throbber
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`Case 2:21-cv-00076—JRG Document 1-1 Filed 03/05/21 Page 1 of 12 PageID #: 24
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`
`
`EXHIBIT A
`EXHIBIT A
`
`
`
`
`
`

`

`Case 2:21-cv-00076-JRG Document 1-1 Filed 03/05/21 Page 2 of 12 PageID #: 25
`caSGZQLW'OOOM'JRG “c“mem 1'1llllllilll|Ililiflfll'flll|||fililflfllI‘lli‘llllfllfll1111111llllillll‘f’
`
`U5006853259B2
`
`(12) United States Patent
`(10) Patent No.:
`US 6,853,259 B2
`
`Norman et al.
`(45) Date of Patent:
`Feb. 8, 2005
`
`(54) RING OSCILLATOR DYNAMIC
`ADJUSTMENTS FOR AUTO CALIBRATION
`
`(75)
`
`(73)
`
`Inventors: RobertD Norman, Blaine, WA (US);
`-
`-
`-
`1331““ J' SChmldt’ Palo Alto’ CA
`(
`)
`.
`.
`.
`ASSIgHCCZ Gallltzm Allegheny LLC> L05 Altos,
`CA(US)
`.
`.
`.
`.
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by0 days.
`
`.
`( * ) Notice:
`
`.
`(21) Appl‘ No" 09/930322
`(22)
`Filed:
`Aug. 15, 2001
`
`(65)
`
`Prior Publication Data
`US 2003/0034848 A1 Feb. 20, 2003
`
`Int. Cl.7 ................................................... G01J 5/00
`(51)
`(52) US. Cl.
`......................... 331/66; 331/176; 374/152;
`374/163; 374/170; 374/171; 374/185; 374/208
`(58) Field Of Search ................... 331/66, 176, 374/152,
`374/163, 170—171, 185, 208
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`3,531,739 A *
`9/1970 GIOVeS ................... 331/116 R
`
`377199838 A *
`3/1973 Pedeto et a1~ ~~~~~~~~~~~~ 310/315
`
`4,308,492 A * 12/1981 Mor1 et al. ............. 322/28
`7/1985 Peterson .............
`.. 324/765
`4,528,505 A *
`
`4,611,181 A *
`9/1986 Fukumura et al.
`..
`331/66
`
`4,746,879 A *
`5/1988 Ma et al.
`............
`331/44
`............. 331/176
`4,922,212 A *
`5/1990 Roberts et al.
`
`
`
`En Samgls
`
`Sync/sample
`
`102
`
`5,379,230 A *
`............ 702/57
`1/1995 Morikawa etal.
`
`5,440,520 A *
`8/1995 Schutz et al.
`......
`365/226
`5,619,430 A *
`.................. 702/63
`4/1997 Nolan et al.
`gaggaggii
`* 313:: gm:
`t
`1
`331/158
`,
`,
`u o e a .
`.................
`5,805,403 A *
`9/1998 Chemla ............ 361/103
`
`5,890,100 A *
`3/1999 Crayford
`...... 702/130
`
`5,912,595 A *
`6/1999 Ma et al.
`........
`.. 331/117D
`5,956,289 A *
`9/1999 Norman etal.
`...... 365/233
`6,002,627 A * 12/1999 Chevallier
`............... 365/212
`6,131,073 A * 10/2000 Honda etal.
`............... 702/107
`6,154,099 A
`11/2000 Suzuki et a1.
`6,160,755 A
`12/2000 Norman et a1.
`6,211,744 B1
`4/2001 Shin
`6,442,500 B1 *
`8/2002 Kim ........................... 702/132
`6,476,682 B1 * 11/2002 Cole etal. ............ 331/176
`
`......
`6,566,900 B2 *
`5/2003 Amick et al.
`324/760
`
`............... 331/66
`2003/0034851 A1 *
`2/2003 Norman et al.
`
`* cited by examiner
`.
`.
`.
`Primary Examiner—Michael Tokar
`Assistant Examiner—Khai Nguyen
`
`ABSTRACT
`(57)
`An apparatus compensates for voltage and temperature
`variations on an integrated circuit With: a voltage sensor
`having a digital voltage output; a temperature sensor having
`a digital temperature output; a register coupled to the voltage
`sensor and the temperature sensor, the register adapted to
`concatenate the digital voltage output and the temperature
`output into an address output; and a memory device having
`an address input coupled to the address output of the register,
`the memory device being adapted to store one or more
`corrective vectors
`'
`
`20 Claims, 6 Drawing Sheets
`
`100
`
`/
`
`I
`~
`
`Ring
`Oscillator
`
`Clock
`
`
`
`
`
`"T—T—T—
`RAM or Reg File
`
`
`Processor
`
`
`
`
`
`Voltage sensor
`
`Combined VfI‘ with l AID
`
`

`

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`Case 2:21-cv-OOO76-JRG Document 1—1 Filed 03/05/21 Page 3 of 12 PageID #: 26
`
`US. Patent
`
`Feb. 8, 2005
`
`Sheet 1 0f 6
`
`US 6,853,259 B2
`
`100
`
`7
`
`108
`
`En Sam I l-_
`
`Sync/sample
`
`
`
`‘I‘I‘
`RAM or Reg File 204
`132
`.‘I‘H', RCTimer
`‘
`.
`Data
`
`Processor
`
`106
`
`
`
`Voltage sensor
`
`Fig. 1 - Combined VI'II‘ with l AID
`
`

`

`Case 2:21-cv-00076-JRG Document 1-1 Filed 03/05/21 Page 4 of 12 PageID #: 27
`Case 2:21-cv-OOO76-JRG Document 1-1 Filed 03/05/21 Page 4 of 12 PageID #: 27
`
`US. Patent
`
`Feb. 8, 2005
`
`Sheet 2 0f 6
`
`US 6,853,259 B2
`
`130
`
`
`
`Fig 2 - RC Timer
`
`

`

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`
`US. Patent
`
`Feb. 8, 2005
`
`Sheet 3 0f 6
`
`US 6,853,259 B2
`
`
`
`300
`
`En
`
`04
`
`Start Ring Osc
`
`Test VT Flag
`
`2O
`
`10
`
`30
`
`322
`
`
`
` 06
`
`
`
`
`Sel T sw
`Toggle VT Flag
`
`
`
`
`
`
`
`
`
`-/3
`/3
`
`12
`
`Sample V
`
`Sample T
`
`Ld V Reg
`
`332
`
`M Set RESET \
`
`314
`
`M Clr RESET \
`334
`
`Fig 3 - SM Sequence
`
`

`

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`Case 2:21-cv-OOO76-JRG Document 1-1 Filed 03/05/21 Page 6 of 12 PageID #: 29
`
`US. Patent
`
`Feb. 8, 2005
`
`Sheet 4 of 6
`
`US 6,853,259 B2
`
`New Vector
`
`/108
`
`Update Hold
`
`Sample SM
`
`410
`
`
`
`NotEqual
`
`HoldingRegister
`
`I
`
`
`
`
`Holding Register
`
`402
`
`New Vector
`
`update Strobe
`
`Figure 4 - SYNC/Sample
`
`
`
`
`
`
`Comparator
`
`404
`
`

`

`Case 2:21-cv-00076-JRG Document 1-1 Filed 03/05/21 Page 7 of 12 PageID #: 30
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`
`US. Patent
`
`Feb. 8, 2005
`
`Sheet 5 0f 6
`
`US 6,853,259 B2
`
`500
`
`./
`
`Not Compare
`
`Set Hold
`
`502
`
`504 506
`
` 508
`
`Strobe 2nd Reg
`
`Clr Hold
`
`FIG 5 - Sync/Sample Sequence
`
`

`

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`Case 2:21-cv-OOO76-JRG Document 1-1 Filed 03/05/21 Page 8 of 12 PagelD #: 31
`
`US. Patent
`
`Feb. 8, 2005
`
`Sheet 6 0f 6
`
`US 6,853,259 B2
`
`600
`
`
`
`
`Elements
`Dela
`
`614
`616
`618
`620
`61
`610
`604
` 606
`622
`
`
`
`
`
`
`
`608
`
`Select Vectors
`
`
`
`
`
`Fig 6 - Adjustable Ring Oscillator
`
`

`

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`US 6,853,259 B2
`
`1
`RING OSCILLATOR DYNAMIC
`ADJUSTMENTS FOR AUTO CALIBRATION
`
`BACKGROUND
`
`The present invention relates to systems and methods
`using ring oscillators.
`To address the ever-increasing need to increase the speed
`of computers and electronic appliances to process ever
`increasing amounts of data, designers have increased the
`clock frequency of a computers central processing unit
`and/or utilized parallel processing. Many electrical and
`computer applications and components have critical timing
`requirements that require clock waveforms that are precisely
`synchronized with a reference clock waveform.
`One type of clock generator is a ring oscillator. Ring
`oscillators are widely used in electronic equipment such as
`computers, televisions, videocassette recorders (VCRs) and
`the like. Typically, a ring oscillator includes a series of
`discrete components including transistors, capacitors,
`among others. As discussed in US. Pat. No. 6,211,744 to
`Shin; US. Pat. No. 6,154,099 to Suzuki, et al.; and US. Pat.
`No. 6,160,755 to Norman, et al., a conventional ring oscil-
`lator can be formed by connecting an odd number of
`inverters in a ring shape. In such a configuration, if Y is the
`state (signal level) at a connection point, the Y signal is
`inverted to Y by the next-stage inverter, and the Y is further
`inverted to Y by the second next-stage inverter. The signal
`level is sequentially inverted, and becomes Y at the connec-
`tion point through one round because an odd number of
`inverters are connected. Through one more round, the signal
`level becomes the original Y.
`In this manner,
`the ring
`oscillator self-oscillates. An oscillation output is obtained
`from the output node of an arbitrary inverter.
`Another conventional ring oscillator can use a NAND
`gate circuit for controlling start/stop of oscillation is inserted
`in a ring formed by connecting a plurality of even number
`of inverters. The start/stop of oscillation is controlled by
`externally inputting a high “H”- or a low “L”-level control
`signal CNT to the NAND gate circuit. That is, the control
`signal CNT is first set at “L” level and then changed to “H”
`level to start oscillation. When the control signal CNT is at
`“L” level, an output signal from the NAND gate circuit is
`fixed at “H” level. Outputs from the odd-numbered inverters
`change to “L” level, outputs from the even-numbered invert-
`ers change to “H” level, and the initial states of the output
`levels of the respective inverters are determined. In this
`state, the ring oscillator does not oscillate. When the control
`signal CNT changes to “H” level, the NAND gate circuit
`substantially operates as an inverter, and the ring oscillator
`oscillates in the above manner where an odd number of
`
`inverters are connected in a ring shape.
`The frequency of the oscillation signal from the conven-
`tional ring oscillator depends on the number of stages of
`inverters and a wiring delay. Hence, the lower oscillation
`frequency is obtained by increasing the number of stages of
`inverters and the length of the signal line. This increases the
`circuit size. Further, although the voltage-controlled oscil-
`lators have an identical circuit configuration,
`they have
`different oscillation frequencies due to certain factors of the
`production process. For example, the process can affect the
`gate delay time that can affect the precision of the oscillator.
`The gate delay value (gate delay time) per inverter as a
`constituent unit has conventionally been obtained by mea-
`suring the oscillation frequency of a ring oscillator having
`the above arrangements. Since the constituent unit is a static
`
`10
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`15
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`30
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`35
`
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`45
`
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`
`60
`
`65
`
`2
`gate inverter, the gate delay value obtained by measuring the
`oscillation frequency includes only delay information of the
`static gate, and delay information of a dynamic gate requir-
`ing pre-charge cannot be obtained. Additionally, for a pre-
`determined combination of stages, a conventional ring oscil-
`lator produces a fixed frequency. That is, once assembled,
`the frequency of the oscillating signal generated by a ring
`oscillator cannot be adjusted to compensate for temperature
`or voltage fluctuations.
`Many applications in electronics can use simple ring
`oscillators if the operating characteristics can be made to
`operate in a tighter range of frequency variation. In an
`integrated circuit there are 3 major causes of shifts in the
`operating frequency. They are Process, Temperature and
`Voltage. Process variations occur during manufacturing,
`while temperature and voltage variations occur during
`operation. For example, flash memory systems can use a
`ring oscillator to provide a flash memory system clock.
`Large performance variations, however, can be seen by the
`system as the ring oscillator output varies over process
`differences, voltage variations and temperature excursions.
`In most cases the resultant wide range of operating param-
`eter frequencies can adversely affect the speed and/or reli-
`ability of the flash memory system.
`
`SUMMARY
`
`In one aspect, an apparatus to compensate for voltage and
`temperature variations on an integrated circuit includes: a
`voltage sensor having a digital voltage output; a temperature
`sensor having a digital
`temperature output;
`a register
`coupled to the voltage sensor and the temperature sensor, the
`register adapted to concatenate the digital voltage output and
`the temperature output into an address output; and a memory
`device having an address input coupled to the address output
`of the register, the memory device being adapted to store one
`or more corrective vectors.
`
`Implementations of the above aspect may include one or
`more of the following. Awake-up oscillator can be provided,
`where the wake-up oscillator periodically enables the
`memory device to output a corrective vector. The wake-up
`oscillator is a low-power oscillator, such as a resistor-
`capacitor (RC) oscillator. Adjustment values are written into
`the memory device during initialization, based on testing
`parameters. A ring oscillator can be connected to the output
`of the memory device. The memory device can generate an
`adjustment vector based on the current voltage and tempera-
`ture and wherein the adjustment vector is applied to the ring
`oscillator. The adjustment vector selects the ring frequency;
`lengthening or shortening the ring delay to maintain the
`desired operating point. The adjustment vectors are deter-
`mined by chip testing and characterization. The apparatus
`can include a processor; and a multiplexor having an input
`coupled to the processor and a second input coupled to the
`register and an output coupled to the memory device, the
`multiplexor allowing the processor to download the adjust-
`ment vectors into the memory device.
`In another aspect, a method for dynamically adjusting for
`temperature and voltage variations on an integrated circuit
`includes periodically sensing the voltage and temperature
`values; and dynamically making adjustments in clock fre-
`quency based on the voltage and temperature values.
`Implementations of the method may include one or more
`of the following. The method includes combining the volt-
`age and temperature values into a digital word. The method
`can store the temperature value in a first register; the voltage
`value in a second register; and merge the first and second
`
`

`

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`US 6,853,259 B2
`
`3
`registers to represent a concatenated address. The concat-
`enated address can be applied to the address of a memory to
`retrieve a corrective value from a corrective table. The
`corrective table can be generated by characterizing the
`integrated circuit. The characterization includes varying the
`voltage and temperature over a predetermined range. The
`method includes applying a corrective vector to a ring
`oscillator. The periodic sensing can include receiving a
`wake-up signal from a low power wake-up oscillator to
`perform the calibration.
`Advantages of the invention include one or more of the
`following. The system addresses major causes of frequency
`variation in a ring oscillator design: process, voltage, and
`temperature variations. Process variation can be reduced by
`allowing for skew adjustment calibration during manufac-
`turing. This adjustment eliminates the majority of timing
`variations in the oscillator due to the process differences.
`The adjustments narrow the frequency range and allow for
`a much tighter range of operation. The system also allows
`for dynamic adjustments for temperature and voltage varia-
`tions. These adjustments are accomplished by sensing the
`voltage and temperature values and dynamically making
`adjustments in clock frequency. The system can dynamically
`adjust for variations by having dedicated hardware for
`automatically sensing the varied parameters and adjust them
`as they occur. This sensing is activated by an RC timer that
`can have its sampling period adjusted to meet the anticipated
`needs of the environment. This method will allow a dormant
`
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`15
`
`20
`
`25
`
`system the ability to wake from sleep, calibrate and go back
`to sleep, in contrast to other approaches require the system
`to become active before calibration is done. This will
`
`30
`
`introduce latencies, depending on the methodology used.
`DESCRIPTION
`
`FIG. 1 shows an exemplary auto-calibration system 100
`with combined voltage and temperature detectors. Aproces-
`sor 102 has address and data lines. The data lines of the
`
`35
`
`processor 102 drives the upper address line inputs of a
`memory or register file 104. The address lines of the
`processor 102 is provided to one input of a multiplexor 106.
`The second input of the multiplexor 106 is connected to the
`output of a register 114. The register 114 can be enabled by
`a voltage enable (enV) signal or a temperature enable (enT)
`signal. The register 114 in turn receives the output of an
`analog to digital converter (ADC) 112. The ADC 112
`receives a reference voltage from a source 110. The ADC
`112 also receives control signals from a state machine 134
`as well as switches 136 and 138. The state machine 134 also
`controls the switches 136 and 138. The switch 136 is
`
`connected to a current source 140 and to a temperature
`sensor 142. The switch 138 in turn is connected to a voltage
`divider having a first resistor 144 and a second resistor 146
`in series between voltage and ground. The state machine 134
`in turn is driven by a resistor-capacitor (RC) timer 130 and
`a small ring oscillator 132. The RC oscillator 130 receives
`a timer enable (EnTimer) signal from a master controller or
`the processor block 102 (not shown). The state machine 134
`generates a reset signal that is provided to the RC timer 130,
`and the RC timer 130 is used to clock the small ring
`oscillator 132.
`
`The output of the memory or register file 104 drives a
`sync/sample module 108, which in turn drives a ring oscil-
`lator 120. The ring oscillator 120 generates a system clock
`and a control signal that is provided to the sync/sample
`module 108. More details on the sync/sample module 108
`and the ring oscillator 120 are shown below.
`The dynamic operation of the ring oscillator 120 is
`discussed next. The circuit of FIG. 1 can adjust frequency
`
`40
`
`45
`
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`55
`
`60
`
`65
`
`4
`drift, due to temperature and voltage variations. As the
`temperature and voltage of the system changes, the operat-
`ing characteristics of the circuits will speed up at lower
`temperatures, and slow down at higher temperatures. To
`adjust for this change and keep the system running at the
`ideal frequency, the temperature and voltage of the system
`needs to be monitored. The current source 140 is applied to
`the temperature sensor 142, which can be any device that
`changes value with changes in temperature. The simplest
`temperature sensor 142 that could be used is a resistor. The
`current source 140 is applied to the temperature sensor 142
`to get a voltage based on the impedance of the device. As the
`temperature changes the impedance also changes, causing
`the voltage of the connection node to increase and decrease.
`This voltage indicating temperature value and changes is
`applied to the ADC 112. The value applied is translated to a
`digital value, which represents a temperature vector. The
`output of the ADC 112 is registered and applied to the
`multiplexor 106, the other side being driven by an address
`from the processor 102. The output of the multiplexor 106
`is applied to the memory 104 as the address input. At
`initialization time the multiplexor source is the processor
`102. At initialization, the processor 102 writes adjustment
`values into the RAM or Register File 104. After these values
`are stored in the RAM 104 the multiplexor source is
`switched, allowing the temperature vectors to be applied to
`the RAM 104 as the address. The output of the RAM 104
`now acts as the adjustment vector that is applied to the ring
`oscillator 120. This value applied selects the ring frequency;
`lengthening or shortening the ring delay to maintain the
`desired operating point. The adjustment vectors are deter-
`mined by chip testing and characterization.
`The circuit of FIG. 1 compensates for changes in voltage
`as follows. The system voltage in question can be applied to
`a voltage divider formed by resistors 144 and 146 that is
`input to the ADC 112. As the voltage changes the input to the
`ADC 112 will change and the resultant output of the ADC
`112 is applied to the memory 104. This value is an address
`used to produce a table compensation vector that will be
`applied to the oscillator circuit 120 in the same manner as
`described above for temperature compensation. Like the
`temperature circuit the vector loaded in memory 104 is done
`at initialization time by the processor from data taken by
`testing and characterization.
`To be able to adjust for voltage and temperature change at
`the same time, the two sensing methods are combined in
`FIG. 1. The temperature and voltage inputs to the A/D are
`switched to give an alternate readout of the A/D. When the
`Temperature is sampled by the A/D its value is stored in a
`register. Likewise, when the voltage is sampled by the A/D
`its value is stored in a holding register. The two register
`values are combined to represent a concatenated address
`applied to the look-up table RAM or register File. While this
`method can be made to work, the value of the temperature-
`compensating sensor becomes critical. Anegative coefficient
`needs to be produced so that an increase in temperature will
`bias the design such that the oscillator will speed up or when
`temperature decreases the oscillator will be vectored to slow
`down.
`If this is not done the temperature and voltage
`components will add in the wrong direction giving the
`wrong results. To build the RAM vector table, extensive
`characterization must be done, by varying the voltage and
`temperature to produce a meaningful table.
`Process variations can be dialed out based on the correc-
`
`tion table vector loaded. The table should produce a desired
`center frequency that operates as close as possible to the
`desired frequency when operating at nominal temperature
`
`

`

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`US 6,853,259 B2
`
`5
`and voltage. To assure the table values are correct; means for
`testing the oscillator and adjusting it to dial in the desired
`frequency need to be assured. This can be done by outputting
`the clock to the outside for monitoring with test equipment
`or in injecting a wide pulse that allows a counter to count
`with the oscillator. The count reached from this enable pulse
`will be a direct correlation to the operating frequency. This
`count can be used by the processor in setting the proper
`vectors,
`for
`the starting point from which voltage and
`temperature can be adjusted.
`Referring now to FIG. 2, details of one implementation of
`an RC timer 130 is shown. The timer 130 has an OR-gate
`200 that receives a Power-on reset signal and a state machine
`reset signal. The output of the OR gate 200 is connected to
`an FET transistor 202 and, during reset, the OR gate 200
`clamps the output of the transistor 202 to ground. The output
`of the transistor 202 is connected to a resistor-capacitor
`network having a resistor 204 connected in series with a
`capacitor 206. The junction between the resistor-capacitor
`network drives a comparator 210 which compares the RC
`signal with a predetermined reference voltage Rer. The
`output of the comparator 210 is provided to a gate 212. The
`gate 212 also receives a timer enable (EnTimer) signal. The
`output of the gate 212 is a sequence enable (EnSeq) signal.
`FIG. 2 shows on method for implementing a “Dead Man”
`timer. In this circuit an RC time constant charges up until the
`voltage value going to the Comparator reaches the trip point.
`When the trip point is reached the EnSeq signal is activated,
`provided the processor has enabled the timer with the setting
`of the enable timer register. When this signal becomes active
`it starts a Ring Oscillator that is used to run a state machine.
`This state machine is used to sample the Voltage and
`Temperature readings and load the resultant values in the
`holding register. FIG. 3 shows a flow chart for a typical state
`machines functional operation. In this example only one
`vector, voltage or temperature is updated on a timer time out.
`As these parameters tend to be slow in changing only limited
`updating is done to meet the desired adjustment require-
`ments.
`If faster changes in temperature or voltage are
`anticipated, then the state machine may be altered to provide
`both vectors being updated in a sample cycle. At the end of
`the State Machines update sequence the State machine will
`set a register that drives the State Machine Reset (SMReset)
`signal. This signal will drive the RC timer to its Reset state,
`arming it to go to its low voltage start state. After the signal
`has been applied for sufficient time, allowing for discharge,
`the SMReset signal is removed. When this is done the State
`Machine goes to its Halt, sleep state and the timer begins
`timing toward its trigger state, where the sequence will
`repeat.
`FIG. 3 illustrates an exemplary state machine sequence
`300. In this sequence, all devices are in a halt state (step
`302). Upon receipt of the EnSeq signal, the ring oscillator
`120 is started (step 304). The process 300 then checks a
`voltage/temperature (VT) flag (step 306). If the flag indi-
`cates that voltage is to be calibrated, the process 300 selects
`the voltage switch (step 310). The sample voltage input is
`taken (step 312), and the result is stored in a voltage register
`(step 314). Correspondingly, if the temperature has been
`selected, the process selects the temperature switch (step
`320). The sample temperature input is taken (step 312), and
`the result is stored in a temperature register (step 314). From
`either step 314 or 324, the VT flag is toggled (step 330).
`Next, the state machine 134 sets a reset signal (step 332) and
`then clears the reset signal (step 334) before looping back to
`the halt state in step 302.
`FIG. 4 shows an exemplary sync/sample module 108. A
`holding register 402 stores a new vector when an update
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`6
`strobe is asserted. The output of the holding register 402 is
`provided to a comparator 404 and a holding register 406.
`The comparator 404 also receives the output of the holding
`register 406. The comparator 404 compares the output of the
`holding registers 402 and 406, and if not equal, enables a
`sample state machine 410. The sample state machine 410
`generates an update hold signal and an update strobe for the
`holding register 406. The output of the holding register 406
`is a new vector.
`
`Whenever a calibration sequence occurs the output of the
`memory may change in value or remain the same. Whenever
`this sequence occurs the Sync/Sample has the job of deter-
`mining if there is a new value or the same value exists. If the
`same value exists the block and SM does nothing. If there is
`a new vector the state machine will be activated by the “not
`Compare” signal generated by comparing the old vector and
`the new vector. When this signal becomes active the state
`machine starts its sequence.
`FIG. 5 illustrates an exemplary sync/sample sequence
`500. The sequence 500 is initially in an idle condition (step
`502). The sequence 500 sets a hold signal (step 504) and
`strobes a second register (step 506). The sequence 500 then
`clears the hold signal (step 508) before looping back to the
`idle condition.
`
`In FIG. 5, the SM puts up a Hold signal that puts a hold
`on the output stage of the Ring Oscillator. The state machine
`then waits a few clocks to assure this has occurred and the
`
`strobes the second stage holding register to transfer the first
`and new vector into the second stage. When this new vector
`is loaded the output will then drive the input to the ring
`oscillator, which will cause the Ring Oscillator to select the
`delay value represented, by the new input select. As the new
`value is loaded the SM will see the not compare input
`change to a new value as they now compare. The SM will
`then drop the Hold signal, as the Ring Oscillator should have
`switched to the new value and should be stable. The drop-
`ping of the hold will allow the output stage to continue
`oscillating. It should be noted that any application that may
`have problems do to a stretched clock, because to do
`calibration it may require the temporary turning off of the
`calibration sequence until such timing changes will not
`cause problems. It is anticipated that such clock stretching
`will not cause problems in most applications as the clock
`will not glitch, but will just have a short temporary pause in
`the clock cycle.
`The Selection Vector picks which delay element will be
`used for the clock period and feedback element. The feed-
`back value is inverted and fed to the delay input. The same
`vale is used to clock a flip-flop, which in turn drives a divide
`by 2 signal to produce the system clock used to run the
`system. The flip-flop is used to produce a 50% duty cycle
`clock and produce a better (square) shaped signal. The
`Holdb signal is used to temporarily halt the FF from toggling
`while the delay elements are switched. This halt is required
`to prevent the clock from glitching as the delay path is
`switched
`
`FIG. 6 shows one embodiment of an adjustable ring
`oscillator 600. The oscillator 600 has a delay select logic
`602, which receives outputs from delay elements 604, 606,
`608, 610, 612, 614, 616, 618, 620 and 622. The delay select
`logic 602 in turn drives an inverter 630. The output of the
`inverter 630 is provided as an input to the delay element 604.
`The output of the inverter 630 is also used to clock a flip-flop
`640. The output of the flip-flop 640 is looped back to the
`D-input of the flip-flop 640. The output of the flip-flop 640
`is also provided to a buffer 650 that provides a plurality of
`
`

`

`Case 2:21-cv-00076-JRG Document 1-1 Filed 03/05/21 Page 12 of 12 PageID #: 35
`Case 2:21-cv-OOO76-JRG Document 1—1 Filed 03/05/21 Page 12 of 12 PageID #: 35
`
`US 6,853,259 B2
`
`7
`clock signals, each of which can be used to clock a portion
`of the chip to prevent clock degradation due to too much
`load on the chip.
`In the above description a RAM was used to load the
`correction vectors to be applied. If the process is stable then
`the RAM may be substituted for a ROM for cost reduction.
`If this method is selected some potential adjustments for
`process may be lost but a more cost effective solution would
`be possible. In such a system the processor would not be
`required to load the RAM so the muXing of the processor
`and A/D would not be required. The Voltage/Temperature
`compensation would then run totally independent of the
`processor, except for enables/disables a designer may still
`which to invoke.
`What is claimed is:
`
`1. An apparatus to compensate for voltage and tempera-
`ture variations on an integrated circuit, comprising:
`a voltage sensor having a digital voltage output;
`a temperature sensor having a digital temperature output;
`a register coupled to the voltage sensor and the tempera-
`ture sensor,
`the register adapted to concatenate the
`digital voltage output and the temperature output into
`an address output; and
`a memory device having an address input coupled to the
`address output of the register, the memory device being
`adapted to store one or more corrective vectors.
`2. The apparatus of claim 1, further comprising a wake-up
`oscillator coupled to the memory device, the wake-up oscil-
`lator periodically enables the memory device to output a
`corrective vector.
`
`3. The apparatus of claim 2, wherein the wake-up oscil-
`lator is a low-power oscillator.
`4. The apparatus of claim 2, wherein the wake-up oscil-
`lator is a resistor-capacitor (RC) oscillator.
`5. The apparatus of claim 1, wherein adjustment values
`are written into the memory during initialization.
`6. The apparatus of claim 1, further comprising a ring
`oscillator coupled to the output of the memory device.
`7. The apparatus of claim 6, wherein the memory device
`generates an adjustment vector based on the current voltage
`and temperature and wherein the adjustment vector is
`applied to the ring oscillator.
`8. The apparatus of claim 7, wherein the adjustment
`vector selects the ring frequency; lengthening or shortening
`the ring delay to maintain the desired operating point.
`
`8
`9. The apparatus of claim 7, wherein the adjustment
`vectors are determined by chip testing and characterization.
`10. The apparatus of claim 7, further comprising:
`a. a processor;
`
`b. a multiplexor having an input coupled to the processor
`and a second input coupled to the register and an output
`coupled to the memory device, the multiplexor allow-
`ing the processor to download the adjustment vectors
`into the memory device.
`11. A method for dynamically adjusting for temperature
`and voltage variations on an integrated circuit, comprising:
`periodically sensing the voltage and temperature values;
`concatenating the voltage and the temperature values into
`an address output;
`the
`applying the address output to a memory device,
`memory device being adapted to store one or more
`corrective vectors; and
`dynamically making adjustments in clock frequency
`based on the voltage and temperature values.
`12. The method of claim 11, further comprising combin-
`ing the voltage and temperature values into a digital word.
`13. The method of claim 12, further comprising storing
`the temperature value in a first register.
`14. The method of claim 13, further comprising storing
`the voltage value in a second register.
`15. The method of claim 14, further comprising merging
`the first and second registers to represent a concatenated
`address.
`
`16. The method of claim 15, further comprising applying
`the concatenated address to the address of a memo

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