An adjustable mixer is disclosed that is capable of operating in different modes in order to satisfy the mixing requirement of multiple radio access technologies (RATs). The adjustable mixer includes a LO signal generating portion and a mixing portion. Depending on the mixing requirements of the RAT, the adjustable mixer can operate in any one of multiple modes, each mode having a specific configuration for the LO signal generating portion and the mixing portion. The LO signal generating portion generates a LO signal having a particular duty cycle, depending on the selected mode, for use by the mixing portion. The mixing portion has an adjustable circuit configuration that can be dynamically reconfigured based on the selected mode, and which allows the mixing portion to successfully mix received signals using the corresponding LO signals generated by the LO signal generating portion.

BACKGROUND

1. Field of Invention

The invention relates to wireless communications, and more specifically to a variable duty cycle mixer module that is configured to select one of multiple duty cycles for the local oscillator depending on the performance of the mixer with respect to one or more radio access technologies.

2. Related Art

Wireless communication devices, such as cellular telephones to provide an example, are becoming commonplace in both personal and commercial settings. The wireless communication devices provide users with access to all kinds of information, as well as the ability to communicate with other such devices across large distances. For example, a user can access the internet through an interne browser on the device, download miniature applications (e.g., “apps”) from a digital marketplace, send and receive emails, or make telephone calls using a voice over internet protocol (VoIP). Consequently, wireless communication devices provide users with significant mobility, while allowing them to remain “connected” to communication channels and information.

Wireless communication devices communicate with one or more other wireless communication devices or wireless access points to send and receive data. Typically, a first wireless communication device generates and transmits a radio frequency signal modulated with encoded information. This radio frequency signal is transmitted into a wireless environment and is received by a second wireless communication device. The second wireless communication device demodulates and decodes the received signal to obtain the information. The second wireless communication device may then respond in a similar manner. The wireless communication devices can communicate with each other or with access points using any well-known modulation scheme, including simple amplitude modulation (AM), simple frequency modulation (FM), quadrature amplitude modulation (QAM), phase shift keying (PSK), quadrature phase shift keying (QPSK), and/or orthogonal frequency-division multiplexing (OFDM), as well as any other communication scheme that is now, or will be, known.

During communication, signals received by the wireless communication device are provided to a mixer, which is generally employed to shift the frequency of the received signals. This can be used, for example, to shift a modulated signal to a baseband frequency.

In non-linear systems, including mixers, the second order intercept point (IP2) is a measure of linearity that quantifies the second-order distortion generated by nonlinear systems and devices. In a wireless transceiver, any leakage from the transmitter into the receiver chain, can exacerbate second order distortion because of the relatively high amplitude level of the transmit signal. As such, improving IP2 of the receiver chain has become imperative in modern communication standards.

Therefore, the standards of most modern RATs (radio access technologies) define strict IP2 levels that must be achieved by mixers that are used with those RATs. For example, the 2G wireless standard (incorporated herein by reference in its entirety) requires approximately 40 dB of IP2 level, the 3G specification (incorporated herein by reference in its entirety) requires approximately 45 dB of IP2 level, and the 4G specification (incorporated herein by reference in its entirety) requires approximately 52 dB of IP2 level.

Because of manufacturing variables, different mixers produce different IP2 performance. However, because any of 2G, 3G and 4G modes share the same RF frequency range, it would be beneficial to employ only a single mixer for receiving signals within each such RAT.

The disclosure will now be described with reference to the accompanying drawings. In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The drawing in which an element first appears is indicated by the leftmost digit(s) in the reference number.

DETAILED DESCRIPTION

The exemplary embodiments described herein are provided for illustrative purposes, and are not limiting. Other exemplary embodiments are possible, and modifications may be made to the exemplary embodiments within the spirit and scope of the disclosure. Therefore, the Detailed Description is not meant to limit the disclosure. Further, the scope of the invention is defined only in accordance with the following claims and their equivalents.

For purposes of this discussion, the term “module” shall be understood to include at least one of software, firmware, and hardware (such as one or more circuit, microchip, or device, or any combination thereof), and any combination thereof. In addition, it will be understood that each module may include one, or more than one, component within an actual device, and each component that forms a part of the described module may function either cooperatively or independently of any other component forming a part of the module. Conversely, multiple modules described herein may represent a single component within an actual device. Further, components within a module may be in a single device or distributed among multiple devices in a wired or wireless manner.

Although the description of the present disclosure is to be described in terms of wireless communication (specifically cellular communication), those skilled in the relevant art(s) will recognize that the present disclosure may be applicable to other communications that use wired or other wireless communication methods without departing from the spirit and scope of the present disclosure.

An Exemplary Adjustable Mixer Module Setting Environment

FIG. 1illustrates an adjustable mixer module setting environment100according to an exemplary embodiment. The adjustable mixer module setting environment100includes an adjustable mixer module120.

The adjustable mixer module setting environment100may represent a testing apparatus configured to test and set the adjustable mixer module120during a testing stage. The adjustable mixer module setting environment100is configured to send or receive signals via an antenna105connected to a front-end module110. The front-end module110may perform one or more functions relating to transmitting or receiving wireless signals, and may include amplifiers (e.g. low noise amplifiers), filters, etc. for pre-processing the signal prior to down-conversion by the adjustable mixer module120. Alternatively, or in addition to the antenna105, the adjustable mixer module setting environment may be configured to send or receive test signals via a test connection108, which allows test signals to be directly input to the front-end module110over a wired connection. In an embodiment, the test connection108is integrated with the antenna105, so that the radiating element of the antenna105is removable and the test connection108is then available for access.

A processing module130performs various backend processes, such as deciphering received signals, setting the adjustable mixer module120, and performing general device control operations, etc.

Upon receipt of signals from a wireless communication environment, the front-end module110forwards the received signals to the adjustable mixer module120. The adjustable mixer module120mixes the received signals using local oscillator (LO) signals and forwards the resulting mixed signals to the processing module for analysis. For example, the mixed signals may be down-converted to baseband or an intermediate frequency by the adjustable mixer module120.

The LO signals are preferably differential LO signals having a maximum 50% duty cycle. It has been determined that a 50% duty cycle gives the mixer basic IP2 levels that may vary among similarly-manufactured mixers. For example, a 50% duty cycle employed by one mixer may provide better IP2 levels than a 50% duty cycle employed by a second mixer. It has also been determined that a 25% duty cycle provides an improved IP2 levels, at the cost of increased power consumption.

The different duty cycles have many additional characteristics, which may be used for setting the adjustable mixer module. For example, a 50% duty cycle LO signal has good LO phase noise characteristics and also consumes less power (because no conversion is required, as discussed below). 25% duty cycle LO signals, on the other hand, produce higher gain, IQ isolation, better noise figure, and enhanced IP2 performance than the 50% duty cycle. In addition, a 12.5% duty cycle appears to provide enhanced image and harmonic rejection over both the 50% and 25% duty cycles. Additional duty cycles with additional characteristics may also be available. For purposes of this discussion, the adjustable mixer module120will be described with respect to the 25% and 50% duty cycle LO signals.

Because the 50% duty cycle has the lowest power consumption, the adjustable mixer module120preferably initially mixes received signals using the 50% duty cycle. The mixed signals thus generated are analyzed by the processing module130, particularly with respect to their IP2 levels. The processing module130may measure the IP2 levels of the signal using any method that is now, or will be known, and compares the result to a predetermined threshold. The predetermined threshold may be set equal to the IP2 performance requirement associated with any of the RATs (preferably equal to the largest requirement among all RATs on which the device may communicate).

If the processing module130determines that the IP2 levels of the mixed signal are sufficient, the processing module130sets the adjustable mixer module120accordingly (discussed below). Alternatively, if the processing module130determines that the IP2 levels of the mixed signal are insufficient, the processing module130sets the adjustable mixer module120to operate at the next-lowest duty cycle (discussed below) and again tests mixed signals. This process repeats until a suitable duty cycle has been discovered to satisfy the IP2 requirements of all desired RATs that may be currently used, or used in the future.

Those skilled in the relevant art(s) will recognize that many modifications may be made to the adjustable mixer module setting environment100within the spirit and scope of the present disclosure. For example, the processing module130may be employed primarily to perform testing operations of the mixed signals, whereas setting of the adjustable mixer module120can be controlled by an external device. In addition, the processing module130need not set the adjustable mixer module120based only on IP2. Instead, the processing module130may set the adjustable mixer module120based on any parameter, including power consumption, gain, IQ isolation, as well as any other parameter that may be directly or indirectly affected by mixer performance, or any combination thereof.

An Exemplary Adjustable Mixer Module

FIG. 2illustrates a block diagram of an adjustable mixer module200according to an exemplary embodiment. The adjustable mixer module200includes a duty cycle generator module220and a mixer module230, and may represent an exemplary embodiment of the adjustable mixer module120.

The adjustable mixer module200includes a wave generator210to generate one or more base LO signal. Preferably the wave generator210generates a differential pair of 50% duty cycle LO signals. However, the wave generator210may alternatively generate only a single 50% duty cycle LO signal or any other duty cycle LO signal within the spirit and scope of the present disclosure. The wave generator210forwards the generated LO signals to the duty cycle generator module220.

As discussed above, the adjustable mixer module200has previously been set to a particular duty cycle (either as an initializing step or corresponding with its IP2 performance). Upon receiving the base LO signals from the wave generator module210, the duty cycle generator module220generates LO signals having the designated duty cycle, and forwards the resulting LO signals to the mixer module230.

The mixer module230receives signals from the front-end module110. The mixer module230mixes the received signals based on the LO signals received from the duty cycle generator module220. The mixer module230then forwards the mixed signals to the processing module130for analysis.

FIG. 3illustrates a block diagram of a mixer module340and a duty cycle generator module390according to an exemplary embodiment. The mixer module340includes an I-mixer340iand a Q-mixer340q, and may represent an exemplary embodiment of the mixer module230. The duty cycle generator module390includes a duty cycle conversion module320and a bypass module310, and may represent an exemplary embodiment of the duty cycle generator module220.

The duty cycle generator module390receives N base LO signals from the wave generator module, where N is a positive integer. For purposes of this discussion, it will be presumed that the wave generator module210provides N=4 base LO signals to the duty cycle generator corresponding to a pair of I-differential LO signals and a pair of Q-differential LO signals that each have a 50% duty cycle.

Depending on the duty cycle set for the mixer module340, the duty cycle generator module390causes the received base LO signals to pass through either a bypass module310or a duty cycle conversion module320. Specifically, if the mixer module340is set to a 50% duty cycle operation, then the received base LO signals do not need converting because they already have the desired duty cycle. Consequently, the duty cycle generator module390causes the received LO signals to bypass the duty cycle conversion module320via the bypass module310.

The bypass module310may constitute any suitable device or component for causing the base LO signals to bypass the duty cycle conversion module320. For example, the bypass module310may be implemented by a switch, and the duty cycle generation module390may cause the base LO signals to bypass the duty cycle conversion module320by closing the switch.

If, on the other hand, the mixer module340is currently set to operate at a duty cycle other than the duty cycle of the base LO signals supplied by the wave generator module210, the duty cycle generation module390causes the base LO signals to pass through the duty cycle conversion module320(e.g., by opening the switch of the bypass module310). The duty cycle conversion module320then converts the base LO signals to have the desired duty cycle to generate LO signals that are to be used by the mixers340iand340q. The signals then pass to the buffer module330.

Duly Cycle Conversion

FIG. 4illustrates a block diagram of a duty cycle conversion module420that may represent an exemplary embodiment of the duty cycle conversion module320, and a buffer module430that may represent an exemplary embodiment of the buffer module330.

As shown inFIG. 4, the wave generator module supplies quadrature/in-phase base LO signals to the duty cycle conversion module420. In particular, the base LO signals include a pair of 50% duty cycle differential LO I-signals: I50+and I50−, and a pair of 50% duty cycle differential LO Q-signals: Q50+and Q50−. As shown, the LO Q-signals are phase shifted by 90 degrees, relative to the LO I-signals.

The duty cycle conversion module420includes a plurality of NAND gates420a-420d, each of which receives an I/Q pair of base LO signals. After the duty cycle conversion module420, LO signals resulting from the NAND operations are forwarded to corresponding buffers430a-430dwithin the buffer module430. Because the Q-signals are 90° out of alignment with the I-signals, the signals output by the buffers430a-430dare 25% duty cycle signals, due to the NAND operations. As shown inFIG. 4, the 25% duty cycle LO signals include a pair of differential LO I-signals: I25+and I25−, and a pair of differential LO Q-signals: Q25+and Q25−. Accordingly, by passing the generated 50% duty cycle base LO signals through the duty cycle conversion module420, 25% duty cycle LO signals can be generated to provide different performance to the mixer module.

Returning toFIG. 3, after the LO signals pass through the buffer module330, the LO Q-signals (Q50+and Q50−, or Q25+and Q25−, depending on the set duty cycle) are forwarded to the Q-mixer340qand the LO I-signals (I50+and I50−, or I25+and I25−, depending on the set duty cycle) are forwarded to the I-mixer340ifor controlling the mixing functionality of the corresponding mixers.

Adjusting Mixer Module

FIG. 5illustrates a circuit diagram of a mixer module500according to an exemplary embodiment. The mixer module500includes an I-mixer510that may represent an exemplary embodiment of the I-mixer340i, and a Q-mixer520that may represent an exemplary embodiment of the Q-mixer340q. The mixer module500also includes a switching module530, and may represent an exemplary embodiment of the mixer module230.

The mixer module500receives a pair of differential input signals IN+and IN−from the front-end module110. The differential input signals IN+and IN−are sent to both the I-mixer510and the Q-mixer520via capacitors C that are preferably equal to, or nearly equal to, each other in capacitance.

The I-mixer510receives the differential input signals and mixes the signals by passing them through a transistor circuit having a plurality of transistors. Each of the transistors of the I-mixer510is controlled by one of either a positive signal LOI+or a negative signal LOI−of a differential signal LO. Specifically, these components of the differential signal LO are applied and control the gates of their corresponding transistors so as to switch the transistors on and off according to the frequency and duty cycle of the corresponding LO signal. LOI+may be one of either I50+or I25+and LOI−may be one of either I50−or I25−, depending on whether the mixer module500operates in 50% duty cycle mode or 25% duty cycle mode. The I-mixer510outputs differential in-phase signals OUTI+and OUTI−as the final mixed signals.

The Q-mixer520operates substantially the same as the I-mixer510. Specifically, the Q-mixer520receives the differential input signals and mixes the signals by passing them through another transistor circuit having a plurality of transistors. Each of the transistors of the Q-mixer520is controlled by one of either a positive signal LOQ+or a negative signal LOQ−of the differential signal LO. Specifically, these components of the differential signal LO are applied and control the gates of their corresponding transistors so as to switch the transistors on and off according to the frequency and duty cycle of the corresponding LO signal. LOQ+may be one of either Q50+or Q25+and LOQ−may be one of either Q50−or Q25−, depending on whether the mixer module500operates in 50% duty cycle mode or 25% duty cycle mode. The Q-mixer520outputs differential quadrature signals OUTQ+and OUTQ−as the final mixed signals.

As discussed above, as part of setting the mixer module500to one of either 50% duty cycle mode or 25% duty cycle mode, the mixer module500is supplied with the proper LO signals LO1+, LO1−, LOQ+and LOQ−. In addition, the switching module530must be set in order to configure the hardware of the mixer module500. The switching module530may be any device or component capable of connecting and disconnecting the outputs of the capacitors at the positive input to each other, and connecting and disconnecting the outputs of the capacitors at the negative input to each other. For simplicity and ease of manufacturing, the switching module preferably comprises a pair of switches.

For the 50% duty cycle mode, the switching module530remains open, breaking the connection between the I-mixer inputs and the Q-mixer inputs. For the 25% duty cycle, on the other hand, the switching module530is closed, thereby short-circuiting the positive input of the I-mixer510with the positive input of the Q-mixer520, and short-circuiting the negative input of the I-mixer510with the negative input of the Q-mixer520. In this manner, the mixer module500can be set to either the 50% or 25% duty cycle mode.

Those skilled in the relevant art(s) will recognize that many modifications may be available for the adjustable mixer module. For example, the mixer module230may be modified to also be adjustable for additional duty cycles, such as 75% or 12.5%, among others. Specifically, the wave generator module210may be modified to output a differential pair of 50% duty cycle LO signals with twice the frequency of the signals described above to allow for the generation of 12.5% duty cycle, and/or the mixer module230may include a plurality of inverters for generating 75% duty cycles. With similar modifications, the duty cycle generator220may generate several additional duty cycle LO signals. The duty cycle conversion module320may have any configuration that allows it to generate desired duty cycle LO signals from one or more base LO signals. The mixer module500may also be further modified in accordance with similar principles in order to operate on those additional LO signals.

An Exemplary Wireless Communication Device

FIG. 6illustrates a block diagram of a wireless communication device600according to an exemplary embodiment. The wireless communication device600includes an adjustable mixer module620that may represent an exemplary embodiment of the adjustable mixer module120.

As discussed above, because of the calculation involved, the mixer module will likely be tested and set at a manufacturing level, prior to its use within a wireless communication device, such as a cellular phone, tablet, etc. However, it is conceivable that such an adjustable mixer module620may be included in a wireless communication device600, and configured to be set and reset during use and/or in real-time.

As shown inFIG. 6, the adjustable mixer module620is connected to the front-end module610, which sends or receives signals via an antenna605. For purposes of this discussion, the front-end module610receives signals. Received signals are sent to the adjustable mixer module620for down-conversion by mixing with the LO signal. The adjustable mixer module620sends the mixed signals to both a controller module650and a testing module640. The controller module650performs additional background processing on the received signals. The testing module640and the controller module650may together constitute a processing module630.

The testing module640measures the IP2 performance of the adjustable mixer module620with respect to the mixed signals. Based on the results of the test, the testing module640is able to determine whether the adjustable mixer module620should operate in a 50% duty cycle mode or a 25% duty cycle mode, and may adjust the adjustable mixer module accordingly. Such testing may occur with a set frequency or after some condition has been satisfied (e.g., only following a change from one RAT to another).

In an example, if the testing module640discovers that the wireless communication device600is communicating using 2G, the testing module640may initiate the test of the adjustable mixer module620. The adjustable mixer module620may currently be operating in 25% duty cycle, which the testing module640determines to be unnecessary. If the IP2 test reveals that the current mode is over-sufficient for the 2G communications, in order to save power, the testing module640sets the adjustable mixer module620to instead operate in 50% duty cycle mode. Similar operations can be performed for other scenarios to adjust the adjustable mixer module620as needed.

By dynamically switching the adjustable mixer module620, the wireless communication device600can be optimized for both performance and power-saving.

In the wireless communication device600, the adjustable mixer module620operates substantially as discussed above with respect to the adjustable mixer module120, and can include any and all of the functionality and configurations thereof, among others that are within the spirit and scope of the present disclosure.

Those skilled in the relevant art(s) will recognize that many modifications may be available for the wireless communication device600. For example, the adjustable mixer module620may be set to different mixing modes based on known information, such as the response of the adjustable mixer module620to a particular RAT. Consequently, the adjustable mixer module620may be set to operate in a particular mixing mode depending solely on the current RAT used by the wireless communication device. The current RAT may also be used in addition to one or more other parameters for determining the mixing mode.

An Exemplary Method for Adjusting a Mixer

FIG. 7illustrates a block diagram of a method for setting an adjustable mixer module according to an exemplary embodiment.

The adjustable mixer module is initially set to a 50% duty cycle mode (710). Using the 50% duty cycle mode, the adjustable mixer module mixes received signals (720) and then tests their IP2 levels (730).

Based on the test, it is determined whether the IP2 performance of the 50% duty cycle is sufficient (740). This may be determined by comparing the IP2 performance of the 50% duty cycle to a predetermined threshold, which may be set based on the IP2 requirements of a RAT on which the adjustable mixer is expected to operate. If the IP2 performance exceeds the threshold (Y in740), the adjustable mixer module remains set to the 50% duty cycle, and the method ends (760).

Alternatively, if the IP2 performance does not exceed the threshold (N in740), the adjustable mixer module is set to a 25% duty cycle (750). This may be accomplished by turning off a bypass module within the duty cycle generator module so as to cause the 50% LO signals to enter a duty cycle conversion module and by turning on a switching module within the mixer to short-circuit the positive input of a Q-mixer to the positive input of an I-mixer and short-circuit the negative input of the Q-mixer to the negative input of the I-mixer. Once set to the 25% mode, the method ends (760).

Those skilled in the relevant art(s) will recognize that the method described above with respect toFIG. 7can additionally or alternatively include any of the functionality of the adjustable mixer module setting environment100and/or the wireless communication device600discussed above, and the above description of the exemplary method should neither be construed to limit the method nor the description of the adjustable mixer module setting environment100or the wireless communication device200.

CONCLUSION