Reference voltage generator for temperature sensor with trimming capability at two temperatures

• US 9,541,456 B2
• Filed: 02/07/2014
• Issued: 01/10/2017
• Est. Priority Date: 02/07/2014
• Status: Active Grant

• Current Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Original Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Inventors: Matsumoto, Masahide, Yamashita, Ryuji
• Primary Examiner(s): Jagan, Mirellys
• Application Number:
  US14/175,226
• Publication Number:
  US 20150226614A1
• Time in Patent Office: 1,068 Days
• Field of Search: 374/170, 374/163, 327/513
• US Class Current: 1/1
• CPC Class Codes: G01K 13/00 Thermometers specially adapted for specific purposes
• CPC Class Codes: G01K 15/005 Calibration
• CPC Class Codes: G01K 2215/00 Details concerning sensor power supply
• CPC Class Codes: G01K 2219/00 Thermometers with dedicated analog to digital converters
• CPC Class Codes: G01K 7/00 Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat giving results other than momentary value of temperature G01K3/00 ; Power supply therefor, e.g. using thermoelectric elements
• CPC Class Codes: G01K 7/01 using semiconducting elements having PN junctions G01K7/02, G01K7/16, G01K7/30 take precedence
• CPC Class Codes: G05F 3/245 producing a voltage or current as a predetermined function of the temperature
• CPC Class Codes: G11C 16/06 Auxiliary circuits, e.g. for writing into memory
• CPC Class Codes: G11C 7/04 with means for avoiding disturbances due to temperature effects
• CPC Class Codes: H03M 1/12 Analogue/digital converters H03M1/001 – H03M1/10 take precedence
• CPC Class Codes: H03M 1/38 sequentially only, e.g. successive approximation type converting more than one bit per step H03M1/14
• CPC Class Codes: H03M 7/165 Conversion to or from thermometric code

Abstract

A temperature sensor circuit has a reference voltage generator that is trimmable at two temperatures for increased accuracy. The reference voltage generation section generates a reference voltage, the level of which is trimmable. A voltage divider section is connected to receive the reference voltage from the reference voltage generation section and generate a plurality of comparison voltage levels determined by the reference voltage and a trimmable resistance. An analog-to-digital converter can then be connected to a temperature dependent voltage section to receive the temperature dependent output voltage, such as a proportional to absolute temperature type (PTAT) behavior, and connected to the voltage divider section to receive the comparison voltage levels. The analog to digital converter generates an output indicative of the temperature based upon a comparison of the temperature dependent output voltage to the comparison voltage levels.

Claims

1. A temperature sensor circuit comprising:

a temperature dependent voltage section providing an output voltage having a linear type dependence on temperature;

a reference voltage generation section generating a reference voltage, wherein the level of the reference voltage is trimmable at a first temperature value in a first trimming process;

a voltage divider section connected to receive the reference voltage from the reference voltage generation section and generate therefrom a plurality of comparison voltage levels having a first level determined by the reference voltage and a second level dependent upon a first trimmable resistance, the second level being lower than the first, where the first trimmable resistance is trimmable at a second temperature value in a second trimming process that is separate from the first trimming process; and

an analog to digital converter connected to the temperature dependent voltage section to receive the temperature dependent output voltage and connected to the voltage divider section to receive the comparison voltage levels, wherein the analog to digital converter generates an output indicative of the temperature based upon a comparison of the temperature dependent output voltage to the comparison voltage levels.

2. The temperature sensor circuit of claim 1, wherein the output voltage of the temperature dependent voltage section has a proportional to absolute temperature type behavior.

3. The temperature sensor circuit of claim 1, wherein the output voltage of the temperature dependent voltage section has an inverse proportional to absolute temperature type behavior.

4. The temperature sensor circuit of claim 1, wherein the temperature dependent voltage section'"'"'s output voltage is generated using a band gap circuit.

5. The temperature sensor circuit of claim 1, where the analog to digital converter is a flash-type analog to digital converter.

6. The temperature sensor circuit of claim 1, where the analog to digital converter is a successive approximation type analog to digital converter.

7. The temperature sensor circuit of claim 1, wherein the temperature sensor circuit is formed as part of non-volatile memory circuit having a flash NAND type of structure for a memory array formed thereon.

8. The temperature sensor circuit of claim 1, wherein the temperature sensor circuit is formed as part of non-volatile memory circuit having a 3D type of structure for a memory array formed thereon.

9. The temperature sensor circuit of claim 1, wherein the voltage divider section includes a set of series connected elements connected between a supply level and ground, including:

a first transistor whose gate voltage is based on the reference voltage;

the first trimmable resistance; and

a plurality of resistances connected in series, where the series of resistances is connected to the supply level through the first transistor and connected to ground through the first trimmable resistance, and wherein the comparison voltage levels are taken from nodes between the elements of the set of series connected elements.

10. The temperature sensor circuit of claim 9, wherein the reference voltage generation section includes:

an op-amp having a first input connected to receive an additional reference level, a second input, and an output; and

a PMOS transistor, a second trimmable resistance, and a fixed resistance connected in series between the supply level and ground,

wherein the second input of the op-amp is connected to a node between the second trimmable resistance and the fixed resistance, and the gate of the PMOS transistor is connected to the output of the op-amp.

11. The temperature sensor circuit of claim 9, wherein the first transistor is a first PMOS transistor.

12. The temperature sensor circuit of claim 11, wherein the voltage divider section further includes:

an op-amp having a first input connected to receive the reference voltage, a second input connected to a node of the set of series connected elements, and an output connected to the gate of the first PMOS transistor.