2.3: Changed single dual, in series Silicon diode to a pair, dual, in series Schottky diode.

2.2: digital I/O for analog board: 8 from FPGA, and 2 from SENSOR_CTRL_40..41

2.1: high speed DAC termination scheme changed for increased current output

2.0: differential amplifier output swap, TDI/TDO on FPGA swap