Ceremorphic, Inc.

Martin Kraemer

Wei Xiong

Ryan P Boesch

An analog machine learning architecture uses modular analog multiplier-accumulator (AMAC) elements of fixed size to form a machine learning (ML) system with increasing feature map size. A single 3×3×64 AMAC array is arranged to provide a three layer ML architecture with first layer 3×3×64, second layer 3×3×128, and third layer 3×3×256 using arrangements of single 3×3×64 AMACs arranged in parallel, where the bias of each AMAC is separately established in a unique interval of time.

Modular analog multiplier-accumulator unit element for multi-layer neural networks

A Gain Balanced Analog Multiply-Accumulator (AMAC) has an inference memory which outputs subsets of inference data comprising X input values and one or more associated W coefficient values, and a number of Analog Multiplier-Accumulator Unit Elements (AMAC UE) in equal number to the number of X input values in each subset of inference data. The X input values and one or more W coefficient values from the inference memory are applied to each AMAC UE to generate a charge corresponding to the multiplication of X input value and W coefficient value of each AMAC UE which is transferred to a shared analog charge bus. The inference memory applies the X input value and W coefficient values of each subset to a different AMAC UE on subsequent cycles to balance the gain of the AMAC such that gain differences from one AMAC UE to another are not cumulative.

Analog multiplier accumulator with unit element gain balancing

A Bias Unit Element (UE) comprises NAND gates with complementary outputs, the complementary outputs coupled through a charge transfer capacitor to a differential charge transfer bus comprising positive charge transfer lines and negative charge transfer lines. Each line of the differential charge transfer bus has a particular binary weighted line weight, such as 1, 2, 4, 2, 4, 8, and 4, 8, 16. Digital bias inputs are provided to the Bias UE NAND gate inputs, with a clear bit to initialize charge, and a sign input for enabling one of a positive Bias UE or negative Bias UE. A low-to-high transition causes a transfer of charge to the binary weighted charge transfer bus, thereby adding or subtracting a bias value from the charge transfer bus.

Bias unit element with binary weighted charge transfer lines

An architecture for a chopper stabilized multiplier-accumulator (MAC) uses a chop clock and common Unit Element (UE), the MAC formed as a plurality of MAC UEs receiving X and W values and a sign bit exclusive ORed with the chop clock, a plurality of Bias UEs receiving E value and a sign bit exclusive ORed with the chop clock, and a plurality of Analog to Digital Conversion (ADC) UEs which collectively perform a scalable MAC operation and generate a binary result. Each MAC UE, BIAS UE and ADC UE comprises groups of NAND gates with complementary outputs arranged in NAND-groups, each NAND gate coupled to a differential charge transfer bus through a binary weighted charge transfer capacitor. The analog charge transfer bus is coupled to groups of ADC UEs with an ADC controller which enables and disables the ADC UEs using successive approximation to determine the accumulated multiplication result.

Chopper stabilized analog multiplier accumulator with binary weighted charge transfer capacitors

A Unit Element (UE) has a digital X input and a digital W input, and comprises groups of NAND gates generating complementary outputs which are coupled to differential charge transfer lines through respective charge transfer capacitor Cu. The number of bits in the X input determines the number of NAND gates in a NAND-group and the number of bits in the W input determines the number of NAND groups. Each NAND-group receives one bit of the W input applied to all of the NAND gates of the NAND-group, and each unit element having the bits of X applied to each associated NAND gate input of each unit element. The NAND gate outputs are coupled through a charge transfer capacitor Cu to charge transfer lines. Multiple Unit Elements may be placed in parallel to sum and scale the charges from the charge transfer lines, the charges coupled to an analog to digital converter which forms the dot product output.

Differential unit element for multiply-accumulate operations on a shared charge transfer bus

A Unit Element (UE) has a digital X input and a digital W input, and comprises groups of NAND gates generating complementary outputs which are coupled to a differential charge transfer bus comprising a positive charge transfer line and a negative charge transfer line. The number of bits in the X input determines the number of NAND gates in a NAND-group and the number of bits in the W input determines the number of NAND groups. Each NAND-group receives one bit of the W input applied to all of the NAND gates of the NAND-group, and each unit element having the bits of X applied to each associated NAND gate input of each unit element. The NAND gate outputs are coupled through binary weighted charge transfer capacitors to a positive charge transfer line and negative charge transfer line.

Multiplier-accumulator unit element with binary weighted charge transfer capacitors

A plurality of unit elements share a charge transfer bus, each unit element accepts A and B digital inputs and generates a product P as an analog charge transferred to the charge transfer bus, each unit element comprised of groups of AND gates coupled to charge transfer lines through a capacitor Cu. Each unit element receives one bit of the B input applied to all of the AND gates of the unit element, and each unit element having the bits of A applied to each associated AND gate input of each unit element. The AND gates of each unit element are coupled to charge transfer lines through a capacitor Cu, and the charge transfer lines couple to binary weighted charge summing capacitors which sum and scale the charges contributed by all unit elements to the charge transfer lines according to a bit weight and converted to a digital value output.

Scaleable analog multiplier-accumulator with shared result bus

A differential multiplier-accumulator accepts A and B digital inputs plus a sign bit and generates a dot product P by applying the bits of the A input and the bits of the B inputs to respective positive and negative unit elements comprised of groups of AND gates coupled to charge transfer lines through a capacitor Cu. One of the positive and negative unit element is enabled by the sign bit, the enabled unit element receives one bit of the B input applied to all of the AND gates of the unit element, and each positive and negative unit element having the bits of A applied to each associated AND gate input of each unit element, which charge to charge transfer lines, and the charge transfer lines are coupled to binary weighted charge summing capacitors and to an analog to digital converter to generate a digital output product.

Differential analog multiplier for a signed binary input

A differential multiplier-accumulator accepts A and B digital inputs and generates a dot product P by applying the bits of the A input and the bits of the B inputs to respective positive and negative unit elements comprised of groups of AND gates coupled to charge transfer lines through a capacitor Cu. Each positive and negative unit element receives one bit of the B input applied to all of the AND gates of the unit element, and each positive and negative unit element having the bits of A applied to each associated AND gate input of each unit element. The AND gates are coupled to charge transfer lines through a capacitor Cu, and the charge transfer lines couple to binary weighted charge summing capacitors and to an analog to digital converter to generate a digital output product. The charge transfer lines may span multiple unit elements.

Differential analog multiplier-accumulator

A multiplier-accumulator accepts A and B digital inputs and generates a dot product P by applying the bits of the A input and the bits of the B inputs to unit elements comprised of groups of AND gates coupled to charge transfer lines through a capacitor Cu. The number of bits in the B input is a number of AND-groups and the number of bits in A is the number of AND gates in an AND-group. Each unit element receives one bit of the B input applied to all of the AND gates of the unit element, and each unit element having the bits of A applied to each associated AND gate input of each unit element. The AND gates are coupled to charge transfer lines through a capacitor Cu, and the charge transfer lines couple to binary weighted charge summing capacitors which sum and scale the charges from the charge transfer lines, the charge coupled to an analog to digital converter which forms the dot product output. The charge transfer lines may span multiple unit elements.

Unit element for asynchronous analog multiplier accumulator

Cascade multiplier using unit element analog multiplier-accumulator

An architecture for a multiplier-accumulator (MAC) uses a common Unit Element (UE) for each aspect of operation, the MAC formed as a plurality of MAC UEs, a plurality of Bias UEs, and a plurality of Analog to Digital Conversion (ADC) UEs which collectively perform a scalable MAC operation and generate a binary result. Each MAC UE, BIAS UE and ADC UE comprises groups of NAND gates with complementary outputs arranged in NAND-groups, each NAND gate coupled to a differential charge transfer bus through a binary weighted charge transfer capacitor to form an analog multiplication product as a charge applied to the differential charge transfer bus. The analog charge transfer bus is coupled to groups of ADC UEs with an ADC controller which enables and disables the ADC UEs using successive approximation to determine the accumulated multiplication result.

Architecture for analog multiplier-accumulator with binary weighted charge transfer capacitors

A Bias Unit Element (UE) has a digital input, a sign input, and a chop clock. The sign input is exclusive ORed with the chop clock to generate a signed chop clock. Each Bias UE comprises a positive Bias UE and a negative Bias UE, each comprising groups of NAND gates generating an output and a complementary output, each of which are coupled to differential charge transfer lines through binary weighted charge transfer capacitors to a differential charge transfer bus comprising a positive charge transfer line and a negative charge transfer line. The chopped sign input enables the positive Bias UE when the sign bit is positive and enables the negative Bias UE when the sign bit is negative.

Chopper stabilized bias unit element with binary weighted charge transfer capacitors

A Unit Element (UE) has a positive UE and a negative UE, each having a digital X input and a digital W input with a sign bit, the sign bit is exclusive ORed with a chop clock to generate a chopped sign bit. The positive UE is enabled when the chopped sign bit is positive and the negative UE is enabled when the chopped sign bit is negative. Each positive and negative UE comprises groups of NAND gates generating an output and complementary output which are coupled to a differential charge transfer bus comprising a positive charge transfer line and a negative charge transfer line. The NAND gate outputs and complementary outputs are coupled through binary weighted charge transfer capacitors the positive charge transfer line and negative charge transfer line.

Chopper stabilized analog multiplier unit element with binary weighted charge transfer capacitors

A planar fabrication charge transfer capacitor for coupling charge from a Unit Element (UE) generates a positive charge first output V_PP and a positive charge second output V_NP, the first output coupled to a positive charge line comprising a continuous first planar conductor, a continuous second planar conductor parallel to the first planar conductor, and a continuous third planar conductor parallel to the first planar conductor and second planar conductor, the charge transfer capacitor comprising, in sequence: a first co-planar conductor segment, the first planar conductor, a second co-planar conductor segment, the second planar conductor, a third co-planar conductor segment, the third planar conductor, and a fourth coplanar conductor segment, the first and third coplanar conductor segments capacitively edge coupled to the UE first output V_PP, the second and fourth coplanar conductor segments capacitively edge coupled to the UE second output V_NP.

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Mountain View, CA, United States of America

Martin Kraemer