Patent ID: 6903989
Filing Date: 2005-06-07
Classification: G11C

Abstract:
1. A data sensing circuit for a magnetic memory cell, comprising: a current source circuit that selectively supplies a current to the magnetic memory cell; a first storage device selectively coupled to the magnetic memory cell that is configured to store a voltage representing a state of the magnetic memory cell; a second storage device selectively coupled to the magnetic memory cell that is configured to store a voltage representing a state of the magnetic memory cell; a differential voltage sense circuit coupled to the first and second storage devices that generates a sensed data output signal for the magnetic memory cell responsive to sensing a difference between voltages stored in the first and second storage devices; and a control circuit that generates control signals to control the current source to supply current to the magnetic memory cell and to control the coupling of the first and second storage devices to the magnetic memory cell; wherein the current source circuit is configured to selectively apply a first current or a second current different from the first current responsive to a control signal from the control circuit and wherein the current source circuit comprises: a plurality of transistors having serially connected current paths and gates connected to receive a first control signal; a first transistor having a gate connected to receive a second control signal; a second transistor coupled to the plurality of transistors and the first transistor; a third transistor coupled to the magnetic memory cell having a gate coupled to a gate and a drain of the second transistor; and wherein the first current or the second current is selected by selective activation of the first and second control signal.