Method and apparatus for computing complex phase
AssigneeTexas Instruments Incorporated
InventorTimothy M. Schmidl
Life of this patent
Estimating the term…
Abstract
The phase of a complex number I+jQ is computed using a hybrid lookup table and computation approach suitable for DSP implementation and useful in remote access/networking and wireless applications. An approximate phase θ˜ for an approximation complex number I˜+jQ˜ is determined through memory table lookup. This is added to a correction phase Δθ which is determined by calculation of a correction term C=(I˜*Q−Q˜*I)/(I*I˜+Q*Q˜) which represents the imaginary part divided by the real part of the complex multiplication of the complex number and the conjugate of the approximate complex number.
Claims3
A method for computing the phase θ of a complex number I+jQ, where I and Q are n-bit binary numbers, comprising the steps of:
- determining an approximate complex number I˜+jQ˜ from m<n most significant bits of the numbers I and Q;
- determining an approximate phase θ through memory table lookup of prestored arctan relationships Q˜/I˜ for complex numbers I˜+jQ˜;
- determining a correction phase Δθ by calculation of a correction term C=(I˜*Q−Q˜*I)/(I*I˜+Q*Q˜) which represents the imaginary part divided by the real part of the complex multiplication of the complex number and the conjugate of the approximate complex number;
- and
- adding the approximate phase θ to the correction phase Δθ.
Dependencies are inferred from the claim text.