I need to bias the inputs to a transformer-coupled communications receiver apart by about 100mV. Since the transformer has split windings, one way to do this would be to add a Schottky diode into the center tap, and bias it with a little current (not enough to saturate the transformer). I would use parallel diodes to maintain the offset when the AC comm signal comes through the transformer. But so far I haven't found any Schottky diodes with a Vf of less than 220mV, and those were big power diodes. I just need small signal diodes in the 10-20mA range. I was doing some reading that suggests that lower Vf diodes are not generally made because the reverse leakage current increases with decreasing Vf, so they are not very good rectifiers if you try to push Vf too low. But I don't really care about reverse leakage current in this application. Does anybody know of custom Schottky diodes where they could maybe be tuned for the lower Vf as a special? Or does anybody know of any other similar electronic device that will drop a constant 100mV for currents in the 1mA-20mA range?