An Auto ranging Data Converter Implementation in FPGA
Jithin Krishnan, Sreekumari B, Jiju K
Abstract
A novel project is being presented here for implementation an auto ranging analog to digital converter for biomedical applications completely inside an FPGA - i.e. an all-digital analog to digital (A/D) converter system. The only analog part is the auto ranging circuitry and an RC Integrator outside FPGA. The system outputs 24 bits and features a sigma delta ADC of 16 bits resolution, a range detection unit with 7 bits and a sign bit for polarity detection. The analog part of the modulator is done utilizing the LVDS transceiver in the FPGA making it a real digital one. The digital section of sigma delta ADC containing the decimation filter banks is done in a cascaded filter structure form including a CIC decimation filter, droop compensation and half-band filters. The top level module was coded using VHDL and the simulation was carried out with ModelSim and MATLAB.
Keyword
Autoranging ADC, Sigma Delta ADC, Digital filter section, 16 bit ADC.