Temperature compensated reference voltage circuit

• US 6,512,412 B2
• Filed: 02/16/1999
• Issued: 01/28/2003
• Est. Priority Date: 02/16/1999
• Status: Expired due to Term

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Casper, Stephen L.
• Primary Examiner(s): Callahan, Timothy P.
• Assistant Examiner(s): Luu, An T.
• Application Number:
  US09/250,592
• Publication Number:
  US 20020014913A1
• Time in Patent Office: 1,442 Days
• Field of Search: 327/512, 327/513, 327/378, 327/538, 327/539, 327/540, 327/541, 327/543, 326/33, 326/34, 323/313, 323/315, 323/316
• US Class Current: 327/538
• CPC Class Codes: H03F 1/301 in MOSFET amplifiers H03F1/303, H03F1/305, H03F1/308 take precedence

Abstract

An integrated circuit voltage regulator compensates for temperature variations by adjusting a gain of an amplifier. In one embodiment, the gain is controlled by a voltage divider circuit comprised of a first resistor having a first temperature coefficient, and a second resistor having a second temperature coefficient which is different from the first coefficient. In one embodiment, the first resistor is a p-channel transistor and the second resistance is fabricated from integrated circuit active area.

Claims

1. An integrated circuit voltage regulator comprising:

an amplifier having a first input coupled to receive an input voltage, a second input, and an output node having an output voltage, wherein the input voltage decreases as temperature increases and increases as temperature decreases; and

a gain adjust circuit connected to the amplifier for adjusting a gain of the amplifier, the gain adjust circuit including a nonlinear device and a linear device coupled in series;

wherein the linear device is a resistor having a first terminal and a second terminal;

wherein the nonlinear device is a transistor including a gate, a drain and a source, one of the source and the drain of the transistor being connected to the first terminal of the resistor, the other of the source and the drain of the transistor being connected to the output node of the amplifier circuit, the gate being connected to ground;

wherein the first terminal of the resistor is connected to the second input of the amplifier; and

wherein the nonlinear device defines a first temperature-dependent resistance, wherein the linear device defines a second temperature-dependent resistance, the first temperature-dependent resistance changes at a greater rate than the second temperature-dependent resistance changes whereby the temperature effect of the input voltage is minimized by the gain adjust circuit when producing the output voltage.

2. The circuit of claim 1, wherein the first temperature-dependent resistance changes at twice the rate of the second temperature-dependent resistance over a same temperature range.

3. The circuit of claim 1, wherein the first temperature-dependent resistance changes at rate of 10% and the second temperature-dependent resistance changes at a rate of 5% over a same temperature range.

4. The integrated circuit voltage regulator of claim 1, wherein the output voltage is an internal reference voltage in an integrated circuit.

5. The integrated circuit voltage regulator of claim 4, wherein the internal reference voltage is in a DRAM.

6. The integrated circuit voltage regulator of claim 4, wherein the internal reference voltage is Vccr.

7. The integrated circuit voltage regulator of claim 1, wherein the second terminal of the resistor is connected to ground.

8. The integrated circuit voltage regulator of claim 1, wherein the nonlinear transistor is a long L transistor.

9. The integrated circuit voltage regulator of claim 8, wherein the nonlinear transistor is a p-channel transistor.

10. The integrated circuit voltage regulator of claim 8, wherein the nonlinear transistor is a large source-drain current transistor.

11. An integrated circuit for producing, from an input voltage, an essentially constant reference voltage having minimized temperature effects, comprising:

an amplifier including a first input coupled to receive an input voltage, a second input, and an output node having an output voltage, wherein the input voltage decreases as temperature increases and increases as temperature decreases; and

a gain adjust circuit connected to the amplifier for adjusting a gain of the amplifier, the gain adjust circuit including a nonlinear, long-L p-channel transistor and an active area resistor, wherein the resistor includes a first terminal and a second terminal, wherein the transistor includes a source, a drain and a gate, wherein one of the source and the drain is connected to the output node, wherein the other of the source and the drain is connected to both the first terminal and the second input, wherein the gate is connected to ground, wherein the second terminal is connected to ground, and wherein a source-to-drain resistance of the transistor changes as a function of temperature more than a resistance of the active area resistor whereby the effects of temperature on the output voltage are minimized.