The present application is related to commonly assigned and co-pending U.S. application Ser. No. 09/633,705 filed on 7 Aug. 2000 entitled “Digital-To-Phase Converter”, U.S. application Ser. No. 09/780,077 filed on 9 Feb. 2001 entitled “Direct Digital Synthesizer Based On Delay Line With Sorted Taps”, U.S. application Ser. No. 10/000,914 filed on 2 Nov. 2001 entitled “Cascaded Delay Locked Loop Circuit, U.S. application Ser. No. 10/365,558 filed on 21 Dec. 2001 entitled Digital-To-Phase Converter With Extended Frequency Range”, U.S. application Ser. No. 10/050,233 filed on 16 Jan. 2002 entitled “Delayed Locked Loop Synthesizer With Multiple Outputs And Digital Modulation”, all of which are assigned commonly and co-pending with the present application.
The present inventions relate generally to radio communications, and more particularly to adaptive and multi-mode radio transceiver architectures, for example in wireless communications devices, and methods therefor.
The various aspects, features and advantages of the present invention will become more fully apparent to those having ordinary skill in the art upon careful consideration of the following Detailed Description of the Invention with the accompanying drawings described below.
The exemplary communications device 100 also comprises generally a processor 120 having a digital signal processor (DSP) coupled to the transceiver 110. The exemplary DSP is integrated with the processor, although in other embodiments the DSP is a discrete component, and in some embodiments the DSP may not be required.
The processor 120 is coupled to memory 130, including for example RAM and ROM and in some embodiments some type of flash memory. The exemplary device includes a display 140, for example a low power LCD display device. The exemplary communications device also includes generally input and output devices 130, for example, an alphanumeric keypad, scrolling and/or pointing devices, a microphone, an audio output, input and output signal ports, etc., depending on the nature of the device.
The communications devices of the present invention include preferably a digital-to-phase synthesizer having one or more fixed or variable frequency and phase outputs coupled to a transmitter and/or to a receiver, or to a transceiver of the type illustrated schematically in
In the exemplary embodiment of
In one embodiment, the delay line is tuned to a single wavelength of the VCO signal output, FCLK 214, input to the delay line 220. In the exemplary embodiment, a serial arrangement of 32 buffers, each having a 31.25 p-second delay, is driven with a 1.0 GHz input clock, FCLK 214, and locked to a total delay of 1000.0 p-seconds.
Digital-to-phase synthesizers and the delay locked loop circuits are disclosed more fully in co-pending U.S. application Ser. No. 09/633,705 filed on 7 Aug. 2000 entitled “Digital-To-Phase Converter”, in co-pending U.S. application Ser. No. 09/780,077 filed on 9 Feb. 2001 entitled “Direct Digital Synthesizer Based On Delay Line With Sorted Taps”, in co-pending U.S. application Ser. No. 10/000,914 filed on 2 Nov. 2001 entitled “Cascaded Delay Locked Loop Circuit”, and in co-pending U.S. application Ser. No. 10/365,558 filed on 21 Dec. 2001 entitled Digital-To-Phase Converter With Extended Frequency Range”, the subject matter of which is incorporated herein by reference.
In the exemplary embodiment of
Digital-to-phase synthesizers are disclosed more fully in co-pending U.S. application Ser. No. 09/633,705 filed on 7 Aug. 2000 entitled “Digital-To-Phase Converter”, in co-pending U.S. application Ser. No. 09/780,077 filed on 9 Feb. 2001 entitled “Direct Digital Synthesizer Based On Delay Line With Sorted Taps”, and in co-pending U.S. application Ser. No. 10/365,558 filed on 21 Dec. 2001 entitled Digital-To-Phase Converter With Extended Frequency Range”, the subject matter of which is incorporated herein by reference.
Digital processing and tap selection windowing of digital-to phase synthesizers of the type utilized in the present invention comprises generally determining when to select a tap or taps and which ones to select. More particularly, the input clock cycle during which to process a tap signal output is determined by a frequency accumulator, and a phase accumulator determines which tap to route to the output path. Routing of selected delayed reference clock signal pulses to a subsequent delay line or output port is controlled by a window trigger signal.
The digital processing and tap selection windowing of digital-to-phase synthesizers is disclosed more fully in co-pending U.S. application Ser. No. 10/050,233 filed on 16 Jan. 2002 entitled “Delayed Locked Loop Synthesizer With Multiple Outputs And Digital Modulation” and in co-pending U.S. application Ser. No. 10/365,558 filed on 21 Dec. 2001 entitled “Digital-To-Phase Converter With Extended Frequency Range”, among the other applications referenced herein, the subject matter of which is incorporated herein by reference.
Phase, amplitude or frequency modulation or a combination thereof can be applied to a digital to phase synthesizer by way of a number of methods, including modulation of the reference input, summing an offset signal with the delay line tuning signal, modulating control words, and modifying a tap selection word. The most direct method of applying phase modulation to the output signal is to sum a digital word with a Cj value. The modulated value would be a digital word representing the normalized phase offset modulation or the desired phase shift in radians divided by 2 p. This can be a positive or negative offset by as much as 2 p. In general, this can be achieved in a delay locked loop having delay line with a plurality of tap outputs using a tap selection processor that selects a sequence of time varying tap addresses C(t) that vary in accordance with a time varying modulating signal A(t), where:
If the harmonic content of the resulting output signal is ignored (or removed, e.g., by filtering), the output signal at output Foutb is given by:
Foutb(t)=x e−j[i t+2pA(t)]
Where x is an amplitude constant. A tap selection processor selects a sequence of time varying tap addresses Cj(t) that vary in time in accordance with a modulating signal m(t). The time varying tap addresses Cj(t) are applied to a multiplexer circuit to select a time varying sequence of tap outputs as a phase modulated output signal Fout(t). In one embodiment, the tap selection processor uses an adder that adds the modulating signal m(t) to a selected sequence of tap addresses Cj to produce Cj(t). By applying a time varying signal A(t) as an input to the summer 312, the values of the Cjb(t) coefficients are time varying and modulated according to the time varying nature of A(t). These time varying coefficients Cjb(t) are then used to select taps using a multiplexer as previously described. This produces a time varying phase shift of the output signal Foutb(t) with the phase of Foutb(t) varying in accordance with A(t) to produce digital phase modulation. These and other aspects of modulation are discussed more fully in co-pending U.S. application Ser. No. 10/050,233 filed on 16 Jan. 2002 entitled “Delayed Locked Loop Synthesizer With Multiple Outputs And Digital Modulation”.
In one embodiment, digital-to-phase synthesizer outputs are coupled to corresponding mixers having corresponding inputs coupled to one or more receiver antennas. In
In some embodiments, there may be included amplification and frequency selection of the received signal prior to mixing. Also, the one or more received signals may be mixed with quadrature components of the digital-to-phase synthesizer output signals. In
The output of the one or more mixers is coupled generally to a demodulator. In
In some embodiments, illustrated in the receiver process flow chart of
In diversity receiver applications, the received signal is down-converted by mixing it with first and second digital-to-phase synthesizer output signals having the same frequency and the same phase. In one embodiment, the signal is received at first and second antennas having a diversity relationship, for example spacial diversity. Other diversity receiver embodiments are characterized by polarizing diversity, or some form of propagation mode diversity, or time diversity, et cetera as known generally by those having ordinary skill in the art.
In multiple input multiple output (MIMO) receiver applications, a signal received at different antennas of the receiver is mixed with at least two digital-to-phase synthesizer output signals having the same frequency.
In adaptive array receiver applications, a signal received by multiple antennas is mixed with a corresponding multiple of digital-to-phase synthesizer output signals having the same frequency. An adaptive array is realized by changing the phases of at least one of the multiple digital-to-phase synthesizer output signals mixed with the received signal.
In multi-mode receiver applications, the receiver receives multiple signals having different frequencies, for example Global Positioning System (GPS) enabled wireless communications devices, and multi-system cellular devices, combination wide area network (WAN) and cellular communications devices, etc. Multi-mode receivers thus generally include one or more baseband processors capable of processing the variety of signals received. In some applications, the receiver includes different antennas for receiving the various signals, for example a GPS antenna and a multi-band cellular antenna. The received signals are mixed with corresponding digital-to-phase synthesizer output signals having different frequencies and/or phases prior to baseband processing, or demodulation.
In cellular network neighbor list scanning applications, at least two signals having different frequencies are received and mixed with corresponding digital-to-phase synthesizer output signals having different frequencies. Neighbor lists may thus be scanned while receiving another signal on a broadcast or a dedicated channel.
In
While the present inventions and what is considered presently to be the best modes thereof have been described in a manner that establishes possession thereof by the inventors and that enables those of ordinary skill in the art to make and use the inventions, it will be understood and appreciated that there are many equivalents to the exemplary embodiments disclosed herein and that myriad modifications and variations may be made thereto without departing from the scope and spirit of the inventions, which are to be limited not by the exemplary embodiments but by the appended claims.
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