An integrator includes a source of {HEAD ~ current} responsive to {TAIL ~ the signal} to be integrated 
An integrator includes a source of { HEAD ~ current } responsive to { TAIL ~ the signal } to be integrated
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH