Digital fast CORDIC for envelope tracking generation

An envelope tracking system comprising:

• a power amplifier module (PAM);
• a fast switch mode power supply (SMPS) converter adapted to supply modulated power to the PAM in response to an envelope tracking signal (ETS);
• an envelope tracking signal (ETS) generator adapted to drive the SMPS converter in response to a stream of vector norms;
• and
• a CORDIC for computing a stream of vector norms, each having a first component and a second component, comprising:
• a first maximum value circuit for outputting a maximum operand that is a larger one of either an absolute value of the first component or an absolute value of the second component;
• a minimum value circuit for outputting a minimum operand that is a smaller one of either an absolute value of the first component or an absolute value of the second component;
• N rotator stages, each corresponding to a unique one of N predetermined vectors, each having a first multiply circuit for multiplying the maximum operand by a cosine coefficient of a corresponding predetermined vector to output a first rotation component, a second multiply circuit for multiplying the minimum operand by a sine coefficient of the corresponding predetermined vector to output a second rotation component and an adder circuit for adding the first rotation component to the second rotation component to output one of N results;
• and
• a second maximum value circuit for outputting a maximum one of the N results.