Temperature sensing circuit and temperature detecting method

Application No. 18/420,785

• Filed: Jan 24, 2024
• Examiner: LIN, ERICA S Y
• Art Unit: 2853
• Tech Center: 2800 — Semiconductors & Electrical Systems
• Assignee: Pixart Imaging Inc.
• OA Round: 1 (Non-Final)

Office Action

DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Election/Restrictions
Applicant’s election without traverse of Invention I, Species Group B in the reply filed on March 30, 2026, is acknowledged. The amendment of claim 9; withdrawal of claims 11-15; and cancellation of claims 19-20, is acknowledged.
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.

Claims 1-10 and 16-18 are rejected under 35 U.S.C. 103 as being unpatentable over U.S. Patent Pub. 2021/0376718 (“Kaufmann”) in view of U.S. Patent Pub. 2017/0016776 (“Excelio”).
Claim 1
Kaufmann discloses a temperature sensing circuit, comprising: a first current source configured to provide a first current, the first current being constant within a temperature range to be detected by the temperature sensing circuit (first current source 318); a second current source configured to provide a second current, the second current being proportional to an absolute temperature within the temperature range (second current source 330); a third current source configured to provide a third current, the third current being constant within the temperature range (third current source 324); a first capacitor coupled to the first current source and a reference voltage (capacitor 244); a second capacitor coupled to the second current source and the reference voltage (capacitor 334); a third capacitor coupled to the third current source and the reference voltage (capacitor 336); a first switch coupled in parallel with the first capacitor (paragraph [0119], first switch); a second switch coupled in parallel with the second capacitor (paragraph [0119], second switch); a third switch coupled in parallel with the third capacitor (paragraph [0119], third switch); a first sensing amplifier having a first input coupled to the second current source and the second capacitor, and a second input coupled to the third current source and the third capacitor (paragraph [0064]).
Kaufmann does not appear to explicitly disclose a second sensing amplifier having a first input coupled to the first current source and the first capacitor, and a second input coupled to the third current source and the third capacitor; an XOR gate having a first input coupled to an output of the first sensing amplifier, and a second input coupled to an output of the second sensing amplifier; and a counter configured to sample an output signal outputted from the XOR gate according to a clock signal.
Excelio discloses a time temperature sensor including a second sensing amplifier, second input, xor gate, and counter (paragraph [0033, 0048]).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have incorporated additional components sensor including a second sensing amplifier, second input, xor gate, and counter, as disclosed by Excelio, into the device of Kaufmann, such to include a second sensing amplifier having a first input coupled to the first current source and the first capacitor, and a second input coupled to the third current source and the third capacitor; an XOR gate having a first input coupled to an output of the first sensing amplifier, and a second input coupled to an output of the second sensing amplifier; and a counter configured to sample an output signal outputted from the XOR gate according to a clock signal, for the purpose of providing higher precision signals (Excelio, paragraphs [0033, 0049]).

Claim 2
Kaufmann in view of Excelio discloses the temperature sensing circuit of claim 1, wherein the first capacitor is charged within a first time duration to provide a first voltage at one end of the first capacitor at an end of the first time duration; wherein the second capacitor is charged within the first time duration to provide a second voltage at one end of the second capacitor at the end of the first time duration; and wherein the third capacitor is charged within a second time duration after the first time duration to pull up a third voltage at one end of the third capacitor (Kaufmann, paragraphs [0060-0061]).

Claim 3
Kaufmann in view of Excelio discloses the temperature sensing circuit of claim 2, further comprising a microcontroller configured to determine a temperature according to a count of samples of the output signal sampled by the counter during a time duration between a time when the third voltage exceeds the first voltage and a time when the third voltage exceeds the second voltage (Kaufmann, paragraph [0050]).

Claim 4
Kaufmann in view of Excelio discloses the temperature sensing circuit of claim 1, further comprising: a first sinking current source coupled to the first current source, and configured to drain a first sinking current from the first current source so as to provide a first charge current to the first capacitor, wherein the first sinking current and the first charge current are less than the first current; a second sinking current source coupled to the second current source, and configured to drain a second sinking current from the second current source so as to provide a second charge current to the second capacitor, wherein the second sinking current and the second charge current are less than the second current; and a third sinking current source coupled to the third current source, and configured to drain a third sinking current from the third current source so as to provide a third charge current to the third capacitor, wherein the third sinking current and the third charge current are less than the third current (Kaufmann. Fig. 4).

Claim 5
Kaufmann in view of Excelio discloses the temperature sensing circuit of claim 4, wherein the first charge current charges the first capacitor within a first time duration to provide a first voltage at one end of the first capacitor at an end of the first time duration; wherein the second charge current charges the second capacitor within the first time duration to provide a second voltage at one end of the second capacitor at the end of the first time duration; and wherein the third charge current charges the third capacitor within a second time duration to pull up a third voltage at one end of the third capacitor (Kaufmann, paragraphs [0060-0067]).

Claim 6
Kaufmann in view of Excelio discloses the temperature sensing circuit of claim 5, further comprising a microcontroller configured to determine a temperature according to a count of samples of the output signal sampled by the counter during a time duration between a time when the third voltage exceeds the first voltage and a time when the third voltage exceeds the second voltage (Kaufmann, paragraph [0050]).

Claim 7
Kaufmann in view of Excelio discloses the temperature sensing circuit of claim 5, wherein the first current source, the second current source, the first sinking current source, and the second sinking current source are turned on and the third current source and the third sinking current source are turned off within the first time duration; and wherein the first current source, the second current source, the first sinking current source, and the second sinking current source are turned off and the third current source and the third sinking current source are turned on within the second time duration (Kaufmann, Fig. 4, timing diagram, paragraphs [0079-0080]).

Claim 8
Kaufmann in view of Excelio discloses the temperature sensing circuit of claim 4, wherein the first sinking current, the second sinking current, and the third sinking current are equal (Kaufmann, Fig. 4).

Claim 9
Kaufmann in view of Excelio discloses the temperature sensing circuit of claim 4, wherein the first sinking current source, the second sinking current source, and the third sinking current source form a current mirror (Excelio, paragraph [0051]).

Claim 10
Kaufmann in view of Excelio discloses the temperature sensing circuit of claim 1, further comprising a sinking current source coupled to the second current source, and configured to drain a sinking current from the second current source so as to provide a charge current to the second capacitor, wherein the sinking current and the charge current are less than the second current (Kaufmann, paragraph [0042]).

Claim 16
Kaufmann in view of Excelio discloses the temperature sensing circuit of claim 1, further comprising a microcontroller configured to determine a temperature according to a count of samples of the output signal sampled by the counter (Kaufmann, paragraph [0050]).

Claim 17
Kaufmann in view of Excelio discloses the temperature sensing circuit of claim 1, wherein the first current and the third current are equal (Kaufmann, paragraph [0073]).

Claim 18
Kaufmann in view of Excelio discloses the temperature sensing circuit of claim 1, wherein the first capacitor, the second capacitor and the third capacitor have equal capacitance (Kaufmann, Fig. 3, Vc2).
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to ERICA S Y LIN whose telephone number is [phone]. The examiner can normally be reached M-F 8-4, TW M,W.
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/ERICA S LIN/Primary Examiner, Art Unit 2853

Prosecution Timeline

• Jan 24, 2024: Application Filed
• Apr 23, 2026: Non-Final Rejection mailed — §103 (current)