JPS601694A - Driver for bloch line pair - Google Patents

Abstract

PURPOSE:To attain a bidirectional shift of a Bloch line pair and at the same time to miniaturize a driving circuit by reducing satisfactorily the fall time of a coil driving current waveform in comparison with its rise time. CONSTITUTION:A positive polarity coil current 701 has a rise when switches Q1 and Q2 are turned on. When the switches Q1 and Q2 are turned off, the coil current flows to a power supply 605 from a power supply 403 via an R604, a D4, a driving coil 401, an R402, an R603 and a D3 respectively. The fall time of a coil current waveform is less shorter than the rise time. While a negative polarity coil current 702 flows to the power supply 605 via an R602, a D2, the coil 401 and a D1 respectively. If switches Q1, Q2 and Q3, Q4 are controlled by a control signal 705 and a control signal 706 respectively, a coil current 704 is produced. Thus a bidirectional shift is possible for a Bloch line pair.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a magnetic thin film memory chip that stores digital information along the periphery of a magnetic domain and the presence or absence of Ploch line pairs corresponding to "0". It relates to a device that drives a pulsed magnetic field.

A magnetic thin film memory chip using the Ploch line pair can achieve a storage capacity of 91.6 Gbit per 1 CD by simply reducing the magnetic domain stripe +j+ to 0.5 pm. Therefore, it is expected to be applied to small, high-performance computer file memories, data recorders mounted on spacecraft, etc.

Since the operating principle of Ploch line pairs is still new, an overview will be given first. FIG. 1 shows the state of domain walls around striped bubble domains formed in a garnet-based magnetic thin film for a conventional magnetic bubble memory. The domain wall is a reed between the inner wall 101 and the outer wall 102, and the inner wall 1
The magnetization of the inner domain of iL1 is shown downward by arrow 103 and the magnetization of the outer side of iL1 outer wall 102 is shown by arrow 1
04 indicates upward direction. Such a striped bubble domain is created by a vertical magnetic field (H
B) continues to exist stably when l41 is applied f.

Among the domain walls of such an elongated (stripe-like) magnetic domain, there are a left-handed Schiploch domain wall 113 and a right-handed Bloch (
There is a magnetic wall 114, and where the blue color collides, the magnetization is on the top surface! There are a Ploch line 111 facing toward the bottom surface and a Ploch line 112 facing downward at the bottom surface.

If you look at the domain wall from t11I, it decreases as you go. Also, the magnetization on the bottom surface faces outward.

The Ploch line 112 is shaped like a trapezoid 122,
As you move toward the top surface, the magnetization that rotates around the outside decreases. The two planes 123 and 124 of the counterclockwise and clockwise Bloch domain walls are sandwiched between the Bloch lines of the inverted trapezoid 121 and the trapezoid 122.

When these two Ploch lines 111 and 112 are held in the form of a Ploch line pair 130, the directions of magnetization on the top and bottom surfaces are reversed where the two Ploch lines 111 and 112 are close, forming a twist of magnetization and perpendicular to each other. When the pulsed magnetic field (Hz) is driven, the magnetization twist formed by the two Proch lines 111 and 112 moves stably. In addition, 4Zi domain 10
When an in-plane bias magnetic field (Hip) 140 is applied in the longitudinal direction of 0, the direction of magnetization of the leftmost Proch line 115 is fixed, and no matter how many Proch line pairs 130 there are, the Bloch-7' between them is fixed. The direction of magnetization of l13 is fixed to the direction of magnetic field (Hip) 140. Therefore, it is possible to make the Bloch line pair 130 correspond to the digital information "1" and to make the portion of the Bloch domain wall 1130 in the section without it correspond to the digital information "0".

The 1300-bit interval between Ploch lines is determined by the moving speed and 4B of moving time, but if the moving speed varies,
Since the storage location is not determined, it is actually necessary to arrange permalloy batan or ion implantation patterns to hold the Ploch line pair l'30 for each bit so as to be perpendicular to the striped magnetic domain 100.

To shift such a Ploch line pair 130e one pit at a time clockwise or counterclockwise N1 along the above-mentioned domain wall, a 6-beam vertical line must be placed in the direction perpendicular to the surface of the thin film, and the line should fall 9.
It is necessary to drive a fast pulsed magnetic field (IIz) of 1.42. The moving speed of the Ploch line pair 130 is determined by the amplitude of the pulsed magnetic field Qh) 142, and the movement in the clockwise direction! 1IIJ period is determined by the rise time of the pulsed magnetic field (IIz) 142, but it is determined by the rate of change of the pulsed magnetic field (ΔHz / △
Tr) is not greater than a certain threshold, Ploch line pair 13
0 does not start moving.

Therefore, a pulsed magnetic field is used that produces a magnetic field change of about 20 ue or more in about 20 n5ec or less. Therefore, at the time of falling, it is necessary to prevent the Ploch line pair 130 from returning by preventing such a sudden change in the magnetic field.

FIG. 2 shows a driving waveform of a vertical pulsed magnetic field that shifts the Ploch line pair. The positive polarity side 201 shifts the Ploch line pair clockwise p, and the negative polarity side 202
shifts in the opposite direction.

Since there is no need to reduce the fall time t, it may be set sufficiently larger than the rise time within the range allowed by the drive cycle, but if it is too thick, the drive speed will be slow and the performance will be degraded.

An example of the configuration and operation of each part of this device will be explained.

The major line is 'tt1.' for both holding and playing. It uses a flowing motion method. A pledge transformer 7 argate consisting of four parallel conductors forms a bubble on the major line and a minor loop th4. It uses interaction with the striped domain head. When there is a bubble domain on the major line line, the head of the stripe domain that makes up the minor loop connected to it takes advantage of the boiling from the bubble due to the repulsive interaction between the bubble and the stripe domain. When there is no bubble on the write major line, the Ploch line (VJ3) perpendicular to the minor loop restripe domain domain wall
Pile L). As a means of making V13L into a stripe domain head, the stripe domain head was dynamically moved by applying a pulse current to the conductor pattern in contact with it, and the head domain wall was dynamically converted. With this method, two VBLs are created, but these have different Shiga and are easy to recombine. Therefore, in order to stabilize the information, we applied an in-plane magnetic field in the longitudinal direction of the striped domain.
By separating the stripe domain head by two conductors on the stripe domain side, two VBLs with the same properties are created in the stripe domain. VBLs with the same properties stably exist even if they are close to each other. The stripe domain head of the minor loop corresponding to the place where the bubble exists on the major line has a repulsive effect with the bubble, and therefore the t(if
Therefore, VBL is not formed. As a result, the major line information "do" is transferred with no VBL pair in the minor loop.

In the minor loop, information is stored using a pair of VBLs with the same properties as one bit. An eVBL pair is used in consideration of the stability of the replicator action.

A transfer pattern is set so that bits can be sequentially transferred one bit at a time so that the bit period and VBL interval within the minor loop are kept constant. - As an example, the stable interval between VBL in the θ direction (directly to the longitudinal force of the stripe domain) on the stripe domain forming the above-mentioned minor loop 11゛4
．． A parallel thin line pattern made of a permalloy thin film with a width S00 was formed with a circumference "υ" of 02 times, and the interaction between the magnetic poles induced on both sides of the parallel thin line and VBL was utilized.

Transfer along the VBL minor loop was performed dynamically by applying a pulsed bias magnetic field to the T1 stripe domain.

A readout transfer gate consisting of three parallel conductors converts the information stored as VBL in the stripe domain domain wall forming the minor loop into a bubble and transfers it to the major line, and also transfers the information on the minor loop. It also has the function of a replicator to prevent it from being destroyed. The operating principle will be explained.

For example, one half of 1 bit formed by VBLNJ is
The striped domain head is fixed by applying an in-plane magnetic field. This striped domain head is then cut out using a conductor pattern to form a nokupuru. Then, a cutout 7' (, VBL 11, which is the same as V'BL) is generated in the striped domain head after the bubble is cut out. Such a VBL replication effect occurs only for VBT with a minus sign.

The bubble taken from Rad to the striped domain of the minor loose is transferred on the major line towards the detector. Here, VB is applied to the striped domain head.
This method utilizes the fact that the pulse current value for cutting off the striped domain head is different depending on whether L is present or not.

There is no VBL in the striped domain head.'' It is difficult to break the bond. Therefore, V
B L p); In some cases, a bubble can be sent to the major line, but if there is no VBL, there is no bubble. However, the VBL on the minor loop is converted to the presence or absence of a bubble on the major line.
ing.

I will explain how to eliminate VBL pairs.
Major line including BL pair = 0? Place it in the last position of the stripe domain head of the minor loop of il. Next, by applying an in-plane magnetic field Hip, bring the VBL pair to be erased and one half of the VBL pair next to it to the stripe domain head, and when writing information, apply a positive VBL.
Cut out the striped domain head using the parallel conductor used to cut out the striped domain head. After the bubble domain is cut out, the VBL brought along with the VBL pair to be deleted is replicated in the striped domain head. In the end, only the VBL pair that is desired to be erased will be erased. In addition, when clearing the entire minor loop, first erase all striped domains by increasing the bias magnetic field, and then form a minor loops drive domain from an S=1 bubble, so that all pits are zero without VBL being completely heated. It is possible to create a state of

FIG. 3 shows the structure of the memory module necessary to hold and move Ploch line pairs.

The memory chip 301 is mounted on a 7-lane board 302 with an output terminal bin, and above and below it are provided an Hz coil 303, a magnetic field shunt plate 304, and a permanent tube 1 & 1305, and the whole is expected to be wrapped in a shield case 306. be done. In such a memory module, the memory chip 30
1, a Hz drive coil 30 that drives a vertical pulse magnetic field Hz.
3 has a thick inductance because it is necessary to increase the winding density in order to uniformly apply a vertical pulse magnetic field over a 10-angle range. Moreover, a large current is required to generate a magnetic field of 20-odd Oe. Hz like this
Coil t4 with a startup time of 20 n5ec or less
i3tr.

An extremely high driving voltage is required to drive this.

Note that the reason why the chip 301 is inclined with respect to the magnetic plate 304 is to apply the in-plane bias magnetic field 1 (ip).

As described above, if the movement of the Ploch line pair is attempted to be achieved by the pulsed magnetic field required by its operating principle, it becomes impossible to realize a pulsed magnetic field driving device.

An object of the present invention is to provide a circuit technology that economically realizes a driving device for such a pulsed magnetic field in a practical size. A further object of the present invention is to provide a driving circuit technology for a pulsed magnetic field necessary for forward and reverse movement of a Ploch line pair.

That is, the present invention provides a perpendicular pulsed magnetic field that moves the Ploch line pair (f81 with respect to a magnetic thin film that stores the presence or absence of the Ploch line pair corresponding to digital information "1" and °0 along the periphery of the air domain). (a drive coil, and a first
a first switch connected between the power supplies; a second switch connected between each of the front ends and a second power supply; and a first diode connected between each of the front ends and a third power supply. and a first resistor, and a series circuit of a second diode and a second resistor connected between each of the ends and a fourth power supply. It is.

Hereinafter, the present invention will be explained in more detail using the drawings.

FIG. 4 shows a conventional triangular wave coil current and drive circuit. When trying to apply a triangular wave coil current as shown in FIG. 2 to the drive coil 303 in FIG. 3, the circuit shown in FIG. 4 is what many engineers come up with.

In FIG. 4, if the potential difference between the second power source 404 and the first power source 403 is Vo, and if . ), the positive polarity = 1 current rises linearly, and then the switch (21-Q) occurs.

When becomes off (h), the positive coil current decreases.

On the other hand, when only switches Q and Ql are turned on (closed) at the same time, the negative polarity coil current starts to rise, and when switches Q, I and Ql f are then turned off (opened), the negative polarity coil current starts to rise. Go down.

In this circuit, the drive coil 303 is shown as a series circuit of a coil 401 and a resistor 402, and the circuit constants are L and h, respectively. Reference numeral 1'1 includes not only the DC resistance component of the drive coil but also the resistor 41 of the transistor switches Q1 to Q4 or the diodes D1 to D1)4.

The rising waveform of the coil current flowing through the drive coil 303 when switches Q and Q are turned on (closed) is expressed as:
When the rise time Tr is a specific number L/r and is sufficiently small, the rise polywaveform is not linear, and is approximated by 1 t(t)=-t, o≦t<Tr, (2). The drive voltage v0 required to realize the specified rise time Tr is calculated by a total of n from V1'=L Io/Tr (3), where Io is the coil current amplitude when t=Tr. It can be seen that in order to reduce Tr to 20 nsec or less, it is necessary to make the 'bk considerably shorter.

Next, the waveform of the coil current flowing through the drive coil 303 when the switches Q1 and Q are turned off (opened) is plotted.

The coil current 1(t) flowing through the drive coil 401 tends to flow even when the switches Q1 and Q are turned off (open).
As a result, the potential v1 at the connection point 405 is changed to the 1'1d source 4
Lower than the potential of 03, and contact = point 40'6 (7)?
lj position Vs e8P12tlidQ404 o' Jump higher than 4th place. Vo becomes a page, and ■, becomes V.

When placed further, diodes D and 1] become conductive, and the coil subcurrent at the time of falling becomes 1'1 (L).
Source 403 to diode D4, coil 401 and resistor 4
02 and diodes D and l to the third power supply 404.

Io is the current amplitude just before turning off switches Q1 and Q.
If the off' (open) time is set to 1=0, the coil current waveform at the time of falling becomes the response waveform when a voltage of -Vt is added to the drive coil 303 as shown in the following equation.

Since the diodes D4 and 1]3 do not allow the negative polarity current 1(t) to pass through, the falling time υ of the coil ′′ shown in equation (4), Tf−, and 1(t) in equation (4) are The time it takes to reach O is calculated by the following formula.

L　rl・I.

Tf = -1n (-V-v+ 1) (5) This\
ni/n is the symbol of natural logarithm, 7! nX takes 1η which is approximately 2.3 times the common logarithm of X.

When the fall time Tf in equation (5) is sufficiently large, the fall time Tf and the rise time Tr become approximated by a series expansion of natural logarithms. Become.

FIG. 5 shows the coil current waveform generated by the drive Ilb circuit of FIG. The positive polarity coil current 501 is determined by on/off control of switches Q0 and Q, and the negative polarity coil current 502 is determined by on/off control of switches Q and Q4. Approximately, it can be said that a triangular temporary coil current with equal rise time Tr and fall time Tf is being driven, but strictly speaking, as long as r8 is not O, the fall time T
f is always shorter than the startup time Tr.

The coil current waveform in FIG. 5 does not match that in FIG. The difference between the rise time Tr and the fall time Tf is not large enough. When Tr is made smaller, Tf also becomes smaller. If you try to make the current swing 1111o less than IA, the inductance will be 10pJ (', (beyond,
In order to reduce TrJ or Tf to 20 nsec or less, it becomes necessary to increase the voltage V to several hundred volts or more. This makes it difficult to put the drive circuit into practical use.

FIG. 6 shows an embodiment of the present invention. In this circuit, the fall time is made to be sufficiently smaller than the rise time.
I am thinking of increasing the difference between Tr and Tf by 1 and thereby shifting the Ploch line pair. Therefore, compared to FIG. 4, the difference is that the diode D1-1 4 is connected in series to a resistor 601°. Note that the resistors 602 and 604 may be connected to a fourth power supply having a negative voltage, but are connected to ground to reduce the difference from FIG.

The positive coil current in this circuit rises when switches Q1 and Q are turned on (closed). When the switches Q0 and Q are turned off, the coil current flows from the first voltage υθ403 to the third voltage 605 through the resistor 604, diode D4, coil 401, resistor 402, resistor 603, and diode 8. When the voltage applied to the drive coil 303 becomes -v2 at the time of falling, the resistance value r is the sum of the resistance values of the resistor 604, the resistor 402, and the resistor 603, and naturally, r,
be sufficiently higher. Therefore, the fall time Tf is T
f = rg 6n(!1) (8) It can be seen that the value can be reduced as much as possible by increasing rl and V.

Regarding the negative polarity coil current, when switches Q and Q4 are turned on in place of switches Q and Q, they rise, and when they are turned off, diode I, resistor 602, and coil 401
falls through resistor 402, resistor 601, and diode D.

FIG. 7 shows a small coil current waveform that can be driven in FIG. 6. The required current Io for one shift is IA, and the coil 401
When the inductance L of is 10μH, 1,K (BA'
MI JfE V t and Vs Car'f: 1L (Ji”
L 10 Holt and 20 volts, resistor 601~6
04 is IKΩ, the rise time Tr is 1 μsec from equation (3), and the fall time Tf is (8
), 23n8ec is obtained. Therefore, switches Q and Q
, is turned on and off according to the 1llJ 3 signal 703, the positive polarity coil? lj flow 701 is driven, switch Q
When s and Q4 are turned on and off according to the same control signal 703, the JN44 coil current 702 becomes jb4 rjh,
Ru. Since the driving frequency of the coil current 701 for the door 02 (Tr+Tf) is approximately 1 tl sec, the driving frequency is 1 T7. It turns out that it is close to. ■If you increase ,
Since Tr decreases, the driving frequency becomes higher.

When the resistance value rt is increased in order to reduce the fall time Tf, the power consumption gradually increases and is concentrated only in the fall time. Power consumption P in the case of continuous operation is expressed as. When Tf is 20 nsec and Tr is 1 μ8ee, P is calculated to be 13.3 Watts when r9 is 2Ω and Io is 1 ampere. This power dissipation is a little too high, but it is almost all resistor 6
It is converted into Joule heat at 01 to 604 h. Therefore, resistance 6
By attaching heat sinks to 01 to 604, it becomes possible to drive the coil current as shown in FIG. When the drive duty ratio is lowered to 1/1o, the Ploch line pair becomes 10
It can move at a speed of 0 Kb/see, and power consumption can be kept down to 1.33 Watts per four resistors 601 to 604.

If the voltage V of the third power supply 605 can be raised to 100 volts, the resistance r can be lowered by half and Tf can be reduced to 23 ng.
I can keep it in ec. In this way, if ■, can be set to 100 volts and r can be reduced by half, the power consumption will also be reduced by half.

FIG. 7 also shows that the drive circuit of FIG. 6 can generate the coil current 704 necessary to move the Ploch line pair in both directions. In that case, switches Q, and Q
, are controlled according to the control signal 7-05, and the switches Q,
and Q4 need to be controlled according to control signal 706.

FIG. 8 is an explanatory diagram of another embodiment of the present invention.

The difference from FIG. 6 is that in addition to the third power source 605, there is a fourth power source 805.
, and make the voltage vs much lower than the ground potential of the first power supply, and the transistor switch Q, -Q4
diodes 801 to 804 for reverse voltage protection, respectively.
This is because they are connected in series.

゛If the heavy pressure VS is made negative, the voltage V can be reduced by that amount, so V in the case of Fig. 6 is -100゜v.
11 = 0 noyo na state wo, m 8 Figure te UV, = 5
0.

It becomes possible to lower the amplitude of the power supply voltage by setting it to a state such as Vs--50.

If it is done like this, the voltage at the connection points 405 and 406 will be
and V, change from the potential of V, to the potential of V, and the setting of the voltage at which the transistor switch Q, -Q, switches
Jv becomes larger, so a large voltage can be applied in the opposite direction when the switches Q1 to Q4 are off (closed). Diodes 801 to 804 are inserted to prevent the switches Q and Q4 from being destroyed by this 4+. switch Q
Diodes 801 to 804 may be omitted if transistors 1 to Q4 are realized by transistors having a large reverse breakdown voltage.

Note that when the second power supply voltage V1 is lower than the first power supply voltage, (2) is made lower than vo and (2) is made higher than the first power supply voltage, and the diodes 601-604 and diode 801 are It is necessary to reverse the direction of ~804. It is still necessary to change the npn transistors to pnp transistors so that the direction of the current in the switches Q1 to Q4 can be reversed, but the control signals and coil current waveforms for the switches Q1 to Q4 are the same, except for the polarity. , as shown in FIG.

This is shown in Figures 6 and 8g8. The drive circuit does not bring about a significant increase in cost compared to the conventional drive circuit shown in Figure 4, except for the addition of resistors and diodes and the increase in the number of power supplies. enables driving of the pulsed magnetic field required for

As described above, it can be seen that according to the present invention, the problem that it is difficult to realize a compact and compact driving circuit for the pulsed magnetic field necessary for bidirectional movement of the Ploch line pair can be easily solved. .

[Brief explanation of the drawing]

Figure 1 is a diagram of the Ploch line pair, Figure 2 is an explanatory diagram of the driving waveform of the pulsed magnetic field that shifts the Ploch line pair, and Figure 3 is the Ploch line memory magnetic domain.
01 and 102...-inner and outer walls of the domain wall surrounding the magnetic domain, 103 and 104...direction of magnetization, 111 and 11
2...Ploch line, 113 and 114...Bloch domain wall, 130...Ploch line pair, 14(1,1
41 and 142... direction of applied magnetic field, 201 and 202...
... Driving waveform of Ploch line pair, 301 ... Memory chip, 302 ... Plane board, 303 ... Output coil, 3o4 ... Magnetic shunt plate, 305 ... Permanent magnet, 3
06... Shield case, 401-: Ifil, 4
02, 601~603-・Resistance, 4o3°404.6
05,805--Power supply, 405,406=-, Drive:
Connection point between both ends of I-il, Q1-Q4...Transistor switch, D, ~D4,801-804...Dimate, 201,202,501゜502.701,702
,704- Coil current waveform, 7o3゜705.706
...Control signal waveform. Deputy J' 11-person patent attorney 1 Susumu □ 7・'';+6 Figure 403 7I-7 Figure December 106 O8 Figure 06

Claims (2)

[Claims] (1) 1 drive for applying a perpendicular pulsed magnetic field that moves the Ploch line pair to a magnetic thin film that stores the presence or absence of the Ploch line pair corresponding to digital information 1'' and 0' along the periphery of the magnetic domain. a first switch connected between each of both ends of the drive coil and a first power supply; a second switch connected between each of the front ends and a second power supply VIA; and each of the two wheels. a series circuit of a first diode and a first resistor connected between and a third power source, and a second diode and a second resistor connected between each of the ends and a fourth power source. A Ploch line pair drive device comprising a series circuit. (2) The second power supply voltage is set higher than the first power supply voltage, the third power supply voltage is set to be lower than the first power supply voltage, and the fourth power supply voltage is set higher than the second power supply voltage, or the second power supply voltage is set higher than the first power supply voltage. Claim 1, characterized in that the power supply voltage is set lower than the first power supply voltage, the third power supply voltage is set higher than the first power supply voltage, and the fourth power supply voltage is set lower than the second power supply voltage. Ploch line pair drive device as described.