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A novel architecture to realize the conversion of rectangular to polar coordinates is presented in this paper. The proposed technique for phase calculation uses a logarithmic number system and does not require any multiplications, but only a few small tables and a few multi-operand additions. The modulus is computed by a constant multiplier, a lookup table, and a full multiplier. A test chip has been designed and fabricated in 0.25 mum CMOS. The realized circuit uses a novel high-speed modified double-pass transistor (DPL) full-adder cell to improve performance. The test chip includes two processors. The first one computes only the phase and reaches 482 MHz maximum clock frequency, with 0.37 mW/MHz power dissipation. The second processor computes the phase and modulus and works up to 430 MHz, with 0.64 mW/MHz. The experimental results compare favorably with previously reported architectures.
Date of Publication: Nov. 2008