Future DVD-systems require optical pickup units with high bandwidth and high sensitivity in the red and blue spectral range. OEICs (OptoElectronic Integrated Circuits) use monolithically integrated photodetectors in order to avoid the bond pad capacitances between photodiode and amplifier and to increase the bandwidth compared to discrete or two-chip optical receivers. For this reason, OEICs are a good approach for future DVD-applications.
We introduce a solution that integrates a PIN photodiode and a transimpedance amplifier in a 0.6μm BiCMOS process. The innovative transimpedance amplifier consists of two branches connected via a common current source in order to achieve differential outputs and to double the transimpedance without increasing the offset voltage. The amplifier is optimized for high bandwidth.
The measured results show a -3dB cut-off frequency of 500MHz and a differential transimpedance of 76kΩ. This is 2.2 times the bandwidth and 1.3 times the transimpedance compared to the results presented in the literature. Measurements also show that the OEIC is appropriate for fiber receiver applications at 1.25Gb/s with a record sensitivity of -27.7dBm.