Successive-approximation analog-to-digital converter using Josephson devices
AssigneeInternational Business Machines Corporation
InventorMelvin Klein
Life of this patent
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Abstract
A comparison means has plural Josephson devices each controlled by an analog input current and an opposing subtraction current. A subtraction means has a series circuit of Josephson devices arranged in groups, each group being switched by one of the comparison devices. The subtraction current is proportional to the number of devices switched in the series circuit. An output means has a string of Josephson devices each providing an output bit from one of the comparison devices. Fixed bias currents control the effective thresholds of the comparison devices.
Claims7
A successive-approximation analog-to-digital converter for an analog input signal, comprising:
- comparison means having a plurality of Josephson junctions adapted to switch to a voltage-drop state at predetermined control-signal levels for producing comparison signals, and control means for applying said input signal and a subtraction signal for controlling certain of said junctions,
- subtraction means having a plurality of further Josephson junctions disposed in groups, and further control means for applying said comparison signals to respective ones of said groups for producing said subtraction signal as a function of the number of said further junctions in said voltage-drop state, and
- output means coupled to said comparison means for producing digital signals representing the magnitude of said analog input signal.
A successive-approximation analog-to-digital converter comprising:
- comparison means having at least a single Josephson junction adapted to switch to a voltage drop state at at least a single predetermined analog signal level for producing at least a single comparison signal,
- means for applying an analog signal to said at least a single junction,
- subtraction means responsive to the switching to the voltage state of said at least a junction to render said junction responsive to at least another level of input signal including a plurality of groups of Josephson devices and control line means electrically connected to said plurality of groups of Josephson devices and to said at least a single Josephson junction, and
- means connected to said at least a junction for generating an output signal.
Dependencies are inferred from the claim text.