Abstract:
In view of the neural network information parallel processing, a digital perceptron device analogous to the build-in neural network hardware systems for parallel processing digital signals directly by the processor&#39;s memory content and memory perception in one feed-forward step is disclosed. The digital perceptron device of the invention applies the configurable content and perceptive non-volatile memory arrays as the memory processor hardware. The input digital signals are then broadcasted into the non-volatile content memory array for a match to output the digital signals from the perceptive non-volatile memory array as the content-perceptive digital perceptron device.

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The invention is related to a digital signal processor, which can interpret the receptive digital signals into the perceptive output digital signals. In particular, the processor parallel processes digital information according to its pre-configured digital content and perceptive non-volatile memories without executing any sequential Boolean logic operations. That is, instead of executing the combinational logic computations given by the programmed instructions in the conventional digital processors, the invented digital signal processor intelligently processes digital information fully based on their configured content and perceptive non-volatile memory hardware. 
     Description of the Related Art 
     In the modern Von Neumann computing architecture as shown in  FIG. 1 , the Central Process Unit (CPU) executes logic operations according to the instructions and data from the main memory  11 . The CPU  10  includes a main memory  11 , an arithmetic and logic unit  12 , an input/output equipment  13  and a program control unit  14 . Prior to the computation process, CPU  10  is set by the program control unit  14  to point to the initial address code for the initial instruction in the main memory  11 . The digital data are then processed with the arithmetic and logic unit  12  according to the sequential instructions in the main memory  11  accessed by the clock-synchronized address pointer in the program control unit  14 . In general, the digital logic computation process for CPU  10  is synchronously executed and driven by a set of pre-written sequential instructions stored in the memory. 
     The power consumption for digital computations is given by P˜f×C×V DD   2 , where f is the clock frequency, C is the total active circuit capacitance and V DD  is the positive voltage supply for digital circuitries. Accordingly, the energy requirement for running a computation sequence is proportional to the numbers of clock steps to complete the set of instructions. Each instruction step includes fetching the instruction and data from the main memory  11 , executing the micro-operations in the arithmetic and logic unit  12 , and storing the resultant data back to the main memory  11  or outputting to the I/O (Input/Output) equipment  13 . The total computation energy for completing a set of instructions is proportional to the frequency of memory accessing and the charging/discharging the total capacitances of the bus-lines and the active digital circuitries (registers, logic gates, and multiplexers). The more frequent memory accessing to complete the computation processing steps, the more energy and processing time are consumed for the digital processors. 
     While for a biologic nerve system the external stimuli such as lights, sounds, touches, tastes, and smells, are received by the fields of sensory organs connected to the nerve system. The neural signals in the forms of electrical pulses and neural transmitters (molecules) generated in the receptor fields are propagated to trigger the activation of next connecting layer of the neural network in the nerve system. The field of neural signals generated from the connecting layer continues to process forward throughout the multiple layers of the neural network hardware in the nerve system. Each neural network layer is parallel processing and extracting the information according to its neuromorphic structures and the receptive fields of neural signals from the previous layers. Unlike the present Von Neumann computing system iterating multiple logic computations for digital data by the pre-written instructions, the neural signals for information processing are propagated layer-to-layer in one-step feed-forward fashion by their neuromorphic structures. Therefore, in terms of information processing efficiencies and energy consumptions, the parallel processing and extracting information for layers of neural network in biologic nerve systems are superior to the processing and extracting information by multiple sequential logic computations in the present computing systems. 
     Inspired by the neural network information parallel processing, we are motivated to invent a digital signal processor analogous to the information processing in neural network systems directly by the processor&#39;s memory hardware for parallel processing digital signals within one feed-forward step. A digital symbol for digital information processing is generally represented by a string of bits (binary digits) in the combination of “0s” and “1s”, where the signals of “1” and “0” are provided by the applying positive voltage V DD  and the ground voltage V SS  in digital circuitries respectively. An input digital symbol with multiple bits representing specific input content information can be intelligently processed to output another digital symbol representing the perceived information by the processor. The processor is given by the name of “Digital Perceptron”. The meaning of “intelligently processed” is that the perceptive information is autonomously processed with the input digital “content” according to a pool of known knowledge of digital “contents”. In contrast to the “content” processing, CPU processes information with logic operations and memory by pointing to the “address” locations and the logic contents of look-up-tables in FPGA (Field Programmable Gate Array) are extracted for digital processing by configuring their “address” multiplexers as well. 
     The digital perceptron can be configured to store a group of digital symbols and the correspondent output digital symbols in the non-volatile memory units similar to the built-in neural network hardware. The group of digital symbols can represent various scenarios in real world as the digital contents. The correspondent output digital symbols could be digital commands to drive an analog device or the input digital symbols for other digital perceptrons. For instance, a group of digital symbols could represent the digital IDs for a group of people and the correspondent output digital symbols are the two digital commands for “grant” or “deny” the access to a facility. When a person tries to access the facility, the signals of the digital symbol representing the person&#39;s digital ID are read and broadcasted into the non-volatile memory database configured with the digital symbols representing the digital IDs for the entire group of people. When the input digital symbol signals are matched with one of the configured digital symbols, the correspondent pre-configured digital command signals are immediately sent out to grant or to deny the person to access the facility. That is, the digital perceptron recognizes the person immediately by his/her digital ID and decides to let him/her access the facility or the opposite. 
     Upon applying the same scenario with the present computing architecture, the input digital symbol for the person&#39;s ID is fed to perform a binary search in the non-volatile memory database storage, where the group&#39;s digital symbols and their correspondent digital commands are stored and can be accessed only by the clock-driven memory addresses. The binary search operation for CPU then applies the bit comparison with the logic gate XOR, where the two input bits with “equal logic value” and “non-equal logic values” yield logic “0” and “1” respectively. Therefore, to perform the binary search for a digital symbol with plural bits requires multiple times of bit-data transmissions and comparisons between the “XOR” logic gate units and the memory in CPU, and data transmissions between CPU I/O equipment and non-volatile memory database storage. The energy and time consumed for searching a digital symbol by addresses in a large memory database storage become very inefficient as the general practice of running programmed software algorithm with many times of memory accessing between CPU and non-volatile memory database storage, and the data comparisons in the present computing system. 
     In another aspect of this invention, the multiple-time configurability of non-volatile memories in the digital perceptrons provides the capability of real-time updating the digital content and output symbols. The digital content and output symbols can be renewed anytime according to the coding efficiency and the learning algorithms for the real world scenarios. From the perspective, the digital perceptron can evolve into a processor for better processing efficiency and more desirable functions set by the learning algorithm as the training for the processor. 
     SUMMARY OF THE INVENTION 
     To fulfill the above described functions of digital perceptrons, we have applied the configurable non-volatile content memory array for storing the non-volatile digital content symbols (U.S. patent application Ser. No. 14/596,886, the disclosure of which is incorporated herein by reference in its entirety), and the Complementary Electrical Erasable Programmable Read Only Memory (CEEPROM) array disclosed in U.S. Pat. No. 8,817,546 B2 (the disclosure of which is incorporated herein by reference in its entirety) for storing the perceptive non-volatile digital symbols, to form the main portion of the digital perceptron. The digital perceptron  200  is shown in  FIG. 2 . In the digital perceptron  200 , an n-bit×m-row non-volatile content memory array  600  through “2n” input lines  205  is connected to an n-bit input buffer and driver unit  700  with the connection of external n-bit input bus lines  250 . When the “enabled high” signal at node  210  is activated by V DD , the input buffer and driver unit  700  receives the digital symbol signals from the external n-bit input bus lines  250  and broadcasts the n-bit digital signals into the n-bit×m-row non-volatile content memory array  600 . The “m” rows of the match-lines  203  in the non-volatile content memory array  600  attach to a match detector  800  connected to the correspondent m-row wordlines of the q-bit×m-row CEEPROM array  100  by the “m” switching lines  204 . When the m-row match detector  800  is activated by the “enabled high” V DD  signal at node  210 , the “matching” signal from one of the m match detector cells  850  in the match detector  800  can switch on the correspondent wordline in the q-bit×m-row CEEPROM array  100 . The q-bit output signals by the “q” output lines  206  are then sent to the q-bit output buffer and driver unit  110 . Meanwhile the “matching” signal from one of the m match detector cells  850  is also fed into the match logic circuitry  900  to generate the “send high” V DD  signal at the node  208  for connecting the q-bit output buffer and driver unit  110  with the external q-bit output bus lines  251  to send out the q-bit output signals. On the other hand, if the n-bit input data does not match any row of the configured non-volatile data in the non-volatile content memory array  600 , the output buffer and driver unit  110  are not connected to the external output bus lines  251 . The digital perceptron  200  then sends no digital signals out to the external output bus lines  251 . This function is to imitate the information processing by biological nerve systems in response to the irrelevant information inputs from the environments. 
     The “inhibition” function can be commonly observed for the neural networks in biologic nerve systems. One classic example is the knee jerk case, where the combination of excitatory and inhibitory synaptic connections mediating the stretch reflex of the quadriceps muscles. To imitate this function, we apply a simple “AND” gate  209  having two input nodes, an “Enable” node  252  and an “Inhibition” node  253 , for turning on and off the digital perceptron  200 . The digital perceptron  200  is turned on by the “enable high” V DD  signal at the node  210 , if and only if for the “high” V DD  signal at the “Enable” node  252  and the “low” V SS  signal at the “Inhibition” node  253 . 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a better understanding of the present invention and to show how it may be carried into effect, reference will now be made to the following drawings, which show the preferred embodiment of the present invention, in which: 
         FIG. 1  shows the conventional Von-Neumann computing architecture for a typical Central Processing Unit (CPU). 
         FIG. 2  shows the schematics of the digital perceptron according to the invention. 
         FIG. 3  shows the schematic of a pair of complementary non-volatile memory devices according to the invention. 
         FIG. 4  illustrates the configuration definition of the non-volatile memory data for the pair of complementary non-volatile memory devices in  FIG. 3 . 
         FIG. 5  summarizes the applied voltage biases for the input digital data signals to match the configured non-volatile memory data defined in  FIG. 4 . 
         FIG. 6  shows the n-bit×m-rom NAND-type non-volatile content memory array in the digital perceptron according to one embodiment of the invention. 
         FIG. 7  shows the schematic of n-bit input buffer and driver unit in the digital perceptron according to an embodiment of the invention. 
         FIG. 8  shows the schematic of a match detector in the digital perceptron according to an embodiment of the invention. 
         FIG. 9  shows the schematic of the Match Logic circuitry in the digital perceptron according to an embodiment of the invention. 
         FIG. 10  shows a q-bit×m-row CEEPROM memory array in the digital perceptron according to an embodiment of the invention. 
         FIG. 11  shows the schematic of q-bit output buffer and driver unit in the digital perceptron according to an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following detailed description is meant to be illustrative only and not limiting. It is to be understood that other embodiment may be utilized and element changes may be made without departing from the scope of the present invention. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. Those of ordinary skill in the art will immediately realize that the embodiments of the present invention described herein in the context of methods and schematics are illustrative only and are not intended to be in any way limiting. Other embodiments of the present invention will readily suggest themselves to such skilled persons having the benefits of this disclosure. In the figures of the accompanying drawings, elements having the same reference numeral designations represent like elements throughout. 
     In one embodiment, the complementary Non-Volatile Memory (NVM) devices  310  and  320  have applied to store a non-volatile binary digit (bit) as shown in  FIG. 3 . The terminals of the two NVM devices  310  and  320  are connected together to form the output node “O”  315  of the complementary non-volatile memory device pair  300 . The other two terminals  311  and  321  of the complementary non-volatile memory pair form the input nodes, a “B” node  311  and a “ B ” node  321 , respectively. The complementary pair of the NVM devices  310  and  320  can be configured as one is in “conducting state” and the other is in “non-conducting state”. As illustrated in  FIG. 4 , we can define the non-volatile datum “1” for the NVM device  310  configured in “conducting state” and the NVM device  320  configured in “non-conducting state”, and the non-volatile datum “0” for the NVM device  310  configured in “non-conducting state” and the NVM device  320  configured in “conducting state”. With the digital signals, V DD  and V SS , biased to the input nodes, the “B” node  311  and the “ B ” node  321 , the signals at the output node “O”  315  are V DD  and V SS  for the non-volatile data “1” and “0”, respectively. 
     For matching the input digital data with the non-volatile data in the complementary non-volatile memory device pairs  300 , we apply (V DD  and V SS ) signals to “B” node  311  and “ B ” node  321  for input datum “1”, and (V SS  and V DD ) signals to “B” node  311  and “ B ” node  321  for input datum “0”, respectively. Accordingly the signals at the output node “O”  315  for “matching” and “not-matching” the input data with the non-volatile data are always V DD  and V SS , respectively. The digital signals for matching the input data and non-volatile data are summarized in  FIG. 5 . 
     We then apply the complementary non-volatile memory pair device  300  and a switching N-type MOSFET (Metal Oxide Semiconductor Field Effect Transistor) device  630  to form the non-volatile content memory cell  650  shown in  FIG. 6 . The output node  315  of the complementary non-volatile memory pair device  300  is connected with the gate of N-type MOSFET device  630  in each non-volatile content memory cell  650 . For the “n”-bit×“m”-row NAND-type content memory array  600  shown in  FIG. 6 , the input nodes  311  and  321  of the complementary non-volatile memory pair devices  300  in each column are connected to form BL(i) line  613  and  BL (i) line  614  for i=1, 2 . . . , n columns. The N-type MOSFET devices  630  in each row are connected in series to form the matching lines ML(j)  615 , for j=1, 2 . . . , m rows, of the NAND-type content memory array  600 . End nodes  612  of the matching lines  615  are connected altogether to form the common source line (CSL)  610  tied to the ground voltage. When the input digital signals, (V DD  and V SS ) for datum “1”, and (V SS  and V DD ) for datum “0”, are applied to BL(i) line and  BL (i) line respectively for searching non-volatile digital data in the n-bit columns, the “matching” signal V DD  at node  315  turns on the N-type MOSFET devices  630  to electrically connect their source electrodes  631  and drain electrodes  633  in the non-volatile content memory cells  650 . While the “not-matching” signal V SS  turns off the N-type MOSFET devices  630  to electrically disconnect their source electrodes  631  from drain electrodes  633  in the non-volatile content memory cells  650 . Therefore if and only if the n-bit input digital signals match the entire row of n-bit non-volatile data for turning on all the N-type MOSFET devices  630  in the row, the output node  611  of the matching line ML(jm)  615  is electrically connected to the ground CSL line  610 . 
     In the embodiment, the n-bit input buffer and driver unit  700  is formed by a row of “n” input buffer and driver cells  750 . Each input buffer and driver cell i  750 , for each i=1, 2 . . . , n, consists of two transmission gates  712  and  713 , cross-inverter buffer  710 , and a pair of bit-datum drivers  720 . When the “V DD ” signal is at the “enable high” node  210 , the transmission gate  712  is “on” to pass the digital signals from the input node D (i)  711  to the cross-inverter buffer  710 . Meanwhile the bit-datum signal and its complementary signal from the cross-inverter buffer  710  are amplified by the bit-datum driver  720  at the nodes  730  and  731  to drive up the bitlines BL(i) and  BL (i) in the non-volatile content memory array  600 . When the “V SS ” signal is at the “enable high” node  210 , the transmission gates  712  are “off” to disconnect from the input node D(i)  711  and the transmission gate  713  are “on” to retain the data in the cross-inverter buffers  710 . The row of “n” input buffer and driver cells  750  are synchronously controlled by the “enable high” signals at node  210  for receiving the n-bit data signals from the n-bit input bus lines  250  and retaining the n-bit data in the data buffers  710 . 
     In the embodiment, the match detector  800  is formed by a column of “m” match detector cells  850 . Each match detector cell  850  consists of the match-line pre-charging PMOSFET  810 , the “hit” PMOSFET  820 , the conversion buffer  830 , the transmission gates  840  and  841 , the match-value buffer  860 , and the wordline driver  870 . When the “enable high” signal V DD  is at the node  210 , for each j=1, 2 . . . , m, the match-line pre-charging PMOSFET devices  810  are “off” to disconnect the match-line nodes ML(j)  811  from V DD , and the transmission gates  840  are “on” to receive the voltage signals from the output lines  831  of the conversion buffers  830 . If and only if the n-bit input digital data match the row of n-bit non-volatile data to connect the row match-line to the ground potential in the non-volatile content memory array  600 , the voltage potential for the matched node ML(jm)  811  is rapidly discharged from the initial voltage V DD  to the ground voltage V SS . The data match signal V DD  at  831  for the matched row is then captured in the match-value buffer  860 . The match signal V DD  in the match-value buffer  860  is amplified by the wordline driver  870  at the connecting node  871  to switch on the correspondent wordline W(jm) in the non-volatile CEEPROM array  100 . Otherwise, the voltage potentials at the ML(j) nodes  811 , j≠jm, for the “not-match” rows remain near V DD  for the period of “enable high” time. The data unmatched signal V SS  in the match-value buffers  860  for the “not-match” rows remains off for the correspondent wordlines in the non-volatile CEEPROM array  100 . Meanwhile for the matched row, the voltage signal V SS  at node  811  by discharging one of the match-lines can turn on the “hit” PMOSFET  820  in the match detector cell  850  to charge the “H” node  211  to V DD . Otherwise, if none of the rows in the n-bit×m-row non-volatile content memory array  600  can match to discharge their match-lines, the output signal at the “H”  211  cannot be charged to V DD  due to all the “hit” PMOSFET devices  820  in the match detector cells  850  being off. The V DD  signal at the “H” node  211  is applied to activate the “Match Logic” circuitry  900  to connect the q-bit output buffer and driver unit  110  with the output bus-lines  251  for sending the output digital signals. 
     In the embodiment, the “Match Logic” circuitry  900  is shown in  FIG. 9 . When the “enable high” node  210  is applied with V SS , the PMOSFET  910  and the NMOSFET  920  are both “on” to have the voltage potential V DD  at node  911  such that the voltage potential at the node “send high”  208  of the half latch  940  is V SS . When the “enable high” node  210  is activated with V DD  to turn off both PMOSFET  910  and NMOSFET  920 , the NMOSFET  930  is “on” only with V DD  at the “H” node  211  to pull down the voltage potential at node  911  to the ground voltage such that the voltage potential at the node “send high”  208  of the half latch  940  is V DD . Therefore the V DD  signal at the node “send high”  208  of the half latch  940  is applied to connect the q-bit output buffer and driver unit  110  to the q-bit output bus-lines  251  only for the V DD  signal at the “H” node  211 . Accordingly, if the n-bit input data match one row of n-bit non-volatile content data in content memory array  600 , the V DD  signal at the “H” node  211  from one of the match detector cells  850  activates the “Match Logic” circuitry  900  to connect the q-bit output buffer and driver unit  110  with the q-bit output bus-lines  251 . Otherwise, the q-bit output buffer and driver unit  110  are not connected with the output q-bit bus-lines  251  for the “no-match” content memory situation. 
     In the embodiment the “q”-bit×“m”-row CEEPROM array  100  is shown in  FIG. 10 . We then apply the complementary non-volatile memory pair device  300  and an access NMOSFET device  130  to form a CEEPROM cell  120 . The input nodes  311  and  321  of the complementary non-volatile memory pair devices  300  in each column are connected to form BL(k) line  101  and  BL (k) line  102  for k=1, 2 . . . , q columns. The output node  315  of the complementary non-volatile memory pair device  300  is connected to the source electrode of the access NMOSFET  130  with the drain electrode attached to the output bitline BC(k)  106 . The gates of the access NMOSFET devices  130  in the row j for j=1, 2 . . . , m, are connected to form the wordline W(j)  105  of the CEEPROM array  100 . When the bitlines BL(k) and  BL (k) for k=1, 2 . . . , q are biased with the V DD  and V SS  respectively, the signals at the output nodes  315  of the complementary non-volatile memory device pairs  300  are V DD  for the non-volatile datum “1” and V SS  for the non-volatile datum “0”. If the match detector  800  sends a match signal V DD  to turn on the correspondent wordline W(j) in response to the matched row in the non-volatile content memory array  600 , the signals of the q-bit data stored in the row of the CEEPROM cells  120  are passed to the output bitlines BC(k)  106  for k=1, 2 . . . , q. Otherwise, the correspondent wordlines with the unmatched signal V SS  from the match detectors  800  in response to the unmatched rows in the non-volatile content memory array  600  remain off to output no data to the output bitlines BC(k)  106  for k=1, 2 . . . , q. 
     In the embodiment, the q-bit output buffer and driver unit  110  are formed by a row of “q” output buffer and driver cells  150 . The input node  155  of the output buffer and driver cell  150  is connected to the output bitline BC(k), for each k=1, 2 . . . , q, of the q-bit×m-row CEEPROM array  100 . The output buffer and driver cell  150  consists of two transmission gates  151  and  152 , cross-inverter buffer  153 , and tri-state output driver  154 . When the “enable high” node  210  is activated with V DD , the row of the transmission gates  151  are turned on for sending the signals from the output bitline BC(k), for k=1, 2 . . . , q, to the cross-inverter buffers  153 . If the row of tri-state drivers  154  is activated by the “send high” signal V DD  at the node  208 , the q-bit data are then amplified by the tri-state driver  154  to drive the q-bit output bus lines  251  for sending the perceptive digital data out of the digital perceptron  200 . 
     The aforementioned description of the preferred embodiments 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 form or to exemplary embodiments disclosed. Accordingly, the description should be regarded as illustrative rather than restrictive. Obviously, many modifications and variations of non-volatile memory elements including the types of non-volatile memory devices such as the conventional MOSFET devices with floating gate, charge trap dielectrics, or nano-crystals for charge storage material, and the non-volatile memory devices having the “conducting” and “non-conducting” states to form a complementary memory device pair such as Read Only Memory (ROM), Phase Change Memory (PCM), Programmable Metallization Cell (PMC), Magneto-Resistive Random Memories (MRAM), Resistive Random Access Memory (RRAM), Carbon Nano-Tube Memory (CNTM), and Nano-Random Access Memory (NRAM) will be apparent to practitioners skilled in this art. The embodiments are chosen and described in order to best explain the principles of the invention and its best mode practical application, thereby to enable persons skilled in the art to understand the invention for various embodiments and with various modifications as are suited to the particular use or implementation contemplated. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents in which all terms are meant in their broadest reasonable sense unless otherwise indicated. The abstract of the disclosure is provided to comply with the rules requiring an abstract, which will allow a searcher to quickly ascertain the subject matter of the technical disclosure of any patent issued from this disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Any advantages and benefits described may not apply to all embodiments of the invention. It should be appreciated that variations may be made in the embodiments described by persons skilled in the art without departing from the scope of the present invention as defined by the following claims. Moreover, no element and component in the present disclosure is intended to be dedicated to the public regardless of whether the element or component is explicitly recited in the following claims.