Patent ID: 8472236
Filing Date: 2013-06-25
Classification: G11C

Abstract:
1. A method of testing a non-volatile latch circuit in an integrated circuit, the latch circuit comprising cross-coupled inverters driving first and second storage nodes, a first ferroelectric capacitor having a first plate coupled to the first storage node, and a second ferroelectric capacitor having a first plate coupled to the second storage node, the method comprising: setting the state of the latch circuit so that the first and second storage nodes are at low and high logic states, respectively; then polarizing the first and second ferroelectric capacitors to opposite polarization states, corresponding to the state of the latch circuit, by applying low and high bias voltages to a second plate of the first ferroelectric capacitor and a second plate of the second ferroelectric capacitor; then removing bias from the cross-coupled inverters of the latch circuit; then biasing the second plate of the first ferroelectric capacitor to a first bias voltage, and biasing the second plate of the second ferroelectric capacitor to a second bias voltage, the second bias voltage lower than the first bias voltage by a selected differential; then applying bias to the cross-coupled inverters of the latch circuit; and then reading the state of the latch circuit.