An apparatus is provided. There is an input terminal that is configured to receive an input signal from a optical receiver and an output terminal. First and second integrators are coupled between the input and output terminals. In the second integrator, there is a current source that is coupled to the input terminal, a first resistor that is coupled to the output terminal, and a second resistor. Also, there is an amplifier having a first input, a second input, and an output, where the first resistor is coupled to the first input of the amplifier and where the second input of the amplifier is configured to receive a reference voltage. A transistor is coupled between the current source the second resistor and is coupled to the output of the amplifier at its gate. A capacitor is also coupled between the first input of the amplifier and the second resistor.