Abstract: Certain aspects of the present disclosure provide multi-way diversity receivers with multiple synthesizers. Such a multi-way diversity receiver may be implemented in a carrier aggregation (CA) transceiver. One example wireless reception diversity circuit generally includes three or more receive paths for processing received signals and two or more frequency synthesizing circuits configured to generate local oscillating signals to downconvert the received signals. Each of the frequency synthesizing circuits is shared by at most two of the receive paths, and each pair of the frequency synthesizing circuits may generate a pair of local oscillating signals having the same frequency.

Abstract: Certain aspects of the present disclosure provide methods and apparatus for dynamically adjusting a voltage-controlled oscillator (VCO) frequency, a local oscillator (LO) divider ratio, and/or a receive path when adding or discontinuing reception of a component carrier (CC) in a carrier aggregation (CA) scheme. This dynamic adjustment is utilized to avoid (or at least reduce) VCO, LO, and transmit signal coupling issues with multiple component carriers, with minimal (or at least reduced) current consumption by the VCO and the LO divider.

Abstract: A radio frequency (RF) front end having multiple low noise amplifiers modules is disclosed. In an exemplary embodiment, an apparatus includes at least one first stage amplifier configured to amplify received carrier signals to generate at least one first stage carrier group. Each first stage carrier group includes a respective portion of the carrier signals. The apparatus also includes second stage amplifiers configured to amplify the first stage carrier groups. Each second stage amplifier configured to amplify a respective first stage carrier group to generate two second stage output signals that may be output to different demodulation stages where each demodulation stage demodulates a selected carrier signal.

Abstract: Methods and apparatus including: setting up a plurality of configurations for a plurality of local oscillator (LO) paths of a carrier aggregation (CA) transceiver operating with a plurality of bands; calculating and comparing frequencies for each LO path of the plurality of LO paths and at least one divider ratio of LO dividers for each band of the plurality of bands to identify frequency conflicts; and reconfiguring the LO dividers for the plurality of LO paths and the plurality of bands when the frequency conflicts are identified.

Abstract: Locking multiple VCOs to generate a plurality of LO frequencies, including: receiving a plurality of divided VCO feedback signals from a plurality of VCOs; receiving a reference signal multiplied by a predetermined number of the plurality of VCOs; generating and processing the predetermined number of phase differences between the multiplied reference signal and the plurality of divided VCO feedback signals in a single PLL circuit including a digital loop filter to receive and process the phase differences and generate (produce) a filter output, wherein the digital loop filter includes a plurality of delay cells equal to the predetermined number; and generating and outputting (delayed) control voltages for the plurality of VCOs based on the filter output.

Abstract: Multiple-input multiple-output (MIMO) low noise amplifiers (LNAs) supporting carrier aggregation are disclosed. In an exemplary design, an apparatus (e.g., a wireless device, an integrated circuit, etc.) includes a MIMO LNA having a plurality of gain circuits, a drive circuit, and a plurality of load circuits. The gain circuits receive at least one input radio frequency (RF) signal and provide at least one amplified RF signal. Each gain circuit receives and amplifies one input RF signal and provides one amplified RF signal when the gain circuit is enabled. The at least one input RF signal include transmissions sent on multiple carriers at different frequencies to the wireless device. The drive circuit receives the at least one amplified RF signal and provides at least one drive RF signal. The load circuits receive the at least one drive RF signal and provide at least one output RF signal.

Abstract: A device includes a reconfigurable receiver front end having variable gain and variable bandwidth configured to tune to a plurality of communication channels in a communication band, the reconfigurable receiver front end responsive to a signal power level.

Abstract: A dual frequency synthesizer architecture for a wireless device operating in a time division duplex (TDD) mode is disclosed. In an exemplary design, the wireless device includes first and second frequency synthesizers. The first frequency synthesizer generates a first oscillator signal used to generate a first/receive local oscillator (LO) signal at an LO frequency for the receiver. The second frequency synthesizer generates a second oscillator signal used to generate a second/transmit LO signal at the same LO frequency for the transmitter. The two frequency synthesizers generate their oscillator signals to obtain receive and transmit LO signals at the same LO frequency when the wireless device operates in the TDD mode.

Abstract: Receiver circuits that can be reconfigured to generate test signals in a wireless device are disclosed. In an exemplary design, an apparatus includes a mixer and an amplifier. The mixer downconverts an input radio frequency (RF) signal based on a local oscillator (LO) signal in a first mode. The amplifier, which is formed by at least a portion of the mixer, amplifies the LO signal and provides an amplified LO signal in a second mode. In another exemplary design, an apparatus includes an amplifier and an attenuator. The amplifier receives and amplifies an input RF signal in a first mode. The attenuator, which is formed by at least a portion of the amplifier, receives and passes an LO signal in a second mode.

Abstract: A circuit includes a digital-to-analog converter with non-uniform resolution for converting a digital signal into an analog signal. The digital-to-analog converter includes high-resolution circuitry, reduced-resolution circuitry coupled to the high-resolution circuitry and a switch coupled to the high-resolution circuitry and to the reduced-resolution circuitry. The switch couples one of the high-resolution circuitry and the reduced-resolution circuitry to an output node. The circuit also includes a decoder coupled to the switch. The decoder receives the digital signal to control the switch.

Abstract: Expandable transceivers and receivers support operation on multiple frequency bands and multiple carriers. In an exemplary design, an apparatus (e.g., a wireless device, an integrated circuit (IC) chip, or circuit module) includes a low noise amplifier (LNA) and interface circuit. The LNA resides on an IC chip and includes a first/on-chip output and a second/off-chip output. The interface circuit also resides on the IC chip, is coupled to the second output of the LNA, and provides an amplified RF signal outside of the IC chip. The apparatus may further include a buffer, load circuit, and downconverter circuit. The buffer resides on the IC chip, is coupled to the first output of the LNA, and receives a second amplified RF signal from outside of the IC chip. The load circuit is coupled to the first output of the LNA. The downconverter circuit is coupled to the load circuit.

Abstract: A method and apparatus for providing total power from one transmit path. The method provides the steps of: selecting a transmit path and closing a first switch, located after a digital to analog converter. A second switch between the two transmit paths is then closed in order to provide for the use of at least one low-pass filter in each transmit path. The signal is then processed through the at least one low pass filter in each transmit path. The signal is then processed through at least one mixer in each transmit path. After the mixer, the signal is then processed through at least one driver amplifier in each transmit path, and one-half of the total power is allocated to each of two transmission paths. A third switch is then closed after the at least one power amplifier in each transmit path to force the half-power from one transmit path into one output.

Abstract: Certain aspects of the present disclosure provide methods and apparatus for calibrating a transceiver for wireless communications. One example method generally includes configuring a first oscillating signal as an input signal to at least a portion of a receiver (RX) path, calibrating a residual sideband (RSB) of the receiver path using a second oscillating signal as a local oscillating signal for the receiver path, and calibrating an RSB of a transmitter (TX) path by routing an output of the transmitter path to the receiver path, after calibrating the RSB of the receiver path. Another example method generally includes routing an output of a transmitter path to a receiver path, using a first local oscillating signal for the transmitter path, using a second local oscillating signal for the receiver path, and measuring an output of the receiver path as a local oscillator (LO) leakage for the transmitter path.

Abstract: Certain aspects of the present disclosure provide methods and apparatus for dynamically secondary cell (SCELL) allocation and frequency planning for carrier aggregation. One example system for radio frequency (RF) signal processing, generally includes a first integrated circuit (IC) comprising two or more receive chains, each receive chain for processing one of multiple component carriers in a carrier aggregation (CA) signal, wherein the first IC is configured to downconvert a signal associated with a primary cell of the CA signal; and a second IC configured to downconvert one or more signals associated with one or more secondary cells of the CA signal. The second IC may also be configured to upconvert a signal having a frequency different than the primary cell by an offset associated with the primary cell.

Abstract: A voltage controlled oscillator (VCO) core for cancelling a supply noise is described. The VCO core includes an input node that receives the supply noise. The VCO core also includes a noise path coupled to the input node. The VCO core additionally includes a cancellation path coupled to the input node and the noise path. The cancellation path includes a programmable gain circuit coupled with a first terminal of a varactor. The supply noise passes through the programmable gain circuit to produce a cancellation noise.

Abstract: Selectable sizes for a local oscillator (LO) buffer and mixer are disclosed. In an exemplary embodiment, LO buffer and/or mixer size may be increased when a receiver or transmitter operates in a high gain mode, while LO buffer and/or mixer size may be decreased when the receiver or transmitter operates in a low gain mode. In an exemplary embodiment, LO buffer and mixer sizes are increased and decreased in lock step. Circuit topologies and control schemes for specific exemplary embodiments of LO buffers and mixers having adjustable size are disclosed.

Abstract: A wireless device supporting concurrent communication with multiple wireless systems of different radio access technologies (RATs) are disclosed. In an exemplary design, an apparatus includes first and second receivers supporting concurrent signal reception from wireless systems of different RATs. The first receiver receives a first downlink signal from a first wireless system of a first RAT. The second receiver receives a second downlink signal from a second wireless system of a second RAT, which is different from the first RAT. The first and second receivers may operate concurrently. The second receiver may be broadband and/or may support carrier aggregation. The apparatus may further include first and second local oscillator (LO) generators to generate LO signals for the first and second receivers, respectively, based on different divider ratios in order to mitigate voltage controlled oscillator (VCO) pulling.

Abstract: A method for reducing power consumption on a wireless communication device is described. The wireless communication device includes a first stage active filter and a second stage active filter. A condition measurement is obtained that includes a signal measurement condition. If it is determined that the condition measurement is above a threshold, the second stage active filter is bypassed.

Abstract: Receiver circuits that can be reconfigured to generate test signals in a wireless device are disclosed. In an exemplary design, an apparatus includes a mixer and an amplifier. The mixer downconverts an input radio frequency (RF) signal based on a local oscillator (LO) signal in a first mode. The amplifier, which is formed by at least a portion of the mixer, amplifies the LO signal and provides an amplified LO signal in a second mode. In another exemplary design, an apparatus includes an amplifier and an attenuator. The amplifier receives and amplifies an input RF signal in a first mode. The attenuator, which is formed by at least a portion of the amplifier, receives and passes an LO signal in a second mode.

Abstract: A method for reducing power consumption on a wireless communication device is described. The wireless communication device includes a first stage active filter and a second stage active filter. A condition measurement is obtained that includes a signal measurement condition. If it is determined that the condition measurement is above a threshold, the second stage active filter is bypassed.