Patent ID: 6911859

Claim:
A conversionless direct detection system, comprising: a number of successive log amplifier gain stages, each gain stage having an RF transistor configured to perform both limiting and logging functions for providing a limited RE output and a log output, said successive log amplifier gain stages including a summing unit for summing the log outputs of said gain stages, the addition of each gain stage extending the dynamic range of said system, each gain stage having a threshold point and a saturation point and a log linear output response therebetween, the log linear response of said gain stages being contiguous so as to provide contiguous linear log segments summed to produce an extended log linear transfer function, the threshold and saturation points of said gain stages being set so that said contiguous linear log functions do not overlap, said log output being tapped from said RE transistor such that said log output is in the form of a rectification current, and further including a low pass filter coupled to said rectification current.