The ALPHA250 is a programmable board built around a Zynq 7020 SoC. It features a 100 MHz RF front end with dual 14-bit ADC 250 MSPS and dual 16-bit DAC 250 MSPS. Analog input to output latency is less than 90 ns. The RF ADC and DAC are clocked by a dual PLL, ultra-low jitter clock generator. It includes a 4 channel 24-bit ADC and 4 channel 16-bit DAC. The board comes with a comprehensive, open source, FPGA / Linux reference design.
- Koheron ALPHA250 board
- 12 V 1.5 A power supply
- Micro-SD card with pre-installed OS
|Programmable logic, processor and memory|
|System On Chip||Zynq 7020 XC7Z020-2CLG400I|
|Memory||512 MB of DDR3L SDRAM|
|Processor||ARM dual-core CPU|
|100 MHz low-noise RF front-ends|
|RF ADC||2 channels, 14-bit, 250 Msps, DC coupled|
|RF DAC||2 channels, 16-bit, 250 Msps, DC coupled|
|Input to output latency||90 ns|
|Input / Output||1 Vpp, 50 Ω|
|Ultra-low jitter clock generation for RF ADC, DAC and FPGA|
|Clock generator||Dual loop PLL, 100-fs RMS jitter (12 kHz to 20 MHz)|
|On-board VCXO||160 dBc / Hz @ 10 kHz|
|Reference clock inputs||FPGA, external clock or internal crystal oscillator|
|On-board TCXO||10 MHz, 280 ppb|
|Precision analog monitoring and control|
|Precision ADC||4 channels, 24-bit|
|Precision DAC||4 channels, 16-bit|
|Voltage reference||2.5 V, low-drift (3 ppm/°C)|
|Temperature sensor||±0.2 °C accuracy|
|Connectivity||10/100/1000 Ethernet, USB 2.0, USB-UART|
|General purpose I/O||16 FPGA I/Os (3V3), 8 user LEDs|
|Dimensions||10 cm x 10 cm|
|Reference designs||FFT Analyzer, ADC / DAC with BRAMs, ADC / DAC with DMA, Phase noise analyzer, Loopback|
The RF ADC and DAC noise floors were characterized with this script available on GitHub. The input referred voltage noise density of the ADC is about 13 nV/√Hz. DAC voltage noise density is about 23 nV/√Hz (19 nV/√Hz after subtraction of the ADC noise floor).
A 1 Vpp sine wave between 100 kHz and 40 MHz was send by DAC0 and measured by ADC0 (see script). The figure below shows the amplitude of the second and third harmonic, relative to the fundamental frequency:
Distortion performance is limited by the DAC. ADC distortion (HD2 and HD3) stays under -80 dB up to 40 MHz.
The crosstalk between the 2 ADC channels was characterized with the following script. Crosstalk is under -95 dB up to 120 MHz.
Crosstalk between the two DAC channels is shown below:
The phase noise of a 10 MHz OCXO reference clock (from Textronix MCA 3027) against the internal TCXO was measured with the Phase Noise Analyzer reference design:
- 2: October 2018 - Improved DAC crosstalk.