The AED-100 daughterboard is designed to facilitate construction of prototypes or quickly make small production runs for high speed sampling applications with Texas Instruments Digital Signal Processors. It fits the expansion slot of Texas Instruments Digital Signal Processing Evaluation Modules (EVM) and DSP Starter Kits (DSK) for TMS320C6xxx and C5xxx DSPs made by Texas Instruments, DNA Enterprises, Inc., and Blue Wave Systems. This expansion slot has both an expansion memory interface and an expansion peripheral interface which allows the daughterboard full access to all of the DSP's resources.
The obvious application of the AED-100 is as a transceiver or software radio. The input can be an RF signal as high as 75 MHz and a bandwidth approaching 20 MHz (40 MS/s). Alternatively, the signal can be sampled in quadrature with the two A/D converters, or the same signal can be sampled with both A/D converters, with a bandwidth approaching 40 MHz (80 MS/s). Using the A/D converters to under-sample the RF input converts the signal to baseband. The D/A converters support a quadrature output of nearly 10 MHz bandwidth. While the D/A settling time is 0.1 usec, the clocking rate can be above 18 MHz. Thus a quadrature modulator can be constructed with the D/A output for a wide range of RF frequencies. Other applications include RF channel simulator, imaging with high performance cameras, and photo-optic communication/industrial applications.
The advantage of this daughterboard over boards that contain only the A/D and D/A converters is that it provides for both analog signal conditioning circuits and for digital preprocessing before the sampled data is placed in the DSP memory. This allows prototypes with the complete front end design which is often essential to successful development in high speed applications of the DSP. The inputs to the A/D converters and the outputs of the D/A converters lead directly to a breadboard area on which conditioning circuits can be constructed. The A/D and D/A converters have their parallel digital interface connected directly to a Xilinx FPGA which provides a flexible digital interface to the DSP.
The strategic location of the FPGA between the DSP and the converters allows it to perform many useful functions. It allows blocking and FIFO buffering of signals before they are placed in the DSP memory. This can optimize the use of DSP memory and memory bus bandwidth which is often a limiting factor in DSP applications. The FPGA can provide an input decimation filter which limits the bandwidth with sharp digital filter edges and reduces the number of samples allowing the application to work with higher initial sample rates than the DSP can handle. The FPGA can construct high speed output samples for the D/A converters based on DSP inputs or the signal coming from the A/D converters. The FPGA also connects to the external digital I/O connector and to the clock/control lines of the converters. This allows synchronization of the converters with both external signals and with DSP signals. To further enhance the synchronization and clock control, the FPGA connects to both the input and output of a Phase-Locked Loop which can provide synchronized frequency multiplying.
The breadboard area consists of 7 sq. in. of 50 mil pitch surface mount or DIP component area. This allows a wide variety of components to be wired into signal conditioning circuits. The breadboard area is served by separate + and - regulated power supplies for sensitive analog components. Locations for six SMB connectors are adjacent to the breadboard at the edge of the daughterboard where coax connectors are easily plugged in.
SIGNALWARE provides technical support for all aspects of the use of the AED-100 including signal conditioning circuit design, FPGA configuration programming, and DSP software programming. SIGNALWARE can provide a turnkey solution to prototyping a DSP application. Signal conditioning circuits can be mounted and wired on the board at the time of manufacture at less cost than having a technician or engineer wire them on the board afterward. SIGNALWARE also provides a 90 day limited warranty against workmanship and component defects.