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