Current drive loopback calibration

Abstract

Certain aspects of the present disclosure generally relate to electronic devices, and more particularly, to techniques and apparatuses for calibrating a transceiver. An example apparatus generally includes a transmitter path including a first transmit amplifier, a receiver path including a transconductance amplifier, and a loopback calibration path coupled between an output of the first transmit amplifier and an output of the transconductance amplifier, where the loopback calibration path includes a voltage-to-current converter.

Description

Cross-references to related applications

[0001] This application claims priority to U.S. Patent Application No. 18 / 631,594, filed April 10, 2024, which is incorporated herein by reference. Technical Field

[0002] Certain aspects of this disclosure relate generally to electronic devices, and more specifically to techniques and apparatus for calibrating transceivers. Background Technology

[0003] Wireless communication devices are widely deployed to provide a variety of communication services, such as telephone, video, data, messaging, broadcasting, and so on. These wireless communication devices can transmit and / or receive radio frequency (RF) signals via any of a variety of suitable radio access technologies (RATs), including but not limited to 5G New Radio (NR), LTE, CDMA, TDMA, WCDMA, GSM, GSM, Bluetooth, Bluetooth Low Energy (BLE), ZigBee, WLAN RATs (e.g., WiFi), etc.

[0004] A wireless communication network may include multiple base stations capable of supporting communication with multiple mobile stations. A mobile station (MS) may communicate with a base station (BS) via downlink and uplink. A downlink (or forward link) refers to the communication link from the base station to the mobile station, while an uplink (or reverse link) refers to the communication link from the mobile station to the base station. The base station may transmit data and control information to the mobile station on the downlink and / or receive data and control information from the mobile station on the uplink. The base station and / or the mobile station may include one or more calibrable transmit and receive paths. Summary of the Invention

[0005] The systems, methods, and apparatus of this disclosure each have several aspects, none of which is solely responsible for their desired properties. Without limiting the scope of this disclosure as set forth in the appended claims, some features will now be briefly discussed. Upon consideration of this discussion, and particularly after reading the section entitled “Detailed Description,” one will understand how the features of this disclosure provide the advantages described herein.

[0006] Certain aspects of this disclosure relate to an apparatus for wireless communication. The apparatus typically includes: a transmitter path including a first transmitting amplifier; a receiver path including a transconductance amplifier; and a loopback calibration path coupled between the output of the first transmitting amplifier and the output of the transconductance amplifier, wherein the loopback calibration path includes a voltage-to-current converter.

[0007] Certain aspects of this disclosure relate to a method for wireless communication. The method typically includes: generating an amplified voltage via a transmit amplifier in a transmitter path; converting the amplified voltage into a current via a voltage-to-current converter in a loopback calibration path; providing the current to the output of a transconductance amplifier in a receiver path via the loopback calibration path; generating a processing signal based on the current via the receiver path; and calibrating the receiver path based on the processing signal.

[0008] Some aspects of this disclosure relate to a wireless device. The wireless device typically includes: at least one antenna; a transmitter path coupled to the at least one antenna and including a transmit amplifier; a receiver path coupled to the at least one antenna and including a transconductance amplifier; and a loopback calibration path coupled between the output of the transmit amplifier and the output of the transconductance amplifier, wherein the loopback calibration path includes a voltage-to-current converter.

[0009] To achieve the foregoing and related objectives, one or more aspects include the features fully described below and specifically pointed out in the claims. The following description and drawings illustrate certain exemplary features of these one or more aspects in detail. However, these features indicate only a few of the various ways in which the principles of the various aspects may be employed. Attached Figure Description

[0010] To gain a more detailed understanding of the foregoing features of this disclosure, a more specific description, which has been briefly summarized above, can be obtained by referring to various aspects, some of which are illustrated in the accompanying drawings. However, it should be noted that the drawings illustrate only certain typical aspects of this disclosure and are therefore not to be construed as limiting its scope, as other equally valid aspects may be acknowledged in this description.

[0011] Figure 1 This is a diagram illustrating an example wireless communication network in which various aspects of the present disclosure can be practiced.

[0012] Figure 2 It is a block diagram conceptually illustrating the design of an example base station (BS) and user equipment (UE) in which various aspects of this disclosure can be practiced.

[0013] Figure 3This is a block diagram of an example radio frequency (RF) transceiver in which various aspects of this disclosure can be practiced.

[0014] Figure 4 This is a block diagram of an example wireless device having RF transceiver circuitry according to certain aspects of this disclosure, the RF transceiver circuitry including a loopback calibration path.

[0015] Figure 5 This is a block diagram of an example wireless device having RF transceiver circuitry according to certain aspects of this disclosure, the RF transceiver circuitry including a loopback calibration path implemented using a voltage-to-current converter and a current-to-voltage converter.

[0016] Figure 6 This is a block diagram of an example wireless device having RF transceiver circuitry according to certain aspects of this disclosure, the RF transceiver circuitry including a loopback calibration path located between the output of a drive amplifier (DA) and the output of a transconductance amplifier.

[0017] Figure 7 This is a flowchart illustrating example operations for wireless communication according to certain aspects of this disclosure.

[0018] For ease of understanding, the same reference numerals have been used where possible to denote common elements in the figures. It is conceivable that elements disclosed in one aspect may be usefully applied to other aspects without specific description. Detailed Implementation

[0019] Certain aspects of this disclosure relate to techniques for calibrating a transceiver using a loopback calibration path between a transmitter and a receiver. The loopback calibration path may be coupled between the output of an amplifier of the transmitter and the output of a transconductance amplifier of the receiver. The loopback calibration path may include a voltage-to-current (VI) converter to convert the amplified voltage at the amplifier's output into a current. This current is then provided to the receiver. The transmitter and receiver may be located far apart to reduce interference between them. Therefore, the loopback calibration path may have a long trace. By converting the amplified voltage from the voltage domain to the current domain, current is provided to the receiver instead of voltage along the long trace of the calibration path, thus avoiding the voltage drop problem that may occur when the amplified voltage is provided to the receiver path in the voltage domain. The current may be provided to the output of the transconductance amplifier of the receiver, thus avoiding the use of a current-to-voltage (IV) converter on the calibration path to convert the current back to voltage, as described in more detail herein.

[0020] Various aspects of this disclosure are described more fully below with reference to the accompanying drawings. However, this disclosure may be embodied in many different forms and should not be construed as limited to any particular structure or function presented throughout this disclosure. Rather, these aspects are provided so that this disclosure will be comprehensive and complete, and will fully convey the scope of protection of this disclosure to those skilled in the art. Based on the teachings herein, those skilled in the art should understand that the scope of this disclosure is intended to cover any aspect of the disclosure herein, whether implemented independently or in combination with any other aspect of this disclosure. For example, any number of aspects set forth herein may be used to implement an apparatus or method of practice. Furthermore, the scope of this disclosure is intended to cover such apparatuses or methods implemented using structures, functions, or structures and functions other than or different from the various aspects of the disclosure set forth herein. It should be understood that any aspect of the disclosure herein may be embodied by one or more elements of the claims.

[0021] The word “exemplary” is used in this document to mean “serving as an example, instance, or illustration.” Any aspect described as “exemplary” in this document is not necessarily to be construed as preferred or superior to other aspects.

[0022] As used in this article, the term "connected with" in various tenses of the verb "connect" can refer to an element. A Directly connected to the component B Or other components can be connected to the component. A With components B Between (i.e., elements) A With components B Indirect connection). In the context of electronic components, the term "connected to" may also be used herein to refer to wires, traces, or other conductive materials used to connect components. A and components B Electrical connections (and any components that are electrically connected between them).

[0023] Example wireless system Figure 1 Example wireless communication network 100 is illustrated in which various aspects of this disclosure can be practiced. For example, wireless communication network 100 may be a new radio (NR) system (e.g., a fifth-generation (5G) NR network), an evolved universal terrestrial radio access (E-UTRA) system (e.g., a fourth-generation (4G) network), a universal mobile telecommunications system (UMTS) (e.g., a second-generation / third-generation (2G / 3G) network), or a code division multiple access (CDMA) system (e.g., a 2G / 3G network), or may be configured to communicate according to IEEE standards such as one or more standards in the 802.11 standard.

[0024] like Figure 1 As illustrated, the wireless communication network 100 may include multiple base stations (BS) 110a to 110z (each individually referred to herein as BS 110 or collectively as BS 110) and other network entities. BS may also be referred to as access point (AP), evolved Node B (eNodeB or eNB), next-generation Node B (gNodeB or gNB), or some other terminology.

[0025] BS 110 can provide communication coverage for a specific geographic area (sometimes referred to as a "cell"), which can be stationary or mobile depending on the location of the mobile BS. In some examples, BS 110 can use any suitable transport network, interconnected with each other through various types of backhaul interfaces (e.g., direct physical connection, wireless connection, virtual network, etc.) and / or connected to one or more other BSs or network nodes (not shown) in the wireless communication network 100. Figure 1 In the example shown, BS 110a, 110b, and 110c can be macro BSs for macro cells 102a, 102b, and 102c, respectively. BS 110x can be a pico BS for pico cell 102x. BS 110y and 110z can be femto BSs for femto cells 102y and 102z, respectively. A BS can support one or more cells.

[0026] In the wireless communication network 100, BS 110 communicates with one or more user equipment (UEs) 120a to 120y (each of which may also be individually referred to as "UE 120" or collectively as "UE 120" herein). UEs may be fixed or mobile, and may also be referred to as user terminals (UTs), mobile stations (MSs), access terminals, stations (STAs), clients, wireless devices, mobile devices, or other terms. User terminals may be wireless devices such as cellular phones, smartphones, personal digital assistants (PDAs), handheld devices, wearable devices, wireless modems, laptop computers, tablet computers, personal computers, etc.

[0027] BS 110 is considered a transmitting entity for downlink and a receiving entity for uplink. UE 120 is considered a transmitting entity for uplink and a receiving entity for downlink. As used herein, a “transmitting entity” is a separately operating apparatus or device capable of transmitting data via a frequency channel, and a “receiving entity” is a separately operating apparatus or device capable of receiving data via a frequency channel. In the following description, the subscript “…” dn " indicates the downlink, subscript " up "Indicates uplink. You can select..." N upEach UE is used for simultaneous transmission on the uplink, and can be selected. N dn Each UE is used for simultaneous transmission on the downlink. N up It can be equal to or not equal to N dn ,and N up and N dn It can be a static value or it can be changed for each scheduling interval. Beam control or some other spatial processing techniques can be used at BS 110 and UE 120.

[0028] UEs 120 (e.g., 120x, 120y, etc.) may be distributed throughout the wireless communication network 100, and each UE 120 may be stationary or mobile. The wireless communication network 100 may also include relay stations (e.g., relay station 110r) (also referred to as repeaters, etc.) that receive data transmissions and / or other information transmissions from upstream stations (e.g., BS 110a or UE 120r) and transmit the data transmissions and / or other information transmissions to downstream stations (e.g., UE 120 or BS 110), or relay transmissions between UEs 120 to facilitate communication between devices.

[0029] BS 110 can communicate with one or more UE 120s on both the downlink and uplink at any given time. The downlink (i.e., the forward link) is the communication link from BS 110 to UE 120, while the uplink (i.e., the reverse link) is the communication link from UE 120 to BS 110. UE 120 can also communicate peer-to-peer with another UE 120.

[0030] Wireless communication network 100 can use multiple transmit antennas and multiple receive antennas to transmit data on the downlink and uplink. BS 110 can be equipped with several ( N ap (Number) antennas to achieve transmit diversity for downlink transmission and / or receive diversity for uplink transmission. A set of ( N u Each UE 120 can receive downlink transmissions and send uplink transmissions. Each UE 120 can send user-specific data to and / or receive user-specific data from the BS 110. Typically, each UE 120 may be equipped with one or more antennas. N u Each UE 120 can have the same or different number of antennas.

[0031] The wireless communication network 100 can be a time-division duplex (TDD) system or a frequency-division duplex (FDD) system. In a TDD system, the downlink and uplink share the same frequency band. In an FDD system, the downlink and uplink use different frequency bands. The wireless communication network 100 can also utilize a single carrier or multiple carriers for transmission. Each UE 120 can be equipped with a single antenna (e.g., to reduce cost) or multiple antennas (e.g., where additional cost can be supported).

[0032] Network controller 130 (sometimes referred to as a "system controller") can communicate with a group of BSs 110 and (e.g., via backhaul) provide coordination and control for these BSs 110. In some cases (e.g., in a 5G NR system), network controller 130 may include centralized units (CUs) and / or distributed units (DUs). In some aspects, network controller 130 can communicate with core network 132 (e.g., a 5G core network (5GC)) that provides various network functions such as access and mobility management, session management, user plane functions, policy control functions, authentication server functions, unified data management, application functions, network openness functions, network repository functions, network slice selection functions, etc.

[0033] In certain aspects of this disclosure, BS 110 and / or UE 120 may include a loopback calibration path coupled between the outputs of transconductance amplifiers in the transmitter path and the receiver path, as described in more detail herein.

[0034] Figure 2 Examples of BS 110a and UE 120a in which aspects of this disclosure may be implemented (e.g., from...) Figure 1 Example components of a wireless communication network 100.

[0035] On the downlink, at BS 110a, the transmitting processor 220 can receive data from data source 212, control information from controller / processor 240, and / or other data (e.g., from scheduler 244). Various types of data can be transmitted on different transport channels. For example, control information can be designated for the Physical Broadcast Channel (PBCH), Physical Control Format Indicator Channel (PCFICH), Physical Hybrid Automatic Repeat Request (HARQ) Indicator Channel (PHICH), Physical Downlink Control Channel (PDCCH), Group Common PDCCH (GC PDCCH), etc. Data can be designated for the Physical Downlink Shared Channel (PDSCH), etc. The Media Access Control (MAC)-Control Element (MAC-CE) is a MAC layer communication structure that can be used for exchanging control commands between wireless nodes. The MAC-CE can be carried in shared channels such as PDSCH, Physical Uplink Shared Channel (PUSCH), or Physical Sidelink Shared Channel (PSSCH).

[0036] Processor 220 can process (e.g., encode and symbol map) data and control information to obtain data symbols and control symbols, respectively. Transmitter processor 220 can also generate reference symbols such as those for primary synchronization signal (PSS), secondary synchronization signal (SSS), PBCH demodulation reference signal (DMRS), and channel state information reference signal (CSI-RS).

[0037] The transmit (TX) multiple-input multiple-output (MIMO) processor 230 can perform spatial processing (e.g., pre-decoding) on ​​data symbols, control symbols, and / or reference symbols where applicable, and can provide the output symbol stream to the modulators (MODs) in transceivers 232a to 232t. Each modulator in transceivers 232a to 232t can process its own output symbol stream (e.g., for orthogonal frequency division multiplexing (OFDM), etc.) to obtain an output sample stream. Each transceiver in transceivers 232a to 232t can further process (e.g., convert to analog, amplify, filter, and up-convert) the output sample stream to obtain a downlink signal. The downlink signal from transceivers 232a to 232t can be transmitted via antennas 234a to 234t, respectively.

[0038] At UE 120a, antennas 252a to 252r can receive downlink signals from BS 110a and can provide the received signals to transceivers 254a to 254r respectively. Transceivers 254a to 254r can adjust (e.g., filter, amplify, down-convert, and digitize) the corresponding received signals to obtain input samples. Each demodulator (DEMOD) in transceivers 232a to 232t can further process the input samples (e.g., for OFDM, etc.) to obtain received symbols. MIMO detector 256 can obtain the received symbols from all demodulators in transceivers 254a to 254r, perform MIMO detection on the received symbols where applicable, and provide the detected symbols. Receiver processor 258 can process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide the decoded data for UE 120a to data sink 260, and provide the decoded control information to controller / processor 280.

[0039] On the uplink, at UE 120a, the transmit processor 264 can receive and process data from data source 262 (e.g., for the Physical Uplink Shared Channel (PUSCH)) and control information from controller / processor 280 (e.g., for the Physical Uplink Control Channel (PUCCH)). The transmit processor 264 can also generate reference symbols for reference signals (e.g., for the Sounding Reference Signal (SRS)). Symbols from the transmit processor 264 can be pre-decoded by the TX MIMO processor 266 where applicable, further processed by modulators (MODs) in transceivers 254a to 254r (e.g., for Single Carrier Frequency Division Multiplexing (SC-FDM), etc.), and transmitted to BS 110a. At BS 110a, the uplink signal from UE 120a can be received by antenna 234, processed by demodulators in transceivers 232a to 232t, detected by MIMO detector 236 where applicable, and further processed by receiver processor 238 to obtain decoded data and control information transmitted by UE 120a. Receiver processor 238 can provide the decoded data to data sink 239 and the decoded control information to controller / processor 240.

[0040] Memory 242 and 282 can store data and program code for BS 110a and UE 120a, respectively. Memory 242 and 282 can also interface with controller / processor 240 and 280, respectively. Scheduler 244 can schedule UEs for data transmission on the downlink and / or uplink.

[0041] In certain aspects of this disclosure, transceiver 232 and / or transceiver 254 may include a loopback calibration path coupled between the outputs of transconductance amplifiers of the transmitter path and the receiver path, as described in more detail herein.

[0042] NR can use Orthogonal Frequency Division Multiplexing (OFDM) with a cyclic prefix (CP) on both the uplink and downlink. NR can use Time Division Duplex (TDD) to support half-duplex operation. OFDM and Single-Carrier Frequency Division Multiplexing (SC-FDM) divide the system bandwidth into multiple orthogonal subcarriers, which are often referred to as tones, frequency bands, etc. Each subcarrier can be modulated with data. Modulation symbols can be transmitted in the frequency domain using OFDM and in the time domain using SC-FDM. The spacing between adjacent subcarriers can be fixed, and the total number of subcarriers can depend on the system bandwidth. The system bandwidth can also be divided into subbands. For example, a subband can cover multiple resource blocks (RBs).

[0043] Example RF transceiver Figure 3 This is a block diagram of an example radio frequency (RF) transceiver circuit 300 according to certain aspects of this disclosure. The RF transceiver circuit 300 includes at least one transmit (TX) path 302 (also referred to as a "transmit chain") for transmitting signals via one or more antennas 306 and at least one receive (RX) path 304 (also referred to as a "receive chain") for receiving signals via antenna 306. When the TX path 302 and RX path 304 share antenna 306, these paths can be connected to the antenna via an interface 308, which may include any of a variety of suitable RF devices, such as switches, duplexers, double-ended converters, multiplexers, etc.

[0044] Receiving in-phase (I) and / or quadrature (Q) baseband analog signals from a digital-to-analog converter (DAC) 310, the TX path 302 may include a baseband filter (BBF) 312, a mixer 314, a driver amplifier (DA) 316, and a power amplifier (PA) 318. The BBF 312, mixer 314, DA 316, and PA 318 may be included in a radio frequency integrated circuit (RFIC). In some respects, the PA 318 may be external to the RFIC.

[0045] BBF 312 filters the baseband signal received from DAC 310, and mixer 314 mixes the filtered baseband signal with the transmit local oscillator (LO) signal to convert the baseband signal of interest to a different frequency (e.g., up-convert from baseband to RF). This frequency conversion process produces a sum and difference frequency between the LO frequency and the frequency of the baseband signal of interest. This sum and difference frequency is referred to as the "beat frequency". The beat frequency is typically in the RF range, such that the signal output from mixer 314 is typically an RF signal, which can be amplified by DA 316 and / or PA 318 before being transmitted by antenna 306. When one mixer 314 is exemplified, several mixers can be used to up-convert the filtered baseband signal to one or more intermediate frequencies and subsequently up-convert the intermediate frequency (IF) signal to the frequency used for transmission.

[0046] The RX path 304 may include a low-noise amplifier (LNA) 324, a mixer 326, and a baseband filter (BBF) 328. In some aspects, the LNA may be implemented using a pre-bias during bypass mode. The LNA 324, mixer 326, and BBF 328 may be included in one or more RFICs, which may be the same RFIC that includes the TX path components, or may not be the same RFIC that includes the TX path components. The RF signal received via antenna 306 may be amplified by the LNA 324, and the mixer 326 mixes the amplified RF signal with a received local oscillator (LO) signal to convert the RF signal of interest to a different baseband frequency (e.g., down-conversion). The baseband signal output from the mixer 326 may be filtered by the BBF 328 before being converted to digital I and / or Q signals by an analog-to-digital converter (ADC) 330 for digital signal processing.

[0047] Some transceivers may employ a frequency synthesizer with a variable frequency oscillator (e.g., a voltage-controlled oscillator (VCO) or a digitally controlled oscillator (DCO)) to generate a stable, tunable LO with a specific tuning range. Thus, the transmit LO may be generated by the TX frequency synthesizer 320, which may be buffered or amplified by the amplifier 322 before being mixed with the baseband signal in the mixer 314. Similarly, the receive LO may be generated by the RX frequency synthesizer 332, which may be buffered or amplified by the amplifier 334 before being mixed with the RF signal in the mixer 326. In some aspects, a single frequency synthesizer may be used for both the TX path 302 and the RX path 304. In some aspects, the TX frequency synthesizer 320 and / or the RX frequency synthesizer 332 may include a divider / multiplier driven by an oscillator (e.g., a VCO) in the frequency synthesizer.

[0048] Controller 336 (e.g., Figure 2 The controller / processor 280 in the controller can direct the operation of the RF transceiver circuit 300A, such as transmitting signals via TX path 302 and / or receiving signals via RX path 304. The controller 336 can be a processor, digital signal processor (DSP), application-specific integrated circuit (ASIC), field-programmable gate array (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components, or any combination thereof. Memory 338 (e.g., Figure 2 The memory 282 in the memory can store data and / or program code used to operate the RF transceiver circuit 300. The controller 336 and / or the memory 338 may include control logic (e.g., complementary metal-oxide-semiconductor (CMOS) logic).

[0049] In some aspects, the RF transceiver circuit 300 may include a loopback calibration path coupled between the output of a transconductance amplifier in the transmitter path (e.g., TX path 302) and the receiver path (e.g., RX path 304), as described in more detail herein.

[0050] although Figures 1 to 3 Wireless communication is provided as an example application in which certain aspects of this disclosure can be implemented to facilitate understanding, but certain aspects described herein can be used in any of a variety of other suitable systems.

[0051] Transceiver Calibration Example Technology Modern receiver architectures use quadrature modulation techniques, where the receiver baseband output includes an in-phase (I) path and a quadrature (Q) path. Ideally, there should be no gain difference between these two paths, and they should have a 90° phase difference. However, these two paths may have a certain gain difference, and / or the phase difference may not be 90°. Therefore, internal calibration can be used. Calibration may involve using a loopback calibration path between the transmitter and receiver paths of the wireless device, enabling the reduction of the gain difference between the receiver I and receiver Q paths and achieving a 90° phase difference (or close to 90°). For example, a loopback calibration path can be used to transmit a signal from the transmitter path to the receiver path. This signal is then processed by the receiver path (e.g., down-converted via a mixer, filtered, and converted to the digital domain via an analog-to-digital converter (ADC), measured in the digital domain, and used to calibrate the I and Q paths.

[0052] Figure 4An example wireless device 400 according to certain aspects of this disclosure has an RF transceiver circuit 401, which includes a loopback calibration path. A digital signal from a controller 402 (e.g., a modem) is converted from the digital domain to the analog domain via a digital-to-analog converter (DAC) 310 of a transmitter path 450 to generate an analog signal, which is filtered via a baseband filter (BBF) 312 of the transmitter path 450. The filtered signal from the BBF 312 is up-converted via a mixer 314 of the transmitter path 450. The up-converted signal from the mixer 314 is amplified by a DA 316 (e.g., a first PA (PA1), also referred to as a preamplifier or pre-power amplifier (pre-PA)) of the transmitter path 450. The output voltage of the DA 316 is transmitted to the output of an LNA 324 of the receiver path 452 via a loopback voltage switch 406 of the loopback calibration path 408 to generate a loopback signal in the voltage domain. That is, the voltage from DA 316 can be fed to the input of transconductance (GM) amplifier 404 in receiver path 452. GM amplifier 404 then converts this voltage into current, which is provided to mixer 326 in receiver path 452 for down-conversion. The down-converted signal is then filtered via BBF 328 in receiver path 452, and the filtered signal can be converted from the analog domain to the digital domain via ADC 330 in receiver path 452. The analog signal from ADC 330 is then processed by controller 402 for calibration as described herein. In other words, calibration is performed based on a processed version of the signal received via the loopback calibration path.

[0053] Figure 4 The mixer 326, BBF 328, and ADC 330 shown can be implemented for each of the receiver's I-path and Q-path (e.g., receiver path 452). The gain difference and phase difference between the I-path and Q-path can be calibrated as described herein.

[0054] Assuming a long distance exists between the transmitter and receiver paths (e.g., it can be designed to reduce transmitter-to-receiver interference), the DA output voltage can be switched from the voltage domain to the current domain in the loopback calibration path to avoid voltage drop issues across the calibration path.

[0055] Figure 5This is an example wireless device 500 having RF transceiver circuitry 501 according to certain aspects of this disclosure, the RF transceiver circuitry including a loopback calibration path implemented using a voltage-to-current converter and a current-to-voltage converter. As shown, the loopback calibration path 408 may include a voltage-to-current (VI) converter 502 that converts the voltage at the output of DA 316 into a current. This current flows through a long trace of the loopback calibration path between the transmitter and the receiver. The loopback calibration path 408 may include a current-to-voltage (IV) converter 504 to convert the current back into a voltage, which is provided to the input of GM amplifier 404, as shown.

[0056] In relative to Figure 4 and Figure 5 In the two specific embodiments described, the voltage transmitted via the loopback calibration path 408 is provided to the output of the LNA (e.g., the input of the GM amplifier 404), and processed by the GM amplifier 404, mixer 326, BBF 328, and ADC 330 to generate a transmitter-to-receiver loopback. Providing the loopback voltage to the output of the LNA 324 can affect the LNA's frequency response and cause a gain or noise figure shift, which may adversely affect the accuracy of the calibration. Furthermore, using... Figure 5 The described VI and IV converters can cause process voltage and temperature-dependent gain and phase variations, which may also reduce calibration accuracy. While the LNA can be turned off (disabled) during calibration, the LNA 324 can be used as a load to draw current from the IV converter 504 when a voltage is supplied to its output, resulting in increased current consumption. Certain aspects of this disclosure relate to a loopback calibration path coupled between the output of the DA 316 and the output of the GM amplifier, thereby reducing current consumption and improving calibration accuracy.

[0057] Figure 6 An example wireless device 600 according to certain aspects of this disclosure has an RF transceiver circuit 601, which includes a loopback calibration path located between the output of DA 316 and the output of GM amplifier 404. As shown, the loopback calibration path 408 may include a VI converter 502 to convert the voltage from DA 316 into a current supplied to the output of GM amplifier 404, but lacks an IV converter 504. That is, the voltage from DA 316 is delivered to the loopback VI converter 502, converted from the voltage domain to the current domain, and delivered to the output of the receiver GM amplifier. Subsequently, the voltage from DA 316 converted to the current domain is processed by mixer 326 and BBF 328 and provided to ADC 330.

[0058] By not using about Figure 5 The described IV converter 504 reduces process voltage temperature-dependent gain and phase variations caused by the loopback calibration path (e.g., caused by the IV converter 504 itself), thereby improving calibration accuracy. Furthermore, by coupling the loopback calibration path to the output of the GM amplifier 404 (e.g., instead of the output of the LNA 324), the LNA can be disabled and not used as a load, thus reducing current consumption during calibration.

[0059] Because the loopback calibration path is coupled to the output of the GM amplifier 404, the loopback path may not load the LNA 324 during receive mode, thereby reducing process voltage-temperature dependent variations in the LNA's frequency selectivity, gain, and noise figure. Furthermore, the loopback calibration path can be used without the GM amplifier as the calibration path. Therefore, the GM amplifier can be completely turned off, reducing process voltage-temperature dependent gain and phase variations caused by the GM amplifier and improving calibration accuracy. With the GM amplifier turned off, current consumption that would otherwise be drawn by the GM amplifier 404 is saved, thus reducing calibration power consumption.

[0060] Figure 7 This is a flowchart illustrating an example operation 700 for wireless communication according to certain aspects of this disclosure. Operation 700 may be performed, for example, by a wireless device (such as wireless device 600).

[0061] At box 702, the wireless device transmits via a transmitter amplifier (e.g., transmitter path 450) through the transmitter path (e.g., transmitter path 450). Figure 6 The DA 316 (also known as a preamplifier PA) is used to generate amplified voltage.

[0062] At block 704, the wireless device converts the amplified voltage into current via a voltage-to-current converter (e.g., VI converter 502) in a loopback calibration path (e.g., loopback calibration path 408). At block 706, the wireless device supplies this current to the output of a transconductance amplifier (e.g., GM amplifier 404) in a receiver path (e.g., receiver path 452) via the loopback calibration path. At block 708, the wireless device generates a processing signal based on this current via the receiver path.

[0063] At block 710, the wireless device calibrates the receiver path based on a processed signal (e.g., via controller 402). In some aspects, the wireless device may turn off the transconductance amplifier during loopback calibration of the receiver path. The receiver path may also include a receiver amplifier (e.g., LNA 324). The wireless device may turn off the receiver amplifier during loopback calibration. Calibrating the receiver path at block 710 may include at least one of the following: reducing (e.g., minimizing) the gain difference between the in-phase (I) path and the quadrature (Q) path of the receiver path; or setting (e.g., adjusting) the phase difference between the I path and the Q path of the receiver path to 90°. Figure 6 The mixer 326, BBF 328, and ADC 330 shown can be implemented for each of the receiver's I-path and Q-path (e.g., the receiver path). The gain difference and phase difference between the I-path and Q-path can be calibrated as described.

[0064] The wireless device can generate an up-converted signal via a transmit mixer (e.g., mixer 314) in the transmitter path. An amplified voltage can be generated based on this up-converted signal. The wireless device can generate a processed signal by generating a down-converted signal based on current from the loopback calibration path via a receive mixer (e.g., mixer 326). The wireless device can generate a filtered signal based on the down-converted signal via a filter (e.g., BBF 328) and a digital signal based on the filtered signal via an analog-to-digital converter (e.g., ADC 330). The receiver path can be calibrated based on the digital signal.

[0065] Example In addition to the various aspects described above, specific combinations of these aspects are also within the scope of this disclosure, some of which are detailed below: Aspect 1: An apparatus for wireless communication, the apparatus comprising: a transmitter path including a first transmitting amplifier; a receiver path including a transconductance amplifier; and a loopback calibration path coupled between an output of the first transmitting amplifier and an output of the transconductance amplifier, wherein the loopback calibration path includes a voltage-to-current converter.

[0066] Aspect 2: The apparatus according to aspect 1, wherein the transconductance amplifier is configured to turn off during calibration of the receiver path using the loopback calibration path.

[0067] Aspect 3: The apparatus according to aspect 1 or 2, wherein the receiver path further includes a receiver amplifier, the receiver amplifier including an output coupled to the input of the transconductance amplifier, the receiver amplifier being configured to turn off during calibration of the receiver path using the loopback calibration path.

[0068] Aspect 4: The apparatus according to aspect 3, wherein the receiver amplifier includes a low-noise amplifier (LNA).

[0069] Aspect 5: The apparatus according to any one of aspects 1 to 4, wherein the transmitter path includes a second transmitting amplifier, the second transmitting amplifier including an input coupled to the output of the first transmitting amplifier.

[0070] Aspect 6: The apparatus according to aspect 5, wherein the first transmitting amplifier includes a drive amplifier (DA), and wherein the second transmitting amplifier includes a power amplifier (PA).

[0071] Aspect 7: The apparatus according to any one of aspects 1 to 6, wherein: the transmitter path includes a transmit mixer, the transmit mixer including an output coupled to an input of the first transmit amplifier; and the receiver path includes a receive mixer, the receive mixer including an input coupled to the output of the transconductance amplifier.

[0072] Aspect 8: The apparatus according to any one of aspects 1 to 7 further includes a controller coupled to the receiver path and configured to perform calibration of the receiver path based on a processed version of a signal received via the loopback calibration path.

[0073] Aspect 9: The apparatus according to aspect 8, wherein, in order to perform the calibration, the controller is configured to reduce the gain difference between the in-phase (I) path and the quadrature (Q) path of the receiver path.

[0074] Aspect 10: The apparatus according to aspect 8 or 9, wherein, in order to perform the calibration, the controller is configured to set the phase difference between the in-phase (I) path and the quadrature (Q) path of the receiver path to 90°.

[0075] Aspect 11: A method for wireless communication, the method comprising: generating an amplified voltage via a transmit amplifier in a transmitter path; converting the amplified voltage into a current via a voltage-to-current converter in a loopback calibration path; providing the current to the output of a transconductance amplifier in a receiver path via the loopback calibration path; generating a processing signal based on the current via the receiver path; and calibrating the receiver path based on the processing signal.

[0076] Aspect 12: The method according to aspect 11, the method further comprising turning off the transconductance amplifier during the calibration of the receiver path using the loopback calibration path.

[0077] Aspect 13: The method according to aspect 11 or 12, wherein the receiver path further includes a receiver amplifier, and the method further includes turning off the receiver amplifier during calibration of the receiver path using the loopback calibration path.

[0078] Aspect 14: The method according to aspect 13, wherein the receiving amplifier includes a low noise amplifier (LNA).

[0079] Aspect 15: The method according to any one of aspects 11 to 14, wherein the transmitting amplifier includes a pre-power amplifier (pre-PA).

[0080] Aspect 16: The method according to any one of aspects 11 to 15, wherein: the method further includes generating an up-converted signal via a transmit mixer of the transmitter path, wherein the amplified voltage is generated based on the up-converted signal; generating the processed signal includes generating a down-converted signal via a receive mixer based on the current from the loopback calibration path; generating a filtered signal based on the down-converted signal via a filter; and generating a digital signal based on the filtered signal via an analog-to-digital converter, wherein calibrating the receiver path includes calibrating the receiver path based on the digital signal.

[0081] Aspect 17: The method according to any one of aspects 11 to 16, wherein calibrating the receiver path includes reducing the gain difference between the in-phase (I) path and the quadrature (Q) path of the receiver path.

[0082] Aspect 18: The method according to any one of aspects 11 to 17, wherein calibrating the receiver path includes setting the phase difference between the in-phase (I) path and the quadrature (Q) path of the receiver path to 90°.

[0083] Aspect 19: A wireless device comprising: at least one antenna; a transmitter path coupled to the at least one antenna and including a transmit amplifier; a receiver path coupled to the at least one antenna and including a transconductance amplifier; and a loopback calibration path coupled between an output of the transmit amplifier and an output of the transconductance amplifier, wherein the loopback calibration path includes a voltage-to-current converter.

[0084] Aspect 20: The wireless device according to aspect 19, wherein the transconductance amplifier is configured to be turned off during calibration of the receiver path using the loopback calibration path.

[0085] Additional Notes The various operations of the methods described above can be performed by any suitable component capable of performing the corresponding function. Components may include various hardware and / or software components and / or modules, including but not limited to circuits, application-specific integrated circuits (ASICs), or processors. Generally, in the presence of operations illustrated in the accompanying drawings, those operations may have corresponding components with similar numbering, plus functional components.

[0086] As used herein, the term "determine" encompasses a wide variety of actions. For example, "determine" can include calculation, operation, processing, deduction, investigation, lookup (e.g., searching in a table, database, or other data structure), assertion, etc. Furthermore, "determine" can include receiving (e.g., receiving information), accessing (e.g., accessing data in memory), etc. Additionally, "determine" can include parsing, selecting, picking, building, etc.

[0087] As used in this article, the phrase “at least one of the items” refers to any combination of these items, including a single member. As an example, “at least one of a, b, or c” is intended to cover: a, b, c, ab, ac, bc, and abc, as well as any combination with multiple identical elements (e.g., aa, aaa, aab, aac, abb, acc, bb, bbb, bbb, cc, and ccc, or any other ordering of a, b, and c).

[0088] The methods disclosed herein include one or more steps or actions for implementing the described methods. The steps and / or actions of the methods may be interchanged without departing from the scope of the claims. In other words, unless a specific order of steps or actions is specified, the order and / or use of a particular step and / or action may be modified without departing from the scope of the claims.

[0089] It should be understood that the claims are not limited to the precise configurations and components illustrated above. Various modifications, variations, and alterations may be made to the arrangement, operation, and details of the methods and apparatus described above without departing from the scope of the claims.

Claims

1. An apparatus for wireless communication, the apparatus comprising: A transmitter path, the transmitter path including a first transmitting amplifier; A receiver path, the receiver path including a transconductance amplifier; and A loopback calibration path is coupled between the output of the first transmitting amplifier and the output of the transconductance amplifier, wherein the loopback calibration path includes a voltage-to-current converter.

2. The apparatus of claim 1, wherein the transconductance amplifier is configured to turn off during calibration of the receiver path using the loopback calibration path.

3. The apparatus of claim 1, wherein the receiver path further comprises a receiver amplifier, the receiver amplifier including an output coupled to an input of the transconductance amplifier, the receiver amplifier being configured to turn off during calibration of the receiver path using the loopback calibration path.

4. The apparatus of claim 3, wherein the receiver amplifier comprises a low-noise amplifier (LNA).

5. The apparatus of claim 1, wherein the transmitter path includes a second transmitting amplifier, the second transmitting amplifier including an input portion coupled to the output portion of the first transmitting amplifier.

6. The apparatus of claim 5, wherein the first transmitting amplifier comprises a drive amplifier (DA), and wherein the second transmitting amplifier comprises a power amplifier (PA).

7. The apparatus according to claim 1, wherein: The transmitter path includes a transmit mixer, which includes an output coupled to the input of the first transmit amplifier; and The receiver path includes a receive mixer, which includes an input section coupled to the output of the transconductance amplifier.

8. The apparatus of claim 1, further comprising a controller coupled to the receiver path and configured to perform calibration of the receiver path based on a processed version of a signal received via the loopback calibration path.

9. The apparatus of claim 8, wherein, in order to perform the calibration, the controller is configured to reduce the gain difference between the in-phase (I) path and the quadrature (Q) path of the receiver path.

10. The apparatus of claim 8, wherein, in order to perform the calibration, the controller is configured to set the phase difference between the in-phase (I) path and the quadrature (Q) path of the receiver path to 90°.

11. A method for wireless communication, the method comprising: An amplified voltage is generated via a transmit amplifier through the transmitter path; The amplified voltage is converted into current via a voltage-to-current converter through a loopback calibration path; The current is supplied to the output of the transconductance amplifier in the receiver path via the loopback calibration path; A processing signal is generated based on the current via the receiver path; as well as The receiver path is calibrated based on the processed signal.

12. The method of claim 11, further comprising turning off the transconductance amplifier during the calibration of the receiver path using the loopback calibration path.

13. The method of claim 11, wherein the receiver path further includes a receiver amplifier, and the method further includes turning off the receiver amplifier during calibration of the receiver path using the loopback calibration path.

14. The method of claim 13, wherein the receiving amplifier comprises a low-noise amplifier (LNA).

15. The method of claim 11, wherein the transmitting amplifier comprises a pre-power amplifier (pre-PA).

16. The method of claim 11, wherein: The method further includes generating an up-converted signal via a transmit mixer through the transmitter path, wherein the amplified voltage is generated based on the up-converted signal; Generating the processed signal includes generating a down-converted signal via a receiving mixer based on the current from the loopback calibration path; A filtered signal is generated based on the down-converted signal via a filter. as well as A digital signal is generated based on the filtered signal via an analog-to-digital converter, wherein calibrating the receiver path includes calibrating the receiver path based on the digital signal.

17. The method of claim 11, wherein calibrating the receiver path comprises reducing the gain difference between the in-phase (I) path and the quadrature (Q) path of the receiver path.

18. The method of claim 11, wherein calibrating the receiver path comprises setting the phase difference between the in-phase (I) path and the quadrature (Q) path of the receiver path to 90°.

19. A wireless device, the wireless device comprising: At least one antenna; A transmitter path, said transmitter path being coupled to said at least one antenna and including a transmit amplifier; A receiver path, said receiver path being coupled to said at least one antenna and including a transconductance amplifier; and A loopback calibration path is coupled between the output of the transmitting amplifier and the output of the transconductance amplifier, wherein the loopback calibration path includes a voltage-to-current converter.

20. The wireless device of claim 19, wherein the transconductance amplifier is configured to be turned off during calibration of the receiver path using the loopback calibration path.

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