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27 Apr 2020, 9:08

FPGA-based Implementation of Signal Processing System

Signal processing applications require high computing performance and power efficiency. Digilent’s latest FPGA board, the Eclypse Z7, (195-3771) is an embedded measurement system that can provide the solution to the signal processing applications. Eclypse Z7 is ideal for high-speed instrumentation, control, and measurement systems for edge-computing, medical, and communications applications.

The Eclypse Z7 ecosystem also includes Zmod ADC 1410 (195-3772) and Zmod DAC 1411 (195-3773) . Zmods products are SYZYGY compliant expansion modules, a high-speed I/O expansion standard for FPGA boards intended to fit between the Pmod standard and FMC. The SYZYGY standard offers a much higher speed/bandwidth digital interface than Pmod but at a much smaller and lower-cost form-factor than FMC, enabling the user to configure a FPGA development board with the right I/O for their application.

The  Zmod ADC 1410 is equipped with Analog Devices AD9648, the dual channel, high speed, low power, 14-bit, 105MS/s Analog to Digital Converter (ADC). Driven by the SYZYGY carrier, the Zmod ADC can acquire two simultaneous signals (1MΩ, ±25V, single-ended, 14-bit, 100MS/s, 70MHz+ bandwidth). Analog inputs can be connected to a circuit using SMA cables. 

The Zmod DAC 1411 is equipped with Analog Devices AD9717 the dual channel, high speed, low power, 14-bit, 125MS/s Digital to Analog Converter (DAC). Driven by the SYZYGY carrier, the Zmod DAC can generate two simultaneous signals (50Ω, ±5V, single-ended, 14-bit, 100MS/s, 40MHz+ bandwidth). The analog outputs can be connected to a circuit using SMA cables.

In this signal processing system, we will use the Digilent Analog Discovery 2 (134-6480) a USB multi-instrument, to generate analog signals and visualize output signals in the frequency domain.

The first step is to connect the Analog Discovery 2 to the Zmod ADC 1410 input channel 1. Next, the analog signals from Analog Discovery 2 are converted to digital through the Zmod ADC 1410 and then passed on to the input of a digital low pass filter. The digital low pass filter is created by Xilinx FIR compiler 7.2 IP Core. The filter's outputs are converted back to analog through the Zmod DAC 1411. These digital signals can be visualized through Zmod DAC 144 output channel 1.

To correct the phase errors, there is a digital loopback by connecting Zmod ADC 1410 output channel directly to the Zmod DAC 1411 input channel 1.

Use of the Xilinx Zynq in the design

The programmable logic of Zynq 7020 is used to 

  1. Initializes the Zmod ADC 1410 hardware and synchronizes the incoming data in the user clock domain
  2. Create a digital low pass FIR filter by Xilinx FIR compiler 7.2 IP Core 
  3. Initializes the Zmod DAC 1411 hardware and formats the output data according to the AD9717 ;DAC requirements

The project details and source files are available at Digilent Wiki

Love learn engineering in hands-on approach. Interested in new technology. Work in Digilent as International Sales and Distribution Manager.

27 Apr 2020, 9:08