定点和浮点DSP比较白皮书

1SPRY061

System developers, especially those who are new to digital signal processors (DSPs),

are sometimes uncertain whether they need to use fixed- or floating-point DSPs for

their systems. Both fixed- and floating-point DSPs are designed to perform the high-

speed computations that underlie real-time signal processing. Both feature system-on-

a-chip (SOC) integration with on-chip memory and a variety of high-speed peripherals

to ensure fast throughput and design flexibility. Tradeoffs of cost and ease of use often

heavily influenced the fixed- or floating-point decision in the past. Today, though, select-

either integer or real arithmetic, the latter normalized in the form of scientific notation.

TI’s TMS320C62x™ fixed-point DSPs have two data paths operating in parallel, each

with a 16-bit word width that provides signed integer values within a range from –2^15 to

2^15. TMS320C64x™ DSPs, double the overall throughput with four 16-bit (or eight 8-

bit or two 32-bit) multipliers. TMS320C5x™ and TMS320C2x™ DSPs, with architec-

tures designed for handheld and control applications, respectively, are based on single

16-bit data pathss.

By contrast, TMS320C67x™ floating-point DSPs divide a 32-bit data path into two

parts: a 24-bit mantissa that can be used for either for integer values or as the base of

a real number, and an 8-bit exponent. The 16M range of precision offered by 24 bits

Comparing Fixed- and Floating-Point DSPs

Does your design need a fixed- or floating-point DSP?

The application data set can tell you.

By

Gene Frantz, TI Principal Fellow, Business Development Manager, DSP

Ray Simar, Fellow and Manager of Advanced DSP Architectures