DSP Primer using ISE

After completing this workshop, you will be able to:

• Understand the fundamentals of fixed point word lengths and related issues
• Know how to control and deal with rounding, truncation, wrap-around, and saturation arithmetic on FPGAs
• Understand the many arithmetic implementation options (for multiply and other operations)
• Know how to design and work with Coordinate Rotation Digital Computer (CORDIC) designs for trigonometric calculations
• Know the features and architectures of the DSP48x slices of the Virtex® and Spartan® FPGAs
• Know how to use the Xilinx System Generator Simulink® software for DSP design
• Be able to run the full ISE® software design flow for DSP systems and examples
• Implement real time DSP examples on the FPGA board using audio input/output codecs
• Understand the reasons for and methods to implement high-speed Cascaded Integrator-Comb (CIC) filters
• Know the methods for implementation of Numerically Controlled Oscillators (NCOs)
• Be able to build a QAM transceiver using various core FPGA components
• Understand how to set up Phase-Locked Loops (PLLs) and early late gates for synchronization
• Understand the use of the QR algorithm for least squares and adaptive algorithm implementation

Day 1:

• The DSP for FPGA history
• Lab 1: Using System Generator, ISE and ChipScope™ Tools
  • Use Xilinx System Generator within the Mathworks Simulink environment to implement simple DSP multiply/add/delay circuits and then synthesize, place and route and inspect the floor plan of some simple designs.  ChipScope will be used with an example running on the FPGA board.
• Arithmetic and CORDIC implementations 
• Lab 2: Multipliers, Adders, Dividers and CORDICs
  • Consider the many ways of implementing a multiplier (DSP48, constant coefficient, distributed, shift and add, etc.), and also looks at divider designs, and CORDIC implementations for calculation of sine, cosine, magnitude and other trigonometric calculations.
• Digital Filters on FPGAs
• Filter Retiming and Pipelining Methods
• Lab 3: Digital Filter Design and Implementation
  • Look at filter designs in parallel and serial form, and also various techniques and methods for pipelining, multichannel filter implementation, and generally implementing efficient and low-cost filters with particular reference to decimation and interpolation filters.  Audio examples will feature noise filtering using the FPGA board.
• CIC and Moving Average Filters

Day 2:

• Lab 4: CIC Filter Implementation
  • Implement CIC filter chains to understand the issues of word length growth, decimation/down-sampling, droop correction and applications at radio front ends (transmitters and receivers).  Also implement filter receive chains featuring CICs, low pass, half band and other efficient filter implementations.
• Numerically Controlled Oscillators (NCOs)
• NCO Receiver Synchronization
• Lab 5: Oscillator Design and Implementation
  • Implementation of numerically controlled oscillators using look-up-table methods and setting appropriate Spurious Free Dynamic Range (SFDR) and frequency accuracies.  Also consider Xilinx cores for NCOs or Direct Digital Synthesis (DDS) and also using CORDIC-based oscillators and marginally stable IIR oscillators.
• The Quadrature Amplitude Modulator (QAM) Tx and Rx
• Lab 6: QAM Transceiver Design
  • A quadrature modulator transmitter and receiver will be implemented to modulate data to an IF carrier (around 3MHz), then receive using a quadrature receiver implementation.  This lab will integrate the implementation of NCOs, standard digital filters, CICs, synchronizers in a single design.
• Adaptive Signal Processing, Least Squares and the QR
• Lab 7: QR Algorithm Implementation
  • A 5x5 (matrix) QR algorithm will be implemented (for least squares, linear system solvers, and general adaptive DSP implementations).  A demonstration of using the QR for system identification will be set up in the lab, and a full CORDIC based design synthesized and placed and routed will be completed.  This represents a high value, high complexity implementation.