Programmable analog bias circuits using floating gate CMOS technology
First Claim
1. An integrated circuit (IC) comprising:
- a first transistor comprising a first floating gate and a first control gate;
a second transistor comprising a second floating gate and a second control gate, the second floating gate being electrically connected to the first floating gate; and
a third transistor comprising a first gate and a second gate located over the first gate, the first gate being electrically connected to the second gate; and
an input terminal, wherein a drain of the first transistor, a drain of the third transistor and the second gate of the third transistor are each coupled to the input terminal.
8 Assignments
0 Petitions
Accused Products
Abstract
A voltage reference circuit includes storage, programming, and test floating gate transistors. The floating gates of the storage and programming transistors are shorted, while the floating and control gates of the test transistor are shorted. The test and storage transistors are connected between an input terminal and the inputs of a comparator, with the control gate of the test transistor also being connected to the input terminal. A reference voltage is programmed by applying the reference voltage to the input terminal and increasing the net positive charge on the floating gate of the storage transistor (via the programming transistor) until its source voltage matches the source voltage of the test transistor. Then, any test voltage at the input terminal can be compared to the programmed reference voltage by comparing the source voltages of the test and storage transistors.
38 Citations
30 Claims
-
1. An integrated circuit (IC) comprising:
-
a first transistor comprising a first floating gate and a first control gate; a second transistor comprising a second floating gate and a second control gate, the second floating gate being electrically connected to the first floating gate; and a third transistor comprising a first gate and a second gate located over the first gate, the first gate being electrically connected to the second gate; and an input terminal, wherein a drain of the first transistor, a drain of the third transistor and the second gate of the third transistor are each coupled to the input terminal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
-
-
10. A method for creating a reference voltage circuit, the method comprising:
-
forming a first transistor having a first floating gate and a first control gate; forming a second transistor having a second floating gate and a second control gate; electrically connecting the second floating gate to the first floating gate; forming a third transistor having a first gate and a second gate located over the first gate; electrically connecting the first gate to the second gate; and electrically connecting a drain of the first transistor, a drain of the third transistor and the second gate. - View Dependent Claims (11, 12, 13, 14)
-
-
15. A voltage reference circuit comprising:
-
an input terminal; a first transistor having a first floating gate; a second transistor having a first gate and a second gate located over the first gate, the second gate being electrically connected to the input terminal and the first gate; and a comparator, wherein the first transistor is connected between the input terminal and a first input of the comparator, and wherein the second transistor is connected between the input terminal and a second input of the comparator. - View Dependent Claims (16, 17, 18, 19, 20, 21)
-
-
22. A method for comparing a test voltage to a reference voltage, the method comprising:
-
providing a charge on a floating gate of a first transistor, the charge being sized such that applying a first voltage to a control gate of the first transistor results in a source voltage of the first transistor being equal to a source voltage of a second transistor when the reference voltage is applied to a gate of the second transistor; applying the first voltage to the control gate of the first transistor; supplying the test voltage to the floating gate of the second transistor; supplying the test voltage to a drain of the first transistor and to a drain of the second transistor; and comparing the source voltage of the first transistor to the source voltage of the second transistor, effectively comparing the test voltage to the reference voltage as represented by the charge provided on the floating gate. - View Dependent Claims (23, 24)
-
-
25. A method for programming a reference voltage into a storage transistor, the method comprising:
-
providing a programming potential across a first transistor to generate a net charge on a floating gate of the first transistor; providing a second transistor, wherein a floating gate of the second transistor is connected to the floating gate of the first transistor; supplying the reference voltage to a first gate of a third transistor, wherein the first gate of the third transistor is located over, and is electrically connected to a second gate of the third transistor; supplying the reference voltage to a drain of the second transistor and to a drain of the third transistor; and removing the programming potential across the first transistor when an output of the second transistor becomes equal to an output of the third transistor, wherein the second transistor functions as the storage transistor which effectively stores the programmed reference voltage. - View Dependent Claims (26)
-
-
27. A method for comparing a test voltage to a reference voltage, the method comprising:
-
providing a first transistor having a first terminal coupled to a test voltage input terminal, a second terminal, a floating gate, and a control gate, providing a second transistor having a first terminal coupled to the test voltage input terminal, a second terminal, a first gate, and a second gate located over the first gate, wherein the first gate of the second transistor is electrically connected to the second gate of the second transistor; providing a charge on the floating gate of the first transistor, the charge being sized such that when a first voltage is applied to the control gate of the first transistor, an output at the second terminal of the first transistor is equal to an output at the second terminal of the second transistor when the reference voltage is applied to the second gate of the second transistor; applying the first voltage to the control gate of the first transistor; supplying the test voltage via the test voltage input terminal; and comparing the output at the second terminal of the first transistor to the output at the second terminal of the second transistor, effectively comparing the test voltage to the reference voltage as represented by the charge provided on the floating gate. - View Dependent Claims (28, 29, 30)
-
Specification