Trim circuit and method for tuning a current level of a reference cell in a flash memory
AssigneeMacronix International Co., Ltd.
InventorsChih-Chieh Yeh, Tso-Hung Fan, Tao-Cheng Lu
Life of this patent
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Abstract
A trim circuit and method for tuning a current level of a reference cell in a flash memory that includes a sense amplifier to compare a cell current from a memory cell whose gate receives a word line signal voltage with a reference current from the reference cell whose gate receives a bias voltage produced by dividing the word line signal voltage by a voltage divider to thereby produce a sense signal. The voltage divider includes at least a programmable flash cell to serve as a variable resistor whose resistance is determined by programming the programmable flash cell by a programming/erasing circuit in reference to the programming of the memory cell.
Claims6
A trim circuit for tuning a current level of a reference cell in a flash memory including a sense amplifier for comparing a cell current from a memory cell having a gate for receiving a word line signal voltage with a reference current from the reference cell having a gate for receiving a bias voltage to produce a sense signal, the trim circuit comprising:
- a first and second units connected in series for producing the bias voltage by dividing the word line signal voltage with at least one of the first and second units having a programmable flash cell to serve as a variable resistor having a programmable resistance;
- and
- a programming circuit connected to the memory cell and flash cell for programming the programmable flash cell to thereby determine a value of the programmable resistance.
A trim method for tuning a current level of a reference cell in a flash memory including a sense amplifier for comparing a cell current from a memory cell having a gate for receiving a word line signal voltage with a reference current from the reference cell having a gate for receiving a bias voltage to produce a sense signal, the trim method comprising the steps of:
- programming a programmable flash cell to thereby determine a resistance thereof;
- connecting the programmable flash cell to a resistor in series to thereby form a voltage divider;
- and
- dividing the word line signal voltage by the voltage divider to thereby produce the bias voltage.
Dependencies are inferred from the claim text.