a fourth switching element disposed between {HEAD ~ a control terminal} of {TAIL ~ the first switching element} and a control terminal of the third switching element 
of
a fourth switching element disposed between { HEAD ~ a control terminal } of { TAIL ~ the first switching element } and a control terminal of the third switching element
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH