CN104575527B - Two-dimentional magnetic recording system and method - Google Patents
Two-dimentional magnetic recording system and method Download PDFInfo
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- CN104575527B CN104575527B CN201410729599.2A CN201410729599A CN104575527B CN 104575527 B CN104575527 B CN 104575527B CN 201410729599 A CN201410729599 A CN 201410729599A CN 104575527 B CN104575527 B CN 104575527B
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- transmission line
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Abstract
Each embodiment of the invention generally relates to two-dimentional magnetic recording system and method.In particular it relates to a kind of system, which includes transmission line, reading element and difference amplifier.Reading element is connected in series with.Each reading element is connected to corresponding pairs transmission line.Difference amplifier is accordingly connected to reading element via transmission line.Difference amplifier is configured as amplifying the differential signal received from corresponding pairs transmission line.
Description
Cross reference to related applications
This application claims enjoy in the U.S. Provisional Application No. 61/888,283 submitted on October 8th, 2013, in 2013
The U.S. Provisional Application No. 61/888,300 submitted on October 8, and in the interim Shen in the U.S. that on October 10th, 2013 submits
Equity that please be No. 61/889,152.The complete disclosure of application cited above is incorporated herein by reference.
Technical field
This disclosure relates to the magnetic recording systems with trace mounting assembly.
Background technology
The description of background technology provided herein is the purpose for the context that present disclosure is usually presented.Currently
The work (work is described in the background technology part to a certain extent) of the inventor of name and the description
The aspect that the prior art may not be otherwise known as when submission had not both been expressed or there is no suggestion that ground is recognized as this
The prior art of disclosure.
Fig. 1 shows hard disk drive (HDD) 10 comprising Hard disc module (HDA) 12 and HDD printed circuit boards (PCB) 14.
HDA 12 includes one or more discs 16, has the magnetic surface for magnetic storage data.Data are deposited in binary form
Storage is the magnetic field of positive polarity or negative polarity.Disc 16 is arranged to stacking (stack).Disc and/or stacking pass through one or more
A spindle motor (spindle motor 18 is shown) rotation.One or more W heads (hereinafter referred to as " magnetic head ") from
The magnetic surface of disc 16 reads data and data is written on the magnetic surface of disc 16.Single magnetic head 20 is shown.Each magnetic head packet
The write element (such as inductor) and reading element (such as magnetic resistance (MR) element) for generating magnetic field are included, reading element senses disc
Magnetic field on one of 16.Magnetic head is installed in the distal end of one or more actuator arms (single actuator arm 22 is shown).It causes
Dynamic device (such as voice coil motor (VCM) 24) moves actuator arm 22 relative to disc 16.
HDA 12 includes preamplifier device 26.Preamplifier device 26 may include being received for amplifying from magnetic head
Signal amplifier.When reading the data, the magnetic field of generation leads to the simulation letter of the low level in the reading element of magnetic head 20
Number.Amplifier amplifies low-level analog signals, and exports the analog signal of amplification to the channel read/write (R/W) (hereinafter referred to as
" reading channel ") module 28.
HDD PCB 14 include reading channel module 28, hard disk controller (HDC) module 30, processor 32, main shaft/VCM
Drive Module 34, volatile memory 36, nonvolatile memory 38 and input/output (I/O) interface 40.In write operation
Period, reading channel module 28 can be by using error correcting code (ECC) (such as run length (RLL) code, Reed-institute sieve
Door code etc.) coded data to be to improve reliability.Channel module 28 is read then by the data transmission of coding to preamplifier device
Part 26.During read operation, reads channel module 28 and receive analog signal from preamplifier device 26.Read channel module
28 convert analog signals into digital signal, and digital signal is decoded to restore the data being previously stored on disc 16.
HDC modules 30 control the operation of HDD 10.For example, HDC modules 30 generate order, order control is one or more
The movement of the speed of spindle motor and one or more actuator arms.Main shaft/VCM driver module 34 implements order and life
At control signal, the speed of the one or more spindle motors of control signal control and determining for one or more actuator arms
Position.In addition, via I/O interfaces 40, (host such as in host equipment is adapted to HDC modules 30 with external equipment (not shown)
Device) communication.HDC modules 30 can receive data to be stored from external equipment, and can send the data fetched outside
Portion's equipment.
Processor 32 handles data, including coding, decoding, filtering and/or formatting.In addition, processor 32 is grasped in read/write
Servo or location information are handled during work to place magnetic head above disc 16.The servo being stored on disc 16 ensures data quilt
It the correct position that is written on disc 16 and is read from the correct position on disc 16.In some embodiments, it watches certainly
Clothes write-in (SSW) module 42 can be to use the writing servo on disc 16 of magnetic head 20 before storing data on HDD 10.
In order to improve the data storage capacity on disc, track density (data volume stored in predetermined surface region) is increasing
Add, track width is reducing, and track pitch (or the distance between magnetic track) is reducing.As a result, the width of magnetic head can be with
It is wider than the width of single magnetic track.Because this relationship between magnetic head and magnetic track, magnetic head can pick up inter-track noise.Magnetic
Noise can refer to magnetic that is detecting and being associated with the one or more magnetic tracks adjacent with the magnetic track being read between road
Field characteristic.
HDA 12 may include two-dimentional magnetic recording (TDMR) system 50 for having trace mounting assembly (TSA) 52.TSA 52
Refer to one or more actuator arms and the transmission line extended between preamplifier part 26 and magnetic head (for example, 54 quilt of transmission line
It shows).Transmission line (otherwise referred to as trace) is suspended above 16 top of disc via one or more actuator arms.TDMR systems
(such as TDMR systems 50) is using multiple magnetic heads adjacent to each other to read the single magnetic track in disc surface.Letter from magnetic head
It number is handled, with counteracting, elimination and/or minimizes the noise (such as inter-track noise) detected during magnetic track is read.This
Signal-to-noise ratio is improved, for improving the recovery for being stored in the data on magnetic track.
Fig. 2 shows the TDMR systems 60 for the HDA 12 that can be used for Fig. 1.TDMR systems 60 include reading element 62, transmission
Line 64 and preamplifier device 66.Preamplifier device 66 includes difference amplifier 68.Each reading element 62 is connected to
The corresponding pairs transmission line in corresponding difference amplifier and transmission line 64 in difference amplifier 68.Reading element 62 divides each other
From.Since reading element 62 is separated from each other, so noise coupling between reading element 62 and being detected by reading element 62
The cross-couplings of signal be minimized.As a result, modulation is inappreciable between the magnetic head of signal.Difference amplifier 68 provides difference
Divide output signal Out1, Out2.The gain of each difference amplifier 68 can be adjusted to increase output signal Out1, Out2
Amplitude and/or the corresponding signal-to-noise ratio of raising.
Invention content
A kind of system is provided, and the system includes transmission line, reading element and difference amplifier.Reading element series connection connects
It connects.Each reading element is connected to the corresponding pairs transmission line in transmission line.Difference amplifier is connected via transmission line
To reading element.Difference amplifier is configured as amplifying the differential signal received from the corresponding pairs transmission line in transmission line.
In other feature, transmission line includes first transmission line, second transmission line and third transmission line.Reading element includes
First element and second element.Difference amplifier includes the first difference amplifier and the second difference amplifier.First element connects
To first transmission line.Second element is connected to second transmission line and third transmission line.First transmission line is connected to the first difference and puts
The first input end of big device.Second transmission line is connected to the second input terminal of the first difference amplifier.Third transmission line is connected to
The first input end of second difference amplifier.
In other feature, system further comprises that module, module are configured as receiving respective channel from difference amplifier
On output signal and data are restored based on output signal.It is defeated to generate that difference amplifier is configured as amplified difference signal
Go out signal.
In other feature, system further comprises device, magnetic head and component.Device includes difference amplifier.Magnetic head quilt
It is arranged on the same surface of disk.Each magnetic head includes the corresponding reading element in reading element.Component includes transmission line.Group
Top suspended transmission line of the part in the part between device and magnetic head of disk.
It in other feature, provides a method, and this method includes：Read operation is executed via reading element,
Wherein reading element is connected in series with, and wherein each reading element is connected to the corresponding pairs transmission line in transmission line；Via
The output of reading element is provided to difference amplifier by transmission line, and wherein difference amplifier is connected respectively to reading via transmission line
Element；And the differential signal received from the corresponding pairs transmission line in transmission line via difference amplifier amplification.
In other feature, this method further comprises：Via difference amplifier amplified difference signal to generate output letter
Number；The output signal in respective channel is received from difference amplifier；And data are restored based on output signal.
In other feature, device includes difference amplifier.Reading element is disposed in corresponding magnetic head.Magnetic head is arranged
On the same surface of disk.Transmission line is suspended above the top in the part between device and magnetic head of disk.
The other aspects of the application of present disclosure will become aobvious and easy from detailed description, claims and attached drawing
See.Purpose that detailed description and specific examples are intended only to illustrate and be not intended to and limit the scope of the disclosure.
Description of the drawings
Fig. 1 is the functional block diagram of hard disk drive according to prior art.
Fig. 2 is the functional block diagram of TDMR systems according to prior art.
Fig. 3 is the functional block diagram for another TDMR systems for being incorporated to the reading element being connected in series with.
Fig. 4 is to be incorporated to the reading element being connected in series with, each two transmission lines of reading element according to present disclosure
TDMR systems functional block diagram.
Fig. 5 is the correspondence equiva lent impedance table of voltage generation and reading element that signal is read according to the diagram of present disclosure
The functional block diagram for the TDMR systems shown.
Fig. 6 includes the first reading element voltage, the first differential voltage and the first extraction voltage of the TDMR systems of Fig. 5
The voltage pattern of (extracted voltage).
Fig. 7 includes the frequency diagram of the first differential voltage and the first extraction voltage of Fig. 6.
Fig. 8 include the second reading element voltage of the TDMR systems of Fig. 5, the second differential voltage and the second extraction voltage electricity
Pressure figure.
Fig. 9 includes the frequency diagram of the second differential voltage and the second extraction voltage of Fig. 8.
Figure 10 is the functional block diagram of the common-mode noise of the TDMR systems of pictorial image 5.
Figure 11 is the functional block diagram in the illusory path that diagram is eliminated for the common-mode noise in the TDMR systems of Fig. 5.
Figure 12 shows the TDMR methods according to present disclosure.
Figure 13 is the diagram according to present disclosure from the intermodulation of the signal of multiple reading elements and gain control module
TDMR systems functional block diagram.
Training, calibration and the operating method of the TDMA system of Figure 14 pictorial images 13.
In the accompanying drawings, reference numeral can be reused, to identify similar and/or identical element.
Specific implementation mode
In order to minimize the space in TDMA system between reading element, reading element can be connected in series with.Fig. 3 is shown can
For the example TDMA system 70 in the HDA 12 of Fig. 1.TDMA system 70 includes：With reading element 72 and transmission line 74
Reading circuit 71；And the preamplifier device 76 with difference amplifier 78.Preamplifier device 76 can replace Fig. 1
Preamplifier device 26.Reading element 72 is connected in series with, and can be located in the magnetic head of driver (for example, Fig. 1's
In the magnetic head 20 of hard disk drive 10).Each reading element 72 is connected to two transmission lines in transmission line 74.It is each to read member
Part 72 shares at least one transmission line in transmission line 74.Each difference amplifier 78 is connected to two transmission in transmission line 74
Line.The quantity of reading element 72 is equal to the quantity of difference amplifier 78.The quantity of transmission line 74 is more than the quantity of reading element 72
One.
Although the space between reading element 72 can be less than the space between the reading element 62 of Fig. 2, due to reading
It takes element 72 to be connected in series with and shares certain transmission lines in transmission line 74, so the noise coupling of signal is presented in TDMR systems 70
Conjunction and cross-couplings.The noise coupling and cross-couplings of signal are provided to difference amplifier 78 via transmission line 74.For example,
In the signal induced in both reading element MR1 and MR2 at least partly difference amplifier A2 is provided to via transmission line T2.
In addition, the impedance of reading circuit 71 seen of input end in each difference amplifier Al, An is different.
For example, the external terminal 80,82 of difference amplifier Al and An are connected respectively to transmission line T1, Tn, it is not attached to reading member
The end between two reading elements in part.The internal terminal 84,86 of difference amplifier Al, An are connected to transmission line T2 and biography
Defeated line Tn-1 has the end being connected between two reading elements in reading element 72.Therefore, external terminal 80,
The impedance for the reading circuit 71 seen at 82 is different from the impedance for the reading circuit 71 seen at internal terminal 84,86.
As an example, the impedance per transmission lines 74 can be 50 ohm (Ω).Each reading element 72 can have resistance
Anti- Rmr.If Rmr>>The impedance of 50 Ω, the then reading circuit 71 seen at each external terminal 80,82 are substantially 50 Ω
(or impedance of single transmission line), and the impedance for the reading circuit 71 seen at each internal terminal 84,86 is substantially 25
Ω (or half of the impedance of one of transmission line).Although one or more difference amplifiers 78 (such as difference amplifier A2) can be with
With the input terminal for seeing same impedance amount, but the reading due to seeing at the input terminal 80-86 of difference amplifier Al, An
The impedance of circuit 71 is different, so difference amplifier Al, An are nonequilibrium.TDMA with non-equilibrium difference amplifier
System is not fully differential system.Non-equilibrium difference amplifier can reduce signal differential ability associated with TDMA system.
In addition, in order to minimize the reflection of the part signal provided via transmission line 74 by reading element 72, impedance matching
It may be provided between (i) transmission line 74 and the input terminal of (ii) difference amplifier 78.For example, the input of difference amplifier 78
The input impedance at one of end can be set to match the impedance for the reading circuit 71 seen at one of input terminal place.The matching can
To be provided for each input terminal of difference amplifier 78.If the input terminal of certain difference amplifiers 78 sees reading circuit
71 different impedances, then increase the complexity of difference amplifier 78.Increased complexity is associated in difference amplifier 78
Each input end provides impedance matching and compensates and/or solve non-equilibrium difference amplifier 78.Difference amplifier 78 amplifies
The differential signal received from transmission line 74, to generate differential output signal OUT1-n.
Fig. 4 shows the TDMR systems 90 that can be incorporated in the HDA 12 of Fig. 1.TDMR systems 90 include：With reading element
The reading circuit 91 of 92 (being properly termed as sensor) and transmission line 94；And the preamplifier device with difference amplifier 98
96.Preamplifier device 96 can replace the preamplifier device 26 of Fig. 1.Reading element 92 is connected in series with, and can be with
In the magnetic head of driver (for example, in magnetic head 20 of the hard disk drive 10 of Fig. 1).The end of reading element 92 is connected to
Node 1-n.
Although TDMR systems 90 may include any number of reading element, transmission line and difference amplifier, read
The quantity of element 92 is identical with the quantity of difference amplifier 98, and the quantity of transmission line 94 is the two of the quantity of reading element 92
Times.In other words, each reading element 92 be connected to corresponding pairs transmission line T1a and T1b, T2a and T2b ..., Tna and Tnb.
Each reading element MR1 and MRn are connected to three transmission lines in transmission line 94.The first end of each reading element MR1, MRn
The correspondence transmission line being connected in transmission line 94.The second end of each reading element MR1, MRn are connected to pair in transmission line 94
Answer two transmission lines.Each other reading element MR2 to MRn-1 are connected to four transmission lines in transmission line.In other words, it reads
Every one end of element MR2 to MRn-1 is taken to be connected to corresponding pairs transmission line 94.Each difference amplifier 98 is connected to corresponding pairs
Transmission line 94.Due to these relationships and because transmission line 94 between reading element 92, transmission line 94 and difference amplifier 98
With same impedance, so difference amplifier 98 can be balance and TDMR systems 90 can be fully differential system.
Although some ends of reading element 92 are connected to a plurality of pairs of transmission line, due at the end of reading element 92
High impedance seeing at portion, relative to ground, so the cross-couplings of signal are minimized.Node between reading element
The impedance seen at (for example, node 2 to n-1) can be referred to as common code impedance.Common code impedance is relatively high, to prevent letter
Number cross-couplings.Common code impedance is present at the node between reading element (such as at node 2 and 3).For example, reading
High impedance at node 2 between element MR1 and MR2 minimize from it is being received at second transmission line T2, reading
The reading semaphore induced in element MR1.Due to the high impedance of reading element 92, the cross-couplings of signal are also minimized.Example
Such as, reading semaphore being transmitted to reading element MR2, being induced in reading element MR1 is negligible.However, every
The differential impedance for each pair of transmission line 94 seen at a difference amplifier 98 is small (such as 100 Ω).
Common code impedance is more than the differential impedance seen by difference amplifier 98.As an example, common code impedance may be greater than
5-10 times of one or more differential impedances.As another example, common code impedance may be greater than one or more differential impedance 10-
100 times.This makes the reading signal that difference amplifier 98 receives and amplification induces in corresponding reading element 92, and minimizes
The reading semaphore received from adjacent reading element.Adjacent reading element refers to the reading element being connected to each other directly and/or is
A series of continuous reading element in reading elements.
In addition, the impedance of reading circuit 91 seen of input end in difference amplifier 98 can be identical.For example,
The external terminal 97 of difference amplifier A1 can see impedance (impedance of transmission line T1a) and the difference amplifier A1 of 50 Ω
Internal terminal 99 it can be seen that 50 Ω impedance (impedance of transmission line T1b).This allows the input terminal of difference amplifier 98
Input impedance is identical, and this simplifies the circuit designs of difference amplifier 98.In addition, the input terminal of difference amplifier 98 is defeated
The impedance for the reading circuit 91 seen by the input terminal of difference amplifier 98 can be matched by entering impedance.This is minimized in differential amplification
The signal reflex of the input end of device 98.Difference amplifier 98 amplifies the differential signal received from transmission line 94, to generate difference
Output signal OUT1-n.
Fig. 5 shows TDMR systems 100 comprising：Reading circuit with reading element 102,104 and transmission line 106
101；And the preamplifier device 108 with difference amplifier 110.Before preamplifier device 108 can replace Fig. 1
Set amplifier device 26.Reading element 102,104 is connected in series with, and can be located in the magnetic head of driver (for example, Fig. 1
In the magnetic head 20 of hard disk drive 10).Each reading element 102,104 is shown by the pairs of resistance with value Rmr/2.Although one
Reading element, transmission line and the difference amplifier of fixed number amount are shown, but TDMA system 100 can have it is any amount of this
A little devices.It generates reading signal and the corresponding reading voltage at reading element 102 is indicated by voltage source 112,114, carry
For corresponding reading element voltage Vs1 and Vs2.Each voltage source 112,114 is illustrated as being connected in reading element 102,104
Between the resistance of corresponding reading element.Each reading element 102,104 can be with the all-in resistance of Rmr.Each difference amplifier
110 are connected to corresponding pairs transmission line T1a and T1b or T2a and T2b.
Three nodes A, B and C are shown.Node A is connected between the first reading element 102 and first transmission line T1a.Node
B is connected between the first reading element 102 and the second reading element 104 and is connected to transmission line T1b, T2a.Node C connections
Between the second reading element 104 and the 4th transmission line T2b.
First difference amplifier A1 is received at the respective input of the first difference amplifier A1 with corresponding current potential Vo1a
With the first differential voltage Vo1 of Vo1b.Second difference amplifier A2 is received at the respective input of the second difference amplifier A2
The second differential voltage Vo2 with corresponding current potential Vo2a and Vo2b.
The correspondence equiva lent impedance of first reading element 102 indicates that 120 are shown, it is assumed that closest to difference amplifier 110
Transmission line 106 the corresponding input resistance of the input terminal of the impedance-matched differential amplifier 110 of reading circuit 101 seen of end
It is anti-.As an example, the impedance per transmission lines can be 50 Ω.Equiva lent impedance indicates that 120 include having the first reading element electricity
Press the first voltage source 112 of Vs1 and output current I.The first reading element 102 for seeing in node B and first transmission line T1a's
Impedance is illustrated as Z1+Rmr/2, and wherein Z1 is the impedance that one of resistance of the first reading element 102 adds corresponding transmission line T1a
Impedance.It is illustrated as Z2+Rmr/2 in the impedance of the second reading element 104 and transmission line T1b-T2b that node B sees, wherein Z2 is
Impedance of one of the resistance of second reading element 104 plus the impedance of corresponding transmission line T2b.Impedance Z 1 can be equal to (Rmr/2)+
50.Impedance Z 2 can be equal to (Rmr+50) // 50//50, and it can be read with transmission line T2b concatenated second to neutralize Rmr+50
The impedance of one of the resistance of element 104, and wherein one of resistance of the second reading element 104 and transmission line T2b is connected in parallel
(//) transmission line T2a and it is connected in parallel transmission line T1b.
If impedance Rmr>>50 Ω can be then 50 Ω in the impedance Z (A) that node A sees, in the impedance that node B sees
Z (B) can be 25 Ω, and electric current I can be equal to Vs1/Rmr, can be equal to (50/Rmr) * Vs1 in the voltage V (A) of node A, and
And-(25/Rmr) * Vs1 can be equal in the voltage V (B) of node B.As a result, the reading signal provided by the first reading element 102
The input of the second difference amplifier A2 is provided at the amplitude of such as (25/Rmr) * Vs1.Due to Rmr>>50 Ω, so (25/
Rmr) * Vs1 are negligible.
In addition, the first differential voltage Vo1 is equal to Vo1a-Vo1b, and it is also equal to V (A)-V (B).V (A)-V (B) of generation
Voltage can be equal to (75/Rmr) * Vs1.Differential voltage Vo2 can be equal to (25/Rmr) Vs1.As a result, differential voltage Vo1 and
Vo2 can be indicated by equation 1-2.
Vo1=(75/Rmr) * Vs1+Vs1+ (25/Rmr) * Vs2 (1)
Vo2=(75/Rmr) * Vs2+Vs1+ (25/Rmr) * Vs1 (2)
Signal with reading element voltage Vs1 and Vs2 can be based on differential voltage Vo1 and Vo2 via difference amplifier
110 are extracted.Reading element voltage Vs1 and Vs2 can be indicated by equation 3-4.
Vs1=(3*Vo1-Vo2) * Rmr/200 (3)
Vs2=(3*Vo2-Vo1) * Rmr/200 (4)
Fig. 6 shows the voltage pattern of the TDMR systems 100 of Fig. 5.Voltage pattern includes：First across the first reading element 102 reads
Take the figure of element voltage Vs1；In the figure of the first differential voltage Vo1 of the input end of the first difference amplifier A1；And it is corresponding
The first extraction voltage Vs1' figure.First extraction voltage Vs1' matches the first reading element voltage Vs1.Accordingly, with respect to first
Cross-couplings (cross-couplings for the including noise) amount of the signal of difference amplifier Al is negligible and/or is not present.
In the illustrated example, the impedance of each reading element 102,104 is 500 Ω, and the frequency of the first reading element voltage Vs1 is
LGHz, and the frequency of the second reading element voltage Vs2 is 2GHz.
Fig. 7 shows the frequency diagram of the extraction voltages of the first differential voltage Vo1 and first Vs1'.As in Fig. 7 as can be seen that by the
The amplitude for the frequency component that two reading element voltage Vs2 are provided is reduced from the frequency diagram of the first differential voltage Vo1 to the first extraction
The figure of voltage Vs1'.First extraction voltage Vs1' can be in the inside of the first difference amplifier A1 and/or in the first differential amplification
The output end of device Al is detected.
Fig. 8 shows other voltage patterns of the TDMR systems 100 of Fig. 5.Voltage pattern includes：Across the of the second reading element 104
Two read the figure of element voltage Vs2；In the figure of the second differential voltage Vo2 of the input end of the second difference amplifier A2；And
The figure of corresponding second extraction voltage Vs2'.Second extraction voltage Vs2' matches the second reading element voltage Vs2.Accordingly, with respect to
Cross-couplings (cross-couplings for the including noise) amount of the signal of second difference amplifier A2 is negligible and/or is not present
's.
Fig. 9 shows the frequency diagram of the extraction voltages of the second differential voltage Vo2 and second Vs2'.As in Fig. 9 as can be seen that by the
The amplitude for the frequency component that one reading element voltage Vs1 is provided is reduced from the frequency diagram of the second differential voltage Vo2 to the second extraction
The figure of voltage Vs2'.Second extraction voltage Vs2' can be in the inside of the second difference amplifier A2 and/or in the second differential amplification
The output end of device A2 is detected.
Figure 10 is shown in the common-mode noise introduced in the TDMR systems 100 of Fig. 5.As shown, TDMR systems 100 include reading
Take the resistance, transmission line 106 and the preamplifier device 108 with difference amplifier 110 of element 102,104.Preceding storing
Big device device 108 can replace the preamplifier device 26 of Fig. 1.Reading element 102,104 is connected in series with, and can be located at
In the magnetic head of driver (for example, in magnetic head 20 of the hard disk drive 10 of Fig. 1).The voltage source of reading element voltage Vs1, Vs2
112,114 is not shown in FIG. 10.Common-mode noise is indicated by noise source 130,132, in the electricity of corresponding reading element 102,104
Relevant voltage Vn1, Vn2 is provided at the node 134,136 between resistance.Noise source 130,132 is connected to node 134,136 and ground connection
Between 138.
The correspondence equiva lent impedance of noise source 142 (indicating noise source 130,132) with voltage Vn indicates that 140 are shown simultaneously
And illustrate the electric current seen in node B and impedance.It is Ia by the node B electric currents transmitted towards node A.Simultaneously by node B
And the electric current far from node A is Ib.
It is illustrated as Z1+Rmr/2 in the impedance of the first reading element 102 and first transmission line T1a that node B sees, wherein
Z1 is that the impedance of one of resistance of the first reading element 102 adds the impedance of corresponding transmission line T1a.Second seen in node B
The impedance of reading element 104 and transmission line T1b-T2b are shown as Z2+Rmr/2, and wherein Z2 is the electricity of the second reading element 104
The impedance of one of resistance adds the impedance of corresponding transmission line T2b.Impedance Z 1 can be equal to (Rmr/2)+50.Impedance Z 2 can be equal to
(Rmr+50) // 50//50 it is one of resistance of the second reading element 104 and the concatenated resistances of transmission line T2b, to neutralize Rmr+50
It is anti-, and wherein one of resistance of the second reading element 104 and transmission line T2b is connected in parallel (//) transmission line T2a and parallel connection
Connect transmission line T1b.
If impedance Rmr>>50 Ω can be then 50 Ω in the impedance Z (A) that node A sees, in the impedance that node B sees
Z (B) can be 25 Ω, and electric current Ia can be equal to Vn/Rmr, and electric current Ib can be equal to Vn/Rmr.In addition, voltage Vo1 is equal to
Vo1a-Vo1b, and Ia*50- (Ib1/2) * 50- (Ib2a) * 50 can be equal to, wherein Ib1 is by second transmission line T1b
Electric current, and wherein Ib2a is the electric current by third transmission line T2a.Differential voltage Vo1 can also be equal to ((Vn1)-(Vn2)/
2-(Vn2)/2)*50/Rmr.If Vn1=Vn2 (that is, reading element 102 and 104 common-mode noises having the same), conduct
Noise source 130,132 as a result, differential voltage Vo1=0.Therefore, because the common-mode signal caused by noise in node B does not influence
The differential signal received at difference amplifier 110.
Figure 11 shows the illusory path 150 eliminated for the common-mode noise in the TDMR systems 100 of Fig. 5.Illusory path
150 can generally indicate the respective impedance for being provided to the noise of second transmission line T1b from node B and seeing in node B
Rdmy.In fig. 11, the noise source 152 of the first reading element 102, first transmission line T1a and the first difference amplifier A1 is shown.
Noise source 152 has voltage Vn.Illusory path 150 has the resistance Rdmy in node B, and includes second transmission line T1b.Electricity
Rdmy is hindered from 152 receiving voltage Vn of noise source.Differential voltage Vo1a, Vo1b is provided to the input terminal of difference amplifier A1.Electricity
Resistance Rdmy can indicate the resistance in node B the second reading elements 104 and transmission line T2a, T2b seen.
The correspondence equiva lent impedance of noise source 152 indicates that 160 are shown and include that (i) passes through node A from noise source 152
Impedance (the Z that electric current I and (ii) see in noise source 1520+Rmr).Impedance Z0It can be the impedance of first transmission line Tla.If
Impedance Rmr>>50 Ω can be then Rmr+50 Ω in the impedance Z (A) that node A sees, the impedance Z (B) that node B sees can be with
It is Rdmy+50 Ω, the electric current Ia by node A can be Vn/Rmr, and can be equal to Vn/ by the electric current Ib of node B
Rmr.In addition, differential voltage Vo1 is equal to Vo1a-Vo1b and can be equal to Ia*50-Ib*50.Differential voltage Vo1 can also be waited
In [(1/Rmr)-(1/Rdmy)] * 50*Vn.Common-mode rejection ratio (CMRR) can be indicated by equation (5).
CMRR=20log [(1/Rmr) * 50] -20log { [(1/Rmr)-(1/Rdmy)] * 50 } (5)
Based on equation (5), if Rdmy=α * Rmr and Rmr=500 Ω, CMRR are equal to 20log | α/(α -1) |,
Middle α is constant.As an example, in order to obtain the CMRR of 20 decibels (db), (10/11)<α<(10/9) or 0.91<α<1.1.If
α is equal or close to 1.0, thenAndAs a result, the difference between voltage Vo1a and Vo1b is can to neglect
Slightly.
System disclosed herein can be operated using a variety of methods, and exemplary method is illustrated in fig. 12.Figure 12 figures
Show the TDMR methods according to present disclosure.Although following task is carried out mainly with respect to the embodiment of Fig. 1 and Fig. 4-11
Description, but these tasks can be easily modified to apply to the other embodiment of present disclosure.These tasks can
To be repeatedly carried out.
The TDMR methods can start at 200.At 202, via reading element (such as reading element 92,102,
104) it generates and reads signal and corresponding voltage.Reading element is connected in series with.Each reading element has corresponding pairs transmission line (example
Such as transmission line 94,106) and corresponding difference amplifier (difference amplifier 98, one of 110).
At 204, reads signal and be provided to corresponding pairs transmission line from reading element.At 205, in difference amplifier
Input terminal via transmission line receive differential input voltage.At 206, read signal and corresponding voltage be extracted as described above with
Generate differential output voltage.Differential input voltage is amplified via difference amplifier to generate differential output voltage.
At 208, it is defeated to receive difference in the corresponding read/write channel of read/write channel module (such as read/write channel module 28)
Go out voltage.At 210, differential output voltage (it is provided as analog signal) is converted to digital signal by read/write channel module.
Digital signal is decoded to restore initial data.
At 212, HDC modules (such as HDC modules 30) store data in memory (such as memory 36, one of 38)
And/or data are provided to host via interface (such as interface 40).This method can terminate at 214.
Above-mentioned task is intended to be illustrative example；According to application, these tasks can sequentially, synchronously, simultaneously, even
Continuous ground is performed during overlapping time section or with different order.In addition, according to embodiment and/or sequence of events, it is any
Task can not be performed or can be skipped.
Figure 13 shows the TDMR systems 170 for the hard disk drive 10 that can be used for Fig. 1.TDMR systems 170 include：With reading
Take the reading circuit 171 of element 172 and transmission line 174；And the preamplifier device 176 with difference amplifier 178.
TDMR systems 170 are similar to the TDMR systems 90 of Fig. 4.TDMR systems 170 include gain control module 180 and memory 182.Increase
Beneficial control module 180 can by including：On HDD PCB 14；In processor 32；In HDC modules 30；In read/write channel
In module 28；On HDA 12；Or in preamplifier device 176 (as shown in the figure).Preamplifier device 176 can be with
Replace the preamplifier device 26 of Fig. 1.Memory 182 can by including：On HDD PCB 14；In nonvolatile memory
In 38；In volatile memory 36；In HDC modules 30；In processor 32；In read/write channel module 28；In HDA
On 12；And/or in preamplifier device 176.
The yield value of the estimation of gain control module 180, adjustment and setting difference amplifier 178, to minimize from neighbouring
The crosstalk of the signal of reading element, neighbouring reading element pickup and the associated signal of adjacent track.Gain control module 180 executes
Training method is to obtain gain profiles (gain profile) of each difference amplifier 178 relative to corresponding reading element 172
184 and in memory 182 store gain profiles 184.Gain profiles 184, which can be included in, to be stored in memory 182
Matrix and/or table 186 in.
Since reading element 172 is connected in series with, and because certain transmission lines 174 are connected to multiple reading elements,
Reading signal from each reading element 172 can be received and amplified by each difference amplifier 178.Although reading
The cross-couplings (also referred to as intermodulation) of signal can be minimized as shown above, but if difference amplifier 178 has
Different gains and transmission line 174 has different impedances, then cross-couplings can become more apparent upon.Each difference amplifier
178 can differently amplify from each of each reading element 172 reading signal.Difference amplifier 178 provides difference respectively
Output signal Out1-n.
For example, the first difference amplifier Al can the gain based on the first difference amplifier A1 and amplify such as from each reading
The reading signal that element MR1-MRn is received.Second difference amplifier A2 can the gain based on the second difference amplifier A2 and put
As large as the reading signal received from each reading element MR1-MRn.The reading that Figure 13 diagrams are received by the second difference amplifier A2
The example of signal.Second difference amplifier A2 can be received：Reading signal from the first reading element MR1 is (by 188 table of dotted line
Show)；Reading signal (being indicated by dotted line 190) from the second reading element MR2；And from including reading element MRn
The one or more of other reading elements read signals (being indicated by dotted line 192).Although the reading from the second reading element MR2
The amplitude for the number of winning the confidence can be more than the amplitude of the reading signal from other reading elements, but it is poor second to be likely difficult to differentiation
Divide the amplifier A2 reading signals received.
Therefore, it if the cross-couplings for reading signal are not solved during the processing for reading signal, is likely difficult to
Distinguish the reading signal received in each difference amplifier 187.In order to solve to read the cross-couplings of signal and in order to distinguish
Corresponding to the reading signal of each difference amplifier 178, gain control module 180 executes training and/or calibration method, to obtain
Gain profiles 184.Gain profiles 184 can for example be determined during manufacturing corresponding hard disk drive and be stored in storage
In device 182.Gain profiles 184 can be used to extensive during the operation of hard disk drive and after manufacturing hard disk drive
The data being stored in again on the disk of hard disk drive.
The training of Figure 14 diagrams, calibration and operating method, can be by TDMA system 170 and/or the hard disk drive 10 of Fig. 1
Implement.Although following task relates generally to Fig. 1 and the embodiment of Figure 13 is described, these tasks can easily by
Modification is with the other embodiment suitable for present disclosure.These tasks can be repeatedly carried out.Although following task master
It to be described about three reading elements and three difference amplifiers, but these tasks can be modified to be used for any number
The reading element and difference amplifier of amount.
Training, calibration and operating method can start at 300.Training and/or calibration method are during task 302-316
It is performed.Training and/or calibration method can during the servo format of disk, in disk (such as disc 16) and/or magnetic
It is performed during the manufacture of disk drive (such as hard disk drive 10), and/or whenever gain calibration to be executed.At 302,
Gain control module (such as gain control module 180) selects scheduled data pattern to be written to one or more magnetic of disk
Road and preassigned pattern is written to one or more magnetic tracks.Preassigned pattern can be written to the presumptive area of disk.
Following table 1- tables 7 provide the example for the data pattern that can be written into during task 302.Table 1- tables 7 include
Track number, the sequence for the place value to be written into and the scan values of execution scanned every time.Scan values may export defeated by difference
Go out the voltage of signal designation.In addition, only for the purposes of illustration, certain patterns of place value are shown, place value it is any it is predetermined, pseudo- with
Machine and/or stochastic model can be written into.Each place value of table 1 is zero (' 0').Each place value of table 2 is one (' 1').3 needle of table
To being written zero in each magnetic track, the magnetic track N+4 in addition to being wherein written one.Table 4 in each magnetic track for being written zero, in addition to it
The magnetic track N+4 and magnetic track N+5 of middle write-in one.Table 5 is directed to is written zero, in magnetic track N+4 to magnetic track N+6 in magnetic track N to magnetic track N+3
It is middle to be written one and be written zero in magnetic track N+7 to magnetic track N+10.Table 6 is directed to is alternately written into zero-sum one every a magnetic track.Table
7 for replacing between the two following：(i) write-in zero and (ii) are written zero in two magnetic tracks in two magnetic tracks.In addition,
Only for the purposes of illustration, the scan values of three reading elements MR1, MR2 and MR3 are shown.The reading element of different number is swept
Retouching value can be included in table.In addition, any number of scanning can be associated with each table and/or each preassigned pattern and by
It executes.
Table 1
Table 2
Table 3
Table 4
Table 5
Table 6
Table 7
Alternately and/or other than the one or more patterns provided by table 1- tables 7 and/or other patterns are provided,
The example of different place value sequences is shown below.Sequence can be written into during the iteration of task 302.Although sequence is provided use
In 2-4 magnetic track, but sequence can be provided for any number of magnetic track, and the pattern of sequence can be recycled and reused for
Other magnetic track.Sequence includes matching sequence, the first alternate sequence, the second alternate sequence, the first pseudo-random sequence and second
Pseudo-random sequence.Matching sequence includes that identical place value sequence is written to each magnetic track in three magnetic tracks.First alternate sequence
Including identical sequence is written to the first magnetic track and third magnetic track, and opposite sequence is written to the second magnetic track.Second alternate sequence
Including identical sequence is written to the first magnetic track and the second magnetic track, while opposite sequence is written to third magnetic track and the 4th magnetic track.The
One pseudo-random sequence includes replacing between zero-sum one for the first magnetic track, and be directed to the second magnetic track in two zero-sums two one
Between alternately.Second pseudo-random sequence includes being directed to the first magnetic track between zero (such as 4 zero) of the first predetermined quantity and one
Alternately, and for the second magnetic track replace between zero (such as 2 zero) of the first predetermined quantity and one.Inverse value (such as one
It replaces one) to be written into for each exemplary sequence instead of zero and zero.
Match sequence
1-01010101010101010...01010101010 of magnetic track
2-01010101010101010...01010101010 of magnetic track
3-01010101010101010...01010101010 of magnetic track
Alternate sequence 1
Magnetic track 1-01010101010101010...01010101010
Magnetic track 2-10101010101010101...10101010101
Magnetic track 3-01010101010101010...01010101010
Alternate sequence 2
Magnetic track 1-01010101010101010...01010101010
Magnetic track 2-01010101010101010...01010101010
Magnetic track 3-10101010101010101...10101010101
Magnetic track 4-10101010101010101...10101010101
Pseudo-random sequence 1
Magnetic track 1-0101010101010101...0101010101
Magnetic track 2-0011001100110011...0011001100
Pseudo-random sequence 2
Magnetic track 1-000010000100001...000010000100001
Magnetic track 2-001001001001001...001001001001001
At 304, gain control module reads one or more magnetic tracks via reading element MR1, MR2, MR3.Read letter
It number is generated by reading element MR1, MR2, MR3 and is amplified by difference amplifier (such as difference amplifier 178) to generate
Differential output signal.At 306, gain control module based on difference amplifier correspondence differential output signal (such as output letter
Number Out1-n) it determines and stores scan values.Scan values can export the voltage indicated by differential output signal.
At 308, gain control module can estimate each difference amplifier based on the scan values read at 306
Gain component value.As an example, gain component value can be determined using following equation 6-8, wherein V1、V2、V3It is difference
The output voltage of amplifier, i1、i2、i3It is the electric current from each reading element, and k11-k33It is and each reading signal
The associated gain component value of each difference amplifier.
V1=k11i1+kl2i2+k13i3 (6)
V2=k2lil+k22i2+k23i3 (7)
V3=k3lil+k32i2+k33i3 (8)
Voltage V can be detected1、V2、V3.Electric current i1、i2、i3It can be detected and/or based on the place value for being written to magnetic track
Known mode and be estimated.Gain component value k11-k33It can be based on voltage V1、V2、V3, electric current i1、i2、i3And it is written into
It is estimated to the known mode of the place value of magnetic track.Gain component value k11-k33Memory (such as memory can be stored in
182) in.Each gain component value k11-k33Different estimations can for each position on each magnetic track and/or magnetic track and
It is determined.
At 310, gain control module determines whether that another preassigned pattern is written.If another preassigned pattern will be write
Enter, then execute task 302, otherwise executes task 312.Each pattern for the data for being written to one or more magnetic tracks,
It can be with iterative task 302-310.
At 312, the post-processing of gain component value can be performed to provide disk each surface and/or one or more
The gain profiles of each difference amplifier on the surface of a other disks.Each gain profiles may include each reading element
Gain component value and corresponding reading signal.Each gain profiles may include each magnetic track on each disk and/or
The gain component value of position.Gain profiles instruction is each to read how signal is amplified by each difference amplifier.
At 314, gain control module can adjust the gain of each difference amplifier and come from adjacent reading to minimize
The component of element and the influence for therefore minimizing crosstalk.For example, gain control module can adjust each difference amplifier
Gain, to change the estimation gain component value k in task 30811-k33.Gain control module can be based on gain component value
k11-k33Predetermined value adjust gain to minimize the component from adjacent reading element.The gain of difference amplifier can be based on
Gain component value k11-k33Predetermined value and k11-k33Estimation gain component value between comparison and be conditioned.
At 316, gain control module determines whether to reevaluate gain component value k11-k33.If gain component value
k11-k33It will be reevaluated, then execute task 302, otherwise execute task 318.Difference is completed when gain control module to put
The adjusting of the gain of big device and gain component value k has been completed as a result11-k33Adjusting when, training and/or calibration side
Method terminates, and operating method starts.
At 318, HDC modules (such as HDC modules 30) can be received via interface (such as interface 40) from host and be accessed
Request signal, and generate read requests signal.At 320, read/write channel module (such as read/write channel module 28) can be with
It is read from disk based on read requests signal.It is generated via reading element and reads signal.Difference amplifier is based on reading signal life
At differential output signal.At 322, read/write channel module is based on the gain profiles determined during training and/or calibration method
The data being written to before restoring on disk.If other data access request is to be processed, operating method can be
Terminate or may return to task 318 at 324.
Foregoing description is merely illustrative in itself, and is in no way intended to limit present disclosure, its application or is used
On the way.The extensive introduction of present disclosure can be implemented in a variety of forms.Therefore, although present disclosure includes specific
Example, but the true scope of present disclosure should not be necessarily so limited, because in research attached drawing, specification and following patent
It is required that when, other modifications will become obvious.As used herein, phrase " at least one in A, B and C " should be solved
It is interpreted as meaning the logic (A or B or C) using non-exclusive logic OR.It should be understood that can in a different order (or simultaneously
Ground) one or more of execution method step, the principle without changing present disclosure.
In this application, including following definition, term " circuit " can be used to replace term " module ".Term " module " can
To refer to the following terms, be a part for the following terms or including the following terms：Application-specific integrated circuit (ASIC)；Number,
Simulation or mixed analog digital discrete circuit；Number, simulation or mixed analog digital integrated circuit；Combinational logic electricity
Road；Field programmable gate array (FPGA)；Execute the processor (shared, dedicated or groups of) of code；Storage by
Manage the memory (shared, dedicated or groups of) for the code that device executes；It provides described functional other suitable hard
Part component；Or the combination of some or all of above items, such as in system on chip.
As used above, term " code " may include software, firmware and/or microcode, and can refer to program,
Routine, function, class and or object.Term " shared processor " includes executing some or all codes from multiple modules
Single processor.Term " processor in groups " includes following processor, which combines with other processor, and execution comes from
Some or all codes of one or more modules.Term " shared memory " include store from multiple modules some or it is complete
The single memory of portion's code.Term " memory in groups " includes following memory, the memory and other memory pool,
Store some or all codes from one or more modules.Term " memory " is the son of term " computer-readable medium "
Collection.As it is used herein, term " computer-readable medium " does not include by the interim of medium (such as on carrier wave) propagation
The electric signal or electromagnetic signal of property；It term " computer-readable medium " therefore is considered tangible and non-transitory.
The non-limiting example of the visible computer readable medium of non-transitory include nonvolatile memory (such as flash memory),
Volatile memory (such as static RAM and dynamic random access memory), magnetic memory (such as tape or
Hard disk drive) and optical memory.
Device and method described herein can be executed partially or completely through by one or more processors
One or more computer programs implement.The computer program includes the tangible calculating for being stored at least one non-transitory
Processor-executable instruction on machine readable medium.The computer program can also include and/or dependent on storage data.
Claims (18)
1. a kind of two dimension magnetic recording system, including：
Plurality of transmission lines；
The multiple reading elements being connected in series with, wherein each reading element in the multiple reading element be connected to it is described a plurality of
Corresponding pairs transmission line in transmission line；And
Multiple difference amplifiers are connected respectively to the multiple reading element, wherein the multiple via the plurality of transmission lines
Difference amplifier is configured as amplifying the differential signal received from the corresponding pairs transmission line in the plurality of transmission lines；
Wherein
The plurality of transmission lines includes first transmission line, second transmission line and third transmission line；
The multiple reading element includes first element and second element；
The multiple difference amplifier includes the first difference amplifier and the second difference amplifier；
The first element is connected to the first transmission line；
The second element is connected to the second transmission line and the third transmission line；
The first transmission line is connected to the first input end of first difference amplifier；
The second transmission line is connected to the second input terminal of first difference amplifier；And
The third transmission line is connected to the first input end of second difference amplifier.
2. two dimension magnetic recording system according to claim 1, wherein the quantity of the plurality of transmission lines is the multiple reading
Take twice of the quantity of element.
3. two dimension magnetic recording system according to claim 1, wherein the quantity of the multiple reading element is equal to described more
The quantity of a difference amplifier.
4. two dimension magnetic recording system according to claim 1, wherein the quantity of the plurality of transmission lines is the multiple difference
Divide the quantity of amplifier twice.
5. two dimension magnetic recording system according to claim 1, wherein：
The plurality of transmission lines includes the 4th transmission line；
The second element is connected to the 4th transmission line；And
4th transmission line is connected to the second input terminal of second difference amplifier.
6. two dimension magnetic recording system according to claim 1, further comprises that module, the module are configured as from described
Multiple difference amplifiers receive the output signal in respective channel and restore data based on output signal,
Wherein the multiple difference amplifier is configured as amplifying the differential signal to generate the output signal.
7. two dimension magnetic recording system according to claim 1, further comprises：
Device, including the multiple difference amplifier；
Multiple magnetic heads are disposed on the same surface of disk, wherein each magnetic head in the multiple magnetic head includes described more
Corresponding reading element in a reading element；And
Component, including the plurality of transmission lines, wherein the component suspends a plurality of biography in the top of the part of the disk
Defeated line, the part is between the device and the multiple magnetic head.
8. a kind of two dimension magnetic recording system, including：
Plurality of transmission lines；
The multiple reading elements being connected in series with, wherein each reading element in the multiple reading element be connected to it is described a plurality of
Corresponding pairs transmission line in transmission line；And
Multiple difference amplifiers are connected respectively to the multiple reading element, wherein the multiple via the plurality of transmission lines
Difference amplifier is configured as amplifying the differential signal received from the corresponding pairs transmission line in the plurality of transmission lines；
And
One module, the module are configured as during training process or calibration process,
Scheduled data pattern is written to one or more magnetic tracks of disk；
One or more of magnetic tracks are read via the multiple reading element；
Based on the reading of one or more of magnetic tracks, scan values are determined based on the output of the multiple difference amplifier；
Based on the scheduled data pattern, estimation can contribute described in each reading element into the multiple reading element
The gain component value of each difference amplifier in multiple difference amplifiers；And
The gain component value based on estimation generates the gain point of each difference amplifier in the multiple difference amplifier
Cloth.
9. two dimension magnetic recording system according to claim 8, wherein the module is configured as the increasing based on estimation
Beneficial component value adjusts the gain of the multiple difference amplifier.
10. two dimension magnetic recording system according to claim 9, wherein the module is configured as putting after the adjusting difference
The gain component value is reevaluated after the gain of big device.
11. two dimension magnetic recording system according to claim 8, further comprises the second module, second module by with
It is set to after executing the training process or the calibration process, before being restored based on the gain profiles on the disk
The data of write-in.
12. a kind of two dimension magnetic recording method, including：
Read operation is executed via multiple reading elements, wherein the multiple reading element is connected in series with, and it is wherein described more
Each reading element in a reading element is connected to the corresponding pairs transmission line in plurality of transmission lines；
The output of the multiple reading element is provided to multiple difference amplifiers via the plurality of transmission lines, wherein described more
A difference amplifier is connected respectively to the multiple reading element via the plurality of transmission lines；And
It is received from the corresponding pairs transmission line in the plurality of transmission lines via the amplification of the multiple difference amplifier
Differential signal；And
During training process or calibration process,
Scheduled data pattern is written to one or more magnetic tracks of disk；
One or more of magnetic tracks are read via the multiple reading element；
Based on the reading of one or more of magnetic tracks, scan values are determined based on the output of the multiple difference amplifier；
Based on the scheduled data pattern, estimation can contribute described in each reading element into the multiple reading element
The gain component value of each difference amplifier in multiple difference amplifiers；And
The gain component value based on estimation generates the gain point of each difference amplifier in the multiple difference amplifier
Cloth.
13. two dimension magnetic recording method according to claim 12, wherein：
The quantity of the plurality of transmission lines is twice of the quantity of the multiple reading element；
The quantity of the multiple reading element is equal to the quantity of the multiple difference amplifier；And
The quantity of the plurality of transmission lines is twice of the quantity of the multiple difference amplifier.
14. two dimension magnetic recording method according to claim 12, further comprises：
Amplify the differential signal via the multiple difference amplifier to generate output signal；
The output signal in respective channel is received from the multiple difference amplifier；And
Restore data based on output signal.
15. two dimension magnetic recording method according to claim 12, wherein：
The multiple difference amplifier is included in device；
The multiple reading element is disposed in corresponding magnetic head；
The magnetic head is disposed on the same surface of disk；And
The plurality of transmission lines is suspended above the top of the part between the device and the magnetic head of the disk.
16. two dimension magnetic recording method according to claim 12, further comprises the gain component value based on estimation
Adjust the gain of the multiple difference amplifier.
17. two dimension magnetic recording method according to claim 16, further comprises after the institute for adjusting the difference amplifier
It states gain and reevaluates the gain component value later.
18. two dimension magnetic recording method according to claim 12, further comprises after the training process or the calibration
After process, restore the data that are written on the disk based on the gain profiles.
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|---|---|---|---|
| US201361888283P | 2013-10-08 | 2013-10-08 | |
| US61/888,283 | 2013-10-08 | ||
| US14/501,255 | 2014-09-30 | ||
| US14/501,255 US9099156B2 (en) | 2013-10-08 | 2014-09-30 | Two-dimensional magnetic recording systems and methods for minimizing and accounting for inter-modulation of signals induced in adjacent read elements |
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| CN104575527B true CN104575527B (en) | 2018-10-09 |
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|---|---|---|---|---|
| US3979775A (en) * | 1975-09-08 | 1976-09-07 | International Business Machines Corporation | Magnetoresistive multitransducer assembly with compensation elements for thermal drift and bias balancing |
| US4266204A (en) * | 1979-09-04 | 1981-05-05 | Sperry Rand Corporation | Delay line signal equalizer for magnetic recording signal detection circuits |
| US4328519A (en) * | 1978-11-11 | 1982-05-04 | E M I Limited | Reading secure magnetic documents |
| US5726821A (en) * | 1995-12-22 | 1998-03-10 | Western Digital Corporation | Programmable preamplifier unit with serial interface for disk data storage device using MR heads |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009117002A (en) * | 2007-11-09 | 2009-05-28 | Fujitsu Ltd | Head ic, read circuit and medium storage device |
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2014
- 2014-10-08 CN CN201410729599.2A patent/CN104575527B/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3979775A (en) * | 1975-09-08 | 1976-09-07 | International Business Machines Corporation | Magnetoresistive multitransducer assembly with compensation elements for thermal drift and bias balancing |
| US4328519A (en) * | 1978-11-11 | 1982-05-04 | E M I Limited | Reading secure magnetic documents |
| US4266204A (en) * | 1979-09-04 | 1981-05-05 | Sperry Rand Corporation | Delay line signal equalizer for magnetic recording signal detection circuits |
| US5726821A (en) * | 1995-12-22 | 1998-03-10 | Western Digital Corporation | Programmable preamplifier unit with serial interface for disk data storage device using MR heads |
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| CN104575527A (en) | 2015-04-29 |
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