AN ADDRESS TRANSITION DETECTION CIRCUIT

Abstract: An address transition detection (ATD) circuit comprises a first (102) and a second (DDS) circuit and an interval timer (300). First circuit (102) receives on a first input (1-1) a change signal corresponding to a transition on one or more address bus lines, and in response transitions the output (O) from a first state to a second state. First circuit (102) receives a reset signal at a second input (1-2) to return the output (O) to the first state. The interval timer (300) has an output coupled to the second input (1-2) of the first circuit (102) and, upon receiving a signal at its input, generates the reset signal at its output after a timed interval. The second circuit (DDS) couples the change signal to the input of the interval timer (300).

Description: AN ADDRESS TRANSITION DETECTION CIRCUIT BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to digital circuits and more particularly to (ATD) Address Transition Detection circuits Description of Related Art ATD circuits are employed in memoiy devices to detect a change in any one of the address lines of memory When a new address is supplied by the user to memory, that address is received by both a memory controller and by the row and column decoders for the memorv array As the address transition is detected by the memory device, a new address has been supplied by the user, and this address must be decoded by the decoding circuitry of the memory device in order to access the actual memory address When a memory address is to be accessed, the data path to and from the memory address must be precharged in preparation for the transfer of this data This precharging may involve charging a capacitor in a row and column to be addressed Tvpicallv, a pulse from the ATD circuit is used in the memoι\ to begin precharging this path A device for precharging a memory circuit in response to an ATD circuits is disclosed in U S Patent No 5,493,538, issued on February 20. 1996, and entitled Minimum Pulse Width Address Transition Detection Circuit, which is herein incorporated by reference This patent discloses a device for detecting a change of address and latching the change for a period of time sufficient to precharge a memory The address changes are detected by an edge detect and output as a series of pulses to the set input of a latch Provided the latch has been reset before a pulse is received, the output of the latch will transition to a set condition The set condition initiates memory precharge The set condition also initiates a delayed feedback to the reset input of the latch Precharge continues until the latch is reset The problem with this device, however, is that when pulses are spaced apart in time bv an interval less than the maximum delay interval, the pulse immediately after a pulse that placed the latch output in a set condition, will not be operated on The '538 device will not therefore precharge memory for a sufficient period of time This can lead to the need to resend an address in order to properly precharge memory It can also lead to incorrect data being written to or read from memory if the memory has not been adequately precharged The shortcomings of the '538 device are compounded in memories having address buses with a large number of address lines In this environment the occurrence of narrowly spaced address changes is relatively frequent and the inability of the '538 device to detect each pulse results in delayed or incorrect memory accesses In memory applications, the ATD pulse is also used to pre bias the sense amplifier, to boost the wordlines. or to precharge the output driver If the ATD does not detect each narrowly spaced address change, it may lead to delayed or incorrect memory accesses in the above application For example, if two address transitions are narrowly spaced and only first address transitions are detected, the memory control circuit will not bias the sense amplifier to the optimized timing corresponding to the second address change since its address transition is not detected In the event the ATD circuit is used to boast or wordline, a specified time interval must exist between the final address transition and the boost of the wordlines Otherwise, the wordlines may be boosted before the decoded wordlines have settled to their final state This may cause the wrong set of wordlines to be boosted and can also lead to incorrect data being read from the memory What is needed is an ATD circuit that will detect each address transition under all conditions SUMMARY OF THE INVENTION A first object of the invention is to provide an ATD circuit which detects each address transitions A second object of the invention is to provide an ATD circuit suitable for use with memories having address buses with a large number of addresses A third object of the invention is to reduce the amount of space required to construct an ATD circuit. The present invention provides a new ATD circuit for use on an address bus having any number of addresses. In a first preferred embodiment, an ATD circuit is disclosed which comprises a first and second circuit and an interval timer. The circuit provides an extended second state at the output of the first circuit, for all including the last received in a series of change signals. The first circuit has a first and second input and an output. The first circuit receives, at the first input, a change signal corresponding to transitions in an address signal. In response, the output of the first circuit transitions from an initial first state to a second state. The first circuit is also responsive to a reset command at the second input to return the output to the first state. The interval timer has an output coupled to the second input of the first circuit and an input. The interval timer responsive to an initialize command at the input initiates a timed interval and after the timed interval generates the reset command at the output. The second circuit has an output coupled to the input of the interval timer and an input. The second circuit is responsive to the change signal at the input to generate an initialize command at the output. In an alternate embodiment, the second circuit is responsive to both the change signal and the output of the first circuit to generate an initialize command at the output. In a second preferred embodiment, a compact circuit for use in address buses with a large number of address lines is disclosed. The novel features of this embodiment allow a single ATD circuit to respond to change signals received from the "N' address of an address bus. A plurality of change signals corresponding to address changes in a respective address of an 'N' address bus are combined in an OR gate. The output of the OR gate is a combined change signal. The combined change signal is received at a first input of the first circuit. The combined change signal is processed by a first and second circuit and interval timer corresponding to that discussed above in connection with the first preferred embodiment. In a third preferred embodiment an integrated circuit memory having a plurality of input pins and comprising an ATD unit is disclosed The plurality of input pins are each connected to the input of a respective edge detect unit The edge detect units respond to rising or falling edge of an address connected to a respective input pin and output a change signal The output of all edge detect units is coupled to a respective input of an OR gate The OR gate responds to change signals at its inputs to output a combined change signal The combined change signal is received and processed by a first and second circuit and interval timer similar to that discussed above in connection with the first preferred embodiment The output of the first circuit may be coupled to a memory controller, decoder, or buffer Other aspects and advantages ot the present invention can be seen upon review of the figures, the detailed description and the claims which follow BRIEF DESCRIPTION OF THE FIGURES Fig 1 is a Prior Art address transition detection unit Fig 2 is a Prior Art address transition detection circuit for an 'N' address bus Fig 3 is an address transition detection circuit for a single address Fig 4 is a detailed view of the reinitialize delay logic Fig 5 is an address transition detection circuit for 'N' address Fig 6 illustrates the waveforms of the Prior Art unit shown in Fig 1 Fig 7 illustrates the waveforms of Fig 3 DETAILED DESCRIPTION The present invention is an ATD circuit for use on a single address or a plurality of address lines, to detect address transitions The ATD detects each address transition even under conditions of rapid address input change The invention may advantageously be used in memories having address buses with a large number of addresses Fig 1 illustrates a Prior Art ATD circuit The circuit consists of a edge detect unit 100, a first cπcuit 102 and maximum delay unit 104 Edge detect unit 100 consists of a minimum delay unit 106 and a difference detector 108 The minimum delay unit has an input coupled to an AIs (address input signal) and an output coupled to one of the two inputs of the difference detector The other input of the difference detector is coupled directly to AIs The difference detector detects a difference between the AIs and the delayed AIs by generating a DDs (Difference Detector signal) on its output DDs comprises pulses corresponding to either one or both of a rising/falling edge in the address input signal The difference signal is received bv the first circuit 102 As disclosed in U S Patent No 5,493,538, the first circuit is an SR latch and the DDs is received at the first input of the latch, the set input The output of the latch is the ATs (address transition signal) The ATs first and a second state, corresponding in the '538 patent to a reset condition and a set condition The set condition is associated with a memorv precharge The ATs is feed back to the input of maximum delav unit 104 When a transition in the ATs to a set condition is detected by the maximum delay unit, that signal is subject to a maximum delay interval At the end of the maximum delay interval an Rs (Reset Signal) is output from maximum delay unit to a reset input of the latch Upon receipt of the reset signal, the latch returns the ATs from a set condition to a reset condition, therebv disabling memory precharge As will be discussed in greater detail in Fig 6, this Prior Art circuit, will not operate on any changes in AIs that occur at intervals spaced apart by less than the maximum delav interval This failure to operate on address transitions narrowly separated in time is a shortcoming in the Prior Art cncuits This deficiency will impair memory accesses Fig 2 illustrates a Prior Art ATD circuit for an address bus having 'N' address lines The circuit of Fig 2 consists of a plurality of edge detect units, each dedicated to a specific address The edge detect units 200A and 200Z are referenced Edge detect unit 200 A. consists of maximum delay unit 204A and difference detector 208 A Edge detect unit 200Z consists of maximum delay unit 204Z and difference detector 208Z The output of all edge detects 220A-Z is connected to each of the inputs of OR gate 202 As illustrated in Fig 2, an address referenced as AIs-1 serves as input to edge detect 200A and specifically to both maximum delay unit 204Z and to the first of two inputs of difference detector 208 A Maximum delay unit 204Z imposes a delay on the address signal and outputs the delayed signal to the second input of difference detector 208A The difference detector 208A detects a difference between the original and delayed signal from bitline AIs-1, and outputs a DDs in the form of pulses corresponding to that difference Edge detect 200Z is connected to AIs-N and consists of a maximum delay unit 204Z and a difference detector 208Z, which perform in the manner discussed above in connection with maximum delav unit 204Z and difference detector 208Z The difference detector 208Z detects a difference between the original and delayed signal from bithne Als-N and outputs a DDs in the form of pulses corresponding to that difference The DDs from all edge detect units including the referenced units is combined in OR gate 202 The output of OR gate is the ATs The circuit is not compact The circuit consumes a large amount of chip 'real estate' because it utilizes a maximum delav circuit for each of the addresses The maximum delay circuit relies on capacitors to produce the maximum delay interval Capacitors particularly large capacitors, associated with maximum delay intervals consume large amounts of chip 'real estate' when realized in an integrated circuit Fig 3 illustrates a preferred embodiment of an ATD circuit suitable for connection to a single address in accordance with the current invention The circuit comprises an edge detect unit 100 with a first circuit 102 and a maximum resettable delay unit 300 Edge detect unit 100 comprises a minimum delay unit 106 and a difference detector 108 The minimum delav unit has an input coupled to an AIs and an output The difference detector has two inputs and an output One of the inputs is connected to the output of the minimum delay unit and the other is connected to the AIs In the manner described and discussed above, minimum delay unit 106 outputs the AIs in delayed form to difference detector 108 Responsive to both the AIs and the delaved AIs on either of its inputs, the difference detector 108 outputs a DDs The DDs mav comprise positive or negative going pulses corresponding to changes in the AIs Changes to which the pulses correspond may be either one or both of a rising/falling edge of the address input signal. Difference detector 108 may be realized in multiple forms including for example, an XNOR or XOR gate The DDs is received by both first circuit 102 and by resettable maximum delay unit 300. First circuit 102 has a first and a second input. The DDs is received at the first input. A reinitialized reset signal is received at the second input. In this embodiment the first circuit is a SR latch and the first input is a set input and the second input is a reset input The SR latch has the properties set forth in the following tables TABLE 1 The first circuit 102 may also be realized for example, as RS, JK, T, D latch, as a sample and hold circuit, and so forth The output of first circuit 102 is the ATs The ATs is feedback to resettable maximum delay unit 300. The maximum resettable delay unit has a first and second input and an output. The first input is connected to the output of the first circuit 102 and the second input is connected to the output of the difference detector 108 This latter connection is lacking in the Prior Ait. The output is connected to the second input of the first circuit 102. Maximum resettable delay unit receives at its first input the ATs and at its second input the DDs and responsive thereto generates, at its output, an RRs (reinitialized reset signal). A difference between this circuit and the circuit in Prior Art Fig. 1 is that the DDs is feed forward to the maximum resettable delay unit 300 This feed forward feature allows all pulses to effect the maximum resettable delay unit. In the Prior Art circuit, only those pulses which produce a transition in the output of the first circuit from a first state to a second state effect the maximum resettable delay unit For pulses spaced apart farther in time than the delay interval resettable maximum delay unit 300 will perform in a manner similar to that shown in Prior Art Fig 1 However, for pulses separated in time by an interval less than the delay interval the circuit disclosed herein will perform substantially differently then that of the Prior Art Specifically, due to the resettable feature, each pulse on the DDs causes the reinitialize delay logic to reinitialize the delay interval and thereby extend the second state, the set condition on the output of the first circuit This assures that the next received pulse, in a string of pulses separated in time by an interval less than the timed interval of the resettable maximum delay unit, will not be ignored and will result in a delay period sufficient to recharge memory Fig 4 illustrates in detail, a preferred embodiment of the resettable maximum delay unit 300 The unit has a first and second input and an output The unit comprises an interval timer and a second circuit The interval timer comprises inverters 408 and 410 The second circuit comprises inverter 400, AND gate 402, NMOS transistor 404 and capacitor 406 The first input of the resettable maximum delay unit 300 is the ATs input which is coupled to the first of the two inputs of AND gate 402 The second input, the DDs input, is coupled in parallel to the input of inverter 400 and the gate of NMOS transistor 404 The output of inverter 400 is coupled to the second of the two inputs of AND gate 402 The AND gate output is coupled to the input of inverter 408 and also to the drain side of NMOS transistor 404 and capacitor 406. The source side of NMOS transistor 404 and capacitor is coupled to ground. The output of inverter 408 is connected to the input of inverter 410 The output of inverter 410 is connected to the second input of first circuit 102 In operation, the output of the AND gate 402 will be a logic 1 only when no change or pulse is present on DDs and when ATs is in a second state, corresponding in this embodiment to a set condition and a memory precharge This condition will correspond to the instance in which a pulse has been received by first circuit 102 thereby placing the output in a second state or set condition Immediately after the pulse and during the extended maximum delay period a logic 1 will be output by AND gate 402 The logic 1 condition of AND gate 402 will cause charge to be placed on capacitor 406 When the charge on capacitor 406 is greater than the threshold voltage of inverter 408, the inverter 408 will transition from a logic 1 output to a logic 0 When this transition has taken place inverter 410 connected to the output of inverter 408 will transition from a logic 0 output to a logic 1 The output RRs of inveπer 410 is communicated to the second input in this embodiment the reset input, of the first circuit 102 When a logic 1 condition is present on RRs, the first circuit will reset and the ATs will return to the first state, in this embodiment the reset state The operation of the reinitialize feature of the current invention involves the cooperative operation of inverter 400, AND gate 402, NMOS transistor 404 and capacitor 406 Given an initial input condition which produces a logic 1 output from AND gate 402, a finite amount of time is required before the output of inverter 408 will flip from a from a logic 1 to a logic 0 The reason for the disparity in state between the output of AND gate 402 and the input of inverter 408 is explained by the presence of capacitor 406 When AND gate 402 transitions to a logic 1 condition a finite amount of current is output from that AND gate and the inverter 408 input will not immediately transition to a logic 1 condition The input of inverter 408 will only be placed in a logic 1 condition when enough charge has been built up on capacitor 406 to elevate the voltage on the inverter to a threshold condition corresponding to a logic 1 If during the charging of capacitor 406 a change signal, in this embodiment a pulse, is output by difference detector 108 then that pulse on the gate of NMOS transistor 404 will cause that transistor to short capacitor 406 to ground All charge will be removed from the capacitor and the voltage on the input of inverter 408 will return to logic 0 At the termination of the change signal or pulse when the NMOS transistor 404 returns to the open condition the capacitor will resume charging from its reinitialized state if the output of AND gate 402 is a logic 1 When the voltage on the capacitor exceeds the threshold voltage, inverter 408 will transition to a logic 1 condition at its input The time associated with this transition is the time constant associated with the charging of capacitor 406 When the voltage on the input of the inverter exceeds the threshold a finite time interval is required for the inverter 408 to transition its output After the output of inverter 408 changes, a further finite time interval is required to transition the output of inverter 410 After the further finite time interval an RRs signal is generated on the output of inverter 410 In this embodiment that signal corresponds to a logic 1 When that signal is received at the second input of the first circuit 102 the output will transition to a first state The first state, in this embodiment corresponds to the reset condition It should be remarked that the timed interval imposed by maximum resettable delay unit 300 is not solely a function of the time constant associated with the charging of capacitor 406 As is well known to those skilled m the art, an additional delay of approximately Ins is added by each gate, in this case inverters 400, 408, 410 and AND gate 402 As will be apparent to one skilled in the art there are numerous logic arrangements which will product the results discussed above in connection with Fig 4 For example the transistor capacitor pair could be implemented as a pull-up rather than a pull-down arrangement Alternately, instead of an RC based delay, the delay and reinitialize feature could be achieved bv numerous analog and digital devices Digital realization of the teachings of this invention, could include a count down or count up timer that could be reinitialized As will also be apparent to those skilled in the art the resettable maximum delay unit 300 need only receive the feed-forward signal DDs in order to achieve the results described above In an alternate preferred embodiment of the invention as illustrated in Fig 5, an ATD circuit suitable for an 'N address system is disclosed A plurality of edge detect units of which 100 A and 100Z are referenced, are shown connected to individual address of an address bus having 'N' addresses of which AJs-1 and AIs-N are referenced The input of edge detect unit 100 A, and specifically minimum delay unit 106A and difference detector 108 A are both connected to AIs-1 The output of minimum delay unit 106 A is connected to the second input of difference detector 108 A The input of edge detect unit lOOz, and specifically minimum delay unit 106Z and difference detector 108Z are both connected to AIs-N The output of minimum delay unit 106Z is connected to the second input of difference detector 108Z The output of each edge detect unit, including the referenced difference detectors 108 A and 108Z, is connected to a respective input of OR gate 500 The output of the OR gate is connected to both the first input of first circuit 102 and the second of two inputs of the resettable maximum delay unit 300 The output of the first circuit is connected to the first of the two inputs of resettable maximum delav unit 300 The output of maximum resettable delav unit 300 is connected to the second input of the first circuit In operation an address signal from AIs-1 is received by both minimum delav unit 106 A. and difference detector 108 A of edge detect unit 100A As discussed in Fig 3 difference detector 108 A receives the address signal both directlv from AIs-1 and indirectly via the output of minimum delay 106A, and responsive to these inputs outputs a DDs The DDs has pulses corresponding to either one or both of a rising/falling edge of the address signal Each of the address lines and edge detect units, including the referenced edge detect unit lOOz, operates in a similar manner The outputs are combined by OR gate 500 The output of OR gate 500 is a series of combined pulses corresponding to changes on all of the address lines of the address bus The CPs (combined pulse signal) is received at the first input in this embodiment the set input, of first circuit 102 and also by the reset input of resettable maximum delay unit 300 The first circuit and maximum resettable delay unit 300 operate in the manner discussed above in connection with Figs 3 and 4 to produce an ATs at the output of first circuit The circuit initiates a second state in this embodiment a set condition on ATs on the occurrence of a CPs If the CPs are narrowly spaced in time, in relation to the timed interval of maximum resettable delay 300, the set state will be maintained until all addresses on an address bus have settled The ATs produced by this address transition detection circuit, may therefore serve as the input of a state machine for controlling memory, or a decoder for a row or column of memory, or a buffer for moving data to and from memory. Fig. 6 illustrates the wave forms of the Prior Art ATD circuit shown in Fig. 1 The example in Fig 6 exhibits a condition in which the shortcomings of the Prior Art ATD circuits is exhibited Specifically, two closely spaced address changes are shown and the second of those changes is not processed properly This will cause any circuit to which that Prior Art device is connected to be prone to a loss of memory or a delay in a memory access Four wave forms are shown in Fig 6 over a time interval of 60 nano seconds. The first λvave form is the AIs input to edge detect unit 100 shown in Fig 1 The second wave form is the DDs output bv the difference detector 108 The third wave form is the Rs output by maximum delav unit 104 The fourth wave form is the ATs output by the first circuit 102 AIs is shown with a falling edge 608 and a rising edge 610 Responsive to the falling edge 608 a first pulse is shown in DDs Responsive to the rising edge 610 a second pulse is shown in DDs The first pulse in DDs has a rising edge 612 and a falling edge 614 The second pulse has a rising edge 616 and a falling edge 618 The rising edge 612 of the first pulse of DDs is received at the first input of first circuit 102 as shown in Fig 1 In response to a change signal or pulse on the first input of the first circuit the output transitions from a first to a second state, evidenced by the rising edge 624 on ATs. At the point when the rising edge 616 of the second pulse is received at the first input of the first circuit, the second input that circuit is already in receipt of a rising edge 620 This corresponds to a reset command on Rs Under these conditions shown in Table 1 is set at logic 0 and reset at logic 1, the ATS is not maintained in a set condition, rather a falling edge 626 of ATs is exhibited immediately after the onset of the rising edge 620 of Rs By the time Rs transitions back to a logic 0 at falling edge 622, the second pulse on DDs has is no longer exhibited, i.e., it has experienced a falling edge 618 As a result the second address rising edge 610 and the corresponding second pulse are not detected Therefore, ATs will only be held in a second state for the timed interval following the first pulse but not the second Even if the second pulse followed the first pulse more closely in time, it would not be operated on There would be no extension of the period of time that ATs was held in the second state or set condition, because the Prior An maximum delav unit 104 as shown in Fig 1 is only responsive to ATs and not to DDs Fig 7 shows the wave forms associated with the current invention as illustrated in Fig 3 Four wave forms are shown over the 60 nano second interval discussed above in Fig 6 The first two wave forms AIs and DDs, are identical to those shown and discussed above in Fig 6 They correspond respectively, to the AIs input to the edge detect unit 100 and the output of difference detector 108 as shown in Fig 3 AIs has a falling edge 608 and a rising edge 610 DDs has a first and a second pulse responsive respectively to the falling edge 608 and the rising edge 610 of AIs The first pulse has a rising edge 612 and a falling edge 614 and the second pulse has a rising edge 616 and a falling edge 618 The third and fourth wave forms are distinctly different, however, then those shown in Fig 6 The fourth wave form, the ATs, corresponds to the output of the first circuit 102 The ATs exhibits a rising edge 624 at the same time as the rising edge shown on the ATs in Fig 6 Significantly, however, a falling edge 706 of that wave form does not occur until approximately 20 nano seconds after the falling edge discussed above in connection with the ATs shown in Fig 6 The falling edge 706 is responsive to a rising edge 702 in the third waveform, the RRs The RRs corresponds to the output of the maximum resettable delay unit 300 shown in Figs 3-4 Significantly, the rising edge 702 of RRs does not occur until 20 nano seconds after the rising edge discussed above in connection with Rs in Fig 6 The extended time interval before the rising edge 702, is a result of the reinitialization feature of the invention When a falling edge 704 on RRs finally occurs, there is no change in ATs because DDs has remained low Accordingly, the present invention provides a new address detection circuit which achieves a number of advantages over the Prior Art In particular, each and every address transition is accorded a corresponding delav interval Additionally the output of ATs is maintained in a second state, corresponding to a set condition, even while the circuitrv is being reinitialized by the receipt of a second pulse Furthermore, a very compact arrangement has been disclosed for detecting address transitions on a plurality of address lines of an address bus The foregoing description of a preferred embodiment of the invention has been presented for purposes of illustration and description It is not intended to be exhaustive or to limit the invention to the precise forms disclosed Obviously many modifications and variations will be apparent to practitioners skilled in this art It is intended that the scope of the invention be defined by the following claims and their equivalents

Claims: CLAIMS What is claimed is 1 An signal transition detection circuit, comprising a first circuit comprising a first input, a second input and an output, responsive to a change signal on said first input to transition said output from a first to a second state and responsive to a reset command on said second input to transition said output from said second state to said first state, an interval timer comprising an output coupled to said second input of said first circuit and an input and said interval timer responsive to an initialize command at said input to initiate a timed interval and after said timed interval to generate said reset command at said output of said interval timer and a second circuit comprising an input and an output said output of said second circuit coupled to said input of said interval timer responsive to said change signal on said input to generate said initialize command at said output of said second circuit 2 The signal transition detection circuit of claim 1 , further comprising an edge detection circuit comprising an input and an output, and said output of said detection circuit coupled to both of said first input of said first circuit and said input of said second circuit and said input of said edge detection circuit responsive to an input signal transition to generate said change signal 3 The signal edge detection circuit of claim 2, wherein said input signal transition is at least one of a rising signal edge and a falling signal edge of an address 4 The signal transition detection circuit of claim 1 wherein said second circuit, further comprises logic responsive to said first circuit output state and said change signal to generate said initialize command at said output of said second circuit 5 The signal transition detection circuit of claim 1 , wherein said interval timer comprises an inverter comprising an input and an output, said inverter output coupled to said output of said interval timer and said inverter input responsive to said initialize command to generate said reset command at said inverter output after termination of said timed interval and wherein said timed interval is a delav associated with said inverter transitioning said output from an initial condition to generate said reset command in response to said initialize command 6 The signal transition detection circuit of claim 4, wherein said interval timer comprises at least two inverters connected in series and comprising an input of a first inverter and an output of a last inverter said output of said last inverter coupled to said output of said interval timer and said inverter input responsive to said initialize command to generate said reset command at said output of said last inverter after termination of said timed interval, and wherein said timed inter al is a delav associated with said at least two inverters transitioning said output of said last inverter from an initial condition to generate a reset command in response to said initialize command 7 The signal transition detection circuit of claim 6, wherein said logic comprises a capacitor comprising a first side connected to said input of said first of said pair of inverters and a first side connected to a ground a first switch responsive to said change signal to short said first side of said capacitor to the ground, and a charge source responsive to a logic combination corresponding to a, (said second state) AND (NOT ( said change signal)), to apply sufficient charge to said capacitor source side to cause said capacitor to generate said initialize command 8 The signal transition detection circuit of claim 7, further comprising an edge detection circuit comprising an input and an output, and said output of said detection circuit coupled to both said first input of said first circuit and said input of said second circuit, and said input of said detection circuit responsive to an input signal transition to generate said change signal 9 The signal transition edge detection circuit of claim 8, wherein said input signal transition is at least one of a rising edge of an address bithne and a falling edge of an address 10 An address transition detection circuit to detect changes in a plurality of addresses of an address bus comprising, a combiner comprising a plurality of inputs and an output, responsive to change signals on said plurality of inputs to generate a combined change signal at said output, a first circuit comprising a first input, a second input and an output said first input coupled to said output of said combiner and responsive to said combined change signal on said first input to transition said output from a first to a second state, and responsive to a reset command on said second input to transition said output from said second state to said first state, an interval timer comprising an output coupled to said second input of said first circuit and an input said interval timer responsive to an initialize command on said input to initiate a timed interval and at after said timed interval to generate said reset command at said output of said interval timer, and a second circuit comprising an input and an output, said output of said second circuit coupled to said input of said interval timer, and said input of said second circuit coupled to said output of said combiner and responsive to said combined change signal on said input to generate said initialize command at said output 11 The address transition detection circuit of claim 10, further comprising a plurality of edge detection circuits each comprising an input and an output, and each input connected to a separate one of said plurality of address signals, and said output of each of said plurality of edge detection circuits coupled to a separate one of said plurality of inputs of said combiner, and said input of each of said plurality of detection circuits responsive to an address signal transition to generate a one of said plurality of change signals 12 The address transition detection circuit of claim 11, wherein said address signal transition is at least one of a rising signal edge and a falling signal edge 13 The address transition detection circuit of claim 10, wherein said second circuit further comprises logic responsive to said output state of said first circuit and said combined change signal to generate said initialize command at said output of said second circuit 14 The address transition detection circuit of claim 10, wherein said interval timer comprises an inverter comprising an input and an output said inverter output coupled to said output of said interval timer and said inverter input responsive to said initialize command to generate said reset command at said inverter output after termination of said timed interval, and wherein said timed interval is a delay associated with said inverter transitioning said output from an initial condition to generate said reset command in response to said initialize command 15 The address transition detection circuit of claim 13, wherein said interval timer comprises at least two inverters connected in series and comprising an input of a first inverter and an output of a last inverter, said output of said last inverter coupled to said output of said interval timer and said inverter input responsive to said initialize command to generate said reset command at said output of said last inverter after termination of said timed interval, and wherein said timed interval is a delay associated with said at least two inverters transitioning said output of said last inverter from an initial condition to generate a reset command in response to said initialize command 16 The address transition detection circuit of claim 15 wherein said logic comprises a capacitor comprising a first side connected to said input of said first of said pair of inverters and a second side connected to a ground, a first switch responsive to said change signal to short said first side of said capacitor to the ground, and a charge source responsive to a logic combination corresponding to a, (said second state) AND (NOT ( aid change signal)), to apply sufficient charge to said capacitor to cause said capacitor to generate said initialize command 17 The address transition detection circuit of claim 16, further comprising a plurality of edge detection circuits each comprising an input and an output, and each input connected to a separate one of said plurality of address lines, and said output of each of said plurality of edge detection circuits coupled to a separate one of said plurality of inputs of said combiner and said input of each of said plurality of detection circuits responsive to an address signal transition to generate a one of said plurality of change signals 18 The edge detection circuit of claim 17, wherein said signal transition is at least one of a rising signal edge and a falling signal edge 19 An integrated circuit memory having a plurality of input pins, comprising, a plurality of edge detection circuits having an input and an output, and each input connected to a separate one of said plurality of input pins, and each of said plurality of edge detection circuits responsive to an address signal transition on said separate one of said input pins to generate a change signal on said output, a combiner comprising a plurality of inputs and an output and each of said plurality of inputs coupled to a separate one of said outputs of said plurality of edge detection circuits and responsive to said change signals on said plurality of inputs to generate a combined change signal at said output, a first circuit comprising a first input, a second input and an output, said first input coupled to said output of said combiner and responsive to said combined change signal on said first input to transition said output from a first to a second state, and responsive to a reset command on said second input to transition said output from said second state to said first state, an interval timer comprising an output coupled to said second input of said first circuit and an input, said interval timer responsive to an initialize command on said input to initiate a timed interval and after said timed interval to generate said reset command at said output, a second circuit comprising an input and an output said output of said second circuit coupled to said input of said interval timer and said input of said second circuit coupled to said output of _.aιd combiner and responsive to said combined change signal on said input to generate said initialize command at said output and a memory control logic having an input and an output, said input coupled to said output of said first circuit and said output coupled to the memorv, and responsive to said first circuit output state on said input to generate a memory control signal 20 The integrated circuit memory of claim 19, wherein said second circuit, further comprises logic responsive to said output state of said first circuit and said combined change signal to generate said initialize command at said output of said second circuit 21 The integrated circuit memory of claim 20, wherein said interval timer comprises at least two inverters connected in series and comprising an input of a first inverter and an output of a last inverter, said output of said last inverter coupled to said output of said interval timer and responsive to said initialize command at said input of said first inverter to generate said reset command at said output of said last inverter after termination of said timed interval, and wherein said timed interval is a delay associated with said at least two inverters transitioning said output of said last inverter from an initial condition to generate a reset command in response to said initialize command 22 The integrated circuit memory of claim 21, wherein said logic comprises, a capacitor comprising a first side connected to said input of said first of said pair of inverters and a second side connected to a ground, a first switch responsive to said change signal to short said source side of said capacitor to the ground, and a charge source responsive to a logic combination corresponding to a, (said second state) AND (NOT ( said change signal)), to apply sufficient charge to said capacitor to cause said capacitor to generate said initialize command

Inventors: CHANG KUEN-LONG, CHUANG WEITONG, HUNG CHUN-HSIUNG, LIU YIN-SHANG, WAN RAY-LIN, CHANG, KUEN-LONG, CHUANG, WEITONG, HUNG, CHUN-HSIUNG, LIU, YIN-SHANG, WAN, RAY-LIN
Applicants: CHANG KUEN LONG, CHUANG WEITONG, HUNG CHUN HSIUNG, LIU YIN SHANG, MACRONIX INT CO LTD, WAN RAY LIN, CHANG, KUEN-LONG, CHUANG, WEITONG, HUNG, CHUN-HSIUNG, LIU, YIN-SHANG, MACRONIX INTERNATIONAL CO., LTD., WAN, RAY-LIN
Application year: 1996
Main classification: H03K19
IPC codes: G11C7, G11C8, G11C11, H03K5