{HEAD ~ The reference voltage Vref} defines the DC level of both the virtual ground and {TAIL ~ the output node} 
{ HEAD ~ The reference voltage Vref } defines the DC level of both the virtual ground and { TAIL ~ the output node }
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL