Texas Instruments Corporation

Michael V Ho

Duy-Loan T Le

Scott E Smith

Kenneth A Poteet

An oscillator (108) for a standby charge pump (102,104)in a dynamic random access memory part (30) includes a fuse (136). The fuse can be blown after testing the part while selecting redundant memory cells to reduce the frequency of the oscillator and obtain a lower power part. The oscillator (108) also drives the on-chip self-refresh circuits (106) that operate slower in response to the reduced frequency. Selecting redundant circuits also includes eliminating memory cells that pass the pause test, but by only a certain margin. Reducing the frequency of the oscillator driving the self-refresh circuits would otherwise cause failure of the cells that pass the pause test by only the certain margin. The oscillator circuit includes a ring of inverter stages (112) and a fused voltage bias circuit (110) generating one or another set of bias voltages (118,120) to the ring oscillator to alter its frequency of oscillation.

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Michael V Ho