Sense amplifier with an integral logic function
First Claim
1. A sense amplifier with an integral logic function, comprising:
- input means, for providing a first difference signal in response to detecting a difference between a first input signal and a second input signal when a control signal coupled thereto is in a predetermined logic state, and for providing a second difference signal in response to detecting a difference between said second input signal and said first input signal when a complement of said control signal is in said predetermined logic state;
output means coupled to said input means, for providing an output signal in response to said first difference signal or said second difference signal; and
enabling means coupled to said input means, for enabling the sense amplifier in response to a select signal, comprising;
a first transistor having a first current electrode coupled to said first difference signal, a control electrode for receiving said select signal, and a second current electrode coupled to said second difference signal; and
a second transistor having a first current electrode coupled to said input means, a control electrode for receiving said select signal, and a second current electrode coupled to a first power supply voltage terminal.
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Accused Products
Abstract
A sense amplifier with an integral logic function for use in a circuit such as a tag cache portion of a microprocessor cache. In one form, the integral logic function is an exclusive-OR function. The sense amplifier senses a differential voltage developed between a differential pair of bit lines which are coupled to predetermined bit positions of a plurality of entries in a tag cache. While sensing the voltage, an exclusive-OR function is performed between the logic state of the sensed bit and a corresponding input address bit. If the input address bit matches the sensed bit, then a match signal is asserted. The value of the corresponding input address bit configures the circuit either to provide an output signal in a predetermined logic state if a true bit line signal voltage exceeds a complement bit line signal voltage, or to provide the output signal in the predetermined state if the complement bit line signal voltage exceeds the true bit line signal voltage.
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Citations
13 Claims
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1. A sense amplifier with an integral logic function, comprising:
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input means, for providing a first difference signal in response to detecting a difference between a first input signal and a second input signal when a control signal coupled thereto is in a predetermined logic state, and for providing a second difference signal in response to detecting a difference between said second input signal and said first input signal when a complement of said control signal is in said predetermined logic state; output means coupled to said input means, for providing an output signal in response to said first difference signal or said second difference signal; and enabling means coupled to said input means, for enabling the sense amplifier in response to a select signal, comprising; a first transistor having a first current electrode coupled to said first difference signal, a control electrode for receiving said select signal, and a second current electrode coupled to said second difference signal; and a second transistor having a first current electrode coupled to said input means, a control electrode for receiving said select signal, and a second current electrode coupled to a first power supply voltage terminal. - View Dependent Claims (2, 3)
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4. In a data processor having means for storing data, a circuit comprising:
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first and second input transistors respectively having first current electrodes coupled to a virtual ground node, and respectively receiving first and second signals on control electrodes thereof; a third transistor having a first current electrode coupled to a second current electrode of said first transistor, a control electrode, and a second current electrode coupled to a positive power supply voltage terminal; a fourth transistor having a first current electrode coupled to a second current electrode of said second transistor, a control electrode coupled to said control electrode of said third transistor, and a second current electrode coupled to said positive power supply voltage terminal; and logic means coupled to said first, second, third, and fourth transistors, for coupling together said control electrode and said first current electrode of said third transistor in response to a complement of a control signal, and for coupling together said control electrode and said first current electrode of said fourth transistor in response to said control signal. - View Dependent Claims (5, 6)
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7. In a data processor having means for storing data, a method of simultaneously performing a logic function and a compare operation in a single circuit comprising the steps of:
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enabling the circuit for operation; making conductive either a first input transistor receiving a first input signal, or a a second input transistor receiving a second input signal, first current electrodes of said first and second transistors each coupled to a negative power supply voltage terminal when the circuit is enabled; selectively coupling second current electrodes of said first and second input transistors substantially to a positive power supply voltage terminal in response to first and second control signals, respectively; and providing an output signal either in response to a difference between said first input signal and said second input signal if said first control signal assumes a predetermined logic state, or in response to a difference between said second input signal and said first input signal if said second control signal assumes said predetermined logic state.
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8. A sense amplifier with an integral logic function, comprising:
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first and second transistors each having a first current electrode coupled to a virtual ground node, and a control electrode for receiving first and second signals, respectively, each transistor having a second current electrode respectively coupled to first and second nodes; and means coupled to said second current electrodes of said first and second transistors, for selectively mirroring either a current conducted through said second transistor into said first node, or a current conducted through said first transistor into said second node, respectively in response to a control signal and a complement of said control signal. - View Dependent Claims (9, 10, 11, 12, 13)
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Specification