizingunit 1, abias compensation unit 2, and asensing unit 3. Thesensing unit 3 includes asense amplifier 30, alatch circuit 31, a firstprecharged bit line 32, and a secondprecharged bit line 33. The firstprecharged bit line 32 is coupled to a cell current source IC and is electrically connected to thesense amplifier 30 to generate a first current In1. The secondprecharged bit line 33 is coupled to a reference current source IR and is electrically connected to thesense amplifier 30 to generate a second current In2. - The equalizing
unit 1 is electrically connected to the firstprecharged bit line 32 and the secondprecharged bit line 33. The equalizingunit 1 is coupled at one of two opposite ends to the cell current source IC and at the other end to the reference current source IR. The equalizingunit 1 is able to regulate a voltage of the firstprecharged bit line 32 and a voltage of the secondprecharged bit line 33 to the same electric potential. Wherein, the cell current source IC is electrically connected at an end to the firstprecharged bit line 32 and the equalizingunit 1, and at another end to ground; and the reference current source IR is electrically connected at an end to the secondprecharged bit line 33 and the equalizingunit 1, and at another end to ground. - The
sense amplifier 30 is electrically connected to thelatch circuit 31 and thebias compensation unit 2, so that thebias compensation unit 2 can output a compensation voltage to thesense amplifier 30 and thelatch circuit 31 for adjusting and compensating an offset voltage of the current-sense amplifier. - Please refer to
FIG. 3 that is a circuit diagram of the current-sense amplifier with low-offset adjustment according to an embodiment of the present invention. As shown, the current-sense amplifier with low-offset adjustment includes an equalizingunit 1, afirst compensation circuit 21, asecond compensation circuit 22, asense amplifier 30, alatch circuit 31, a firstprecharged bit line 32, a secondprecharged bit line 33, a cell current source IC, and a reference current source IR. - The equalizing
unit 1 has a first transistor M1, which is a p-type metal-oxide-semiconductor field-effect transistor (MOSFET) and is briefly referred to as a PMOS herein; thelatch circuit 31 has a second transistor M2, which is an n-type MOSFET and is briefly referred to as an NMOS herein, and a third transistor M3, which is also an NMOS; the firstprecharged bit line 32 has a fourth transistor M4, which is a PMOS; the secondprecharged bit line 33 has a fifth transistor M5, which is a PMOS; and thesense amplifier 30 has a sixth transistor M6, which is a PMOS, a seventh transistor M7, which is a PMOS, and an eighth transistor M8, which is a PMOS. Further, thefirst compensation circuit 21 has a first transmission gate T1 and a first voltage source V1; and thesecond compensation circuit 22 has a second transmission gate T2 and a second voltage source V2. - The fourth transistor M4 has a source connected to VDD, and a drain coupled to a drain of the first transistor M1 and an end of the cell current source IC, while another end of the cell current source IC is connected to ground. The fourth transistor M4 has a gate coupled to a gate of the sixth transistor M6 to generate a first current In1; and the drain of the fourth transistor M4 can be coupled to the gate thereof to form a short circuit. The fifth transistor M5 has a source connected to VDD, and a drain coupled to a source of the first transistor M1 and to an end of the reference current source IR, while another end of the reference current source IR is connected to ground. The fifth transistor M5 has a gate coupled to a gate of the seventh transistor M7 to generate a second current In2; and the drain of the fifth transistor M5 can be coupled to the gate thereof to form a short circuit. Further, the first transistor M1 has a gate, at where an EQ signal is input for controlling the first transistor M1 to turn on or cut off.
- The eighth transistor M8 has a source connected to VDD, a gate inputting an SED signal for controlling the eighth transistor M8 to turn on or cut off, and a drain coupled to a source of the sixth transistor M6 and a source of the seventh transistor M7. The second transistor M2 has a drain coupled to a drain of the sixth transistor M6 and an output of the first transmission gate T1; and the drain of the sixth transistor M6 outputs a first signal of
sense amplifier 30 and is deemed as a first output O1 of thesense amplifier 30. The second transistor M2 has a gate coupled to a drain of the third transistor M3 and an output of the second transmission gate T2, and has a source connected to ground. The drain of the third transistor M3 is coupled to a drain of the seventh transistor M7 and the output of the second transmission gate T2; and the drain of the seventh transistor M7 outputs a second signal of thesense amplifier 30 and is deemed as second output O2 of thesense amplifier 30. The third transistor M3 has a gate coupled to the drain of the second transistor M2 and the output of the first transmission gate T1, and a source connected to ground. - The first voltage source V1 is coupled at one of two opposite ends to an input of the first transmission gate T1, and connected at the other end to ground. The second voltage source V2 is coupled at one of two opposite ends to an input of the second transmission gate T2, and connected at the other end to ground. The first and the second transmission gate T1, T2 are both controlled by an SE signal and an SEB signal to turn on or cut off
- Please refer to
FIG. 4 that is a time-domain graph of the current-sense amplifier with low-offset adjustment according to an embodiment of the present invention. When the EQ signal is low and the SED signal is high, the current-sense amplifier is in an equalize phase, the first transistor M1 is turned on to pull the first current In1 and the second current In2 to the same potential, so as to reduce the clock-skew sensitivity of the current-sense amplifier and enable increased memory data read speed. At this point, the first transmission gate T1 outputs the first voltage source V1 to the first output O1, and the second transmission gate T2 outputs the second voltage source V2 to the second output O2. Since the eighth transistor M8 is cut off, no current will flow to the first output O1 and the second output O2; and since the first voltage source V1 and the second voltage source V2 are smaller than a threshold voltage of the fourth transistor M4 and of the fifth transistor M5, respectively, the fourth and the fifth transistor M4, M5 would not be brought to turn on, and the first and the second voltage source V1, V2 are present at the first and the second output O1, O2, respectively. - However, since the first and the second voltage source V1, V2 have voltage values determined according to the offset voltage of the current-sense amplifier, the first voltage source V1 and the second voltage source V2 are not necessarily the same in electric potential thereof. A main purpose of the voltage difference between the first and the second voltage source V1, V2 is to compensate the offset voltage, so that the offset voltage is reduced and approaches to an ideal value of 0V.
- At the end of the equalize phase, the current-sense amplifier goes into a development phase. At this point, the EQ signal changes from low to high, the first transistor M1 is cut off, the first current In1 and the second current In2 generate different voltages due to different current values of the cell current source IC and the reference current source IR. Then, the current-sense amplifier goes into a sense phase, in which the first transmission gate T1 and the second transmission gate T2 are cut off, the EQ signal keeps at high, the SED signal changes from high to low, the eighth transistor M8 is turned on, and the first output O1 and the second output O2 produce electric potentials. When the voltages reach the threshold voltages of the fourth transistor M4 and the fifth transistor M5, respectively, the fourth and the fifth transistor M4, M5 will be turned on, and the potential at one of the first output O1 and the second output O2 will be pulled to ground. From the first output O1 and the second output O2, it is able to know the digital data read out by the memory is 0 or 1.
- Please note, while MOSFETs are used as circuit elements in the illustrated embodiment of the present invention, it is obvious to one of ordinary skill in the art these circuit elements can be otherwise bipolar transistors or combinations of bipolar transistors and field-effect transistors without departing from the spirit and the scope of the present invention. It is understood the above embodiment is illustrated only as an exemplary and is not intended to limit the present invention in any way.
-
FIG. 5 is a flowchart showing the steps included in a low-offset adjustment method according to the present invention. As shown, the low-offset adjustment method is applicable to the compensation of the offset voltage of the above-described current-sense amplifier. The current-sense amplifier includes a sensing unit, an equalizing unit, and a bias compensation unit; and the sensing unit further includes a sense amplifier, a latch circuit, a first precharged bit line, and a second precharged bit line. The low-offset adjustment method includes the following steps: - S51: when the EQ signal is low and the SED signal is high, the first transistor of the equalizing unit is turned on while the eighth transistor of the sense amplifier is cut off, and the sense amplifier goes into an equalize phase;
- S52: in the equalize phase, the equalizing unit regulates the voltages of the first and the second precharged bit line to the same electric potential;
- S53: when the EQ signal changes from low to high while the SED signal keeps at high, the first transistor of the equalizing unit is cut off while the eighth transistor of the sense amplifier is turned on, and the sense amplifier goes into a development phase;
- S54: in the development phase, the bias compensation unit outputs a compensation voltage to the sense amplifier to compensate an offset voltage of the sense amplifier;
- S55: when the EQ signal keeps at high, the SED signal changes from high to low, and a transmission gate of the compensation unit is cut off, the sense amplifier goes into a sense phase; and
- S56: in the sense phase, the sense amplifier outputs a current detection result.
- Since the details and the implementation of the low-offset adjustment method have also been recited in the previous description of the structure of the current-sense amplifier with low-offset adjustment according to the present invention, they are not repeated herein.
- In conclusion, in the current-sense amplifier with low-offset adjustment according to the present invention and the low-offset adjustment method thereof, the equalizing unit reduces the input offset voltage of the current-sense amplifier to enable increased current detection accuracy and accordingly, increased memory data read speed. Further, the compensation circuit supplies compensation voltage to reduce the offset voltage of the current-sense amplifier to ensure good current detection quality and increased memory data read accuracy.
- The present invention has been described with some preferred embodiments thereof and it is understood that many changes and modifications in the described embodiments can be carried out without departing from the scope and the spirit of the invention that is intended to be limited only by the appended claims.
Claims (15)
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US13/108,550 US8320211B1 (en) | 2011-05-16 | 2011-05-16 | Current-sense amplifier with low-offset adjustment and method of low-offset adjustment thereof |
TW100118545A TWI464743B (en) | 2011-05-16 | 2011-05-27 | Low bias trimmed current sense amplifier and operating method thereof |
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US13/108,550 US8320211B1 (en) | 2011-05-16 | 2011-05-16 | Current-sense amplifier with low-offset adjustment and method of low-offset adjustment thereof |
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US20120294090A1 true US20120294090A1 (en) | 2012-11-22 |
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US9202543B2 (en) | 2012-11-30 | 2015-12-01 | Intel Deutschland Gmbh | System and methods using a multiplexed reference for sense amplifiers |
US9601165B1 (en) | 2015-09-24 | 2017-03-21 | Intel IP Corporation | Sense amplifier |
US9704554B2 (en) * | 2015-08-25 | 2017-07-11 | Texas Instruments Incorporated | Sense amplifier with offset compensation |
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US20230223052A1 (en) * | 2021-07-09 | 2023-07-13 | Daryl G. Dietrich | Integrated Multilevel Memory Apparatus and Method of Operating Same |
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US20070024325A1 (en) * | 2005-08-01 | 2007-02-01 | Chung-Kuang Chen | Sense amplifier with input offset compensation |
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US9070466B2 (en) | 2012-09-06 | 2015-06-30 | Infineon Technologies Ag | Mismatch error reduction method and system for STT MRAM |
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US9704554B2 (en) * | 2015-08-25 | 2017-07-11 | Texas Instruments Incorporated | Sense amplifier with offset compensation |
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US20190164579A1 (en) * | 2015-08-25 | 2019-05-30 | Texas Instruments Incorporated | Sense amplifier with offset compensation |
US10504567B2 (en) * | 2015-08-25 | 2019-12-10 | Texas Instruments Incorporated | Sense amplifier with offset compensation |
US9601165B1 (en) | 2015-09-24 | 2017-03-21 | Intel IP Corporation | Sense amplifier |
US10127959B2 (en) | 2015-09-24 | 2018-11-13 | Intel IP Corporation | Sense amplifier |
CN108231100A (en) * | 2018-03-26 | 2018-06-29 | 安徽大学 | Offset voltage adaptive digital calibration type sense amplifier |
US20230223052A1 (en) * | 2021-07-09 | 2023-07-13 | Daryl G. Dietrich | Integrated Multilevel Memory Apparatus and Method of Operating Same |
Also Published As
Publication number | Publication date |
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TWI464743B (en) | 2014-12-11 |
TW201248645A (en) | 2012-12-01 |
US8320211B1 (en) | 2012-11-27 |
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