The first bias circuit has {TAIL ~ a first reference load element} formed of {HEAD ~ a first material} and generates a first bias voltage 
The first bias circuit has { TAIL ~ a first reference load element } formed of { HEAD ~ a first material } and generates a first bias voltage
OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH