High-throughput CORDIC coprocessor for signal and display processing

Abstract

A GaAs application-specific integrated circuit (ASIC) has been designed to provide 40 million non-linear operations (trigonometric functions, divisions, and multiplications) in a configuration that is compatible with many sensor preprocessing and display processing applications. The ASIC is based on the Coordinate Rotation by DIgital Computer (CORDIC) algorithm and will be fabricated with Honeywell's low-power, high-speed complementary hetmsaucture field-effect transistor (C-HFET) GaAs process. The CORDIC chip can be used for radar/electrooptic sensor preprocessing and display coordinate transformation applications. We will show how one CORDIC ASIC could replace several digital signal processors @SPs) in e.g., future Synthetic Vision Systems (SVS). The C-HFET GaAs CORDIC has four times higher throughput than CMOS implementations of the same algorithm. Implementation of the same functions with off-the-shelf Silicon ASKS would require 4 times higher power and yield 16 times lower throughput. IntroduEtinnTo handle a wide range of weather conditions and landing support provided at airports encountered by commercial and military planes, enhanced landing runway/taxiway situation awareness is required. One of the bottlenecks in the signal processing required for those synthetic vision computations is real-time coordinate transformation of the sensor data to a large display. Similarly the most demanding tasks for radar and surveillance signal pmessing are adaptive beamforming and fast Fourier transform (FFT) algorithms.Military missions, as well as commercial airline demands, have lead to the concept of modular, digital avionics. That means that avionic modules can be used to perform several tasks and can interface with different systems. That modular approach will reduce the product cost. simplify maintenance, and provide more flexibility in the system. The CORDIC ASIC described will be able to be applied to coordinate rotation, magnitude/phase, Givens rotation, Kalman filter and perspective view transformation computations.In this paper, we propose the CORDIC algorithm implemented in GaAs ASIC technology as a modular coprocessor that can solve many high throughput signal processor requirements. We will discuss the CORDIC algorithm, the CORDIC applications, and the design and specifications of the C-HFET GaAs ASIC. 1The CORDIC algorithm was first proposed by Volded and subsequently unified by Waltherz. The algorithm is an iterative process that consists of N iterations, where N is slightly larger than the precision of the input data. The iterations rotate the initial data in circular, linear, or hyperbolic coordinate systems. Thus trigonometric, hyperbolic functions and multiplication/division can be easily realized. For the COFIDIC ASIC implementation we selected the following subset of non-linear floating-point functions:-Multiply This subset of functions will allow the CORDIC coprocessor to become a processing module for other operations such as adaptive beamforming, FFT, enhanced vision system, and many other avioni...