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 .
Summary of Current Invention
The invention targets RF power-amplifier linearity and efficiency (used in a Doherty or other dual-path amplifier).
It introduces a dynamic phase-reconfigurable front-end that not only imposes an adjustable static phase offset between the carrier and peaking paths, but also dynamically modulates that phase difference as a function of input-signal power (envelope).
Architecturally, the circuit chain is: Envelope detector → single-ended–to-differential converter → I/Q generator (polyphase filter) → two vector-sum phase-shifters whose gains depend on the instantaneous envelope. The phase-shifters output two differential signals that feed the carrier and peaking amplifiers.
Hardware examples use gm-C or RC polyphase filters, mixer-like Gilbert-cell blocks, and transconductance amplifiers multiplying the baseband envelope into the RF in-phase and quadrature components. The technique reduces AM–PM distortion and improves Doherty linearity across wide modulation bandwidths.
Claim Rejections - 35 USC § 112
The following is a quotation of 35 U.S.C. 112(b):
(b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph:
The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.
Claim 12 is rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention.
Claim 12 teaches a second differential-to-single-ended converter but acts exactly as a first differential-to-single-ended converter as recited in claim 11. It might have been a typographical error. The applicant should consider altering the claim.
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.
The factual inquiries 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.
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Fig. 10 of Harris annotated by the examiner for ease of reference.
Claims 1, 7-13, 15-26, and 30 are rejected under 35 U.S.C. 103 as being unpatentable over Greene et al. (“A 60-GHz Dual-Vector Doherty Beamformer”, IEEE JOURNAL OF SOLID-STATE CIRCUITS, VOL. 52, NO. 5, MAY 2017, cited by the applicant) in view of Woo et al. (KR 101097391 B1, a machine translation has been relied upon and a marked copy is attached for ease of reference).
Regarding claims 1, 16, 20 and 25, Greene teaches phased array antennas integrated in transmit arrays for 60-GHz communications for 16–32 elements to achieve the effective isotropic radiated power (EIRP) needed to support multigigabit per second links. As part of the transmit array, Greene teaches a dual-input amplifier (Doherty Amplifier) with dynamic phase modulation (Dual-vector interpolator), comprising:
an envelope detector (Greene is not explicit about an envelope detector) configured to process an envelope of an RF input signal to form an envelope signal;
a single-ended-to-differential converter (Greene functionally teaches the Doherty amplifier is driven by a dual-vector phase rotator (DVR) uses a differential Lange coupler and differential amplifiers) configured to convert a version of the RF input signal (single ended RF signal see Fig. 2(b)) into a differential RF input signal (Vector generator converts the single ended RF signal into differential i.e., dual I & Q vector signals);
an I/Q generator circuit (explicitly the Lange coupler creates I/Q signals used by the DVR (Fig. 4 – Fig. 6)) configured to convert the differential RF input signal into a differential in-phase signal and into a differential quadrature-phase signal (Differential quadrature signal generator, Fig. 2(b));
a first and a second vector-sum phase-shifter (the DVR performs dual vector interpolation, producing two phase shifted outputs; corresponds directly to the two vector sum phase shifters of the patent);
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Fig. 2 of Woo annotated by the examiner for ease of reference.
a first and second pair of output terminals (inside the dual vector interpolator, Fig. 2(b)); and
wherein the first vector-sum phase-shifter and the second vector-sum phase shifter are configured to process the differential in phase signal and the differential quadrature-phase signal to form a first differential output signal at the first pair of output terminals and to form a second differential output signal at the second pair of output terminals (the DVR provides two differential outputs (drives to carrier and peaking paths)) and
Greene doesn’t teach explicit about an envelope detector adjustment of a phase difference between the first differential output signal and the second differential output signal responsive to the envelope signal.
In a similar field of endeavor, of increasing transmission speed and capacity through beam forming, Woo teaches in Fig. 2, the phase adjusting of the phase between the input signals for the Doherty amplifier formed by elements 102 and 103 which is provided by phase shifters 205 and 207, being responsive to the difference (comparison) of the input envelope detected by coupler 101, detector 202 via the control element 208, and the output envelope detected by coupler 108, detector 203.
Please note that the deficit of Greene of lack of envelope detector and phase adjuster responsive to the envelope signal are taught by Woo for an obvious benefit of real-time phase adjusting between the main amplifier and the peaking amplifier paths based on the envelope distortion ensuring optimal efficiency and linearity.
The DVR of Greene performs the phase shifting for each phased array element necessary for beamforming, as well as providing tunable amplitude balance and phase separation between input signals to the Doherty amplifier.
Therefore, it would have been obvious to person of ordinary skill in the art to utilize the same DVR and introduce the phase adjustments necessary based on the distortion of the envelope signal between the input and output of the Doherty amplifier, thereby further optimizing the efficiency and linearity of the amplifier.
Wherein per claim 7, wherein the envelope signal is a differential envelope signal in order for Woos phase adjuster to be incorporating into the DVR of Greene , and also Greene teaches in Fig. 4, a double-pole, double-throw switch to couple the differential envelope signal from the envelope detector (of Woos) into the first vector-sum phase-shifter and the second vector-sum phase-shifter (of Greene. Also, per claim 8, it would have been obvious for incorporating the please phase adjustment responsive to the envelope signal (as taught by Woo) into the Greene DVR circuit (Fig. 5) each of the quad plurality of circuits, would implement digital to analog controls for the two differential in-phase signals with the differential envelope signal as well as differential quadrature-phase signal with the differential envelope signal (pp. 1376, right col., last par.);
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Fig. 5 (part) of Greene for ease of reference.
Also, per claim 9, Greene discloses a combining network configured to couple the quad plurality of circuits to the first pair of output terminals and to the second pair of output terminals (see Fig. 5 above in the current steering section). Wherein per claim 10, the vector-sum phase shifter (DVR of Greene as shown in Fig. 5) comprises four pluralities of mixer-like (signals are mixing with each other) circuits.
wherein per claim 15, Greene teaches the weighting functions for the phase shifter are realized with variable gain transconductance amplifiers or a cross-coupled Gilbert cell topology. As such incorporating Woos envelope detectors into Greene’s integrated circuit, a person of ordinary skill in the art would find it obvious to use transconductance amplifier to form the differential envelope signal responsive to a difference between the envelope of the RF input signal and the RF output signal for the obvious reason of compatibility of the circuit technologies.
Also, per claim 17, Greene teaches in the circuit of Fig. 2(b) a dual differential amplifying stage (Gm) that pre-amplify the first differential output signal to form a pre-amplified first differential output signal and pre-amplify the second differential output signal to form a pre-amplified second differential output signal.
Further per claims 11, 12, 18, 19, 20, 21, 24, 26 and 30, Greene also teaches a first differential-to-single-ended converter coupled to the first pair of (through the Balun at the left, Fig. 5, current steering section) output terminals and configured to convert the first differential output signal into a first single-ended output signal and a second differential-to-single-ended converter coupled to the second pair of (through the Balun at the right, Fig. 5, current steering section) output terminals and configured to convert the second differential output signal into a second single-ended output signal;
a first driver amplifier (The resultant combination would obviously adapt the driver amplifiers of Woo into the main amplifier and peaking amplifier paths for the obvious advantage of higher gain, and thus driver 209 of Fig. 2 of Woo) configured to amplify the first single-ended RF output signal to form a first driver output signal and the second single-ended output signal to form a second driver (210 of Fig. 2 of Woo) output signal; and
a carrier amplifier (102 of Fig. 2 of Woo) configured to amplify the first driver output signal and peaking amplifier (103 of Fig. 2 of Woo) configured to amplify the second driver output signal.
And per claims 13, 19 and 22, the resultant Doherty amplifier (Greene complemented following Woos teaching) includes a combiner configured to combine a carrier output signal from the carrier amplifier with a peaking output signal from the peaking amplifier to form a combined output signal (see Fig. 2 of Woo).
Regarding claim 23, Greene teaches phased array antennas integrated in transmit arrays for 60-GHz communications for 16–32 elements to achieve the effective isotropic radiated power (EIRP) needed to support multigigabit per second links.
Claims 2-6 and 26-29 are rejected under 35 U.S.C. 103 as being unpatentable over Greene in view of Woos and further in view of SAFAVI NAEINI et al. (US20190058245) and Hong et al. (US 20210028768).
Regarding claims 2-6 and 26-29, Greene and Woo together teach all limitations of claims 1, 16 and 25, where, in the combination Greene teaches DVR 60 GHz Doherty PA beamformer from a single ended RF input to differential I/Q via Lange coupler and buffers and interpolation of dual vectors with two differential outputs leads to the current steering vector modulators that combine I/Q for two outputs, i.e., one for the carrier amplifier path and one for the peaking amplifier path. Wherein, envelope detection and envelope-based phase adjustment (feed forward envelope detector to dynamically adjust phase between main and peaking paths) and included in the resultant combination based on Woo’s teaching improving AM/AM and AM/PM linearity.
However, the resultant combination doesn’t explicitly teach that the I/Q generator is a polyphase filter (Claim 2 and 27), specifically gm C polyphase (Claims 3 and 28), specifically RC polyphase (Claims 4 and 29) and the polyphase filter is two stages (Claims 5, 6, 27–29).
Hong teaches an RF vector modulator/beamforming domain like that of Greene a variable gain phase shifter having an I/Q generator (3020 / 1020) with explicit implementations of an RC ladder (3310) to support a polyphase filter (3320, Fig. 17; §0222–§0230). Wherein the I/Q generator is designed to produce accurate 0°, 90°, 180°, 270° phases, minimize phase and gain error over a wide band (Fig. 18A–B; §0227–§0230).
Hong explicitly calls it an RC ladder and polyphase filter in series to reduce both phase error and amplitude error, providing wideband I/Q generation. Hong also teaches that the polyphase filter is two stage RC (and analogously gm C in other embodiments) to generate high quality I/Q for vector sum phase shifter / vector modulator.
Safavi in a mm wave phased array / beamforming field discloses adaptive phased arrays, phase shifters, and phase conjugating phase shifters (PCPS) and polyphase filters (PCPS (408) + polyphase filter 452, Fig. 14–15; §0097–§0103). Wherein the polyphase filter 452 generates in phase and quadrature components (+VinI, +VinQ, −VinI, −VinQ) from differential LO, exactly like a polyphase I/Q generator. Safavi follows the same design constraints, like Hong, i.e., fixed 90° relationship, low phase and amplitude error, used in beamforming LO distribution.
Safavi therefore reinforces that polyphase based I/Q generation for RF vector/beamforming blocks and hence it is a well-established design choice in this art of beamforming before the filing of the current invention.
In this context, please note, all four references operate in closely related art (RF beamformers, phase shifters, Doherty amplifiers). The polyphase filter in Hong and Safavi is drop in conceptually for Greene’s quadrature hybrid with same input (differential/single ended RF), same output (I and Q, 90° apart), same use (drive vector sum phase shifters / DVR), thus the substitution does not require any new principle; it is a routine layout/implementation choice.
Thus a person of ordinary skill in the art having working knowledge of Lange couplers, baluns, polyphase filters (RC/gm C) as interchangeable I/Q generation options and tradeoffs in bandwidth, insertion loss, area, and phase/gain mismatch, to improve Greene’s DVR performance (reduce phase error, amplitude imbalance and mismatch for high order QAM or wideband modulation) would routinely consider replacing the Lange coupler with a polyphase based I/Q generator as taught by Hong and Safavi.
It would have been an obvious choice to improve the band limited performance and error reduction of Greene’s DVR which requires accurate I and Q signals over a band (60–66 GHz). Hong explicitly shows that combining RC ladder + polyphase filter minimizes both phase and amplitude errors across a band (Fig. 18A–B; §0227–0230). Safavi similarly uses a polyphase filter for precise quadrature generation (Fig. 15; §0101–0103). It would have been obvious because of the well-known equivalence of I/Q generation methods and in 60 GHz RF IC design, it is standard engineering practice to choose between a quadrature hybrid (Lange coupler), or a polyphase filter (RC, gm C, multi-stage), depending on layout, bandwidth, and loss constraints. Hong and Safavi are explicit that polyphase filters are used for the same application: generating quadrature signals for vector modulators/phase shifters in phased array/RF front ends. Thus, substituting Greene’s quadrature hybrid with a polyphase filter is a predictable design choice with reasonable expectation of success.
Allowable Subject Matters
Claim 14 is objected to as being dependent upon a rejected base claim 1 but would be allowable if rewritten in independent form including all the limitations of the base claim 8 and any intervening claims.
Claim 14 is allowable because the closest prior art of records, Greene or Woo doesn’t teach explicitly a delay and a pre-amplifier to create the delayed matched signal version of the RF input signal.
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.
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) 272-1769. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
/HAFIZUR RAHMAN/Primary Examiner, Art Unit 2843.