Abstract 1,028,650. Semi-conductor circuits. INTERNATIONAL BUSINESS MACHINES CORPORATION. Sept. 30, 1964 [Oct. 31, 1963], No. 39742/64. Heading H3T. [Also in Division G4] A threshold circuit for comparing an input voltage with a decreasing ramp voltage comprises a pair of diodes 16, 18, the junction 14 of which is at the lower voltage as shown in Fig. 2. When the ramp voltage becomes less than the input voltage a signal is passed via capacitor 62 to switch a tunnel diode and cause transistor 68 to give an output at 72. A number of threshold circuits 100, 102, 104 are arranged in Fig. 3 to indicate, by comparison with a ramp voltage from a common generator 106, which of a number of signals is the highest. The first circuit to respond sends a pulse to single-shot 110 to enable gates 112, 114, 116 passing the threshold circuit signal to a corresponding latch 118, 120, 122. The output from the latch activates an indicator 124, 126 or 128.
A THRESHOLD LOGIC CIRCUIT COMPRISING: AN INPUT VOLTAGE SUMMING NETWORK FOR PRODUCING A SINGLE INPUT VOLTAGE, SAID NETWORK HAVING A PLURALITY OF PARALLEL-WIRED RESISTORS IN SERIES WITH A FIRST DIODE, A LINEARLY TIME-VARYING REFERENCE VOLTAGE GENERATOR FOR PROVIDING A VOLTAGE OF SUBSTANTIALLY CONSTANT SLOPE, SAID GENERATOR COMPRISING A SAWTOOTH VOLTAGE SIGNAL SOURCE IN SERIES WITH A VOLTAGE DIVIDING NETWORK, SAID NETWORK BEING IN SERIES WITH A SECOND DIODE, A NODAL POINT CONNECTED BETWEEN SAID FIRST DIODE, A CONSTANT VOLTAGE SOURCE AND SAID SECOND DIODE FOR PASSING SAID REFERENCE VOLTAGE WHEN SAID REFERENCE VOLTAGE IS OF A LOWER POTENTIAL THAN SAID SINGLE INPUT VOLTAGE, AN OUTPUT SIGNAL GENERATOR CONNECTED TO SAID NODAL POINT FOR DETECTING AN EQUALITY CONDITION BETWEEN SAID SINGLE INPUT VOLTAGE AND SAID REFERENCE VOLTAGE AND PROVIDING AN OUTPUT UPON SAID EQUALITY CONDITION DETECTION, SAID OUTPUT SIGNAL GENERATOR COMPRISING A CAPACITIVELY COUPLED, NONLINEAR CONDUCTIVE ELEMENT CONNECTED TO AN OUTPUT TRANSISTOR.