Each diode 162, 164 and 166 has its cathode coupled to ground and its anode coupled to a node between {TAIL ~ the divider resistors} 144/146, 150/152 and 156/158 of {HEAD ~ each stage} 
Each diode 162 , 164 and 166 has its cathode coupled to ground and its anode coupled to a node between { TAIL ~ the divider resistors } 144/146 , 150/152 and 156/158 of { HEAD ~ each stage }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD