# Patent

## Title
Devices and methods for improving yield of scalable periphery amplifiers

## Abstract

Device and methods for improving consistency of operation and therefore yield of scalable periphery amplifiers is described. Amplifier size of the scalable periphery architecture can be adjusted to obtain part-to-part consistency of operating performance as per a defined/desired set of criteria. Amplifier segments of the scalable periphery architecture can be rotated to distribute wear. Further, extra amplifier segments can be implemented on amplifier dies to extend the overall lifetime of amplifiers.

## Background
CROSS REFERENCE TO RELATED APPLICATIONS
Priority Claim
This application is a continuation of co-pending U.S. application Ser. No. 14/082,004 filed Nov. 15, 2013, entitled “Devices and Methods for Improving Yield of Scalable Periphery Amplifiers”, the disclosure of which is incorporated herein by reference in its entirety. Application Ser. No. 14/082,004 may be related to U.S. patent application Ser. No. 13/797,779 entitled “Scalable Periphery Tunable Matching Power Amplifier”, filed on Mar. 12, 2013 (now U.S. Pat. No. 9,294,056 issued Mar. 22, 2016), the disclosure is incorporated herein by reference in its entirety. application Ser. No. 14/082,004 may also be related to International Application No. PCT/US2009/001358, entitled “Method and Apparatus for use in digitally tuning a capacitor in an integrated circuit device”, filed on Mar. 2, 2009, the disclosure of which is incorporated herein by reference in its entirety. Application Ser. No. 14/082,004 may also be related to U.S. Pat. No. 7,248,120, issued on Jul. 24, 2007, entitled “Stacked Transistor Method and Apparatus”, the disclosure of which is incorporated herein by reference in its entirety.
The present application may also be related to U.S. application Ser. No. 14/081,678 entitled “Methods and Devices for Testing Segmented Electronic Assemblies” filed on Nov. 15, 2013 and incorporated herein by reference in its entirety. The present application may also be related to U.S. application Ser. No. 14/081,856 entitled “Devices and Methods for Increasing Reliability of Scalable Periphery Amplifiers” filed on Nov. 15, 2013 and incorporated herein by reference in its entirety.


BACKGROUND
1. Field
The present application relates to power amplifiers.
2. Description of Related Art
In the field of mobile radios, a manufacturer of power amplifiers (PA) or a Power Amplifier Module (PAM) can lose valuable production time and parts due to a low manufacturing/production yield. Also, product variation due to unstable manufacturing/production process can cause performance issues on products using such PA's and PAM's and often call for tedious in-system calibration or parts screening and elimination. Achieving part-to-part consistency at a level acceptable by today's various specification governing mobile radio systems is a very difficult task for those PA's and PAM's dependent on silicon technologies and inherent process variations. These technologies include, but are not limited to, CMOS, SOI CMOS, SOS CMOS and BiCMOS.
SUMMARY
According to a first aspect of the present disclosure, an amplifier assembly is presented, the amplifier assembly comprising: a plurality of amplifier segments; and a controller configured to enable and/or disable one or more amplifier segments of the plurality of amplifier segments according to a set profile, the set profile determining a number of amplifier segments required to be enabled for a given operating performance of the amplifier assembly.
According to a second aspect of the present disclosure, a method for controlling an operating performance of a power amplifier is presented, the method comprising: providing the power amplifier with a plurality of amplifier segments, the plurality of amplifier segments adapted to be turned on or turned off, thus providing the power amplifier with a scalable configuration; providing the power amplifier with a memory storage location; establishing an amplifier operating parameter value associated to a desired operating performance of the power amplifier; establishing a number of amplifier segments to be turned on to obtain the operating parameter value, the established number of amplifier segments being inferior to the plurality of amplifier segments, and storing the established number of segments and the operating parameter value into the memory storage location.
According to a third aspect of the present disclosure, a method for improving manufacturing yield of power amplifiers is presented, the method comprising: establishing a pass/fail criterion based on a desired value of an operating performance of a power amplifier; manufacturing a plurality of power amplifiers; based on the manufacturing, providing the power amplifiers with a plurality of amplifier segments, the plurality of amplifier segments adapted to be turned on or turned off, thus providing the power amplifiers with a scalable configuration; based on the manufacturing, providing the power amplifiers with memory storage locations; testing the operating performance of the power amplifiers; based on the testing, adjusting a size of the power amplifiers; based on the adjusting, determining a number of segments of the plurality of segments to be turned on for obtaining a value of the operating performance of the power amplifiers close to the desired value and satisfying the pass/fail criterion; storing values in correspondence of the number of segments and the desired value of the operating performance in the memory storage locations; based on the storing, creating a lookup table associating the number of the segments and the value of the operating performance, and improving manufacturing yield by operating the power amplifiers based on the values of the lookup table.



BRIEF DESCRIPTION OF DRAWINGS
The accompanying drawings, which are incorporated into and constitute a part of this specification, illustrate one or more embodiments of the present disclosure and, together with the description of example embodiments, serve to explain the principles and implementations of the disclosure.
FIG. 1 shows and overview of an amplifier arrangement connected with a transmitter, a matching network and an antenna.
FIG. 2 shows an example scalable periphery arrangement on a die comprising N number of amplifier segments configured to be turned on and turned off according to various tasks and/or sequences.
FIG. 3 shows an example scalable periphery arrangement on a die comprising four amplifier segments configured to be turned on and turned off according various tasks and/or sequences.
FIGS. 4A-4B show example scalable periphery arrangements on a die with a logic controller located on the die (FIG. 4A) or separate from the die (FIG. 4B).
FIGS. 4C-4D show example scalable periphery arrangement on a die with a lookup table (LUT) which can be used for product calibration located on the die.
FIGS. 5A-5D show example implementations of enabling and/or disabling stacked transistors in an amplifier segment of the amplifier arrangement.
FIG. 6 shows an example scalable periphery arrangement on a die comprising a plurality of amplifier segments with spare disabled amplifier segments configured to be enabled when the enabled amplifier segments fail.
FIG. 7 shows an example failure detector of the amplifier segments as described in some embodiments of the present disclosure.



DETAILED DESCRIPTION
Integrated circuit designs are implemented with ever refining techniques and architectures. In some of these architectures, an electronic circuit comprises an assembly of parts, which can be denoted as segments. The purpose of such an implementation using segments can be varied. For example, digitally tunable capacitors are referred to, for example, in International Application No. PCT/US2009/001358, entitled “Method and Apparatus for use in digitally tuning a capacitor in an integrated circuit device”, filed on Mar. 2, 2009, the disclosure of which is incorporated herein by reference in its entirety. Such capacitors comprise a number of segments. Another example (U.S. Ser. No. 13/797,779) discloses power amplifiers comprising a number of amplifier segments. These examples are not meant as a limitation of the present disclosure, but serve to exemplify what is intended as an electronic assembly comprising a number of assembly segments. The present disclosure relates to methods for testing such electronic assemblies.
As used in the present disclosure, the terms “switch ON” and “activate” may be used interchangeably and can refer to making a particular circuit element electronically operational. As used in the present disclosure, the terms “switch OFF” and “deactivate” may be used interchangeably and can refer to making a particular circuit element electronically non-operational. As used in the present disclosure, the terms “amplifier” and “power amplifier” may be used interchangeably and can refer to a device that is configured to amplify a signal input to the device to produce an output signal of greater magnitude than the magnitude of the input signal.
The present disclosure describes electrical circuits in electronics devices (e.g., cell phones, radios) having a plurality of devices, such as for example, transistors (e.g., MOSFETs). Persons skilled in the art will appreciate that such electrical circuits comprising transistors can be arranged as amplifiers. As described in a previous disclosure (U.S. Ser. No. 13/797,779), a plurality of such amplifiers can be arranged in a so-called “scalable periphery” (SP) architecture of amplifiers where a total number (e.g., 64) of amplifier segments are provided. Depending on the specific requirements of an application, the number of active devices (e.g., 64, 32, etc.) can be changed for each application. For example, in some instances, the electronic device may desire to output a certain amount of power, which in turn, may require 32 of 64 SP amplifier segments to be used. In yet another application of the electronic device, a lower amount of output power may be desired, in which case, for example, only 16 of 64 SP amplifier segments are used. In other words, in a given first time period, a first number of devices can be used, while in a subsequent time period, a different number of devices can be used based on desired output power.
The term “amplifier” as used herein the present disclosure is intended to refer to amplifiers comprising single or stacked transistors configured as amplifiers, and can be used interchangeably with the term “power amplifier (PA)”. Stacked transistor amplifiers are described for example in U.S. Pat. No. 7,248,120, issued on Jul. 24, 2007, entitled “Stacked Transistor Method and Apparatus”, the disclosure of which is incorporated herein by reference in its entirety. Such amplifier and power amplifiers can be applicable to amplifiers and power amplifiers of any stages (e.g., pre-driver, driver, final), known to those skilled in the art. The scalable periphery amplifier devices can be connected to corresponding impedance matching circuits. Such scalable periphery amplifier devices have a particular impedance value according to the number of amplifier segments that are turned on or turned off at a given moment, the modulation applied, the required output power, the linearity requirements of the amplifier or any number of other requirements.
As described above, an electronic circuit where all of the amplifiers of the scalable periphery architecture are turned on can be considered to be operating at full power, and such configuration can have a certain overall impedance based on the number of amplifiers that are turned on. In some instances, it can be desirable to turn off some amplifiers to operate the electronic circuit, for example, at reduced power consumption. Similar to measuring a total resistance of a plurality of resistors connected in parallel with each other, the total impedance of the plurality of amplifiers in a SP amplifier architecture can be calculated, simulated or measured in a similar manner. As known by those skilled in the art, the greater the number of amplifiers devices (in parallel), the lower the total impedance, and vice versa.
For determining the overall impedance of the plurality of amplifiers in an SP amplifier architecture, an amplifier that is off can be considered an open circuit (e.g., power amplifier device removed). Thus, if a certain number of amplifiers are turned off, then the total impedance of the SP amplifier will be higher. To the contrary, if the amplifier devices are on, then the total impedance of the amplifier circuit will be lower. As the amplifiers are turned on or turned off, the number of active amplifiers in the SP amplifier is decreased or increased, and therefore the overall impedance of the amplifier circuit is also changed.
As it is known to those skilled in the art, the performance of amplifiers (e.g. high power amplifiers made of MOSFETs) can vary greatly due to manufacturing process-based variations which can affect the physical attributes (e.g. length, width, oxide thickness) of the transistors (e.g. MOSFETs) making up the amplifiers. Such variations become particularly more important at smaller fabrication processes as a variation becomes a larger percentage of the full length or width of the transistors. As such, amplifiers made from a same mask can have a measurable difference in their output performance based on a manufacturing batch or even based on a time of manufacturing within a same batch. Although such measurable difference may be within a manufacturing specification tolerance/range, it can create performance degradation and inconsistency in a final product (e.g. mobile cell) wherein the amplifier is used.
As it is known by those skilled in the art, the performance of amplifiers (e.g., high power amplifiers made of MOSFETs) can degrade over time due to several degradation mechanisms. Such mechanisms may comprise, among others, electromigration (EM), time-dependent dielectric breakdown (TDDB), and hot carrier injection (HCI). Therefore, a lifetime is usually estimated for amplifiers (and other electronic components), indicating a time period over which the device is expected to be operational with significant statistical confidence. As previously mentioned, another cause of variation in the performance of amplifiers is process variation. Due to a variety of causes, during fabrication an amplifier might have small variations in one or more of its operational parameters, which may vary, to a degree, within an expected range of values. In some cases, an amplifier may fall outside the specified range and therefore may need to be discarded. Similarly, during operation of an amplifier, its performance, before or after the expiration of the expected lifetime, may fall outside a specified range, and therefore may be deemed to have failed. Operation of an electronic device which comprises the amplifier may be adversely affected, up to the point of total failure for the electronic device.
The present disclosure describes structures and methods to improve overall reliability and consistency of electronic devices by improving reliability and consistency of amplifiers used in such electronic devices. By “reliability” it is intended of the capacity of an amplifier to operate within an expected range of parameters, for example: at fabrication, after which the amplifier may be tested to verify its operation before sale or further fabrication steps; during operation, when an amplifier may be monitored and, if it is determined to have failed, deactivated; during operation, when an amplifier segment may be activated to replace a failed amplifier segment; during operation, when amplifier segments may be activated in a timewise rotation pattern to decrease the wear on individual amplifier segments, thereby increasing overall lifetime of an electronic device.
By “consistency” it is intended of the capacity of an amplifier to operate within an expected range of parameters (e.g. nominal power output, nominal current output, etc. . . . ) after the amplifier is tested to verify and possibly adjust its operation, similar to a production test which includes a calibration step, before sale or other fabrication steps of the amplifier. Such range of parameters (e.g. associated values of each parameter) can be more stringent to those possible given afore mentioned manufacturing tolerances due to process variation and which can affect transistors and other components of the amplifier. Such calibration can include determining a number of required segments of the amplifier to be activated for a nominal operating parameter (e.g. associated values within an admissible/desired range of values), such as output power or current, of the amplifier, and storing a corresponding profile into a memory space, such as a lookup table, within the amplifier.
For example, a first amplifier manufactured during an early morning run may have a nominal output power of 2 mW per segment consistently (e.g. across all segments), whereas a second amplifier of the same batch but manufactured in the late morning run may have a nominal output power of 2.5 mW per segment consistently. The lookup table of the first amplifier (e.g. as obtained during the calibration step) will indicate that for a nominal output power of 50 mW, 25 segments can be activated and the lookup table of the second amplifier will indicate 20 segments for the same 50 mW output power. In a system where such amplifier is integrated, a system controller can specify a value of a nominal operating parameter (e.g. output power, current) to the amplifier, and the amplifier can use the embedded lookup table to activate the number of segments required without further intervention of the controller (e.g. controller does not directly activate a segment and does not need know how many segments are activated). Alternatively the content of the lookup table can be made accessible to the system controller and the system controller can have the option to directly activate the required number of segments. Given the provision of an internal lookup table mapping nominal operating parameter values to the number of required active (e.g. and deactivated) segments, the skilled person will know of many different ways to create a control interface to the amplifier.
As previously explained, semiconductor process variations can certainly impact the performance of a PA or PAM. One can devise compensating circuitries, such as a constant bias circuit for controlling biasing (e.g. power) of the amplifier, but further improvements can be made by adjusting the size (e.g. number of activated segments) in production testing before shipment (e.g. to a handset manufacturer), per the method provided above. The consistency in operating parameters provided by such method can make the amplifiers (e.g. PA's, PAM's) seem as identical as possible and make such amplifiers drop-in replaceable in target systems. Moreover, improving consistency can also improve yield, as inherent process variations, although within manufacturing tolerances of an amplifier production facility, can render amplifiers unusable in certain systems made by integrators of the amplifiers. Or alternatively and keeping in mind system integrators' requirements, manufacturing tolerances for the amplifier can be relaxed such as to improve yield as amplifier consistency is dialed in post manufacturing (e.g. during the production test/calibration). According to some embodiments of the present disclosure, a production test such as described in the previous paragraphs can map a variety of vital operating parameters of the amplifier, such as, but not limited to, gain, output power, output current, efficiency, output distortion, etc. . . . and accordingly adjust a nominal amplifier (e.g. PA, PAM) size (e.g. number of activated segments) to center or normalize response of the amplifier such as to create a consistent product (e.g. all manufactured amplifiers). Although the lookup tables or mappings are individualized (e.g. amplifier specific), the product as a whole is consistent in performance. Although a totality of operating parameters can be used to generate a centered or normalized response, according to further embodiments of the present disclosure, operating parameters can be considered individually, in groups or in totality, and accordingly different mappings (e.g. segment sizes) can be generated and stored within the internal lookup table. Given the teachings according to the various embodiments disclosed, the skilled person will know of alternative implementations which are based on such teachings.
FIG. 1 shows a generic diagram of an example electronic circuit comprising an SP amplifier 100, which in turn, is comprised of a scalable periphery architecture 102 of amplifiers. An electronic circuit 108 can be connected to an input of the amplifier 100. In one embodiment, the electronic circuit may be a transmitter 108. The transmitter may be part of a transceiver. An output of the amplifier can be connected to a matching circuit 104, which can be connected to an antenna 106. In this embodiment, the antenna 106 would be a load, and a tunable matching component 104 is connected between the SP amplifier 100 and the antenna 106. The load impedance seen by the SP amplifier at its output is the sum of the impedance of the antenna 106 plus the impedance of the tunable matching circuit 104. A person skilled in the art will understand that the diagram shown in FIG. 1 is generic and that the electronic circuit can comprise more or less component such as, for example, a plurality of amplifiers (e.g., pre-driver stage, driver stage) or an antenna switch, which are not shown.
According to some embodiments, amplifier segments can be part of an SP amplifier as shown in FIG. 2. FIG. 2 shows a die 200 (on wafer) comprising a plurality of amplifier segments 204A, 204B . . . 204N electrically connected in parallel with one another. Each of the amplifier segments 204A, 204B . . . 204N can be turned on or turned off independently of one another by a logic controller (shown later in FIGS. 4A-4B) that is connected to each of the enable inputs 205A, 205B . . . 205N on the amplifier segments. For example, the logic controller can send an independent disable signal to the enable input 205A in order to turn off amplifier segment 204A, and send an independent enable signal to the enable inputs 205B . . . 205N in order to turn on (or leave on) amplifier segments 204B . . . 204N. Such enable and/or disable signals can be independent of one another, such that the enable and/or disable signal applied to an enable input of a one amplifier segment is unrelated and/or unaffected by the enable and/or disable signal applied to the enable input of another amplifier segment. Since the amplifier segments 204A, 204B . . . 204N are connected in parallel with one another, as described above, similar to a plurality of resistors that are connected in parallel, the overall output impedance of the amplifier segments 204A, 204B . . . 204N is reduced as the number of active amplifier segments increase. On the other hand, the overall impedance of the amplifier segments increase as the number of amplifier segments 204A, 204B . . . 204N connected in parallel decrease. When the number of active amplifier segments is varied to optimize a desired parameter of the SP amplifier (as described in detail in the previous disclosure U.S. Ser. No. 13/797,779), the impedance of the SP amplifier may decrease or increase.
FIG. 3 shows an example scalable periphery amplifier that comprises four amplifier segments 303A, 303B, 303C, 303D for ease of explanation instead of the 64 amplifier segments as described above. The numbers four, or 64, refer to example embodiments and any number of amplifier segments may be used in the disclosure. In the example of FIG. 3, normal operation of the amplifier 300, which comprises a total of four amplifiers segments 303A, 303B, 303C, 303D, only requires two active segments, for example 303A and 303B. According to an embodiment of the present disclosure, in order to increase the lifetime of such amplifier assemblies (or to allow trimming the size of the amplifier 300 for product consistency, as described in the next paragraph), extra amplifier segments 303C, 303D in addition to the minimum required number of amplifier segments 303A, 303B can be built into the amplifier 300. In other words, more amplifier segments than required to perform the desired application can be incorporated into the amplifier 300. The additional amplifier segments 303C, 303D and the required amplifier segments 303A, 303B can be turned on or turned off according to tasks (e.g., applications) being performed by the device comprising the amplifier 300, thus the amplifiers have a scalable configuration where the various amplifier segments can be turned on and/or turned off. Further to the amplifier segments being turned on and/or turned off based on the task, the amplifier segments can also be turned on and/or turned off based on a set sequence and a set time interval, thus reducing the amount of time that each of the amplifier segments are turned on. Such rotational sequence (cycling) of the amplifier segments 303A-303D can reduce the degradation of the amplifier segments, which in turn, can extend the lifetime of the overall amplifier. For example, if it is desired to design an amplifier assembly that will last, for example, 10 years, but may be known by those skilled in the art that the amplifier segments comprising the amplifier may last only five years, then at least twice as many amplifier segments than initially required for the application can be used to build the amplifier. Hence, an application-dependent number of amplifier segments to be kept on during performance of the application can be selected.
According to an embodiment of the present disclosure the required active segments 303A and 303B of FIG. 3 are amplifier-specific and can be generated via the product test phase, during which a pool of the extra segments, as described in the previous section, can be used to generate the mapping and calibration of individual amplifiers as needed. Such mapping and calibration data can be stored in a lookup table such as depicted in FIGS. 4C-4D later described.
FIG. 3 shows an example case when two amplifier segments 303A, 303B are required in order to perform the desired application, while instead four amplifier segments 303A-303D are incorporated into the amplifier configuration. A set sequence and a set time schedule can be selected to cycle the amplifier segments 303A-303D. For example, during a first period of operation, amplifier segments 303A and 303B can be turned on, while amplifier segments 303C and 303D are turned off. During a second period of operation, amplifier segments 303B and 303C can be turned on, while amplifier segment 303A and amplifier segment 303D are turned off. During a third period of operation, amplifier segments 303C and 303D can be turned on, while amplifier segments 303A and 303B are turned off. During a fourth period of operation, amplifier segments 303A and 303D can be turned on, while amplifier segments 303B and 303C are turned off. By cycling the amplifier segments 303A-303D according to the sequence described above, the number of amplifier segments that are turned on during each time period is constant. A person skilled in the art would appreciate that variations of such cycle can be used based on the task that is performed with the amplifiers. Such sequence can be cycled at set time intervals, for example, every day, hour, minute, second, millisecond, or every GSM slot (e.g., 20 millisecond interval between transmission bursts), which can be set by according to the application for which the amplifier was designed. According to the configuration and sequence described above, the amplifier can last twice as long by including four amplifier segments into the amplifier assembly instead of including just two amplifier segments (e.g., the minimum required number of amplifiers for the desired application). Since two of the four amplifier segments are turned off during each period of operation, the degradation of the two “off” amplifier segments is reduced or halted, thus increasing the overall lifetime of the amplifier.
In some embodiments, the amplifier can comprise a logic controller (shown later in FIGS. 4A-4D) that can be configured to turn on and turn off the plurality of amplifier segments 303A-303D according to the set sequence and time interval. The logic controller can send an independently controllable enable or a disable signal to the enable inputs 305A-305D in order to turn on or turn off the amplifier segments 303A-303D, respectively. By way of example and not of limitation, in order to cycle the amplifier segments 303A-303D as described above, the logic controller can be configured to send an enable signal to the enable inputs 303A and 303B during the first period of operation, while a disable signal is sent to the enable inputs 303C and 303D. Accordingly, the logic controller can be programmed to send various combinations of enable and/or disables signals to the enable inputs 305A-305D of amplifiers 303A-303D according to a selected algorithm for cycling the amplifier segment.
FIGS. 4A-4D show example implementations of the logic controller 405, 409 for the amplifiers according to the embodiments of the present disclosure. FIGS. 4A and 4C show an SP amplifier 403 (alternatively denoted as simply an ‘amplifier’, as opposed to its ‘amplifier segments’), said SP amplifier comprising a plurality of amplifier segments 402 on a die 400, with a logic controller 404 located on the die 400. In such configuration, an external testing logic controller 405 can be connected to the internal logic controller 404 in order for the amplifier 406 to perform test procedures by turning on and/or turning off the amplifier segments as described earlier according to various embodiments of the present disclosure. FIGS. 4B and 4D show an amplifier 406 similar to the amplifier 403 shown in FIGS. 4A, 4C, also comprising a plurality of amplifier segments 408 on a die 407. Differently from the amplifier 403 in FIGS. 4A, 4C, the amplifier 406 in FIGS. 4B, 4D comprises a logic controller 409 located externally to the die 407, through an interface 411. By way of example and not of limitation, such logic controller 409 can be located in a transceiver (similarly to 108 in FIG. 1) or in a baseband processor such that during operation of the amplifier 406, the control signals are provided from the transceiver or the baseband processor. On the other hand, when in the test mode, the external controller 409 can be provided, for example, by a test equipment to turn on and/or turn off the amplifier segments 408 to perform the test procedures according, for example, to the embodiment of FIG. 3. Similarly, the controller 409 in FIGS. 4B and 4D may comprise different external logic controllers.
Furthermore and according to an embodiment of the present disclosure, the amplifier of FIGS. 4C and 4D comprises a lookup table (LUT) 420 which can be used to store the mapping profiles (e.g. number of segments per operating parameter value) generated during the production and testing phase of the amplifier. During this production phase, the internal controller 404 or the external controller 409 can be used to control the segments and to store and verify the mapping profile onto the LUT 409. The skilled person will know that there are multitude of ways to implement such a lookup table and an associated interface. According to some embodiments of the present disclosure the lookup table 420 can comprise a non-volatile memory (NVM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM) or other memory types known to the skilled person. In some cases it may be desirable that the memory content is not erased after initial calibration at the manufacturing plant, whereas in some cases it may be desirable to allow re-calibration (e.g. remapping) of the amplifier. Such limitations may be set by the type of memory used in the lookup table 409 and/or the interface to the memory and/or the device.
Examples of different functions implemented by a controller (such as 409 in FIGS. 4B, 4D) comprise, by way of examples and not of limitation, timewise selection of different amplifier segments to spread ‘wear and tear’ of the amplifier segments, and deactivation of faulty amplifier segments, which may be accompanied by a corresponding activation of ‘spare’ amplifier segments which were inactive at the time a partial failure occurred in the SP amplifier. As those skilled in the art will understand, such exemplificatory implementation may be realized, in some embodiments, by fabricating the SP amplifier with a higher number of amplifier segments than needed by basic operation of the SP amplifier. For example, if the SP amplifier can normally be operated with 64 amplifier segments with an average lifetime for the SP amplifier of 5 years, it may alternatively be built with 128 amplifier segments which are operated on a time rotation, thereby increasing the overall lifetime for the SP amplifier to 10 years. The amplifier segments may be rotated on any timescale, depending on the desired implementation, for example the segments may be rotated every few milliseconds, or every year. Such examples are not intended as a limitation. In fact, the mode of failure may be non linear with active operational time; for example, after a certain usage period a heat build-up might increase the amplifier segment degradation. In such cases, a time rotation designed to turn off an amplifier segment before it reaches a point of heat build-up, and substituting it with a newly activated amplifier segment, might even increase the overall lifetime of the SP amplifier by more than twice a value compared to an SP amplifier with only as many amplifier segment as needed by normal operation.
In one embodiment of a segmented amplifier architecture (scalable periphery), extra amplifier segments are built into the SP amplifier. For example, referring to FIGS. 4A and 4C, the amplifier segments 402 may include a total number of N amplifier segments. At peak required output, segments from 1 to N/2 may be activated while the remainder segments, those from (N+1)/2 to N, may be deactivated. During normal operation of the amplifier, by way of example and not of limitation, only a maximum of N/2 amplifier segments may be needed for optimal operation. After a specified time, the controller 404 will deactivate all segments from 1 to N/2 and utilize instead those from N/2 to N, thereby distributing the wear and tear across multiple segment amplifiers. It should be noted that the number of activated segments during the normal operation of the amplifier can be different from one amplifier to another, as the amplifiers can have a calibration profile stored within a lookup table such as depicted in FIG. 4C and previously described.
In another embodiment, a different fraction of inactive amplifier segments may be provided. For example, if the total number of amplifier segments is N, the maximum number of simultaneously active segment amplifiers might be N/3. The remaining 2N/3 amplifier segments might be kept as spare, or activated at different times to spread wear, or a combination of the two. Other purposes might be possible for the surplus amplifier segments. Any fraction of inactive to total amplifier segments may be used in the present disclosure.
FIGS. 5A-5D show example implementations for enabling and/or disabling each of the amplifier segments. A single amplifier segment 500 (e.g., 303A from FIG. 3) can comprise, for example, stacked transistors 501, 502, 503, where a DC bias voltage is applied to the top two transistors 502, 503. The gate 504 of the bottom transistor 501 can be adapted to receive an input RF signal to be amplified by the amplifier segment 500. The middle transistor 502 can comprise a switch 506 that can ground the gate of transistor 502 when the logic controller (405 or 409 from FIGS. 4A-4B) sends a disable (turn off) signal to the amplifier segment 500. When the logic controller sends an enable (turn on) signal to the amplifier segment 500, then the switch 506 can unground the gate of transistor 502 and complete the electrical path of the DC bias between the DC power supply 505 and the gate of transistor 502. Accordingly, FIG. 5A shows the amplifier segment 500 in the disabled (turned off) configuration and FIG. 5B shows the amplifier segment 500 in the enabled (turned on) configuration.
Alternatively, FIGS. 5C-5D show similar configurations as in FIGS. 5A-5B, except that switch 507 is located at the gate of the bottom transistor 501 by interrupting the RF input signal and ground the gate of transistor 501 when the logic controller sends a disable (turn off) signal to the amplifier segment 500. Accordingly, FIG. 5C shows the amplifier segment 500 in the disabled (turned off) configuration and FIG. 5D shows the amplifier segment 500 in the enabled (turned on) configuration. Disabling the lowermost transistor 501 of the stacked transistors 501, 502, 503 allows for a more distributed voltage division of the power supply voltage (e.g., Vdd) when the stacked transistors are turned off, thus reducing the amount of stress that would be placed on a single transistor if the entire supply voltage was dropped over just a single transistor (for example, see U.S. Pat. No. 7,248,120, whose disclosure is incorporated herein by reference in its entirety).
According to another embodiment of the present disclosure as shown in FIG. 6, the amplifier assembly on a die 600 can comprise a desired number of amplifier segments 604A, 604B . . . 604N, based on the application for which the amplifier assembly is designed. The normal operation of the amplifier assembly may require a maximum of N/2 segments to be operational at the same time, therefore it may comprise N/2 extra amplifier segments which can be used interchangeably with the minimum required amplifier segments to improve overall reliability (e.g., to increase overall lifetime, or to recover from partial failure of the assembly). The amplifier assembly may comprise a failure detector 605 (shown in detail in FIG. 7) on the die 600 to sense when any of the amplifier segments fails or malfunctions by monitoring, for example, quiescent current, RF current, RF output power, and/or output voltage waveforms. Other parameters may be monitored which may be relevant to a malfunction. The failure detector 605 can then inform a logic controller 609 of the failed or malfunctioned amplifier segments and the logic controller 609 can decide which of the additional amplifier segments should be turned on and enabled to replace the failed amplifier segments. As described earlier, such logic controller 609 can be located either on the same die 600 as the amplifier segments or can be located on devices external to the amplifier segments such as, for example, a transceiver or a baseband processor.
According to an embodiment of the present disclosure, the failure detector 605 can be connected to the amplifier segments 604A, 604B . . . 604N via failure outputs 607A, 607B . . . 607N to sense failure or malfunction of the amplifier segments, and the logic controller 605 can be connected to enable inputs 606A, 606B . . . 606N to turn on or turn off the amplifier segments according to instructions received from the failure detector 605. Therefore, when the failure detector 605 senses an indication of failure or malfunction of an amplifier segment, the failure detector 605 will indicate the logic controller 609 to send a disable signal to the failed amplifier segment and send an enable signal to the alternate amplifier segment that is to be turned on to replace the failed amplifier segment.
In one embodiment, a quiescent current parameter, as described above, may be monitored by a failure detector (such as 605 in FIG. 6). As it is known by those skilled in the art, the quiescent current is the current of an amplifier not under load. FIG. 7 shows an example circuital arrangement of a quiescent current sensing failure detector 700 for an amplifier segment 704. The quiescent current sensing failure detector 700 can comprise a current sensing resistor 702 connected at the source of a bottom stacked transistor 701 (e.g., connected between the source and ground) with a voltage sensor 703 configured to measure the voltage of the current sensing resistor 702. The voltage sensor 703 can be set so that it monitors a specific voltage that is expected when the transistor is functioning properly, when under bias but not under load. If a voltage is measured that is higher or lower than the expected voltage by the voltage sensor 703, then the voltage sensor 703 will trigger a failure flag. In some embodiments, the failure flag can be sent to a logic controller (such as 609 in FIG. 6), and the logic controller can take appropriate action to disable the failed amplifier segment and enable one of the spare amplifier segments.
Those skilled in the art will understand that FIG. 7 depicts a possible embodiment of a failure detector, but several variations, or entirely different designs, might be implemented. For example, a switch might be present between bias 705 and transistor 701, in such a way as to enable transistor 701 to be connected either to bias 705 or to another signal (e.g., an RF signal).
According to an example configuration, if the amplifier requires two amplifier segments to meet the minimum number of required amplifier segments for the specific application, then the two required amplifier segments can be initially enabled, and the two extra amplifier segments can be initially disabled. The failure detector can continuously monitor the enabled amplifier segments for proper operation. If the failure detector senses that one or more of the enabled amplifier segments has failed (e.g., operating outside of specifications), then the logic controller can disable the failed amplifier segments and enable the extra amplifier segments that were initially disabled. Although the present example describes a configuration comprising an equal number of required amplifier segments and extra amplifier segments, those skilled in the art would understand that there can be more or less extra amplifier segments than the required amplifier segments depending on the level of reliability desired with the amplifiers.
The examples set forth above are provided to give those of ordinary skill in the art a complete disclosure and description of how to make and use the embodiments of the present disclosure, and are not intended to limit the scope of what the inventors regard as their disclosure. Modifications of the above described modes for carrying out the disclosure may be used by persons of skill in the art, and are intended to be within the scope of the following claims. All patents and publications mentioned in the specification may be indicative of the levels of skill of those skilled in the art to which the disclosure pertains. All references cited in this disclosure are incorporated by reference to the same extent as if each reference had been incorporated by reference in its entirety individually.
It is to be understood that the disclosure is not limited to particular methods or systems, which can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting. As used in this specification and the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the content clearly dictates otherwise. The term “plurality” includes two or more referents unless the content clearly dictates otherwise. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the disclosure pertains.
A number of embodiments of the disclosure have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the present disclosure. Accordingly, other embodiments are within the scope of the following claims.

## Claims

1. An amplifier assembly comprising:
a plurality of amplifier segments;
a memory storage location storing therein, for each operating parameter value of the amplifier assembly of a plurality of operating parameter values of the amplifier assembly, a number of amplifier segments to be turned on in correspondence of the each operating parameter value; and
a controller configured to read from the memory storage location a number of amplifier segments to be turned on responsive to an operating parameter value of the amplifier assembly of the plurality of operating parameter values and accordingly enable and/or disable one or more amplifier segments of the plurality of amplifier segments to obtain said number of turned on amplifier segments,
wherein the operating parameter value is associated to a given operating performance of the amplifier assembly.

2. The assembly of claim 1, wherein the controller is further configured to enable and/or disable the one or more amplifier segments of the plurality of amplifier segments according to an operating parameter value associated to a set task, the set task determining a number of amplifier segments required to be enabled in a given time period.

3. The assembly of claim 1 or claim 2, wherein the controller is further configured to enable and/or disable the one or more amplifier segments of the plurality of amplifier segments based on a set sequence at set time intervals.

4. The assembly of claim 3, wherein the number of enabled amplifier segments and the number of disabled amplifier segments is constant through different time intervals.

5. The assembly of claim 3, wherein the set sequence is a timewise rotation sequence rotating through the amplifier segments.

6. The assembly of claim 1, wherein the controller is located on a same die as the amplifier segments.

7. The assembly of claim 1, wherein the memory storage location comprises a lookup table used to store a mapping between the each operating parameter value of the amplifier assembly and the number of amplifier segments to be turned on in correspondence of the each operating parameter value of the amplifier assembly.

8. The assembly of claim 7, wherein the lookup table is implemented using one of: a) a programmable read-only memory, b) an erasable programmable read-only memory, c) a nonvolatile memory, and d) any kind of memory.

9. The assembly of claim 7, wherein the lookup table comprises data obtained via a calibration procedure of the amplifier assembly.

10. The assembly of claim 1, wherein the operating performance is based on a value of one of: a) gain, b) output power, c) output current, d) efficiency, e) output distortion, and f) a combination of any one of a)-e) of the amplifier assembly during operation.

11. The assembly according to claim 3, wherein the assembly further comprises:
one or more additional amplifier segments in a disabled condition, wherein one or more enabled amplifier segments of the plurality of amplifier segments are adapted to be replaceable, upon failure, with the one or more additional amplifier segments in the disabled condition upon enabling the disabled additional one or more amplifier segments; and
a failure detector adapted to detect failure of each one of the amplifier segments, wherein
the controller is further configured to disable the one or more enabled amplifier segments, and configured to enable the one or more additional amplifier segments in the disabled condition upon indication of failure by the failure detector, of the one or more amplifier segments in the enabled condition.

12. The assembly according to claim 11, wherein a fraction of a total number of the plurality of amplifier segments are amplifier segments in an enabled condition and a remainder of the total number of the plurality of amplifier segments are amplifier segments in a disabled condition.

13. The assembly according to claim 12, wherein the fraction is one half of the total number of the plurality of amplifier segments.

14. The assembly according to claim 11, wherein the failure detector and the controller are located on a same die.

15. The assembly according to claim 11, wherein the failure detector and the controller are located on different dies.

16. The assembly according to claim 11, wherein the failure detector is a quiescent current detector.

17. An amplifier assembly comprising:
a plurality of amplifier segments;
one or more additional amplifier segments in a disabled condition, wherein one or more enabled amplifier segments of the plurality of amplifier segments are adapted to be replaceable, upon failure, with the one or more additional amplifier segments in the disabled condition upon enabling the disabled additional one or more amplifier segments;
a failure detector adapted to detect failure of each one of the amplifier segments;
a controller configured to:
enable and/or disable one or more amplifier segments of the plurality of amplifier segments according to a set profile, the set profile determining a number of amplifier segments required to be enabled for a given operating performance of the amplifier assembly; and

disable the one or more enabled amplifier segments, and enable the one or more additional amplifier segments in the disabled condition upon indication of failure by the failure detector, of the one or more amplifier segments in the enabled condition.