Motorola Corporation

Yangming Su

Bruce L Morton

Kuo-Tung Chang

A non-linear charge pump (1120) provides various voltages for use in a nonvolatile memory (400) and operates at low power supply voltages. The non-linear charge pump (1120) includes at least two non-linear voltage doubling stages (1132, 1134), which allows a capacitor formed with relatively thin gate oxide in a first stage (1132) to be made larger than a capacitor formed using relatively thick gate oxide in a second stage (1134). An output of a last voltage doubling stage (1136) is then input to a linear stage (1150) to generate a precise voltage. Another charge pump (1140) including non-linear stages (1142, 1144) followed by a linear stage (1146) is used to generate a reference voltage for the main non-linear charge pump (1130). The nonlinear stage (1130) includes a special bulk biasing circuit to bias the bulk of a transistor (1285) on the output side of the charging circuit (1284, 1285, 1286, 1287) continuously to prevent forward biasing the parasitic drain-bulk diode.

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Cedar Park, TX, United States of America

Yangming Su