Low-level commutator with means for providing common mode rejection

Claim 1

A LOW LEVEL COMMUTATING CIRCUIT FOR SUCCESSIVELY CONNECTING A PLURALITY OF SIGNAL SOURCES ACROSS THE INPUT TERMINALS OF A DIFFERENTIAL AMPLIFIER WHEREIN EACH SIGNAL SOURCE HAS A POTENTIAL REFERENCE POINT WHICH MAY VARY IN VOLTAGE WITH RESPECT TO A GROUND POINT CONNECTED TO THE DIFFERENTIAL AMPLIFIER, THE COMMUTATING CIRCUIT COMPRISING A PLURALITY OF SOLID STATE SWITCHING ELEMENTS FOR SELECTIVELY CONNECTING EACH OF THE SIGNAL SOURCES ACROSS THE INPUT TERMINALS OF THE DIFFERENTIAL AMPLIFIER, EACH SWITCHING ELEMENT PROVIDING LOW IMPEDANCE CURRENT PATH IN RESPONSE TO A CURRENT PULSE ACROSS A PAIR OF CONTROL ELECTRODES, A PLURALITY OF SWITCHING ELEMENTS FOR SELECTIVELY CONNECTING THE POTENTIAL REFERENCE POINT OF EACH SIGNAL SOURCE TO A COMMON TERMINAL, A FLOATING POWER SUPPLY HAVING OUTPUT TAPS AT DIFFERENT RELATIVE POTENTIALS, ONE TAP OF THE POWER SUPPLY BEING CONNECTED TO SAID COMMON TERMINAL, MEANS INCLUDING A PLURALITY OF DIODES RESPECTIVELY CONNECTING ANOTHER TAP OF THE POWER SUPPLY TO ONE OF THE CONTROL ELECTRODES OF EACH OF THE SOLID STATE SWITCHING ELEMENTS, AND FIRST AND SECOND CURRENT SOURCES HAVING THEIR OUTPUT TERMINALS CONNECTED RESPECTIVELY BETWEEN EACH OF THE INPUT TERMINALS OF THE DIFFERENTIAL AMPLIFIER AND SAID GROUND POINT.