Vivante Corporation

Zhenyu Wang

Lefan Zhong

Guosong Li

Rui Zhao

A circuit is disclosed that uses a four element dot product circuit (DP4) to approximate an argument t=x/pi for an input x. The argument is then input to a trigonometric function such as Sin Pi( ) or Cos Pi( ). The DP4 circuit calculates x times a representation of the reciprocal of pi. The bits of the reciprocal of pi that are used are selected based on the magnitude of the exponent of x. The DP4 circuit includes four multipliers, two intermediate adders, and a final adder. The outputs of the multipliers, intermediate adders, and final adder are adjusted such that the output of the final adder is a value of the argument t that will provide an accurate output when input to the trigonometric function.

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San Jose, CA, United States of America

Zhenyu Wang