Abstract
A series of design guidelines is introduced for Bessel-type (maximally flat delay) transimpedance preamplifiers for optimum position detection using a lateral-effect photodiode. A distributed parameter network model for the lateral-effect photo-diode and a one-pole model for the preamplifiers are used in a complete analysis of the sensor. The analysis yields the necessary unity gain bandwidth of the preamplifiers for a given transimpedance gain and positioning resistance and junction capacitance of the detector such that constant group delay is achieved within the prescribed bandwidth. This criterion ensures that the position of edges is not affected by the response of the preamplifiers. Experimental results are provided to demonstrate the technique for video and quasi-video bandwidths. The analysis is complemented by the derivation of equations for the temperature drift and the noise level of the combined lateral-effect photo-diode and preamplifiers. These equations clearly show the presence of crosstalk between the preamplifiers.

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