Designing a GFSK Receiver in Arx

This technical note documents the design of a GFSK receiver in Arx. While GFSK is used in many telecommunication standards, the version described here uses toy parameters that are not related to any standard. The code is distributed as free IP on the Bibix website.1 The note starts by a presentation of the theory and then spends some attention on how Arx can be combined with testbenches in IT++2 and VHDL. The intention is not so much to explain GFSK, but to show how Arx can be used in a larger design. One performs the design and verification using the C++ generated from Arx, taking advantage of the high simulation speeds attainable in C++. When the design is ready, the corresponding VHDL is directly available and can be used for synthesis. 1 About Bibix, Arx, and This Document Bibix is a University of Twente spin-off company. Next to offering consultancy services, Bibix focuses on the development of Arx, a domain-specific language and toolset for register-transfer level design. The Arx toolset contains code generators for C++ and VHDL, such that models with identical behavior in both languages can be obtained from a single source code. The Bibix website gives free access to the description of several IP blocks, such as FIR filters, CORDICs and FFTs. This technical note provides some background information on one of the larger examples on the website consisting of several IP blocks: a GFSK receiver. The design is a multirate system. Given the fact that the current version of Arx only supports a single clock, the system needs to be described by means of multiple Arx files. Testbenches in C++ or VHDL connect the different blocks into a single top level and provide the appropriate clocks. This document does not explain the Arx syntax and semantics for which the reader is referred to the on-line manual available at the Bibix website. 2 Introduction to GFSK Gaussian frequency shift keying (GFSK) is a modulation method for digital communication found in many standards such as Bluetooth, DECT and Wavenis. Digital communication amounts to http://www.bibix.nl http://sourceforge.net/apps/wordpress/itpp/