Prosecution Insights
Last updated: April 19, 2026
Application No. 18/182,101

Switching Amplifier Circuits with Supply Tracking

Non-Final OA §102
Filed
Mar 10, 2023
Examiner
PINERO, JOSE E
Art Unit
2843
Tech Center
2800 — Semiconductors & Electrical Systems
Assignee
Apple Inc.
OA Round
2 (Non-Final)
89%
Grant Probability
Favorable
2-3
OA Rounds
3y 5m
To Grant
97%
With Interview

Examiner Intelligence

Grants 89% — above average
89%
Career Allow Rate
71 granted / 80 resolved
+20.8% vs TC avg
Moderate +8% lift
Without
With
+7.9%
Interview Lift
resolved cases with interview
Typical timeline
3y 5m
Avg Prosecution
32 currently pending
Career history
112
Total Applications
across all art units

Statute-Specific Performance

§103
40.4%
+0.4% vs TC avg
§102
55.4%
+15.4% vs TC avg
§112
4.3%
-35.7% vs TC avg
Black line = Tech Center average estimate • Based on career data from 80 resolved cases

Office Action

§102
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 . Information Disclosure Statement The information disclosure statement (IDS) submitted on 3/10/2023 is acknowledged. The submission is in compliance with the provisions of 37 CFR 1.97. Accordingly, the information disclosure statement is being considered by the examiner. Response to Arguments Applicant’s arguments, filed 11/14/2025, with respect to the rejection(s) of claim(s) 1 - 20 under 35 U.S.C. 102(a)(2) have been fully considered and are persuasive. Therefore, the rejection has been withdrawn. However, upon further consideration, a new ground(s) of rejection is made in view of Mortazavi. Claim Rejections - 35 USC § 102 The following is a quotation of the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action: A person shall be entitled to a patent unless – (a)(1) the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention. Claims 1-20 are rejected under 35 U.S.C. 102(a)(1) as being anticipated by Mortazavi (US 9209762 B1). Regarding Independent Claim 1, Mortazavi teaches, An apparatus (Fig. 1, 10), comprising: an input circuit (Fig. 1, 12) configured to: receive an input signal (Fig. 1, signal input at 12); and generate a buffered signal (Fig. 1, signal output at 12) using the input signal (Fig. 1, signal input at 12); a power supply circuit (Fig. 1, LDO1) configured to adjust, based on a magnitude of the buffered signal (Fig. 1, signal output at 12), a voltage level (Fig. 1, Vdd) of a driver power supply node (Fig. 1, Vdd node) over a first continuous range of voltages (Figs. 3A and 3B, Vdd); a ground supply circuit (Fig. 1, LDO2) configured to adjust, based on the magnitude of the buffered signal (Fig. 1, signal output at 12), a voltage level (Fig. 1, Vss) of a driver ground supply node (Fig. 1, Vss node) over a second continuous range of voltages (Figs. 3A and 3B, Vss); and a switching amplifier circuit (Fig. 1, 14, N1, and N2) configured to generate an amplified version of the buffered signal (Fig. 1, signal output of 14, N1, and N2) that switches between the voltage level of the driver power supply node and the voltage level of the driver ground supply node (See column 3, lines 48 – 59, “Switching transistors N1 and N2 alternatively conduct to generate an output signal that is filtered by an inductor L1 and a capacitor C1, to provide a power audio output signal Audio Out. Power supply rail voltages VDD and VSS are provided to switching transistors N1 and N2 from the outputs of low-dropout regulators (LDOs) LDO1 and LDO2, respectively. In order to provide volume control in class-D power amplifier integrated circuit 10, the power supply rail voltages are varied by changing power supply control input signals CV1 and CV2 provided to reference voltage inputs of LDOs LDO1 and LDO2, which improves performance of class-D power amplifier integrated circuit 10.”). Regarding claim 2, The apparatus (Fig. 1, 10) of claim 1, wherein to adjust the voltage level (Fig. 1, Vdd) of the driver power supply node (Fig. 1, Vdd node) over the first continuous range of voltages (Figs. 3A and 3B, Vdd), the power supply circuit is further configured to increase the voltage level of the driver power supply node in response to a determination that the magnitude of the buffered signal has increased (Figs. 3A and 3B, Vdd and Vss both respectively increase or decrease in response to input signals CV1 and CV2. See column 3, lines 54 – 59, “In order to provide volume control in class-D power amplifier integrated circuit 10, the power supply rail voltages are varied by changing power supply control input signals CV1 and CV2 provided to reference voltage inputs of LDOs LDO1 and LDO2, which improves performance of class-D power amplifier integrated circuit 10.”). Regarding claim 3, The apparatus (Fig. 1, 10) of claim 1, wherein to adjust the voltage level (Fig. 1, Vss) of the driver ground supply node (Fig. 1, Vss node) over the second continuous range of voltages (Figs. 3A and 3B, Vss), the ground supply circuit is further configured to decrease the voltage level of the driver ground supply node relative to a ground reference (Figs. 3A and 3B, Vdd and Vss both respectively increase or decrease in response to input signals CV1 and CV2. See column 3, lines 54 – 59, “In order to provide volume control in class-D power amplifier integrated circuit 10, the power supply rail voltages are varied by changing power supply control input signals CV1 and CV2 provided to reference voltage inputs of LDOs LDO1 and LDO2, which improves performance of class-D power amplifier integrated circuit 10.”). Regarding claim 4, The apparatus (Fig. 1, 10) of claim 1, wherein to adjust the voltage level (Fig. 1, Vss) of the driver ground supply node (Fig. 1, Vss node) over the second continuous range of voltages (Figs. 3A and 3B, Vss), the ground supply circuit is further configured to increase the voltage level of the driver ground supply node relative to a ground reference (Figs. 3A and 3B, Vdd and Vss both respectively increase or decrease in response to input signals CV1 and CV2. See column 3, lines 54 – 59, “In order to provide volume control in class-D power amplifier integrated circuit 10, the power supply rail voltages are varied by changing power supply control input signals CV1 and CV2 provided to reference voltage inputs of LDOs LDO1 and LDO2, which improves performance of class-D power amplifier integrated circuit 10.”). Regarding claim 5, The apparatus (Fig. 1, 10) of claim 1, wherein to adjust the voltage level (Fig. 1, Vdd) of the driver power supply node (Fig. 1, Vdd node) over the first continuous range of voltages (Figs. 3A and 3B, Vdd), the power supply circuit is further configured to decrease the voltage level of the driver power supply node in response to a determination that the magnitude of the buffered signal has decreased (Figs. 3A and 3B, Vdd and Vss both respectively increase or decrease in response to input signals CV1 and CV2. See column 3, lines 54 – 59, “In order to provide volume control in class-D power amplifier integrated circuit 10, the power supply rail voltages are varied by changing power supply control input signals CV1 and CV2 provided to reference voltage inputs of LDOs LDO1 and LDO2, which improves performance of class-D power amplifier integrated circuit 10.”). Regarding claim 6, The apparatus (Fig. 1, 10) of claim 1, wherein to generate the amplified version of the buffered signal (Fig. 1, signal output of 14, N1, and N2), the switching amplifier circuit (Fig. 1, 14, N1, and N2) is configured to: generate a series of pulses (Fig. 3A and 3B, 14 generates pulse signals to N1 and N2. See column 3, lines 45 – 48, “…Class D Amplifier/Gate driver circuit 14 receives audio input signal Audio In and provides pulse-width modulated output gate control signals to the gates of switching transistors N1 and N2.”) that switch between the voltage level (Fig. 1, Vdd) of the driver power supply node (Fig. 1, Vdd node) and the voltage level (Fig. 1, Vss) of the driver ground supply node (Fig. 1, Vss node); and adjust respective widths of the series of pulses based on the magnitude of the buffered signal (See column 3, lines 48 – 51, “Switching transistors N1 and N2 alternatively conduct to generate an output signal that is filtered by an inductor L1 and a capacitor C1, to provide a power audio output signal Audio Out.”). Regarding independent claim 7, Mortazavi teaches, A method, comprising, receiving an input signal (Fig. 1, signal input at 12) by a switching amplifier circuit (Fig. 1, 14, N1, and N2) that is coupled to a driver power supply node (Fig. 1, Vdd node) and a driver ground supply node (Fig. 1, Vss node); adjusting, by a power supply circuit (Fig. 1, LDO1) and based on a magnitude of the input signal (Fig. 1, signal output at 12), a driver power supply voltage (Fig. 1, Vdd) of the driver power supply node (Fig. 1, Vdd) over a first continuous voltage range (Figs. 3A and 3B, Vdd); adjusting, by a ground supply circuit (Fig. 1, LDO2) and based on the magnitude of the input signal (Fig. 1, signal output at 12), a driver ground supply voltage (Fig. 1, Vss) of the driver ground supply node (Fig. 1, Vss node) over a second continuous voltage range (Figs. 3A and 3B, Vss); and generating, by the switching amplifier circuit (Fig. 1, 14, N1, and N2), an output signal (Fig. 1, output signal of 14, N1, and N2) that is an amplified version of the input signal (Fig. 1, signal output of 12) that switches between the driver power supply voltage and the driver ground supply voltage (See column 3, lines 48 – 59, “Switching transistors N1 and N2 alternatively conduct to generate an output signal that is filtered by an inductor L1 and a capacitor C1, to provide a power audio output signal Audio Out. Power supply rail voltages VDD and VSS are provided to switching transistors N1 and N2 from the outputs of low-dropout regulators (LDOs) LDO1 and LDO2, respectively. In order to provide volume control in class-D power amplifier integrated circuit 10, the power supply rail voltages are varied by changing power supply control input signals CV1 and CV2 provided to reference voltage inputs of LDOs LDO1 and LDO2, which improves performance of class-D power amplifier integrated circuit 10.”). Regarding claim 8, The method of claim 7, wherein adjusting the driver power supply voltage (Fig. 1, Vdd) includes increasing the driver power supply voltage in response to determining that the magnitude of the input signal has increased (Figs. 3A and 3B, Vdd and Vss both respectively increase or decrease in response to input signals CV1 and CV2. See column 3, lines 54 – 59, “In order to provide volume control in class-D power amplifier integrated circuit 10, the power supply rail voltages are varied by changing power supply control input signals CV1 and CV2 provided to reference voltage inputs of LDOs LDO1 and LDO2, which improves performance of class-D power amplifier integrated circuit 10.”). Regarding claim 9, The method of claim 7, wherein adjusting the driver ground supply voltage (Fig. 1, Vss) includes decreasing the driver ground supply voltage relative to a ground reference (Figs. 3A and 3B, Vdd and Vss both respectively increase or decrease in response to input signals CV1 and CV2. See column 3, lines 54 – 59, “In order to provide volume control in class-D power amplifier integrated circuit 10, the power supply rail voltages are varied by changing power supply control input signals CV1 and CV2 provided to reference voltage inputs of LDOs LDO1 and LDO2, which improves performance of class-D power amplifier integrated circuit 10.”). Regarding claim 10, The method of claim 7, wherein adjusting the driver ground supply voltage (Fig. 1, Vss) includes increasing the driver ground supply voltage relative to a ground reference (Figs. 3A and 3B, Vdd and Vss both respectively increase or decrease in response to input signals CV1 and CV2. See column 3, lines 54 – 59, “In order to provide volume control in class-D power amplifier integrated circuit 10, the power supply rail voltages are varied by changing power supply control input signals CV1 and CV2 provided to reference voltage inputs of LDOs LDO1 and LDO2, which improves performance of class-D power amplifier integrated circuit 10.”). Regarding claim 11, The method of claim 7, further comprising adjusting the driver ground supply voltage (Fig. 1, Vss) in phase with adjusting (See column 3, lines 54 – 59, “In order to provide volume control in class-D power amplifier integrated circuit 10, the power supply rail voltages are varied by changing power supply control input signals CV1 and CV2 provided to reference voltage inputs of LDOs LDO1 and LDO2, which improves performance of class-D power amplifier integrated circuit 10.”) the driver power supply voltage (Fig. 1, Vdd). Regarding claim 12, The method of claim 7, further comprising adjusting the driver ground supply voltage (Fig. 1, Vss) out-of-phase with the adjusting (See column 3, lines 54 – 59, “In order to provide volume control in class-D power amplifier integrated circuit 10, the power supply rail voltages are varied by changing power supply control input signals CV1 and CV2 provided to reference voltage inputs of LDOs LDO1 and LDO2, which improves performance of class-D power amplifier integrated circuit 10.”) the driver power supply voltage (Fig. 1, Vss). Regarding claim 13, The method of claim 7, wherein the input signal (Fig. 1, signal input at 12) includes a plurality of data packets (Fig. 1, Digital Volume In) encoded according to a communication protocol, and further comprising: translating, by a buffer circuit (Fig. 1, 12), the plurality of data packets to a plurality of words (Fig. 1, Digital Volume In gets translated into CV1 and CV2); adjusting, by the power supply circuit (Fig. 1, LDO1) using the plurality of words (Fig. 1, CV1), the driver power supply voltage (Fig. 1, Vdd); and adjusting, by the ground supply circuit (Fig. 1, LDO2) using the plurality of words (Fig. 1, CV2), the driver ground supply voltage (Fig. 1, Vss). Regarding independent claim 14, Mortazavi teaches, An apparatus, comprising: a supply tracking amplifier circuit (Fig. 1, 10) including a switching amplifier circuit (Fig. 1, 14, N1, and N2), wherein the supply tracking amplifier circuit (Fig. 1, 10) is configured to: receive an input signal (Fig. 1, signal input at 12); adjust, over a first continuous range of voltages (Figs. 3A and 3B, Vdd), a first magnitude of a first voltage level (Fig. 1, Vdd) of a driver power supply node (Fig. 1, Vdd node) based on a magnitude of the input signal (Fig. 1, signal output at 12); adjust, over a second continuous range of voltages (Figs. 3A and 3B, Vss), a second magnitude of a second voltage level (Fig. 1, Vss) of a driver ground supply node (Fig. 1, Vss node) based on the magnitude of the input signal (Fig. 1, signal output at 12); and generate an amplified signal (Fig. 1, signal output of 14, N1, and N2) based on the input signal (Fig. 1, signal input at 12), wherein the amplified signal switches (See column 3, lines 48 – 59, “Switching transistors N1 and N2 alternatively conduct to generate an output signal that is filtered by an inductor L1 and a capacitor C1, to provide a power audio output signal Audio Out. Power supply rail voltages VDD and VSS are provided to switching transistors N1 and N2 from the outputs of low-dropout regulators (LDOs) LDO1 and LDO2, respectively. In order to provide volume control in class-D power amplifier integrated circuit 10, the power supply rail voltages are varied by changing power supply control input signals CV1 and CV2 provided to reference voltage inputs of LDOs LDO1 and LDO2, which improves performance of class-D power amplifier integrated circuit 10.”) between the first voltage level (Fig. 1, Vdd) and the second voltage level (Fig. 1, Vss); and a speaker (Fig. 1, L1 and C1) configured to generate sounds waves (Fig. 1, Audio Out) using the amplified signal (Fig. 1, signal output at 14, N1, and N2. See column 3, lines 48 – 51, “Switching transistors N1 and N2 alternatively conduct to generate an output signal that is filtered by an inductor L1 and a capacitor C1, to provide a power audio output signal Audio Out.”). Regarding claim 15, The apparatus of claim 14, wherein to adjust the second magnitude of the second voltage level (Fig. 1, Vss) of the driver ground supply node (Fig. 1, Vss node), the supply tracking amplifier circuit (Fig. 1, 10) is further configured to increase the second voltage level of the driver ground supply node in response to a determination that the magnitude of the input signal has increased (Figs. 3A and 3B, Vdd and Vss both respectively increase or decrease in response to input signals CV1 and CV2. See column 3, lines 54 – 59, “In order to provide volume control in class-D power amplifier integrated circuit 10, the power supply rail voltages are varied by changing power supply control input signals CV1 and CV2 provided to reference voltage inputs of LDOs LDO1 and LDO2, which improves performance of class-D power amplifier integrated circuit 10.”). Regarding claim 16, The apparatus of claim 14, wherein to adjust the second magnitude of the second voltage (Fig. 1, Vss) of the driver ground supply node (Fig. 1, Vss node), the supply tracking amplifier circuit (Fig. 1, 10) is further configured to decrease the second voltage level of the driver ground supply node relative to a ground reference (Figs. 3A and 3B, Vdd and Vss both respectively increase or decrease in response to input signals CV1 and CV2. See column 3, lines 54 – 59, “In order to provide volume control in class-D power amplifier integrated circuit 10, the power supply rail voltages are varied by changing power supply control input signals CV1 and CV2 provided to reference voltage inputs of LDOs LDO1 and LDO2, which improves performance of class-D power amplifier integrated circuit 10.”). Regarding claim 17, The apparatus of claim 14, wherein to adjust the second magnitude of the second voltage (Fig. 1, Vss) of the driver ground supply node (Fig. 1, Vss node), the supply tracking amplifier circuit (Fig. 1, 10) is further configured to increase the second voltage level of the driver ground supply node relative to a ground reference (Figs. 3A and 3B, Vdd and Vss both respectively increase or decrease in response to input signals CV1 and CV2. See column 3, lines 54 – 59, “In order to provide volume control in class-D power amplifier integrated circuit 10, the power supply rail voltages are varied by changing power supply control input signals CV1 and CV2 provided to reference voltage inputs of LDOs LDO1 and LDO2, which improves performance of class-D power amplifier integrated circuit 10.”). Regarding claim 18, The apparatus of claim 14, wherein the supply tracking amplifier circuit (Fig. 1, 10) is further configured to adjust the second magnitude of the second voltage level (Fig. 1, Vss) of the driver ground supply node in phase with adjusting the first magnitude of the first voltage level (Fig. 1, Vdd) of the driver power supply node (Figs. 3A and 3B, Vdd and Vss both respectively increase or decrease in response to input signals CV1 and CV2. See column 3, lines 54 – 59, “In order to provide volume control in class-D power amplifier integrated circuit 10, the power supply rail voltages are varied by changing power supply control input signals CV1 and CV2 provided to reference voltage inputs of LDOs LDO1 and LDO2, which improves performance of class-D power amplifier integrated circuit 10.”). Regarding claim 19, The apparatus of claim 14, wherein to generate the amplified signal (Fig. 1, signal output at 14, N1, and N2), the supply tracking amplifier circuit (Fig. 1, 10) is configured to: generate a series of pulses (Fig. 3A and 3B, 14 generates pulse signals to N1 and N2. See column 3, lines 45 – 48, “…Class D Amplifier/Gate driver circuit 14 receives audio input signal Audio In and provides pulse-width modulated output gate control signals to the gates of switching transistors N1 and N2.”) that switch between the first voltage level (Fig. 1, Vdd) of the driver power supply node and the second voltage level (Fig. 1, Vss) of the driver ground supply node; and adjust a frequency of the series of pulses based on the magnitude of the input signal (See column 3, lines 48 – 51, “Switching transistors N1 and N2 alternatively conduct to generate an output signal that is filtered by an inductor L1 and a capacitor C1, to provide a power audio output signal Audio Out.”). Regarding claim 20, The apparatus of claim 14, wherein the input signal (Fig. 1, signal input at 12) includes a plurality of data packets (Fig. 1, Digital Volume In) encoded according to a communication protocol, and wherein the supply tracking amplifier circuit (Fig. 1, 10) is further configured to: translate the plurality of data packets to a plurality of words (Fig. 1, Digital Volume In gets translated into CV1 and CV2); adjust the first magnitude of the first voltage level (Fig. 1, Vdd) of the driver power supply node using the plurality of words (Fig. 1, CV1); and adjust the second magnitude of the second voltage level (Fig. 1, Vss) of the driver ground supply node using the plurality of words (Fig. 1, CV2). Conclusion Any inquiry concerning this communication or earlier communications from the examiner should be directed to JOSE E PINERO whose telephone number is (703)756-4746. The examiner can normally be reached M-F 8:00 AM - 5:00 PM (ET). Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Andrea Lindgren Baltzell can be reached on (571) 272-5918. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000. /JOSE E PINERO/Examiner, Art Unit 2843 /ANDREA LINDGREN BALTZELL/Supervisory Patent Examiner, Art Unit 2843
Read full office action

Prosecution Timeline

Mar 10, 2023
Application Filed
Jul 12, 2025
Non-Final Rejection — §102
Oct 09, 2025
Applicant Interview (Telephonic)
Oct 09, 2025
Examiner Interview Summary
Nov 14, 2025
Response Filed
Mar 04, 2026
Non-Final Rejection — §102 (current)

Precedent Cases

Applications granted by this same examiner with similar technology

Patent 12597896
SLEW-RATE BOOST CIRCUITRY
2y 5m to grant Granted Apr 07, 2026
Patent 12592671
AMPLIFIER FOR A RADIO FREQUENCY RECEIVER
2y 5m to grant Granted Mar 31, 2026
Patent 12587150
POWER AMPLIFIER LINEARITY CONTROL BASED ON POWER AMPLIFIER OPERATING MODE OR POWER LEVEL
2y 5m to grant Granted Mar 24, 2026
Patent 12580534
TIME-ADVANCED PHASE CORRECTION IN A POWER AMPLIFIER CIRCUIT
2y 5m to grant Granted Mar 17, 2026
Patent 12580524
APPARATUS AND METHODS FOR BIASING OF LOW NOISE AMPLIFIERS
2y 5m to grant Granted Mar 17, 2026
Study what changed to get past this examiner. Based on 5 most recent grants.

AI Strategy Recommendation

Get an AI-powered prosecution strategy using examiner precedents, rejection analysis, and claim mapping.
Powered by AI — typically takes 5-10 seconds

Prosecution Projections

2-3
Expected OA Rounds
89%
Grant Probability
97%
With Interview (+7.9%)
3y 5m
Median Time to Grant
Moderate
PTA Risk
Based on 80 resolved cases by this examiner. Grant probability derived from career allow rate.

Sign in with your work email

Enter your email to receive a magic link. No password needed.

Personal email addresses (Gmail, Yahoo, etc.) are not accepted.

Free tier: 3 strategy analyses per month