Frequency control circuit for oscillator and method therefor
First Claim
1. A frequency control circuit for an oscillator, comprising:
- a flash cell having a cell transistor;
a switching unit for outputting a first voltage to the flash cell in a program mode according to an enable signal and outputting a second voltage in a read mode;
a write driver for outputting a program voltage to the flash cell in the program mode according to the enable signal;
a bias unit for supplying a current to the flash cell in the read mode according to the enable signal and generating a frequency control voltage which is proportional to a threshold voltage of the flash cell; and
an oscillator for varying an oscillation frequency based on the frequency control voltage.
2 Assignments
0 Petitions
Accused Products
Abstract
A frequency control circuit for an oscillator and a method therefor are disclosed and which frequency control circuit includes a flash cell having a cell transistor, a switching unit for outputting a first voltage to the flash cell in the program mode in accordance with an enable signal and outputting a second voltage in the read mode, a write driver for outputting a program voltage to the flash cell in the program mode in accordance with the enable signal, a bias unit for supplying a current to the flash cell in the read mode in accordance with the enable signal and generating a frequency control voltage which is proportional to a threshold voltage of the flash cell, and an oscillator for varying the frequency in accordance with the thusly generated frequency control voltage.
7 Citations
26 Claims
-
1. A frequency control circuit for an oscillator, comprising:
-
a flash cell having a cell transistor; a switching unit for outputting a first voltage to the flash cell in a program mode according to an enable signal and outputting a second voltage in a read mode; a write driver for outputting a program voltage to the flash cell in the program mode according to the enable signal; a bias unit for supplying a current to the flash cell in the read mode according to the enable signal and generating a frequency control voltage which is proportional to a threshold voltage of the flash cell; and an oscillator for varying an oscillation frequency based on the frequency control voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
-
-
14. In an oscillator circuit of a flash memory having an oscillator frequency control circuit which varies the frequency of an oscillator based on a frequency control voltage, wherein the frequency control circuit comprises:
-
a flash cell having a cell transistor; a switching unit for outputting a first voltage for varying a threshold voltage of the cell transistor in a program mode and outputting a second voltage in a read mode; a write driver for outputting a program voltage to the drain of the cell transistor in the program mode; and a bias unit for supplying a current to the flash cell in the read mode and generating a frequency control voltage which is proportional to a threshold voltage of the flash cell. - View Dependent Claims (15, 16, 17, 18)
-
-
19. A frequency control circuit for an oscillator, comprising:
-
a flash cell having a cell transistor; a switching unit for outputting a first voltage to the flash cell in a program mode; a write driver for outputting a second voltage to the flash cell in the program mode; a bias unit for supplying a current to the flash cell in a read mode of the flash cell and generating a frequency control voltage proportional to the threshold voltage of a flash cell; and an oscillator for varying the frequency based on the generated frequency control voltage. - View Dependent Claims (20, 21, 22)
-
-
23. A frequency control method for an oscillator circuit, said the oscillator circuit varies a frequency control voltage based on a threshold voltage of a flash cell and varies the frequency of an oscillator based on the varied frequency control voltage, said method comprising the steps of:
-
measuring a oscillation frequency of an oscillator by performing a read operation of the flash cell; comparing the measured frequency with a reference frequency; varying the threshold voltage of the cell transistor by outputting first and second voltages to the gate and drain of the cell transistor when two frequencies are not identical; measuring the oscillation frequency of the oscillator according to a frequency control voltage set based on the varied threshold voltage by performing a read operation of the flash cell; and repeating the above-described steps until the measured frequency and reference frequency become identical.
-
- 24. The method of 23, wherein the first voltage is a boosted voltage, and the second voltage is a program voltage.
Specification