An optical receiver with automatic gain control circuit for 4G RoF technology

An optical receiver with automatic gain control (AGC) function is presented in this paper, which is based on the 0.15um low power InGaAs pHEMT technology provided by WIN semiconductors corp in Taiwan and used in the RoF technologies in IMT-Advanced (4G) system. The gain of the optical receiver varies from 55dB to 85dB. The -3dB bandwidth is about 9GHz, the noise current is about 700nA and the sensitivity is -24dBm. The characteristics of this optical receiver meet the requirements of the RoF techniques. The performance of the optical receiver greatly exceeds th e initial requirements because of the better high frequency performance of the pHEMT technology. Therefore, this circuit can be used for other applications, such as the RoF technology of wideband radar signals.