CA2467201A1 - Dynamic and static spurious correction and control - Google Patents
Dynamic and static spurious correction and control Download PDFInfo
- Publication number
- CA2467201A1 CA2467201A1 CA002467201A CA2467201A CA2467201A1 CA 2467201 A1 CA2467201 A1 CA 2467201A1 CA 002467201 A CA002467201 A CA 002467201A CA 2467201 A CA2467201 A CA 2467201A CA 2467201 A1 CA2467201 A1 CA 2467201A1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/06—Receivers
- H04B1/16—Circuits
- H04B1/30—Circuits for homodyne or synchrodyne receivers
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B15/00—Suppression or limitation of noise or interference
- H04B15/02—Reducing interference from electric apparatus by means located at or near the interfering apparatus
- H04B15/04—Reducing interference from electric apparatus by means located at or near the interfering apparatus the interference being caused by substantially sinusoidal oscillations, e.g. in a receiver or in a tape-recorder
- H04B15/06—Reducing interference from electric apparatus by means located at or near the interfering apparatus the interference being caused by substantially sinusoidal oscillations, e.g. in a receiver or in a tape-recorder by local oscillators of receivers
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03D—DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER
- H03D7/00—Transference of modulation from one carrier to another, e.g. frequency-changing
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B2215/00—Reducing interference at the transmission system level
- H04B2215/064—Reduction of clock or synthesizer reference frequency harmonics
- H04B2215/065—Reduction of clock or synthesizer reference frequency harmonics by changing the frequency of clock or reference frequency
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- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Superheterodyne Receivers (AREA)
- Noise Elimination (AREA)
Description
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HIGHLY CONFT17ENTIAL INFORMATION - Page 1 of 13, :;/13/04 SiRiFIC WIRELESS CORP. - dNVENTIONDISCLOSURE' FORM
DATE: May 11 st TITLE OF INVENTION: Dynamic and Static Spurious correction and control SUBMITTED BY: Tajinder Manku ADDRESS:
SiRiFIC Wireless Corporation 460 Phillip Street Suite 300 Waterloo, Ontario phone - 519-747-2292 fax - 519-747-3996 Please Answer the following questions and attach any docu.ments/publications/disclosures;
A. Discuss the relevant area or areas of technology.
The area in which this technology fits is in radio technology and in particular the receiver chain of a radio. However, it could be extended to those areas in which spurious issues are generated by down converting a signal from a carrier to a lower frequency (for example a cable modem).
The technology is used to move or place spurious components generated by the radio and an unwanted RF (Radio Frequency) signal (denote the unwanted l~F signal by a "blocking signal") to a frequency location that does not desensitize the wanted RF~ signal.
Desensitization by the Mocker can occur in varies forms: (i) raising the noise floor, (iii) causing the overall gain of the receiver to reduce, or (iii} both (i) and (ii).
B. What problem or problems exist that your invention may solve?
This invention reduces or eliminates blocking signals from desensitizing the receiver chain.
C. How has this problem, or similar problems, been mitigated in the past?
There are several methods which have been used to mitigate this problem before. However, in most of the cases some Mockers do not pass the radio test and are denoted as exceptions. For a HIGHLY CONFIDENTIAL INFORMATION - Page 2 of 13, 5/13/04 given standard there are a number of exceptions allowed and if you exceed this amount the radio will not pass type approval. Below is a listing of the various methods and the disadvantages/
advantages associated with them:
Super-heterodyne: The super-heterodyne receiver uses a two si:ep frequency translation method to convert the signal at RF to a base hand signal. First, the incoming signals and corruptive noise are passed through a band pass filter that attenuates out of band signals and passes the desired signal. At this stage some of the blocking signals that are out of band are filtered. The desired signal, plus residual blocking signals, are amplified and mixed with a first local oscillator. This causes both a downconversion and an up conversion in the frequency domain. Usually the downconverted portion is retained at the so-called "Intermediate Frequency" (IF). Further faltering is performed on the signal at the IF frequency using a discrete device. This filter is a band pass filter and retains the radio channel required and further reduces the residual blocking signal. The signal is then mixed with a second oscillator that causes frequency translation to base band.
The main problems with super-heterodyne are:
1. The location of the spurious signals is fixed relative to the :EtF wanted signal in hardware - i.e.
they cannot be changed using a software change.
E i~7ures:
h 1~T~S
Unscannable items recei~jed with this anpLication (Request original dccuments in File Prep. Szction on tlm 1(~" floor) DocumeWs i~e:;u a~,~ec ceC;. deLnande ne pouvant titre balal~es Commander Ies documents ori~inau:c Bans La section de przparation des dossiers au IOeme zta?e) _ ______ . _ _... _. .Lw4 ~u._._.~ae,,roo~~.r~..~.. ..___ _ ..~.~."
..~~:..~..~~M_~~ ~~.m. n,~.~~~ __.__.._._.
HIGHLY CONFT17ENTIAL INFORMATION - Page 1 of 13, :;/13/04 SiRiFIC WIRELESS CORP. - dNVENTIONDISCLOSURE' FORM
DATE: May 11 st TITLE OF INVENTION: Dynamic and Static Spurious correction and control SUBMITTED BY: Tajinder Manku ADDRESS:
SiRiFIC Wireless Corporation 460 Phillip Street Suite 300 Waterloo, Ontario phone - 519-747-2292 fax - 519-747-3996 Please Answer the following questions and attach any docu.ments/publications/disclosures;
A. Discuss the relevant area or areas of technology.
The area in which this technology fits is in radio technology and in particular the receiver chain of a radio. However, it could be extended to those areas in which spurious issues are generated by down converting a signal from a carrier to a lower frequency (for example a cable modem).
The technology is used to move or place spurious components generated by the radio and an unwanted RF (Radio Frequency) signal (denote the unwanted l~F signal by a "blocking signal") to a frequency location that does not desensitize the wanted RF~ signal.
Desensitization by the Mocker can occur in varies forms: (i) raising the noise floor, (iii) causing the overall gain of the receiver to reduce, or (iii} both (i) and (ii).
B. What problem or problems exist that your invention may solve?
This invention reduces or eliminates blocking signals from desensitizing the receiver chain.
C. How has this problem, or similar problems, been mitigated in the past?
There are several methods which have been used to mitigate this problem before. However, in most of the cases some Mockers do not pass the radio test and are denoted as exceptions. For a HIGHLY CONFIDENTIAL INFORMATION - Page 2 of 13, 5/13/04 given standard there are a number of exceptions allowed and if you exceed this amount the radio will not pass type approval. Below is a listing of the various methods and the disadvantages/
advantages associated with them:
Super-heterodyne: The super-heterodyne receiver uses a two si:ep frequency translation method to convert the signal at RF to a base hand signal. First, the incoming signals and corruptive noise are passed through a band pass filter that attenuates out of band signals and passes the desired signal. At this stage some of the blocking signals that are out of band are filtered. The desired signal, plus residual blocking signals, are amplified and mixed with a first local oscillator. This causes both a downconversion and an up conversion in the frequency domain. Usually the downconverted portion is retained at the so-called "Intermediate Frequency" (IF). Further faltering is performed on the signal at the IF frequency using a discrete device. This filter is a band pass filter and retains the radio channel required and further reduces the residual blocking signal. The signal is then mixed with a second oscillator that causes frequency translation to base band.
The main problems with super-heterodyne are:
1. The location of the spurious signals is fixed relative to the :EtF wanted signal in hardware - i.e.
they cannot be changed using a software change.
2. It requires an expensive off chip IF filter 3. The off chip components require design trade-offs that incrc;ase power consumption and reduce system gain.
4. Frequency plan is fixed in hardware Image Rejection Architectures: There are several image rejection architectures that exist. Among these, the two most well known are the Hartley Image Rej ection Architecture and the Weaver Image Rejection Architecture. Here a spurious signal is created and is located at a fixed location in frequency relative to frequency of the wanted signal. This spurious signal is commonly referred to as the imagining frequency. The imagining blocking signal is removed using a combination of phase shifters and adders that are applied directly to the radio signal itself or/and the LO signal. Some methods employ poly-phase filters to cancel the image componf;nts. Generally, either accurate phase shifters or accurate generation of a quadrature mixing signal are employed in these architectures to cancel the image frequency. The amount of image (or blocker) cancellation is directly dependent upon the degree of accuracy in producing the phase shift or in producing the quadrature mixing signals. Although the integratability of these architectures is high, them penfonmance is relatively poor due to the ~equi~ed accuracy of the phase shifts and quadrature oscillators. Another disadvantage here is the location of the Mocker signal (or image frequency) is fixed relative to the wanted signal and cannot be moved to another location.
Direct Conversion: Direct conversion architectures performs the RF to base band frequency translation in a single step. The RF' signal is mixed with a local oscillator at the carrier frequency.
There is therefore no image frequency, and no image compe~nents to corrupt the signal. Direct conversion receivers offer high integratability, but also have several important problems. Classical HIGHLY CONFIDENTIAL INFORMATION - Page 3 of 13, 5/13/04 direct conversion receivers have thus far proved useful only for signaling formats that do not place appreciable signal energy near DC after conversion to base band. Though direct conversion does not suffer from blocking signals in general, there are several typical problems found in integrated direct conversion receivers follow:
1. Noise near base band (i.e. 1/f noise) corrupts the desired signal.
Z. Local oscillator leakage creates DC offsets.
3. Local oscillator leakage causes desensitization.
4. Noise inherent to mixed-signal integrated circuits corrupts the desired signal.
Direct Conversion: Direct conversion architectures performs the RF to base band frequency translation in a single step. The RF' signal is mixed with a local oscillator at the carrier frequency.
There is therefore no image frequency, and no image compe~nents to corrupt the signal. Direct conversion receivers offer high integratability, but also have several important problems. Classical HIGHLY CONFIDENTIAL INFORMATION - Page 3 of 13, 5/13/04 direct conversion receivers have thus far proved useful only for signaling formats that do not place appreciable signal energy near DC after conversion to base band. Though direct conversion does not suffer from blocking signals in general, there are several typical problems found in integrated direct conversion receivers follow:
1. Noise near base band (i.e. 1/f noise) corrupts the desired signal.
Z. Local oscillator leakage creates DC offsets.
3. Local oscillator leakage causes desensitization.
4. Noise inherent to mixed-signal integrated circuits corrupts the desired signal.
5. Large on-chip capacitors are required to remove unwanted noise and signal energy near DC.
Near Zero-IF Conversion: This receiver architecture is similar to the direct conversion architecture, in that the RF band is brought close to base band in a single step. The desired signal is not brought exactly to base-band however, and therefore DC offsets and 1/f noise do not contaminate the signal.
Image frequencies (i.e. the Mocker) are again a problem as in the super-heterodyne and image rejection architectures. Specific problems encountered with these architectures include:
1. The second down conversion to bring the IF' signal to base-band has to occur in digital domain due to spurious issues 2. The relative frequency of the image is fixed based on the. frequency planning and cannot be changed.
3. The filters used to filter the IF signal inherently contributes to the frequency planning, making them standard specific 4. The need for several balanced signal paths for purposes of image cancellation.
5. Noise inherent to mixed-signal integrated circuits corrupts the desired signal.
Harmonic Mixing architectures: This approach uses a number of mixing signals that are phase shifted by some desired amount. Irf we assuming x(t) is the incoming RF
signal, and al, az, and a3 are the mixing signals, the output of a harmonic mixing structure equals x(t)*(al+a2+a3). In this example, we have assumed three mixing signals. Here, al, a2, and a3 are constructed so that when they add they have significant energy at the wanted earner frequency. The frequency of al, a2, and a3 are usually the same. In all cases, al+a2+a3 will have other iFrequency components other than the wanted carrier frequency. This produces a fixed spurious response. The disadvantage here is the spurious are fixed based on the frequency planning of the additive signals (for example al, a2, and a3) VLO technology: VLO technology consists of two mixers coru2ected together. At the LO ports of the two mixers (labeled M1 and M2) the signals ~1 and ~2 are applied such that the overall RF signal (denoted as x(t)) is multiplied by a signal having significant power at the RF
carrier frequency; that is y *~z has significant power at the RF frequency. However, in reality there will be power generated in places other than the RF earner frequency - denote this power as unwanted power - this can be seen in the figure below. This amount of unwanted power is determined by the timing delay and HIGHLY CONFIDENTIAL INFORMATION - Page 4 of 13, 5/13/01 frequency of signal ~2. The unwanted power will down convert signals located at the "unwanted power frequencies". For example, if there is unwanted power at 2104MHz in ~l*c~2 and there is an out off band blocker signal at 2100MHz, this Mocker will be down converted on top of the wanted signal. However, this down converted power will be attenuated by the difference between "the power of the wanted" minus "the power of the unwanted" (for the figure below this is ~37dB) -denote this amount as WmU (Wanted minus Unwanted). If RFwanted denotes the wanted P.F
power, the total amount of power at base band is:
BBpower = RFwanted + 10~(-WmU/ 10)'~RFunwanted ( 1 ) There are two ways to fix this problem - (i) adjust the time delay of ~2 thereby modifying the value of WmU (ii) adjusting the frequency of c~2 such that the RFunwanted tone does not fall on top of the wanted signal at base band (iii) select several values of ~2 u.p front by making sure it does not produce a problem (these values are stored in memory and be .applied to the radio chip in a matter that is related to the RF standard in question). In either approach, the BBpower is minimized.
Solution (i) does not give significant improvement because of various physical and circuit limitations. This patent addresses solutions (ii) and (iii).
x(t) ~-- H PF
~1 c~2 ~l (t) J~~ LJ-L. -L
~2 (t) ~.
a ff (t) øl (t) ~ ~2 (t) ~J~~I~I~LI~IJ~ L.~1 unwanted HIGHLY CONFIDENTIAL INFORMATION - Page 5 of 13, 5/13/04 D. What are the advantages of your invention?
There are several advantages to the patent, however the key advantage is the location of the spurious profile of ~1*~2 in frequency domain can be modified by adjusting c~z (which will in turn modify ~1 accordingly), but the dominate frequency (i.e. with the highest power) of ~1*~2 equals the RF frequency and depends of what ~2 is set to. This property is a property of VLO. No other radio architecture (to our knowledge) has this fundamental property.
Key Advantages:
1. Spurious profile of ~l*~2 in frequency domain can be modified by adjusting ~2 (which will in turn modify ~I accordingly), but the dominate frequency (i.e. highest power tone) of ~1*~2 equals the RF frequency and is independent of the frequency ~Z is set to.
2. The spurious profile can change using only software (as in other architectures the spurious content is based on the hardware implementation). For example, ~Z can be generated via a PLL that can be programmed to generate a range of frequency.
3. using the signal between the two mixers an estimate can be made on the level of blocking signal that will in turn determine if ~2 needs adjusting 4. The output of the RX path can be used to determine if a blocker is present (see equation (1) by relocating the spurious profile 5. The spurious profile can dynamically change using correction software/hardware in combination with the properties in items 2, 3, and 4 6. All the spurious control can be implemented on the radio chip itself (opposed to the baseband microprocessing chip) E. Explain, in detail, preferably with the assistance of drawings or flowcharts, the best embodiments or examples of your invention. Include a list of components, if' appropriate.
There are two basic implementations. One consists of dynamically correcting the spurious profile so a Mocker will not be placed onto of the desired signal in base band. The other is initially selecting a number of ~Z values such that they do not case a problem. The selection in this case is based on making sure the RF signal is not corrupted under normal operation. Any one skilled in the art of radio would be able to set up some criteria for this selection from the teachings herein. The selection could be based on field trials for various ~Z
values or simulation data.
A. Selecting a number of ~Z values:
For this case the values of ~2 are stored in memory. The memory can be in the radio, in the processor, memory on the PCB, or any combination of. Bf;low is a simplified diagram - see;
HIGHLY CONFIDENTIAL INFORMATION - Page 6 of 13, 5/13/04 figure (2). The RF signal (i.e. RFin) contains the wanted signal and any blocker signal. The "RX path" is the receiver path and consists of a low noise amplifier, mixers, base band filters, and gain elements which are control by in some closed loop manner. The output of the RX
path consists of two signals (I and Q). These signals can either be analog or digital signals.
If they are digital signals, an analog to digital element woulLd be absorbed in the "RX path"
element. The element "VLO generation" generates the signals cal and ~Z from a "LO" signal that is controlled via a PLL, and an input from an element i:hat specifies the frequency of ~Z.
The various frequency values of ~2 are stored in memory. Different frequency values of ~Z
values may be used for different channels within a standard or for different standards all together. The selection of c~Z is based on a system understanding of where spurious tones can be placed so that they do not significantly degrade the want;ed RF signal.
Also, ~2 can be selected so that the least number of exceptions are used. As an example, ~2 can be selected based on the following criteria:
1. No spurious content is within the band width of the all the channels 2. The first spurious value is >1 OMHz from the edges of the band RF in RX path I and Q
signals ~1 f ~2 VLO generator hid LO within Phiz 2 PLL loop n Memory Phil Memory could be in radio or base band processor B. Dynamic Spurious correction Figure (2) The dynamic spurious approach is based on making a measurement that indicates if a blocker is present, and then adjusting ~G so the Mocker moves to a location that does not degrade performance. Below is a simplified diagram - see figure (3). The RF signal (i.e. RFin) contents the wanted signal and any blocker signal. The "R:K path" is the receiver path and contents a low noise amplifier, mixers, base band filters, artd gain elements which are HIGHLY CONFIDENTIAL INFORMATION - Page 7 of 13, ,S/13/04 controlled by some closed loop manner. The output of the RX path consists of two signals (I
and Q). These signals can either be analog or digital signals. If they are digital signals, an analog to digital element would be absorbed in the "RX path" element. The element "VLO
generation" generates the signals ~1 and ~Z from a (i) "LO" signal that is controlled via a PLL
and (ii) an input from an element that specifies the frequency of c~z. The I
and Q signal is ported into a detector that determines the power of the signal; this may not be a true power detector, but an element that determines the strength of the signal. A timer is implemented and determines when the next power measurement should he made after a new ~Z
value is loaded in. The timer may have information of which RF frame it is looking at, or when the next value of ~Z has settled so the next power measurement can be taken. The two values of power are compared and the frequency of c~2 is selected based on which ~2 value measures the minimum amount of power. In general N values of c~z could be compared; where N
is a number greater than 2 and is an integer.
The element labeled "sense Mocker," is used to sense if a b~locker is present.
The enable and disable block decides if the correction scheme is enabled based on various inputs; some may include if the receiver is enabled, ifthe amplifier gains are set in a particular condition, and the registers enable the condition to occur. There may be base-band processor control for disabling or enabling the correction scheme directly. The acceptable values of c~2 are stored in memory. The acceptable values are determined from a system understanding of the radio standard in question.
Additional information on the generation of VLO signals i:9 available in the following co-pending patent applications:
a. PCT International Application Serial No. PCT/CA00/00995 Filed September l, 2000, titled: "Improved Method And Apparatus For Up-Conversion Of Radio Frequency (RF) Signals";
b. PCT International Application Serial No. PCT/CA00/00994 Filed September 1, 2000, titled: "Improved Method And Apparatus For Down-Conversion Of Radio Frequency (RF) Signals";
c. PCT International Application Serial No. PCT/CA00/00996 Filed September 1, 2000, titled: "Improved Method And Apparatus For Up-And-Down-Conversion Of Radio Frequency (RF) Signals"; and d. PCT International Application Serial No. PCT/CA01/00876 Filed June 19, 2001, titled:
"Improved Method And Apparatus For Up-And-Down-Conversion Of Radio Frequency (RF) Signals".
HIGHLY CONFIDENTIAL INFORMATION - Page 8 of 13, 5/13/04 Memory Enablel Sense disable Compare blodcer l Power Signal to Timers detector sense blodcer presense RF i~ RX path IandQ
signals ~1 ~2 VLO generator LO within J PLL loop Figure (3) Figure (4) shows an actual implementation of Figure (3). Figure (5) relates some of the blocks to those shown in Figure (3). This figure uses three frequency values of ~2 to make the comparison on which ~2 minimizes the base-band power. The values of power are stored on caps while the next power value is established. The sensing of the blocker is done by looking at the power between the two mixers. The power is compared to some threshold value. If the power is above this threshold value this would trigger that a blocker is present. For the implementation in Figures (4) and (5), the threshold value is made programmable. If the amount of power is high compared to the threshold, and all the other enabling conditions are correct the correction loop will the enabled. During this spurious correction, the gain of the RX path has to be constant. If the gain changes, the measurement is corrupted and the loop is reset. One method of holding a constant gain is to disable the receiver from reading the any new gain value. The ~2 values are stored in the element labeled "MA Storage register". 'The radio in this example is control via the processor thru a 3-wire bus and an enabling pin for the receiver (RX enable).
In both Figure (4) and (5), all the elements in the RX path are :not explicitly shown.
In this implementation, there is also a 4 bit counter that counts the number of frames (for example in GSM). The maximum number of frames that is allowed is 2~4 = 16 frames.
HIGHLY CONFIDENTIAL INFORMATION - Page 11 of 13, S/13/04 F. Repeat item E above, for any other important embodiments or examples of your invention.
In the illustrations (2) to (S), any of the blocks can be partitioned into other elements of the wireless device. For example, the power detector element can be placed in the baseband processor and does not have to be located in 'the radio device.
The sensing element for a Mocker can be removed completely. In this case, the loop will be activated when an enable signal is provided. The enable signal may be provided by the base band processor.
It is assumed in (2) to {5) that a known sub-set of ~ZValues are stored in memory.
However, the values can be selected in any matter that is achif;vable. For example, if the frequency of ~Z increases in increments of ~f, ~2 can change by multiplies of 8f. Another example is ~2 can change in a random or pseudo-random manner.
More aggressive schemes can be implemented to close the dynamic loop faster.
G. Who is/are the inventor(s)? Please provide their name(s), acidress(es) and citizenship.
Tajinder Manku 263 Lion's Court Waterloo, ON
Canadian Citizen Masoud Kahrizi 617 Breakwater Cr.
Waterloo, N2K 4H6 Canadian Citizen
Near Zero-IF Conversion: This receiver architecture is similar to the direct conversion architecture, in that the RF band is brought close to base band in a single step. The desired signal is not brought exactly to base-band however, and therefore DC offsets and 1/f noise do not contaminate the signal.
Image frequencies (i.e. the Mocker) are again a problem as in the super-heterodyne and image rejection architectures. Specific problems encountered with these architectures include:
1. The second down conversion to bring the IF' signal to base-band has to occur in digital domain due to spurious issues 2. The relative frequency of the image is fixed based on the. frequency planning and cannot be changed.
3. The filters used to filter the IF signal inherently contributes to the frequency planning, making them standard specific 4. The need for several balanced signal paths for purposes of image cancellation.
5. Noise inherent to mixed-signal integrated circuits corrupts the desired signal.
Harmonic Mixing architectures: This approach uses a number of mixing signals that are phase shifted by some desired amount. Irf we assuming x(t) is the incoming RF
signal, and al, az, and a3 are the mixing signals, the output of a harmonic mixing structure equals x(t)*(al+a2+a3). In this example, we have assumed three mixing signals. Here, al, a2, and a3 are constructed so that when they add they have significant energy at the wanted earner frequency. The frequency of al, a2, and a3 are usually the same. In all cases, al+a2+a3 will have other iFrequency components other than the wanted carrier frequency. This produces a fixed spurious response. The disadvantage here is the spurious are fixed based on the frequency planning of the additive signals (for example al, a2, and a3) VLO technology: VLO technology consists of two mixers coru2ected together. At the LO ports of the two mixers (labeled M1 and M2) the signals ~1 and ~2 are applied such that the overall RF signal (denoted as x(t)) is multiplied by a signal having significant power at the RF
carrier frequency; that is y *~z has significant power at the RF frequency. However, in reality there will be power generated in places other than the RF earner frequency - denote this power as unwanted power - this can be seen in the figure below. This amount of unwanted power is determined by the timing delay and HIGHLY CONFIDENTIAL INFORMATION - Page 4 of 13, 5/13/01 frequency of signal ~2. The unwanted power will down convert signals located at the "unwanted power frequencies". For example, if there is unwanted power at 2104MHz in ~l*c~2 and there is an out off band blocker signal at 2100MHz, this Mocker will be down converted on top of the wanted signal. However, this down converted power will be attenuated by the difference between "the power of the wanted" minus "the power of the unwanted" (for the figure below this is ~37dB) -denote this amount as WmU (Wanted minus Unwanted). If RFwanted denotes the wanted P.F
power, the total amount of power at base band is:
BBpower = RFwanted + 10~(-WmU/ 10)'~RFunwanted ( 1 ) There are two ways to fix this problem - (i) adjust the time delay of ~2 thereby modifying the value of WmU (ii) adjusting the frequency of c~2 such that the RFunwanted tone does not fall on top of the wanted signal at base band (iii) select several values of ~2 u.p front by making sure it does not produce a problem (these values are stored in memory and be .applied to the radio chip in a matter that is related to the RF standard in question). In either approach, the BBpower is minimized.
Solution (i) does not give significant improvement because of various physical and circuit limitations. This patent addresses solutions (ii) and (iii).
x(t) ~-- H PF
~1 c~2 ~l (t) J~~ LJ-L. -L
~2 (t) ~.
a ff (t) øl (t) ~ ~2 (t) ~J~~I~I~LI~IJ~ L.~1 unwanted HIGHLY CONFIDENTIAL INFORMATION - Page 5 of 13, 5/13/04 D. What are the advantages of your invention?
There are several advantages to the patent, however the key advantage is the location of the spurious profile of ~1*~2 in frequency domain can be modified by adjusting c~z (which will in turn modify ~1 accordingly), but the dominate frequency (i.e. with the highest power) of ~1*~2 equals the RF frequency and depends of what ~2 is set to. This property is a property of VLO. No other radio architecture (to our knowledge) has this fundamental property.
Key Advantages:
1. Spurious profile of ~l*~2 in frequency domain can be modified by adjusting ~2 (which will in turn modify ~I accordingly), but the dominate frequency (i.e. highest power tone) of ~1*~2 equals the RF frequency and is independent of the frequency ~Z is set to.
2. The spurious profile can change using only software (as in other architectures the spurious content is based on the hardware implementation). For example, ~Z can be generated via a PLL that can be programmed to generate a range of frequency.
3. using the signal between the two mixers an estimate can be made on the level of blocking signal that will in turn determine if ~2 needs adjusting 4. The output of the RX path can be used to determine if a blocker is present (see equation (1) by relocating the spurious profile 5. The spurious profile can dynamically change using correction software/hardware in combination with the properties in items 2, 3, and 4 6. All the spurious control can be implemented on the radio chip itself (opposed to the baseband microprocessing chip) E. Explain, in detail, preferably with the assistance of drawings or flowcharts, the best embodiments or examples of your invention. Include a list of components, if' appropriate.
There are two basic implementations. One consists of dynamically correcting the spurious profile so a Mocker will not be placed onto of the desired signal in base band. The other is initially selecting a number of ~Z values such that they do not case a problem. The selection in this case is based on making sure the RF signal is not corrupted under normal operation. Any one skilled in the art of radio would be able to set up some criteria for this selection from the teachings herein. The selection could be based on field trials for various ~Z
values or simulation data.
A. Selecting a number of ~Z values:
For this case the values of ~2 are stored in memory. The memory can be in the radio, in the processor, memory on the PCB, or any combination of. Bf;low is a simplified diagram - see;
HIGHLY CONFIDENTIAL INFORMATION - Page 6 of 13, 5/13/04 figure (2). The RF signal (i.e. RFin) contains the wanted signal and any blocker signal. The "RX path" is the receiver path and consists of a low noise amplifier, mixers, base band filters, and gain elements which are control by in some closed loop manner. The output of the RX
path consists of two signals (I and Q). These signals can either be analog or digital signals.
If they are digital signals, an analog to digital element woulLd be absorbed in the "RX path"
element. The element "VLO generation" generates the signals cal and ~Z from a "LO" signal that is controlled via a PLL, and an input from an element i:hat specifies the frequency of ~Z.
The various frequency values of ~2 are stored in memory. Different frequency values of ~Z
values may be used for different channels within a standard or for different standards all together. The selection of c~Z is based on a system understanding of where spurious tones can be placed so that they do not significantly degrade the want;ed RF signal.
Also, ~2 can be selected so that the least number of exceptions are used. As an example, ~2 can be selected based on the following criteria:
1. No spurious content is within the band width of the all the channels 2. The first spurious value is >1 OMHz from the edges of the band RF in RX path I and Q
signals ~1 f ~2 VLO generator hid LO within Phiz 2 PLL loop n Memory Phil Memory could be in radio or base band processor B. Dynamic Spurious correction Figure (2) The dynamic spurious approach is based on making a measurement that indicates if a blocker is present, and then adjusting ~G so the Mocker moves to a location that does not degrade performance. Below is a simplified diagram - see figure (3). The RF signal (i.e. RFin) contents the wanted signal and any blocker signal. The "R:K path" is the receiver path and contents a low noise amplifier, mixers, base band filters, artd gain elements which are HIGHLY CONFIDENTIAL INFORMATION - Page 7 of 13, ,S/13/04 controlled by some closed loop manner. The output of the RX path consists of two signals (I
and Q). These signals can either be analog or digital signals. If they are digital signals, an analog to digital element would be absorbed in the "RX path" element. The element "VLO
generation" generates the signals ~1 and ~Z from a (i) "LO" signal that is controlled via a PLL
and (ii) an input from an element that specifies the frequency of c~z. The I
and Q signal is ported into a detector that determines the power of the signal; this may not be a true power detector, but an element that determines the strength of the signal. A timer is implemented and determines when the next power measurement should he made after a new ~Z
value is loaded in. The timer may have information of which RF frame it is looking at, or when the next value of ~Z has settled so the next power measurement can be taken. The two values of power are compared and the frequency of c~2 is selected based on which ~2 value measures the minimum amount of power. In general N values of c~z could be compared; where N
is a number greater than 2 and is an integer.
The element labeled "sense Mocker," is used to sense if a b~locker is present.
The enable and disable block decides if the correction scheme is enabled based on various inputs; some may include if the receiver is enabled, ifthe amplifier gains are set in a particular condition, and the registers enable the condition to occur. There may be base-band processor control for disabling or enabling the correction scheme directly. The acceptable values of c~2 are stored in memory. The acceptable values are determined from a system understanding of the radio standard in question.
Additional information on the generation of VLO signals i:9 available in the following co-pending patent applications:
a. PCT International Application Serial No. PCT/CA00/00995 Filed September l, 2000, titled: "Improved Method And Apparatus For Up-Conversion Of Radio Frequency (RF) Signals";
b. PCT International Application Serial No. PCT/CA00/00994 Filed September 1, 2000, titled: "Improved Method And Apparatus For Down-Conversion Of Radio Frequency (RF) Signals";
c. PCT International Application Serial No. PCT/CA00/00996 Filed September 1, 2000, titled: "Improved Method And Apparatus For Up-And-Down-Conversion Of Radio Frequency (RF) Signals"; and d. PCT International Application Serial No. PCT/CA01/00876 Filed June 19, 2001, titled:
"Improved Method And Apparatus For Up-And-Down-Conversion Of Radio Frequency (RF) Signals".
HIGHLY CONFIDENTIAL INFORMATION - Page 8 of 13, 5/13/04 Memory Enablel Sense disable Compare blodcer l Power Signal to Timers detector sense blodcer presense RF i~ RX path IandQ
signals ~1 ~2 VLO generator LO within J PLL loop Figure (3) Figure (4) shows an actual implementation of Figure (3). Figure (5) relates some of the blocks to those shown in Figure (3). This figure uses three frequency values of ~2 to make the comparison on which ~2 minimizes the base-band power. The values of power are stored on caps while the next power value is established. The sensing of the blocker is done by looking at the power between the two mixers. The power is compared to some threshold value. If the power is above this threshold value this would trigger that a blocker is present. For the implementation in Figures (4) and (5), the threshold value is made programmable. If the amount of power is high compared to the threshold, and all the other enabling conditions are correct the correction loop will the enabled. During this spurious correction, the gain of the RX path has to be constant. If the gain changes, the measurement is corrupted and the loop is reset. One method of holding a constant gain is to disable the receiver from reading the any new gain value. The ~2 values are stored in the element labeled "MA Storage register". 'The radio in this example is control via the processor thru a 3-wire bus and an enabling pin for the receiver (RX enable).
In both Figure (4) and (5), all the elements in the RX path are :not explicitly shown.
In this implementation, there is also a 4 bit counter that counts the number of frames (for example in GSM). The maximum number of frames that is allowed is 2~4 = 16 frames.
HIGHLY CONFIDENTIAL INFORMATION - Page 11 of 13, S/13/04 F. Repeat item E above, for any other important embodiments or examples of your invention.
In the illustrations (2) to (S), any of the blocks can be partitioned into other elements of the wireless device. For example, the power detector element can be placed in the baseband processor and does not have to be located in 'the radio device.
The sensing element for a Mocker can be removed completely. In this case, the loop will be activated when an enable signal is provided. The enable signal may be provided by the base band processor.
It is assumed in (2) to {5) that a known sub-set of ~ZValues are stored in memory.
However, the values can be selected in any matter that is achif;vable. For example, if the frequency of ~Z increases in increments of ~f, ~2 can change by multiplies of 8f. Another example is ~2 can change in a random or pseudo-random manner.
More aggressive schemes can be implemented to close the dynamic loop faster.
G. Who is/are the inventor(s)? Please provide their name(s), acidress(es) and citizenship.
Tajinder Manku 263 Lion's Court Waterloo, ON
Canadian Citizen Masoud Kahrizi 617 Breakwater Cr.
Waterloo, N2K 4H6 Canadian Citizen
Claims (14)
1. A synthesizer for generating signals to be input to successive mixers for demodulating an input signal x(t) to an output y(t), said synthesizer comprising;
a first signal generator for producing a first time-varying signal .phi.1 for inputting to a first one of said successive mixers, to mix said input signal x(t) with said first time-varying signal .phi.1 to generate a x(t) * .phi.1 signal;
a second signal generator for producing a second time-varying signal .phi.2 for inputting to a second one of said successive mixers, to mix said x(t) * .phi.1 signal with said second time-varying signal .phi.2 to generate said output y(t);
where .phi.1 * .phi.2 has significant power at the frequency of a local oscillator signal being emulated, and one of said .phi.1 and .phi.2 has minimal power around the frequency of said output y(t), while the other of said .phi.1 and .phi.2 has minimal power around the centre frequency, fRF, of said input signal x(t); and means for reducing the power of the unwanted signal with respect to the wanted signal.
a first signal generator for producing a first time-varying signal .phi.1 for inputting to a first one of said successive mixers, to mix said input signal x(t) with said first time-varying signal .phi.1 to generate a x(t) * .phi.1 signal;
a second signal generator for producing a second time-varying signal .phi.2 for inputting to a second one of said successive mixers, to mix said x(t) * .phi.1 signal with said second time-varying signal .phi.2 to generate said output y(t);
where .phi.1 * .phi.2 has significant power at the frequency of a local oscillator signal being emulated, and one of said .phi.1 and .phi.2 has minimal power around the frequency of said output y(t), while the other of said .phi.1 and .phi.2 has minimal power around the centre frequency, fRF, of said input signal x(t); and means for reducing the power of the unwanted signal with respect to the wanted signal.
2. The synthesizer of claim 1, wherein said means for reducing comprises means for adjusting the frequency of .phi.2 such that the RFunwanted tone does not fall on top of the wanted signal at base band.
3. The synthesizer of claim 1, wherein said means for reducing comprises means for selecting one of several stored values of .phi.2 designed to mitigate the power of the unwanted signal with respect to the wanted signal.
4. The synthesizer of claim 1, wherein said means for reducing comprises means for adjusting the frequency profile of .phi.2 and means for adjusting the frequency profile of .phi.1 such that the dominate frequency of .phi.1 * .phi.2 equals the RF frequency.
5. The synthesizer of claim 1, wherein said means for reducing comprises a closed loop feedback means for adjusting the frequency of .phi.2 such that the; blocker moves to a location that does not degrade performance.
6. The synthesizer of claim 5, wherein said closed loop feedback means comprises a power detector and a comparator.
7. The synthesizer of claim 1, wherein said means for reducing comprises a means for measuring the presence of a blocker after the first mixer or by looking at the signal x(t) * .phi.1
8. A method of demodulating an input signal x(t) to an output y(t), comprising the steps of:
generating a first time-varying signal .phi.1;
generating a second time-varying signal .phi.2, where .phi.1 * .phi.2 has significant power at the frequency of a local oscillator signal being emulated, and one of said .phi.1 and .phi.2 has minimal power around the frequency of said output y(t), while the other of said .phi.1 and .phi.2 has minimal power around the centre frequency, fRF, of said input signal x(t);
mixing said input signal x(t) with said first time-varying signal .phi.1 to generate a x(t) * .phi.1 signal;
mixing said x(t) * .phi.1 signal with said second time-varying signal .phi.2 to generate said output y(t); and adjusting the frequency of .PHI.2 such that the RFunwanted tone does not fall on top of the wanted signal at base band.
generating a first time-varying signal .phi.1;
generating a second time-varying signal .phi.2, where .phi.1 * .phi.2 has significant power at the frequency of a local oscillator signal being emulated, and one of said .phi.1 and .phi.2 has minimal power around the frequency of said output y(t), while the other of said .phi.1 and .phi.2 has minimal power around the centre frequency, fRF, of said input signal x(t);
mixing said input signal x(t) with said first time-varying signal .phi.1 to generate a x(t) * .phi.1 signal;
mixing said x(t) * .phi.1 signal with said second time-varying signal .phi.2 to generate said output y(t); and adjusting the frequency of .PHI.2 such that the RFunwanted tone does not fall on top of the wanted signal at base band.
9. The method of claim 8, further comprising the step of:
determining the amount of blocker power that is present in the output of the RX path.
determining the amount of blocker power that is present in the output of the RX path.
10. The method of claim 8, further comprising the step of:
changing .PHI.2 the spurious profile changes and the blocker position changes.
changing .PHI.2 the spurious profile changes and the blocker position changes.
11. The method of claim 8, further comprising the step of:
selecting .PHI.2 to minimize the effects of the blocker.
selecting .PHI.2 to minimize the effects of the blocker.
12. The method of claim 8, wherein said step of adjusting comprises the step of:
employing a closed loop to adjust the frequency of .PHI.2 such that the RFunwanted tone does not fall on top of the wanted signal at base band.
employing a closed loop to adjust the frequency of .PHI.2 such that the RFunwanted tone does not fall on top of the wanted signal at base band.
13. The method of claim 8, further comprising the step of:
measuring the presence of a blocker after the first mixer
measuring the presence of a blocker after the first mixer
14. A method of down conversion in which spurious signals are relocated to a region away from the signals of interest comprising the steps of:
generating a first time-varying signal .PHI.1;
generating a second time-varying signal .PHI.2, where .PHI. 1 * .PHI.2 has significant power at the frequency of a local oscillator signal being emulated, and one of said .PHI.l and .PHI.2 has minimal power around the frequency of said output y(t), while the ether of said .PHI.
1 and .PHI.2 has minimal power around the centre frequency, fRF, of said input signal x(t);
mixing said input signal x(t) with said first time-varying signal .PHI. 1 to generate a x(t) * .PHI. 1 signal;
mixing said x(t) * .PHI.1 signal with said second time-varying signal .PHI.2 to generate said output y(t); and adjusting the frequency of .PHI.2 such that the RFunwanted tone does not fall on top of the wanted signal at base band.
generating a first time-varying signal .PHI.1;
generating a second time-varying signal .PHI.2, where .PHI. 1 * .PHI.2 has significant power at the frequency of a local oscillator signal being emulated, and one of said .PHI.l and .PHI.2 has minimal power around the frequency of said output y(t), while the ether of said .PHI.
1 and .PHI.2 has minimal power around the centre frequency, fRF, of said input signal x(t);
mixing said input signal x(t) with said first time-varying signal .PHI. 1 to generate a x(t) * .PHI. 1 signal;
mixing said x(t) * .PHI.1 signal with said second time-varying signal .PHI.2 to generate said output y(t); and adjusting the frequency of .PHI.2 such that the RFunwanted tone does not fall on top of the wanted signal at base band.
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002467201A CA2467201A1 (en) | 2004-05-13 | 2004-05-13 | Dynamic and static spurious correction and control |
| PCT/CA2005/000732 WO2005112281A1 (en) | 2004-05-13 | 2005-05-13 | Method and system for spurious signal control in receivers |
| US11/569,031 US7715814B2 (en) | 2004-05-13 | 2005-05-13 | Method and system for spurious signal control in receivers |
| CA002566476A CA2566476A1 (en) | 2004-05-13 | 2005-05-13 | Method and system for spurious signal control in receivers |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002467201A CA2467201A1 (en) | 2004-05-13 | 2004-05-13 | Dynamic and static spurious correction and control |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2467201A1 true CA2467201A1 (en) | 2005-11-13 |
Family
ID=35452149
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
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| CA002467201A Abandoned CA2467201A1 (en) | 2004-05-13 | 2004-05-13 | Dynamic and static spurious correction and control |
| CA002566476A Abandoned CA2566476A1 (en) | 2004-05-13 | 2005-05-13 | Method and system for spurious signal control in receivers |
Family Applications After (1)
| Application Number | Title | Priority Date | Filing Date |
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| CA002566476A Abandoned CA2566476A1 (en) | 2004-05-13 | 2005-05-13 | Method and system for spurious signal control in receivers |
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|---|---|
| US (1) | US7715814B2 (en) |
| CA (2) | CA2467201A1 (en) |
| WO (1) | WO2005112281A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2421174A1 (en) * | 2009-04-15 | 2012-02-22 | Huawei Technologies Co., Ltd. | Method for supporting multiple band coexistence in radio frequency module and device thereof |
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| US20090080669A1 (en) * | 2007-09-26 | 2009-03-26 | Seiko Epson Corporation | Noise cancel method, noise cancel type amplifying circuit, and receiving circuit and electronic device including noise cancel type amplifying circuit |
| US8099068B2 (en) * | 2008-10-10 | 2012-01-17 | Cambridge Silicon Radio Limited | Downconversion strategies for reducing interference in wanted signals |
| SG178529A1 (en) * | 2009-08-24 | 2012-03-29 | Agency Science Tech & Res | A front-end transceiver |
| US8185078B2 (en) * | 2009-10-22 | 2012-05-22 | Anritsu Company | Dynamic spur avoidance for high speed receivers |
| WO2011060198A1 (en) | 2009-11-11 | 2011-05-19 | Maxlinear, Inc. | Crystal control scheme to improve preformance of a receiver |
| WO2011060194A1 (en) * | 2009-11-11 | 2011-05-19 | Maxlinear, Inc. | Dynamic bandwidth control scheme of a frac-n pll in a receiver |
| US8224279B2 (en) | 2009-12-18 | 2012-07-17 | Silicon Laboratories, Inc. | Radio frequency (RF) receiver with dynamic frequency planning and method therefor |
| US8874060B2 (en) * | 2009-12-18 | 2014-10-28 | Silicon Laboratories Inc. | Radio frequency (RF) receiver with frequency planning and method therefor |
| US8542775B2 (en) * | 2010-11-12 | 2013-09-24 | Csr Technology Inc. | Serial data interface for software-defined radio system |
| US8606194B2 (en) * | 2011-08-15 | 2013-12-10 | Renesas Mobile Corporation | Receiver |
| US8675789B2 (en) * | 2012-04-23 | 2014-03-18 | Cambridge Silicon Radio Limited | Receiver with variable gain elements and automatic gain control to maintain a positive signal to noise ratio margin |
| CN108369264B (en) * | 2015-12-16 | 2021-08-10 | 皇家飞利浦有限公司 | System and method for wireless communication synchronization for Magnetic Resonance Imaging (MRI) systems |
| EP3868024B1 (en) * | 2018-11-14 | 2023-10-04 | Huawei Technologies Co., Ltd. | Downconversion using digital carrier signals |
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| US4661995A (en) * | 1985-02-21 | 1987-04-28 | Anritsu Electric Co., Limited | Multi-superheterodyne receiver |
| US5097221A (en) * | 1990-12-21 | 1992-03-17 | The United States Of America As Represented By The Secretary Of The Navy | Adaptive filter technique for suppression of wideband or offset narrowband radio frequency interference |
| US5307515A (en) * | 1991-08-05 | 1994-04-26 | Ford Motor Company | Adjacent channel controller for radio receiver |
| US5564097A (en) * | 1994-05-26 | 1996-10-08 | Rockwell International | Spread intermediate frequency radio receiver with adaptive spurious rejection |
| US5847612A (en) * | 1997-08-01 | 1998-12-08 | Microtune, Inc. | Interference-free broadband television tuner |
| US6807405B1 (en) * | 1999-04-28 | 2004-10-19 | Isco International, Inc. | Method and a device for maintaining the performance quality of a code-division multiple access system in the presence of narrow band interference |
| CA2281236C (en) * | 1999-09-01 | 2010-02-09 | Tajinder Manku | Direct conversion rf schemes using a virtually generated local oscillator |
| US6567654B1 (en) * | 1999-10-28 | 2003-05-20 | Matsushita Electronic Components De Baja California, S.A. De C.V. | Elimination of spurious signals in double conversion tuner using a dynamic intermediate frequency and a preselected crystal reference frequency |
| US6785527B2 (en) * | 2001-04-02 | 2004-08-31 | Tektronix, Inc. | Conversion spur avoidance in a multi-conversion radio frequency receiver |
| WO2003071673A2 (en) * | 2002-02-25 | 2003-08-28 | Sirific Wireless Corporation | Frequency down converter using a multitone local oscillator |
| US6727764B2 (en) * | 2002-03-08 | 2004-04-27 | Sirific Wireless Corporation | Generation of virtual local oscillator inputs for use in direct conversion radio systems |
-
2004
- 2004-05-13 CA CA002467201A patent/CA2467201A1/en not_active Abandoned
-
2005
- 2005-05-13 CA CA002566476A patent/CA2566476A1/en not_active Abandoned
- 2005-05-13 WO PCT/CA2005/000732 patent/WO2005112281A1/en active Application Filing
- 2005-05-13 US US11/569,031 patent/US7715814B2/en active Active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2421174A1 (en) * | 2009-04-15 | 2012-02-22 | Huawei Technologies Co., Ltd. | Method for supporting multiple band coexistence in radio frequency module and device thereof |
| EP2421174A4 (en) * | 2009-04-15 | 2012-07-11 | Huawei Tech Co Ltd | Method for supporting multiple band coexistence in radio frequency module and device thereof |
| EP3512111A3 (en) * | 2009-04-15 | 2019-07-31 | Huawei Technologies Co., Ltd. | Method and device for supporting multiple bands coexistence in a radio frequency module |
Also Published As
| Publication number | Publication date |
|---|---|
| WO2005112281A1 (en) | 2005-11-24 |
| CA2566476A1 (en) | 2005-11-24 |
| US7715814B2 (en) | 2010-05-11 |
| US20080014894A1 (en) | 2008-01-17 |
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