of an electrical circuit showing a high level description of controlled gain tia core 22 the circuit comprises a high gain amplifier 38 and a feedback resistor r n where gain control 24 is provided gain control 24 is controlled by selecting different resistances one preferred detailed implementation of the circuit in fig3 is shown in fig4 fig4 shows a schematic block diagram of an electrical circuit showing controlled gain tia core 22 in which different resistances r 1 through r n are achieved by the opening or closing of various switches s 1 through s n based on the signal to gain control 24 the gain of controlled gain tia core 22 is one of n gains gain 1 to gain n embodiments of the present invention with different configurations of power detector 28 are possible fig5 a shows a schematic block diagram of an electrical circuit showing a high level description of power detector 28 including an envelope detector ed 42 in this embodiment power detector 28 comprises two components a low pass filter lpf 40 and ed 42 power detector 28 samples the output of controlled gain tia core 22 via cpl 30 and passes its processed output signal level 46 to gain selector 26 which selects the gain according to the level sent from power detector 28 i e signal level 46 fig5 b shows a schematic block diagram of an electrical circuit showing a high level description of power detector 28 including a low.