Memory sense amplifier inherently tolerant of large input disturbances

Claim 2

An amplifier, comprising input terminals, a capacitor, a balanced output circuit including difference voltage output terminals, two transistors of opposite conductivity types each having a base connected to a respective input terminal, an emitter connected to a respective terminal of said capacitor, and a collector connected to a respective side of said balanced output circuit, bias and current source means to make said transistors normally conductive, to charge said capacitor, to supply substantially constant currents to said output circuit, and to provide a substantially zero voltage at said difference voltage output terminals, whereby a large disturbing change in input voltage in a direction to cause increased conduction in said transistors causes an additional current surge from said capacitor to said balanced output circuit, and a clamp diode in said output circuit which is poled to conDuct said current surge and limit the resulting difference voltage at the output terminals.

Claim 3

A sense amplifier useful in a memory in which the application of a selection drive current to a memory line causes large voltage changes from plus and minus power supply voltage levels to low voltage levels, after which there appears a small differential information signal to be sensed, comprising a capacitor, a balanced output circuit including difference voltage output terminals, two transistors of opposite conductivity types each having a base connected to a respective end of said memory line, an emitter connected to respective terminals of said capacitor, and a collector connected to a respective side of said balanced output circuit, bias and current source means to make said transistors normally conductive, to charge said capacitor, to supply substantially constant currents to said output circuit, and to provide a substantially zero voltage at said difference voltage output terminals, whereby the application of a selection drive current to the memory line results in large reductions in base voltages, which causes said transistors to conduct an additional current surge from said capacitor to said balanced output circuit, and a clamp diode in said output circuit which is poled to conduct said current surge and limit the resulting difference voltage at the output terminals, whereafter the capacitor is discharged, the transistor conductions return to normal values, and the output difference voltage returns to near zero, and then the occurrence of an information signal to be sensed at the bases of the transistors results in an amplified information signal at the difference voltage output terminals.

Claim 4

A sense amplifier useful in a memory in which the application of a selection drive current to a memory line causes large voltage changes from plus and minus power supply voltage levels to low voltage levels, after which there appears a small differential information signal to be sensed, comprising a capacitor, a balanced output circuit including difference voltage output terminals, two transistors of opposite conductivity types each having a base connected to a respective end of said memory line, an emitter connected to respective terminals of said capacitor, and a collector connected to a respective side of said balanced output circuit, bias and current source means to make said transistors normally conductive, to charge said capacitor, to supply substantially constant currents to said output circuit, and to provide a substantially zero voltage at said difference voltage output terminals, whereby the application of a selection drive current to the memory line results in large reductions in base voltages, which causes said transistors to conduct an additional current surge from said capacitor to said balanced output circuit, and a clamp diode in said output circuit which is poled to conduct said current surge and limit the resulting difference voltage at the output terminals, whereafter the capacitor is discharged, the transistor conductions return to normal values, and the output difference voltage returns to near zero, and then the occurrence of an information signal to be sensed at the bases of the transistors results in an amplified information signal at the difference voltage output terminals.

Claim 5

An amplifier, comprising differential input terminals receptive to a disturbing high potential followed by a relatively small signal to be amplified, capacitor means, a balanced output circuit, two transistors of opposite conductivity types each having a base connected to a respective input terminal, an emitter connected to said capacitor means, and a collector connected to a respective side of said balanced output circuit, two constant current sources each connected to the parallel combination of said capacitor means and the emitter-collector path of a respective transistor, said capacitor means maintaining relatively stable low potentials on said emitters which cut off the transistors during the presence of the high input potential on the bases, and allow the transistors to be conductive when the high input potential is removed, and clamp diode means in said output circuit which is poled to conduct a current surge passing through said transistors from said capacitor means when said high input potential is removed, so that the transistors are kept out of saturation, and so that the relatively stable potentials provided by the capacitor means to the emitters cause the amplifier to be quickly stabilized to linearly amplify the desired small input signal applied to the bases.

Claim 6

An amplifier, comprising differential input terminals receptive to a disturbing high potential followed by a relatively small signal to be amplified, capacitor means, a balanced output circuit, two transistors of opposite conductivity types each having a base connected to a respective input terminal, an emitter connected to said capacitor means, and a collector connected to a respective side of said balanced output circuit, two constant current sources each connected to the parallel combination of said capacitor means and the emitter-collector path of a respective transistor, said capacitor means maintaining relatively stable low potentials on said emitters which cut off the transistors during the presence of the high input potential on the bases, and allow the transistors to be conductive when the high input potential is removed, and clamp diode means in said output circuit which is poled to conduct a current surge passing through said transistors from said capacitor means when said high input potential is removed, so that the transistors are kept out of saturation, and so that the relatively stable potentials provided by the capacitor means to the emitters cause the amplifier to be quickly stabilized to linearly amplify the desired small input signal applied to the bases.