US 4,910,698 A · Sine wave generator using a cordic algorithm

Abstract

A circuit for generating successive points on a sine wave using the Coordinate Rotational Digital Computer (CORDIC) algorithm. An angle memory and an amplitude memory store respective angle and amplitude values from which a CORDIC logic processor calculates a point on a sine wave. A frequency memory stores an increment value unique to the frequency of the sine wave to be formed, and an arithmetic logic unit adds the increment value to the stored angle value after the point on the sine wave is calculated. The CORDIC logic processor then calculates the next point on the sine wave from the incremented angle value. A digital-to-analog converter may be used to provide an analog output signal. For generating multi-tone signals, the angle, amplitude and frequency memories are configured to store a plurality of angle, amplitude and increment values, and an address memory is connected to each memory for simultaneously addressing them. A periodic counter is connected to the address memory and cyclically selects the addresses in the address memory to be used for addressing the angle, amplitude and frequency memories. The multi-tone signals are then produced by serially time-multiplexing the CORDIC processor among the frequencies.

Claims16

Dependent claims

A circuit for generating succesive points on a sine wave comprising:

an angle memory for storing a plurality of angle values at addresses therein;
CORDIC logic means, connected to the angle memory, for calculating a sine value from a selected angle value from the angle memory;
an increment angle memory for storing a plurality of increment angle values for the selected angle value at addresses therein;
incrementing means, connected to the angle memory and to the increment angle memory, for successively adding a selected increment angle value from the increment angle memory to the selected angle value and for providing each incremented angle value to the CORDIC logic means for calculating successive points on a sive wave therefrom;
and
addressing means, connected to the increment angle memory to the angle memory, for selecting an increment angle value and an angle value to be used for each sine value calculation.

3 more elements

A circuit for generating successive points on a sine wave comprising:

angle storing means for storing an angle value;
CORDIC logic means, connected to the angle storing means, for calculating a sine value from the angle value, the CORDIC logic means comprising:
sign determining means, connected to the angle storing means, for determining the algebraic sign of the angle value;
angle constant storing means for storing a plurality of angle constant values;
angle arithmetic means, connected to the angle constant means, to the angle storing means, and to the sign determining means, for performing N arithmetic operations on the angle value, for any integer N greater than zero, each operation comprising:
(i) adding an angle constant value to the angle value if the angle value is negative;
or
(ii) subtracting the angle constant value from the angle value if the angle value is positive;
wherein the result of each arithmetic operation is the angle value for the next arithmetic operation, and the angle constant values are chosen so that the angle value after the N arithmetic operations is substantially equal to zero;
X-storing means for storing a value of an X-coordinate (X);
Y-storing means for storing a value of a Y-coordinate (Y);
and
X/Y-arithmetic means, connected to the X storing means, to the Y storing means and to the sign determining means, for performing, for each arithmetic operation on the angle value, a cross-arithmetic operation with an X-coordinate (X) value and a Y-coordinate (Y) value;
increment angle storing means for storing an increment value for the angle value;
and
incrementing means, connected to the angle storing means and to the increment angle storing means, for successively adding the increment value to the angle value after each sine value is calculated and for providing each incremented angle value to the CORDIC logic means for calculating successive points on a sine wave therefrom.

13 more elements

Dependencies are inferred from the claim text.

Sine wave generator using a cordic algorithm

Life of this patent

Sine wave generator using a cordic algorithm

Life of this patent

Abstract

Claims16