I'm trying to understand the behaviour of output modulation current (IMOD+) with respect to the differential voltage input (DIN+ - DIN-) in VCSEL Driver ONET4291VA. Specifically, when the VCSEL turns ON from OFF state, when does the modulation current begin to ramp up? In the figure below, of the possible options A1, A2, A3, I'd assume it is A1 but would like to get confirmation.
Difference between the 3 options are as follows:
A1 --> Output roughly follows the ramp up of differential input voltage (Datasheet provides relationship of output rise/fall time to input rise/fall time)
A2 --> Output ramp up starts only after the differential input voltage has increased above -200mV (200mV is the min spec for Differential Inputs. Note the negative sign.)
A3 --> Output ramp up starts only after the differential input voltage has increased above +200mV (200mV is the min spec for Differential Inputs. Note the positive sign.)
Thanks,
Satish