Broadband predistortion circuit design for electro-absorption modulator in radio over fiber system

A low-cost broadband predistortion circuit using zero bias diodes is designed to remove 3^rd order intermodulation distortion of electro-absorption modulator in radio-over-fiber system. Experiments show that input power at 1-dB compression point is improved by 0.8-3.8 dB from 8 to 17 GHz; and spurious free dynamic range is improved by ~9 dB from 7 to 14 GHz and ~4 dB from 15 to 18 GHz, limited by 5^th order intermodulation distortion. The power consumption is reduced and no matching network is required because of characteristics of zero bias diode.