Analog to digital signal conversion

Claim 1

APPARATUS FOR CONVERTING ANALONG SIGNALS REPRESENTATIVE OF NUMERICAL QUANTITIES INTO DIGITAL SIGNALS CORRESPONDING TO THE QUANTITIES, SAID APPARATUS COMPRISING AN INPUT SWITCHING MEANS, AN AMPLIFIER HAVING AN INPUT SUMMING POINT, AND A FIRST DIGITAL LADDER CIRCUIT AND A SECOND DIGITAL LADDER CIRCUIT BOTH COUPLED TO THE SUMMING POINT OF THE AMPLIFIER, SAID INPUT SWITCHING MEANS INCLUDING A PLURALITY OF IMPEDANCE COUPLING DEVICES EACH OPERABLE TO PASS A CORRESPONDING ONE OF THE ANALOG SIGNALS TO THE SUMMING POINT OF THE AMPLIFIER, A CONTROLLABLE CONDUCTION DEVICE COUPLED TO EACH OF THE IMPEDANCE COUPLING DEVICES FOR SELECTIVELY DISABLING THE IMPEDANCE COUPLING DEVICES AND BLOCKING THE ANALOG SIGNAL FROM THE SUMMING POINT OF THE AMPLIFIER, A DIGITAL COUNTER CIRCUIT COUPLED TO EACH OF THE CONTROLLABLE CONDUCTION DEVICES AND OPERABLE TO RENDER NON-CONDUCTIVE THE CONTROLLABLE CONDUCTION DEVICES IN A SEQUENTIAL ORDER, A FIRST OF THE IMPEDANCE COUPLING DEVICES BEING COUPLED TO A POINT OF REFERENCE POTENTIAL WHEREBY THE REFERENCE POTENTIAL IS IMPRESSED UPON THE SUMMING POINT OF THE AMPLIFIER TO INITIATE A CYCLE OF OPERA-