Current amplifier providing sum of absolute values of signals

Claim 1

IN A SUMMING AMPLIFIER CIRCUIT FOR OBTAINING THE ABSOLUTE SUM OF POSITIVE AND NEGATIVE CURRENT SIGNALS, THE COMBINATION COMPRISING: FIRST AND SECOND SUMMING AMPLIFIERS, EACH OF SAID SUMMING AMPLIFIERS INCLUDING AN INPUT COMMON-EMITTER-CONNECTED TRANSISTOR, AN OUTPUT EMITTER-FOLLOWER-CONNECTED TRANSISTOR, COUPLING MEANS FOR CONNECTING THE BASE OF SAID EMITTER-FOLLOWER-CONNECTED TRANSISTOR TO THE COLLECTOR OF SAID COMMON-EMITTER-CONNECTED TRANSISTOR, AND A FEEDBACK CIRCUIT CONNECTED BETWEEN THE EMITTER OF SAID EMITTER-FOLLOWER-CONNECTED TRANSISTOR AND THE BASE OF SAID COMMON-EMITTER-CONNECTED TRANSISTOR; IMPEDANCE MEANS FOR COUPLING SAID CURRENT SIGNALS OF ONE POLARITY TO THE BASE OF SAID INPUT COMMONEMITTER-CONNECTED TRANSISTOR OF SAID FIRST SUMMING AMPLIFIER; IMPEDANCE MEANS FOR COUPLING SAID CURRENT SIGNALS OF ANOTHER POLARITY TO THE BASE OF SAID INPUT COMMONEMITTER-CONNECTED TRANSISTOR OF SAID SECOND SUMMING AMPLIFIER; IMPEDANCE MEANS FOR COUPLING SAID SECOND SUMMING AMPLIFIER IN CASCADE WITH SAID FIRST SUMMING AMPLIFIER; AND MEANS FOR COUPLING AN OUTPUT TERMINAL TO THE EMITTER OF SAID EMITTER-FOLLOWER-CONNECTED TRANSISTOR OF SAID SECOND AMPLIFIER.