Activation accelerator for neural network accelerator

A method of applying a non-linear activation function to an input value using an activation accelerator, the method comprising:

• storing in a look-up table a plurality of values representing the non-linear activation function, the plurality of values stored in the look-up table in accordance with a mode of a plurality of modes;
• generating, at the activation accelerator, a converted value from an input value;
• generating, at the activation accelerator an index and an interpolation value from the converted value based on the mode of the plurality of modes;
• retrieving multiple values from the look-up table based on the index;
• and
• generating, at the activation accelerator, an estimated result of the non-linear activation function for the input value by interpolating between the multiple values retrieved from the look-up table based on the interpolation value.

A non-transitory computer readable storage medium having stored thereon a computer readable dataset description of an activation accelerator for use in a neural network accelerator that, when processed in an integrated circuit manufacturing system, causes the integrated circuit manufacturing system to manufacture an integrated circuit embodying an activation accelerator comprising:

• a look-up table configured to store a plurality of values representing a non-linear activation function, the plurality of values stored in the look-up table in accordance with a mode of a plurality of modes;
• and
• one or more activation pipelines, each activation pipeline comprising:
• a range conversion unit configured to receive an input value and generate a converted value from the input value;
• an index generation unit configured to receive information identifying the mode of the plurality of modes and generate an index and an interpolation value from the converted value based on the identified mode;
• a look-up table interface unit configured to retrieve multiple values from the look-up table based on the index;
• and
• an interpolation unit configured to generate an estimated result of the non-linear activation function for the input value by interpolating between the multiple values retrieved from the look-up table based on the interpolation value.