A Low Cost 4 bit 16 Giga-sample-per-second Analog-to-digital Converter for Radio Astronomy

Abstract

In this study, a 4 bit, 16 giga samples per second analog-to-digital converter (ADC) printed circuit board assembly (PCBA) was designed, manufactured, and characterized for digitizing signals from radio telescopes. For this purpose, an Adsantec ANST7123-KMA flash ADC chip was used. Because this design of chip is not followed the serial ADC JESD204 standard completely, we used a novel channel bonding scheme developed in our previous project for the high-speed serial data input alignment. The PCBA was equipped with a field-programmable gate array (FPGA) mezzanine card (FMC) connector. FMC allowed us to use the FPGA evaluation board by Xilinx as the testing platform. The PCBA enables data acquisition with a wide bandwidth and simplifies the intermediate frequency section. In the current version, the PCBA and the chip exhibit an analog bandwidth of 16 GHz, which facilitates a second Nyquist sampling. The following minimum to maximum performance parameters were obtained from the first and second Nyquist zones: a spurious-free dynamic range of 18–33 dB and an effective number of bits of 2.1–3.7 bits. The board will be ported to the Collaboration for Astronomy Signal Processing and Electronics Research environment, which is open for use by non-profit scientific teams, including the Event Horizon Telescope.