Photodiode Amplifier with cascode input

The input sources approximately model the photodiode responsivity, but not the output impeadance. To create and scale the bode plot correctly, set the dependent current source gain to 1V/A and set the independent voltage source to 1V. The output node is at the junction of the 82k res and the emitter of the output xstr. At 1khz, the sim gain is 98.3 db (82.2k V/A). For the time response set the current source gain to 1uV/A and leave the voltage source at 1 V. To observe all the dc operating points on the schematic, disconnect the output lead of the voltage source at the input and run the transient response test. Hand calculations with feedback approx show the transresistance gain at about 98.13 db (80.6 V/A). The current mirror should be built using a xstr array for matching. The other xstrs can be general purpose types. This experimental circuit was designed, built, tested and used as part of the receiver to an audio optical link 6 yrs ago (it performed as designed)

published 8 years ago