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 .
Claim Rejections - 35 USC § 103
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
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.
Claim(s) 1, 3, 6, 11, 12, and 14-20 is/are rejected under 35 U.S.C. 103 as being unpatentable over Anvari (US 20130307618 A1) in view of Kenington (US 20060209984 A1).
Regarding claim 1, Anvari teaches a transmit chain (Anvari discloses a radio transmitter/circuit architecture comprising a "main signal path 220" and a "digital pre-distortion path 210". This transmit path is used to process and transmit wireless communication signals to an antenna, para. 0011-27) comprising:
a power amplifier that imposes amplifier distortion on a digitally predistorted signal to be transmitted (Anvari discloses the power amplifier 228 is a "non-linear device" that "cause[s] distortion to the amplified signal". It receives a baseband signal 207 that is digitally predistorted by a "digital pre-distorter 212" in the digital pre-distortion path, para. 0016-38); and
an analog predistortion (APD) circuit coupled to the power amplifier (Anvari teaches an "analog pre-distorter 616" in the analog domain. The output of the analog pre-distorter is coupled to the power amplifier 228 by being added to the main signal path 220 prior to the amplifier via switch 219, para. 0050-72),
the APD circuit configured to normalize the amplifier distortion imposed on the digitally predistorted signal by the power amplifier (Anvari teaches that the predistortion is divided into higher-order and lower-order distortions. The APD (analog pre-distorter 616) receives pre-distortion coefficients 612 corresponding to higher-order distortions to perform analog predistortion. By taking care of these high-order deviations in the analog domain, the APD normalizes (flattens and standardizes) the physical distortion profile of the power amplifier, para. 0050-83) such that digital predistortion (DPD) applied to create the digitally predistorted signal may be achieved with coefficients corresponding to normalized amplifier distortion (In Anvari, because the analog pre-distorter 616 takes care of the higher-order distortions, the digital predistorter (DPD) 212 only has to compensate for the remaining lower-order distortions. The DPD achieves its predistortion utilizing coefficients (or lookup values) that correspond directly to this simplified, "normalized" distortion profile (the baseline amplifier profile after high-order distortions have been subtracted/offset by the APD), para. 0072-83).
Anvari is silent to teaching that wherein the amplifier distortion is a function of supply voltage provided to the power amplifier.
In the same field of endeavor, Kenington teaches a device comprising a power amplifier (Kenington discloses an RF power amplifier 10, fig. 1, para. 0019), wherein the amplifier distortion is a function of supply voltage provided to the power amplifier (Kenington teaches that an envelope-tracking power supply 60 varies the level of power supplied to the amplifier 10, and notes that "imperfections or non-linearities in the tracking behavior of the power supply [affect] the resulting output voltage... [which can greatly increase] the distortion produced by the amplifier". Thus, the physical distortion is a function of the supply voltage provided to the PA, para. 0033-37).
Therefore, a person of ordinary skill in the art (PHOSITA) would be highly motivated to modify Anvari’s predistortion architecture by integrating Kenington’s envelope-tracking technology to resolve the critical trade-off between power amplifier efficiency and the bandwidth limitations of digital converters. By modifying Anvari's hybrid architecture with Kenington's envelope tracking, a designer can leverage Anvari's split analog/digital predistortion to handle the supply-dependent distortions.
Anvari's Analog Pre-distorter (APD) can be configured to absorb the wideband, higher-order distortions (which spread far from the main signal carrier) caused by the tracking imperfections of Kenington's power supply. Anvari's Digital Pre-distorter (DPD) is then only responsible for compensating for the lower-order, lower-bandwidth distortions closer to the main signal. This integration yields a highly efficient envelope-tracking transmitter that bypasses digital processing bandwidth bottlenecks while keeping component costs and overall power consumption low.
Regarding claim 3, the combination of Anvari and Kenington teaches the transmit chain of claim 1, further comprising a supply voltage detector coupled to an output of the power amplifier (Kenington teaches a feedback path 42 coupled from the power amplifier output 14 via a coupler 40. This feedback path is configured to tap and sample a fraction of the RF output signal power to extract amplitude and down-convert it, fig. 1, para. 0019,30-33).
Regarding claim 6, the combination of Anvari and Kenington teaches the transmit chain of claim 1, further comprising a power tracking circuit configured to set the supply voltage responsive to a control signal from a baseband processor (BBP) (Kenington discloses an envelope-tracking power supply 60 that varies the level of power supplied to the amplifier 10. The input to the power supply is a predistorted envelope signal 74 generated in the digital domain by the predistortion circuit 70 and DSP 72 based on baseband input signals 12. Under BRI, this functions as a power tracking circuit responsive to control/envelope signals from a baseband processor, fig. 1, para. 0023-25,30-33).
Regarding claim 16, the combination of Anvari and Kenington teaches the transmit chain of claim 3, wherein the supply voltage detector is configured to detect voltage levels continuously (Kenington discloses that the feedback path 42 couples the RF output to the DSP 72 to adaptively populate and update the predistortion lookup tables (LUTs) in a closed-loop fashion. Under BRI, this represents detecting the voltage/power levels continuously during active transmission, para. 0019-22,30-33).
Regarding claim 11, the combination of Anvari and Kenington teaches the transmit chain of claim 1, further comprising a baseband processor (BBP) coupled to the power amplifier and configured to provide the signal to be transmitted (Anvari teaches a "baseband unit 120" (BBU) configured to generate and process a baseband signal 207. The baseband signal is transmitted through the main signal path and amplified by the power amplifier 228. Under BRI, this BBU functions as the baseband processor (BBP), para. 0016-26).
Regarding claim 12, the combination of Anvari and Kenington teaches the transmit chain of claim 11, wherein the BBP comprises a digital predistortion (DPD) circuit configured to provide the digitally predistorted signal that offsets a normalized distortion profile of the power amplifier (Kenington teaches DSP 50, fig. 1).
Regarding claim 14, the combination of Anvari and Kenington teaches the transmit chain of claim 1, wherein the APD circuit is configured to provide phase distortion APD (Anvari teaches that the higher-order distortions processed in the analog predistortion path are "phase and gain adjusted", para. 0062-78).
Regarding claim 15, the combination of Anvari and Kenington teaches the transmit chain of claim 1, wherein the APD circuit is configured to provide gain distortion APD (Anvari teaches that the higher-order distortions processed in the analog predistortion path are "phase and gain adjusted", para. 0062-78).
Regarding claim 17, Anvari teaches a method for providing predistortion to a power amplifier, comprising:
receiving at a power amplifier a digitally predistorted signal to be transmitted (Anvari discloses the power amplifier 228 is a "non-linear device" that "cause[s] distortion to the amplified signal". It receives a baseband signal 207 that is digitally predistorted by a "digital pre-distorter 212" in the digital pre-distortion path, para. 0016-38); and
providing analog predistortion (APD) to the power amplifier (Anvari teaches an "analog pre-distorter 616" in the analog domain. The output of the analog pre-distorter is coupled to the power amplifier 228 by being added to the main signal path 220 prior to the amplifier via switch 219, para. 0050-72), wherein the APD normalizes the digitally predistorted signal (Anvari teaches that the predistortion is divided into higher-order and lower-order distortions. The APD (analog pre-distorter 616) receives pre-distortion coefficients 612 corresponding to higher-order distortions to perform analog predistortion. By taking care of these high-order deviations in the analog domain, the APD normalizes (flattens and standardizes) the physical distortion profile of the power amplifier, para. 0050-83) such that digital predistortion, DPD, applied to create the digitally predistorted signal may be achieved with coefficients corresponding to normalized amplifier distortion (In Anvari, because the analog pre-distorter 616 takes care of the higher-order distortions, the digital predistorter (DPD) 212 only has to compensate for the remaining lower-order distortions. The DPD achieves its predistortion utilizing coefficients (or lookup values) that correspond directly to this simplified, "normalized" distortion profile (the baseline amplifier profile after high-order distortions have been subtracted/offset by the APD), para. 0072-83).
Anvari is silent to teaching that wherein providing predistortion based on a supply voltage.
In the same field of endeavor, Kenington teaches a method comprising providing predistortion based on a supply voltage (Kenington teaches that an envelope-tracking power supply 60 varies the level of power supplied to the amplifier 10, and notes that "imperfections or non-linearities in the tracking behavior of the power supply [affect] the resulting output voltage... [which can greatly increase] the distortion produced by the amplifier". Thus, the physical distortion is a function of the supply voltage provided to the PA, para. 0033-37).
Therefore, a person of ordinary skill in the art (PHOSITA) would be highly motivated to modify Anvari’s predistortion architecture by integrating Kenington’s envelope-tracking technology to resolve the critical trade-off between power amplifier efficiency and the bandwidth limitations of digital converters. By modifying Anvari's hybrid architecture with Kenington's envelope tracking, a designer can leverage Anvari's split analog/digital predistortion to handle the supply-dependent distortions.
Anvari's Analog Pre-distorter (APD) can be configured to absorb the wideband, higher-order distortions (which spread far from the main signal carrier) caused by the tracking imperfections of Kenington's power supply. Anvari's Digital Pre-distorter (DPD) is then only responsible for compensating for the lower-order, lower-bandwidth distortions closer to the main signal. This integration yields a highly efficient envelope-tracking transmitter that bypasses digital processing bandwidth bottlenecks while keeping component costs and overall power consumption low.
Regarding claims 18-20, the dependent claims are interpreted and rejected for the same reasons as set forth above in claims 11, 12, 14 and 15, respectively.
Claim(s) 2 is/are rejected under 35 U.S.C. 103 as being unpatentable over Anvari and Kenington as applied to claim 1 above, and further in view of Wessel (US 6646501 B1).
Regarding claim 2, the combination of Anvari and Kenington teaches the transmit chain of claim 1.
The combination of Anvari and Kenington is silent to teaching that wherein the APD circuit comprises a varactor coupled to the power amplifier.
In the same field of endeavor, Wessel teaches a device wherein the APD circuit comprises a varactor coupled to the power amplifier (Wessel, fig. 10, variable capacitor 98).
Therefore, a person of ordinary skill in the art (PHOSITA) would have been highly motivated to combine the hybrid predistortion architecture of Anvari with the dynamic supply-modulated transmitter of Wessel to resolve the critical trade-off between high power-amplifier efficiency and the processing bandwidth limits of digital components in wideband transmission systems.
Claim(s) 4 and 5 is/are rejected under 35 U.S.C. 103 as being unpatentable over Anvari and Kenington as applied to claim 1 above, and further in view of Morimoto (US 20080175335 A1).
Regarding claim 4, the combination of Anvari and Kenington teaches the transmit chain of claim 1.
The combination of Anvari and Kenington is silent to teaching that further comprising a second power amplifier coupled in series to the power amplifier.
In the same field of endeavor, Morimoto teaches a device comprising a second power amplifier coupled in series to the power amplifier (Morimoto discloses an amplifying circuit 20 that contains a "first power amplifier 201" and a "second power amplifier 202". Morimoto teaches that "the second power amplifier is for amplifying an output signal of the first power amplifier". Thus, the second power amplifier is coupled in series to the first, para. 0042-44).
Therefore, a PHOSITA would have been highly motivated to combine the hybrid predistortion of Anvari, the envelope supply tracking of Kenington, and the series multistage amplifier architecture of Morimoto for maximizing efficiency.
While Kenington teaches that dynamic supply-voltage tracking (envelope tracking) dramatically optimizes efficiency, rapid supply changes introduce severe supply-dependent gain and phase variations. Morimoto teaches that in a series multistage design, these supply-dependent variations are compounded in the second stage (PA 202), which depends on the output of the first stage (PA 201). This configuration yields the predictable result of achieving the ultra-high power efficiency of dynamic envelope-tracking and the high gain of series amplification, while keeping the digital predistorter's (DPD) lookup tables simple and operating within highly relaxed digital converter sampling bandwidths.
Regarding claim 5, the combination of Anvari, Kenington and Morimoto teaches the transmit chain of claim 4, wherein the APD circuit is further configured to predistort the second power amplifier to offset variations as a function of the supply voltage (Morimoto explicitly teaches that separate adjustment of these voltages is used to offset sensitivity and gain variations (distortion) in the second stage power amplifier 202).
Claim(s) 7-10 is/are rejected under 35 U.S.C. 103 as being unpatentable over Anvari and Kenington as applied to claims 3 and 6 above, and further in view of Henzler (US 20200304082 A1).
Regarding claim 7, the combination of Anvari and Kenington teaches the transmit chain of claim 6.
The combination of Anvari and Kenington is silent to teaching that wherein the power tracking circuit is configured to set the supply voltage on a per-slot basis.
In the same field of endeavor, Henzler teaches a device wherein the power tracking circuit is configured to set the supply voltage on a per-slot basis (Henzler teaches that the set of supply voltages is constant for certain time intervals, and that these intervals can be an "LTE slot" or "LTE subframe". The voltages change from one set of levels to another at slot boundaries. This meets the per-slot setting limitation under BRI).
Therefore, a person of ordinary skill in the art (PHOSITA) would be highly motivated to modify Anvari’s hybrid predistortion transmit chain by integrating Henzler’s dynamic voltage supply tracking to resolve the critical trade-off between power efficiency and wideband distortion.
Regarding claim 8, the combination of Anvari and Kenington teaches the transmit chain of claim 6.
The combination of Anvari and Kenington is silent to teaching that wherein the power tracking circuit is configured to set the supply voltage on a per-symbol basis.
In the same field of endeavor, Henzler teaches a device wherein the power tracking circuit is configured to set the supply voltage on a per-symbol basis (Henzler teaches that the supply voltage set can transition on a symbol boundary, such as "one OFDM symbol" or "several OFDM symbols". This meets the per-symbol setting limitation under BRI).
Therefore, a person of ordinary skill in the art (PHOSITA) would be highly motivated to modify Anvari’s hybrid predistortion transmit chain by integrating Henzler’s dynamic voltage supply tracking to resolve the critical trade-off between power efficiency and wideband distortion.
Regarding claim 9, the combination of Anvari and Kenington teaches the transmit chain of claim 3.
The combination of Anvari and Kenington is silent to teaching that wherein the supply voltage detector is configured to sample a voltage level on a per-slot basis (Henzler teaches that the set of supply voltages is constant for certain time intervals, and that these intervals can be an "LTE slot" or "LTE subframe". The voltages change from one set of levels to another at slot boundaries. This meets the per-slot setting limitation under BRI).
Therefore, a person of ordinary skill in the art (PHOSITA) would be highly motivated to modify Anvari’s hybrid predistortion transmit chain by integrating Henzler’s dynamic voltage supply tracking to resolve the critical trade-off between power efficiency and wideband distortion.
Regarding claim 10, the combination of Anvari and Kenington teaches the transmit chain of claim 3.
The combination of Anvari and Kenington is silent to teaching that wherein the supply voltage detector is configured to sample a voltage level on a per-symbol basis (Henzler teaches that the supply voltage set can transition on a symbol boundary, such as "one OFDM symbol" or "several OFDM symbols". This meets the per-symbol setting limitation under BRI).
Therefore, a person of ordinary skill in the art (PHOSITA) would be highly motivated to modify Anvari’s hybrid predistortion transmit chain by integrating Henzler’s dynamic voltage supply tracking to resolve the critical trade-off between power efficiency and wideband distortion.
Claim(s) 13 is/are rejected under 35 U.S.C. 103 as being unpatentable over Anvari and Kenington as applied to claim 1 above, and further in view of Tabatabai (US 20170201275 A1)
Regarding claim 13, the combination of Anvari and Kenington teaches the transmit chain of claim 1.
The combination of Anvari and Kenington is silent to teaching that wherein the power amplifier comprises a bipolar transistor.
In the same field of endeavor, Tabatabai teaches a device wherein the power amplifier comprises a bipolar transistor (Tabatabai teaches that the power amplifier (e.g., power amplifier 104 or 224) can be physically implemented using power transistors such as BJTs (Bipolar Junction Transistors) or HBTs (Heterojunction Bipolar Transistors), para. 0012).
Therefore, a person of ordinary skill in the art (PHOSITA) would have been highly motivated to modify or combine Anvari’s hybrid predistortion system with the specific physical implementation and lookup table reduction techniques of Tabatabai. While Anvari teaches a hybrid digital-analog predistortion transmit chain, it describes its power amplifier generally as a non-linear device without detailing the underlying transistor technology. A PHOSITA looking to construct Anvari's circuit for high-frequency or cellular base station applications would look to Tabatabai's disclosure of utilizing bipolar transistors (such as BJTs or HBTs). Tabatabai teaches that these bipolar technologies are highly suited for power amplifiers to deliver high output gain (e.g., 20 dB to 55 dB) and sufficient driving current, making them the logical physical choice for Anvari's amplifier 228.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
Arno: US 20150126141 A1, Brobston: US 20090256630 A1, Menkhoff: US 20160182100 A1, Pinon: US 20110032032 A1, Pratt: US 20110201287 A1, teach predistortion techniques.
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/WEN W HUANG/Primary Examiner, Art Unit 2648
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