Integrated circuit transceiver array synchronization
Transceiver array synchronization by receiving a clock signal and at least one synchronization pulse signal at each transceiver IC of a plurality of transceiver integrated circuit (IC) subarrays, wherein each transceiver IC subarray contains a respective set of serially connected transceiver ICs; and synchronizing the transceiver IC with other transceiver ICs of the respective set of serially connected transceiver ICs by resetting a delta-sigma modulator (DSM) circuit to a predetermined state in accordance with the received at least one synchronization pulse signal.
1. A method comprising:
receiving a clock signal and at least one synchronization pulse signal at each transceiver IC of a plurality of transceiver integrated circuit (IC) subarrays, wherein each transceiver IC subarray contains a respective set of serially connected transceiver ICs;
at each transceiver IC:
synchronizing the transceiver IC with other transceiver ICs of the respective set of serially connected transceiver ICs by resetting a delta-sigma modulator (DSM) circuit to a predetermined state in accordance with the received at least one synchronization pulse signal;
generating a carrier frequency signal using a phase-locked loop (PLL) circuit that includes the DSM circuit; and
using the generated carrier frequency signal to process frequency domain in-phase and quadrature (IQ) data.
2. The method of claim 1 , wherein generating the carrier frequency signal using the PLL circuit comprises:
using the DSM circuit to set a divide ratio of a multiple-modulus divider (MMD); and
providing a divided-frequency signal from the MMD to a phase/frequency detector (PFD) for comparison against the clock signal to further adjust the divide ratio of the multiple-modulus divider.
3. The method of claim 1 , wherein the DSM circuit includes a plurality of accumulators and wherein resetting the DSM circuit to the predetermined state in accordance with the received at least one synchronization pulse signal comprises setting the plurality of accumulators of the DSM circuit in accordance with the received at least one synchronization pulse signal.
4. The method of claim 1 , wherein the frequency domain IQ data is downlink (DL) frequency domain IQ data, and the method further comprises:
receiving, by at least one transceiver IC of the respective set of serially connected transceiver ICs, the DL frequency domain IQ data in a frequency domain IQ data packet sent over a serial data connection from another transceiver of the respective set of serially connected transceiver ICs.
5. The method of claim 1 , wherein the frequency domain IQ data is downlink (DL) frequency domain IQ data, and wherein
using the generated carrier frequency signal to process the DL frequency domain IQ data comprises:
modulating a discrete time-domain signal representative of the DL frequency domain IQ data onto the generated carrier frequency signal for a DL transmission from the transceiver IC.
6. The method of claim 5 , further comprising generating the discrete time-domain signal from the DL frequency domain IQ data via an inverse Fast-Fourier Transform (iFFT).
7. The method of claim 6 , further comprising:
resetting, at the transceiver IC, a numerically controlled oscillator (NCO) in accordance with the received at least one synchronization pulse signal; and
performing a frequency translation of the discrete time-domain signal using the NCO.
8. The method of claim 7 , wherein resetting the NCO comprises resetting a phase accumulator of the NCO in accordance with the received at least one synchronization pulse signal.
9. The method of claim 7 , wherein performing the frequency translation of the discrete time-domain signal using the NCO comprises:
after the iFFT transformation, using the NCO to perform time-domain complex frequency multiplication that shifts a frequency of a desired component carrier.
10. The method of claim 7 , further comprising adding the frequency-translated discrete time-domain signal representing a first component carrier with another discrete time domain signal representing a second component carrier.
11. The method of claim 5 , wherein modulating the discrete time-domain signal representative of the DL frequency domain IQ data onto the generated carrier frequency signal comprises:
using a multi-phase digital power amplifier (DPA), wherein the multi-phase DPA uses selected phases of the generated carrier frequency signal for radio frequency (RF) modulation, the phases being selected in accordance with the discrete time-domain signal.
12. The method of claim 1 , wherein the frequency domain IQ data is uplink (UL) frequency domain IQ data, and the method further comprises:
sending, by at least one transceiver IC of the respective set of serially connected transceiver ICs, the UL frequency domain IQ data over a serial data connection to another transceiver IC of the respective set of serially connected transceiver ICs.
13. The method of claim 1 , wherein the frequency domain IQ data is uplink (UL) frequency domain IQ data, and wherein using the generated carrier frequency to process the UL frequency domain IQ data comprises:
receiving, at the transceiver IC, a modulated radio frequency (RF) signal;
downconverting the modulated RF signal using the generated carrier frequency signal; and
generating the UL frequency domain IQ data from the downconverted modulated RF signal.
14. The method of claim 13 , wherein downconverting the received modulated RF signal using the generated carrier frequency signal comprises:
using a mixer driven by the generated carrier frequency signal to generate baseband in-phase (I) and quadrature (Q) analog signals corresponding to the received modulated RF signal; and
sampling the baseband I and Q analog signals using an analog to digital converter (ADC) to generate a discrete time-domain signal representative of the UL frequency domain IQ data.
15. The method of claim 14 , further comprising:
generating the UL frequency domain IQ data from the discrete time-domain signal via a Fast Fourier Transform (FFT); and
forming a frequency domain IQ data packet that includes the UL frequency domain IQ data.
16. An apparatus comprising:
a plurality of transceiver integrated circuit (IC) subarrays, wherein each transceiver IC subarray contains a respective set of serially connected transceiver ICs;
a beamformer processor coupled to the plurality of transceiver IC subarrays, wherein the beamformer processor is configured to generate at least one synchronization pulse signal, and to provide the at least one synchronization pulse signal to each transceiver IC; and
a plurality of clock buffer circuits coupled to the beamformer processor via a clock distribution circuit, wherein the plurality of clock buffer circuits are configured to output a plurality of clock signals, and to provide a respective clock signal to each transceiver IC, and wherein each transceiver IC is configured to:
receive the respective clock signal and the at least one synchronization pulse signal;
synchronize the transceiver IC with other transceiver ICs of the respective set of serially connected transceiver ICs by resetting a delta-sigma modulator (DSM) circuit to a predetermined state in accordance with the received at least one synchronization pulse signal;
generate a carrier frequency signal using a phase-locked loop (PLL) circuit that includes a delta-sigma modulator (DSM) circuit; and
use the generated carrier frequency signal to process frequency domain IQ data.
17. The apparatus of claim 16 , wherein the clock distribution circuit is driven by another clock signal from the beamformer processor and a system reference clock.
18. The apparatus of claim 16 , wherein to generate the carrier frequency signal using the PLL circuit, each transceiver IC is further configured to:
use the DSM circuit to set a divide ratio of a multiple-modulus divider (MMD); and
provide a divided-frequency signal from the MMD to a phase/frequency detector (PFD) for comparison against the clock signal to further adjust the divide ratio of the multiple-modulus divider.
19. The apparatus of claim 18 , wherein the MMD is configured to utilize a sequence of divisor values provided by the DSM and to synchronize the sequence of divisor values using the at least one synchronization pulse.
20. The apparatus of claim 16 , wherein the DSM circuit includes a plurality of accumulators, and wherein to reset the DSM circuit to the predetermined state in accordance with the received at least one synchronization pulse signal, each transceiver IC is further configured to:
set the plurality of accumulators of the DSM circuit in accordance with the received at least one synchronization pulse signal.
21. The apparatus of claim 16 , wherein the plurality of clock buffer circuits are configured to adjust clock signal timing at an output of each clock buffer circuit so that the respective clock signal is received by each transceiver IC at substantially same time.
22. The apparatus of claim 21 , wherein:
the plurality of transceiver IC subarrays, the beamformer processor and the plurality of clock buffer circuits are all physically co-located within an antenna array assembly, and
each clock buffer circuit is physically distributed across the antenna array assembly in physical locations corresponding to physical locations of one or more transceiver IC subarrays.