DETAILED ACTION
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
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 of this title, 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.
The factual inquiries set forth in Graham v. John Deere Co., 383 U.S. 1, 148 USPQ 459 (1966), that are applied for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
Claims 1, 7-8, 14 and 18 are rejected under 35 U.S.C. 103 as being unpatentable over Bouisse (US 11,990,871 B2, henceforth referred to as Bouisse and cited by the applicant) in view of Llyod (WO 2006/066461 A1, henceforth referred to as Llyod).
Regarding claim 1, An inverted Doherty-type amplifier (Bouisse: FIGS. 1, 2, and 3; Paras. [0002], [0031]–[0035] describing an inverted Doherty amplifier configuration where the output impedance inverter is disposed in the peaking path) comprising:
a distribution network comprising a first signal port configured to provide a first signal to a main path of the inverted Doherty-type amplifier from a received input signal, and a second signal port configured to provide a second signal to a peak path of the inverted Doherty-type amplifier from the received input signal (Bouisse: FIG. 1, splitter/distribution network 102 having a input receiving RF signal, a first output port delivering main path signal to main path 104, and a second output port delivering peaking path signal to peak path 106; Paras. [0033]–[0034]);
a first amplifier coupled to the first signal port and configured to amplify the first signal to obtain a first amplified signal;"(Bouisse: FIG. 1, main power amplifier 108 coupled to the first port of distribution network 102; Para. [0033]);
a second amplifier [in the peak path] configured to amplify [a] second signal to obtain a second amplified signal (Bouisse: FIG. 1, peaking power amplifier 110 coupled in the peak path 106; Para. [0033]);
a signal combiner having a first input coupled to an output of the first amplifier, and a second input coupled to an output [of the peak path], the signal combiner configured to combine a signal based on the first amplified signal and a signal based on [the peak path signal] to obtain a combined signal (Bouisse: FIG. 1, summing/combining node 114 coupled to the output of main amplifier 108 and output of peaking amplifier 110 via impedance inverter 112; Para. [0034]).
However, Bouisse does not explicitly show:
a driver circuit (54) in the peak path, wherein the first phase correction network is configured to at least partially compensate for a phase shift caused by the driver circuit
a first phase correction network (46) coupled to the second signal port and configured to adjust a phase of a second signal to obtain a phase corrected second signal
a second phase correction network (62) coupled to an output of the second amplifier and configured to adjust a phase of the second amplified signal to obtain a phase corrected second amplified signal and
Regarding Claim 14, A method for amplifying a signal, the method (Bouisse: FIG. 1; Paras. [0002], [0031]–[0035]) comprising:
providing a first signal for a main path of an inverted Doherty-type amplifier from a received input signal; and providing a second signal for a peak path of the inverted Doherty-type amplifier from the received input signal (Bouisse: FIG. 1, distribution network 102 splitting input signal into main path 104 and peak path 106; Para. [0033]);
amplifying a signal based on the first signal to obtain a first amplified signal (Bouisse: FIG. 1, main amplifier 108 amplifying main path signal; Para. [0033]);
amplifying a signal based on [the second signal] to obtain a second amplified signal (Bouisse: FIG. 1, peaking amplifier 110 amplifying peak path signal; Para. [0033]);
combining a signal based on the first amplified signal and a signal based on [the peak path signal] to obtain a combined signal (Bouisse: FIG. 1, output combining node 114 combining signals from main path and peak path; Para. [0034]).
However, Bouisse doesn’t teach
adjusting a phase of a signal based on the second signal to obtain a phase corrected second signal;
adjusting a phase of a signal based on the second amplified signal to obtain a phase corrected second amplified signal;
at least partially compensating a phase shift caused by a driver circuit in the peak path using a phase correction network, and
Regarding Claim 18 An inverted Doherty-type amplifier (Bouisse: FIGS. 1–3; Paras. [0002], [0031]–[0035]), comprising:
a distribution network having a first input port (Bouisse: FIG. 1, splitter 102 with input port; Para. [0033]);
a main signal path coupled to a first output port of the distribution network, the main signal path comprising a main amplifier (Bouisse: FIG. 1, main signal path 104 with main power amplifier 108; Para. [0033]);
a first peak signal path coupled to a second output port of the distribution network, the first peak signal path comprising a [first peak amplifier] (Bouisse: FIG. 1, peaking path 106 with peaking amplifier 110; Para. [0033]);
and a combining network coupled to an output of the main amplifier and an output of [the peak path] (Bouisse: FIG. 1, summing node 114 coupled to main output and peaking path output; Para. [0034]).
However, Bouisse doesn’t teach:
a first phase adjustment network, a first peak amplifier having an input coupled to an output of the first phase adjustment network, and a second phase adjustment network having an input coupled to an output of the first peak amplifier
Now, in the identical field of endeavor (RF power amplifiers, driver stage designs, and phase alignment in Doherty-type networks) Llyod explicitly teaches:
Driver circuit in an amplification branch: Placing pre-driver amplification circuits (FIG. 5, driver amplifiers 509, 510; Para. [0043]) upstream of primary amplification stages.
First phase correction network (input phase adjustment): A first fine/coarse phase adjustment network (FIG. 5, phase adjuster 507/508 in fine phase setting stage 530 / gain difference setting stage 531; Paras. [0041]–[0044]) coupled before the driver/amplifier stages configured to adjust input signal phase to compensate for phase shifts caused by driver and amplifier stages (Paras. [0042], [0050]).
Second phase correction network (output phase adjustment): A second phase adjustment/delay setting network (FIG. 5, coarse phase difference setting stage 532, elements 514, 515; Paras. [0045]–[0048]) coupled to the output of the amplifier stage to perform output phase alignment before combining.
It would have been obvious to a Person Having Ordinary Skill in the Art (PHOSITA) before the effective filing date of the claimed invention to modify the inverted Doherty amplifier of Bouisse:
To include a driver circuit (as taught by Llyod, FIG. 5, driver 509/510; Para. [0043]) in the peaking path to boost driving signal levels, also
To place a first phase correction network (as taught by Llyod, FIG. 5, phase adjuster 507/508; Para. [0041]) at the input of the peaking branch driver to adjust input signal phase and directly compensate for the phase shift/delay introduced by the driver circuit and
To place a second phase correction network (as taught by Llyod, FIG. 5, phase setting stage 532, elements 514/515; Para. [0045]) at the output of the peaking amplifier prior to the output signal combiner node.
A PHOSITA would have been motivated to modify Bouisse with the driver circuit and dual-stage (input/output) phase correction networks of Llyod for the following technical reasons:
Driver Phase Compensation: Active driver stages inherently introduce power-dependent phase shifts, group delays, and phase distortion. Llyod explicitly teaches that applying input phase adjustment upstream of driving stages compensates for phase deviations across varying drive levels (Para. [0042]).
Optimal Constructive Combining: In inverted Doherty amplifiers, constructive power combining at the output load requires strict phase alignment between the main branch signal and the peaking branch signal across operating power levels. Placing phase correction networks at both the input (before driver) and output (after peaking amplifier) ensures precise phase tracking and maximizes output efficiency and linearity (Llyod, Paras. [0047]–[0050]).
Therefore, the subject matter of Claims 1, 14, and 18 is unpatentable under 35 U.S.C. § 103 as being obvious over Bouisse in view of Llyod.
Further, per Claim 7, The inverted Doherty-type amplifier according to claim 1, wherein the first amplifier is a class AB amplifier (Bouisse explicitly teaches that the main power amplifier 108 is biased and operated as a Class AB amplifier; Para. [0033]).
And per Claim 8, The inverted Doherty-type amplifier according to claim 1, wherein the second amplifier is a class C amplifier (Bouisse explicitly teaches that the peaking power amplifier 110 is biased and operated as a Class C amplifier to remain off during low power conditions and turn on at peak power levels; Para. [0033]).
The biasing of the main amplifier in Class AB and the peaking amplifier in Class C is explicitly disclosed in the primary reference Bouisse (Para. [0033]) to achieve classic Doherty load modulation behavior.
Claims 2, 6, and 15 are rejected under 35 U.S.C. 103 as being unpatentable over Bouisse in view of Llyod, and further in view of Zhou et al. ("DESIGN OF AN S-BAND TWO-WAY INVERTED ASYMMETRICAL DOHERTY POWER AMPLIFIER FOR LONG TERM EVOLUTION APPLICATIONS", Progress In Electromagnetics Research Letters, Vol. 39, 73-80, 2013).
Regarding Claims 2 and 15, The inverted Doherty-type amplifier according to claim 1, wherein the first phase correction network is configured to adapt the phase of the second signal by 90° (Bouisse in view of Llyod teaches the base combination of Claim 1. While Llyod teaches phase correction/delay networks, Llyod does not explicitly specify a 90° phase adaptation. However, Zhou et al. explicitly teaches that in an inverted Doherty architecture, the input/peaking path phase correction network is configured to provide a 90° phase adaptation (l/4 or 90° offset) to align phase at the output combining node; Page 74-75, Fig. 1, Section 2).
Per Claim 6, The inverted Doherty-type amplifier according to claim 1, wherein the second phase correction network is configured to provide a phase shift of 90° (Bouisse in view of Llyod teaches the output phase correction network. Zhou et al. explicitly teaches configuring the output phase correction network/impedance inverter on the peaking amplifier branch to provide a 90° phase shift (l/4 line) to achieve active load modulation at the output summing node; Page 74-75, Fig. 1, Section 2).
It would have been obvious to a PHOSITA before the effective filing date to configure the first and second phase correction networks of Bouisse/Llyod to provide a 90° phase shift (l/4 line) as taught by Zhou et al. because providing a nominal 90° phase shift between main and peaking paths is standard design practice in inverted Doherty amplifiers to achieve dynamic load modulation and ensure constructive phase combination at the load node.
Claims 3, 4, 5, and 16 are rejected under 35 U.S.C. 103 as being unpatentable over Bouisse in view of Llyod, and further in view of Wu (US 2018/0226922 A1).
Regarding Claim 3, The inverted Doherty-type amplifier according to claim 1, wherein the distribution network comprises an unequal lumped Wilkinson splitter, a lumped coupler or a lumped hybrid coupler (Bouisse teaches a signal splitter 102. Wu explicitly teaches an RF distribution network comprising an unequal lumped Wilkinson splitter or lumped hybrid coupler; FIG. 3, element 302; Paras. [0028]–[0031]).
Regarding Claim 4, The inverted Doherty-type amplifier according to claim 1, wherein the distribution network is configured to provide the first signal having a higher power level than the second signal (Bouisse teaches splitting an input signal. Wu explicitly teaches an asymmetric/unequal splitter network where the first signal port (main path) receives a higher power level than the second signal port (peaking path) to optimize back-off efficiency; FIG. 3; Paras. [0029], [0035]).
Regarding Claim 5, The inverted Doherty-type amplifier according to claim 1, wherein the distribution network is configured to provide a gain between -1.25 dB and -0.5 dB to the first signal port and provide a split ratio of between -14 dB and -6 dB to the second signal port (Wu explicitly teaches configuring unequal input power splitting networks for Doherty amplifiers providing a main-path coupling/gain between -1.25dB and -0.5dB (e.g., -1dB) and a peaking path split ratio between -14dB and -6dB (e.g., -7dB to -10dB); Paras. [0032]–[0036]).
Regarding Claim 16, The method of claim 14, wherein providing the first signal comprises providing the first signal having a higher power than the second signal (Wu explicitly teaches splitting an input signal such that the main path receives higher power than the peaking path; FIG. 3; Paras. [0029], [0035]).
It would have been obvious to a PHOSITA to incorporate the asymmetric lumped Wilkinson splitter and specified power split ranges of Wu into the distribution network of Bouisse/Llyod in order to lower the turn-on threshold of the main amplifier, optimize extended back-off power efficiency, and minimize overall circuit footprint through lumped-element realization.
Claims 9, 10, 11, 17, 19, and 20 are rejected under 35 U.S.C. 103 as being unpatentable over Bouisse and Llyod, further in view of Yanduru (US 10,250,197 B2) and/or Hue (US 2021/0376796 A1).
Regarding Claim 9, The inverted Doherty-type amplifier according to claim 1, wherein: the peak path is a first peak path; the distribution network comprises a third signal port configured to provide a third signal for a second peak path of the inverted Doherty-type amplifier; the inverted Doherty-type amplifier further comprises: a third phase correction network coupled to the third signal port and configured to adjust a phase of the third signal to obtain a phase corrected third signal, a third amplifier coupled to an output of the third phase correction network and configured to amplify the phase corrected third signal to obtain a third amplified signal; and a fourth phase correction network coupled to an output of the third amplifier, the fourth phase correction network configured to adjust a phase of the phase third amplified signal to obtain a phase corrected third amplified signal that is provided to the signal combiner.
(Bouisse and Llyod teach the primary peak path structure. Yanduru explicitly teaches a multi-way/N-way Doherty amplifier architecture comprising a 3-port distribution network driving a main path, a first peak path, and a second peak path, wherein each peak path comprises dedicated input phase correction networks, peaking amplifiers, and output phase correction networks coupled to a common combiner; FIGS. 2 and 4, elements 202, 206a, 206b, 208a, 208b; Paras. [0038]–[0045]).
Regarding Claim 10, The inverted Doherty-type amplifier according to claim 1, wherein: the peak path is a first peak path; and the inverted Doherty-type amplifier further comprises: a signal splitter coupled between the distribution network and the second amplifier, the signal splitter comprising an input coupled to the second signal port of the distribution network, wherein the signal splitter is configured to split the second signal into a first portion and a second portion, the signal splitter comprises a first output configured to provide the first portion and a second output configured to provide the second portion, and the first output of the signal splitter is coupled to the second amplifier, a second peak path configured to receive the second portion, a third phase correction network coupled to the second output port of the signal splitter and configured to adjust a phase of the second portion of the second signal to obtain a phase corrected third signal, a third amplifier coupled in the second peak path, the third amplifier coupled to an output of the third phase correction network and configured to amplify the phase corrected third signal to obtain a third amplified signal, and a fourth phase correction network coupled to an output of the third amplifier, the fourth phase correction network configured to adjust a phase of the third amplified signal to obtain a phase corrected third amplified signal that is provided to the signal combiner (Hue explicitly teaches a multi-stage peaking topology where a single peak path signal from a primary distribution network is further split by a second signal splitter into first and second portions to drive a first peak amplifier branch and a second peak amplifier branch, each equipped with input phase adjustment networks, peaking amplifiers, and output phase adjustment networks; FIG. 3, elements 304, 310, 312; Paras. [0041]–[0049]).
Regarding Claim 11, The inverted Doherty-type amplifier according to claim 10, further comprising a driver circuit coupled between the distribution network and the signal splitter (Hue in view of Llyod explicitly teaches placing a pre-driver amplifier circuit (Llyod: FIG. 5, driver 509/510; Hue: FIG. 3, driver 308) upstream between the primary distribution network and the peaking path signal splitter).
Regarding Claim 17, The method of claim 14, further comprising: providing a third signal for further a peak path of the inverted Doherty-type amplifier from the received input signal; adjusting a phase of a signal based on the third signal to obtain a phase corrected third signal; amplifying a signal based on the phase corrected third signal to obtain a third amplified signal; adjusting a phase of a signal based on the third amplified signal to obtain a phase corrected third amplified signal; and at least partially compensating a phase shift caused by a driver circuit in the further peak path, wherein combing the signal further comprises combining a signal based on the first amplified signal, a signal based on the phase corrected second amplified signal, and a signal based on the phase corrected third amplified signal to obtain the combined signal (Yanduru explicitly teaches the process steps of generating a third signal for a second peak path, phase-adjusting, amplifying, and phase-compensating for driver shifts across multiple peaking paths before combining; FIGS. 2 & 4; Paras. [0040]–[0048]).
Regarding Claim 19, The inverted Doherty-type amplifier of claim 18, further comprising: a second peak signal path coupled to a third output port of the distribution network, the second peak signal path comprising a third phase adjustment network, a second peak amplifier having an input coupled to an output of the third phase adjustment network, and a fourth phase adjustment network having an input coupled to an output of the second peak amplifier, wherein the a combing network is further coupled to an output of the fourth phase adjustment network (Yanduru explicitly teaches a 3-port distribution network driving a main path and two distinct peak signal paths each having input/output phase adjustment networks and peak amplifiers; FIGS. 2 & 4; Paras. [0038]–[0045]).
Regarding Claim 20, The inverted Doherty-type amplifier of claim 18, further comprising: a splitter having a first input coupled to the second output port of the distribution network and a first output coupled to an input of the first peak signal path; a second peak signal path coupled to second output of the splitter, the second peak signal path comprising a third phase adjustment network, a second peak amplifier having an input coupled to an output of the third phase adjustment network, and a fourth phase adjustment network having an input coupled to an output of the second peak amplifier, wherein the a combing network is further coupled to an output of the fourth phase adjustment network (Hue explicitly teaches providing a splitter at the output of the distribution network's peaking port to split the signal into two peak paths containing respective phase adjustment networks and amplifiers; FIG. 3; Paras. [0041]–[0049]).
It would have been obvious to a PHOSITA to expand the single peaking path of Bouisse/Llyod into a multi-peaking path (3-way / 4-way) configuration as taught by Yanduru or Hue to extend dynamic range, increase efficiency at deeper back-off levels (e.g., 9 dB to 12 dB back-off), and allow staged turn-on of peaking transistors.
Claim 12 is rejected under 35 U.S.C. 103 over Bouisse, Llyod, and further in view of Ember (US 2019/0140593 A1).
Regarding Claim 12, Bouisse and Llyod together teaches all limitations of The inverted Doherty-type amplifier according to claim 1, However the combination together or individually doesn’t teach "wherein: the peak path is a first peak path;"
"the distribution network comprises a third signal port configured to provide a third signal for a second peak path of the inverted Doherty-type amplifier from the received input signal; and"
"a third phase correction network is coupled between a third amplifier of the second peak path and the second phase correction network."
Ember (US 2019/0140593 A1) is in the identical field of endeavor (multi-way Doherty power amplifiers) and explicitly teaches:
Multi-port distribution network for multiple peak paths: An RF distribution network having a third signal port configured to deliver a third signal portion to a second peaking path (FIG. 4, signal splitter/distribution network 402 having three output ports; Paras. [0036]–[0037]).
Third amplifier in the second peak path: A third amplifier (second peaking amplifier) positioned in the second peak path to amplify the third signal (FIG. 4, second peaking amplifier 410; Para. [0037]).
Third phase correction network cascaded into the second phase correction network: A third phase correction/delay line network coupled at the output of the third amplifier (second peaking amplifier) and connected in series/cascaded into the output phase adjustment network (second phase correction network) of the first peak path before reaching the combining node (FIG. 4, output phase transformation network 416 coupled between peaking amplifier 410 and the primary output phase network 412; Paras. [0038]–[0041]).
It would have been obvious to a Person Having Ordinary Skill in the Art (PHOSITA) before the effective filing date of the claimed invention to modify the inverted Doherty-type amplifier of the Bouisse/Llyod combination by:
Expanding the distribution network (Bouisse: 102) to include a third signal port to drive a second peak path as taught by Ember (FIG. 4, splitter 402; Para. [0036]).
Placing a third amplifier (second peaking amplifier) in the second peak path as taught by Ember (FIG. 4, amplifier 410; Para. [0037]).
Coupling a third phase correction network between the output of the third amplifier and the second phase correction network of the first peak path as taught by Ember (FIG. 4, element 416 coupled to element 412; Paras. [0038]–[0041]).
A PHOSITA would have been motivated to combine the teachings of Ember with the Bouisse/Llyod combination for the following clear technical benefits taught in the prior art:
Extended Efficiency Back-off Range: Standard 2-way Doherty amplifiers maintain high efficiency down to 6 dB back-off. Ember explicitly teaches that adding a second peaking path (creating a 3-way/multi-way Doherty configuration) extends the high-efficiency operating range to deeper back-off levels (e.g., 9 dB to 12 dB back-off), which is critical for modern high peak-to-average power ratio (PAPR) communication signals (Ember: Paras. [0003], [0036]).
Cascaded Phase Rotation & Output Matching Consolidation: Ember explicitly teaches that coupling the third phase correction network directly into the second phase correction network allows the second peaking amplifier to share the impedance transformation and phase rotation of the main peaking output line (Ember: Paras. [0039]–[0041]). This cascading approach ensures proper phase alignment at the output load while significantly reducing circuit area and output matching complexity compared to routing separate, parallel high-power impedance conversion lines to the combiner node.
Allowable Subject Matter
Claim 13 is objected to as being dependent upon a rejected base claim 12 but would be allowable if rewritten in independent form including all of the limitations of the base claim 12 and any intervening claims (such as 1).
Claim 12 is allowable because while prior art references such as Llyod, Wu, and Yanduru teach placing phase adjustment elements in individual branches, none of the cited prior art references (Bouisse, Llyod, Wu, Hue, Yanduru, Ember, or Zhou et al.) disclose or suggest the specific combination of Claim 13, namely:
Placing a fourth phase correction network in the main amplifier path (between the first signal port and the first/main amplifier), AND
Explicitly configuring this main-path phase correction network to provide identically the same phase correction as the first phase correction network in the peaking path.
In standard Doherty art, 90° phase correction is added to the peaking path to offset peaking driver delays or impedance inverter rotations, while the main path is either left uncompensated or given a fixed delay. Structurally duplicating the peaking path's driver-compensating phase network inside the main input path to track and apply the exact same phase adjustment is contrary to conventional asymmetric Doherty design. Because no reference teaches or provides a motivation to mirror the driver-compensation phase shift in the main amplifier path in an inverted Doherty arrangement, claim 13 overcomes all obviousness rejections and contains allowable subject matter.
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to HAFIZUR RAHMAN whose telephone number is (571)270-0659. The examiner can normally be reached M-F: 10-6.
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If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Jessica Han can be reached on (571) 272-2078. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
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/HAFIZUR RAHMAN/Primary Examiner, Art Unit 2843.
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