Sensitivity-enhanced OEIC with capacitance multiplier for reduced lower-cutoff frequency

A BiCMOS optoelectronic integrated circuit for the use in future optical storage systems is presented. In this approach a PIN photodiode is integrated together with the transimpedance amplifier (TIA). The amplifier consists of two branches, connected via common current source. Thereby it is possible to realize differential outputs and to double the overall transimpedance of the circuit. In order to adhere this doubling effect down to deep frequencies, we, in addition, present an active capacitance multiplier which is used to realize high capacitance values with a minimum of area consumption. The measurement results of the OEIC showed a differential transimpedance of 84k/spl Omega/ and a -3dB bandwidth of 500MHz.