Q: How Does the Drain Current of HMC634LC4 change as the Gate Voltage approaches to 0V?
A: As Vgg approaches 0 Volts from the negative region, the current increases. The Current increase to almost 400mA with 2W power which is beyond HMC634LC4 Absolute Maximum Rating.
It is advised to keep the current to 200mA limit and to operate the Vgg in the Negative region. Though the device may survive the 400mA Gate Current it is not recommended specially in a long period of time.