Characterization of photoreceivers for LISA

LISA will use quadrant photoreceivers as front-end devices for the phasemeter measuring the motion of drag-free test masses in both angular orientation and separation. We have set up a laboratory testbed for the characterization of photoreceivers. Some of the limiting noise sources have been identified and their contribution has been either measured or derived from the measured data. We have built a photoreceiver with a 0.5 mm diameter quadrant photodiode with an equivalent input current noise of better than 1.8 pA/sqrt[Hz] below 20 MHz and a 3dB bandwidth of 34 MHz.