DESC:TECHNICAL FIELD
[0001] The present invention relates generally to a method for self-interference cancellation circuit for simultaneous transmit and receive systems. The invention, more particularly, relates to a Ku-Band self-interference cancellation circuit.
BACKGROUND
[0002] In any Simultaneous Transmit and Receive (STAR) RADAR system, both a transmitter and a receiver operate simultaneously, due to which a portion of the high level transmit signal will always leak into the receiver. This leakage level depends on the isolation between the transmitter and the receiver. The inherent transmit and receive isolation is established by the physical separation of the transmitter and the receiver. However, in compact RADAR systems, achieving higher physical separation is not possible. But, if the necessary isolation is not maintained between the transmitter and the receiver, the transmit signal will leak into the receiver and this being a very high level compared to the normal receive signal, will saturate and may even damage the receiver. Also, the dynamic range of system will get affected.
[0003] To address this issue, a cancellation circuit is incorporated at a receiver frontend to bring a transmit leakage signal level low enough to avoid saturation of the receiver, without compromising the system noise figure.
[0004] The following prior art documents describe the different methods of generating the cancellation signal. The method adopted in each of these prior art documents is different.
[0005] US 9,331,735 B1 titled “GAN BASED ACTIVE CANCELLATION CIRCUIT FOR HIGH POWER SIMULTANEOUS TRANSMIT AND RECEIVE SYSTEMS” describes about a design of an X-band cancellation circuit using GAN devices in a single antenna topology. This prior art provides an option for inclusion or disconnection of the cancellation circuit. In this, a system is designed and fabricated on a die.
[0006] US 7,633,435 B2 titled “DUPLEXER FOR SIMULTANEOUS TRANSMIT AND RECEIVE RADAR SYSTEMS” describes about using of High Dynamic Range (HDR) amplifiers in a cancellation circuit.
[0007] US 3,021,521 titled “FEED-THROUGH NULLING SYSTEMS” de-scribes about how to achieve cancellation in a single antenna and separate antenna topologies; cancellation is achieved by incorporating Gyrators, Balanced detectors, rheostats.
[0008] All these cancellation circuits are designed to operate upto X-Band. As the frequency of operation increases, achieving the best amplitude and phase match between the transmit sample signal and the leakage signal at the receiver frontend, becomes very difficult.
[0009] Therefore, there is a need of an invention which solves the above de-fined problems and provides a self-interference cancellation circuit and method for achieving this for best cancellation in an analog domain in Ku-Band, and same is presented.
SUMMARY
[0010] This summary is provided to introduce concepts related to a Ku-band self-interference cancellation circuit for simultaneous transmit and receive systems and method thereof. This summary is neither intended to identify essential features of the present invention nor is it intended for use in determining or limit-ing the scope of the present invention.
[0011] For example, various embodiments herein may include one or more cancellation circuits and methods thereof are provided. In one of the embodi-ments, a method for cancelling signal leakage in simultaneous transmit and receive systems includes a step of receiving a signal from a transmitter, by a low insertion loss transmit sampler. The method includes a step of performing, by the low insertion loss transmit sampler, sampling on the transmitter signal and generating at least one reference sample of the transmitter signal. The method includes a step of adjusting, by an IQ mixer, phase of the sample by performing phase shifting on the sample. The method includes a step of performing, by a Time Delay Block with Attenuator, attenuation on the sample. The method includes a step of applying, by the Time Delay Block with Attenuator, phase shifting on the sample. The method includes a step of adjusting, amplitude of the sample by an amplifier. The method includes a step of injecting, by a plurality of low insertion loss couplers, the above generated processed sample signal at a receiver front end.
[0012] In another embodiment, a Ku-band self-interference cancellation circuit for simultaneous transmit and receive systems includes a low insertion loss trans-mit sampler, an IQ mixer, a Time Delay Block with Attenuator, an amplifier, and a plurality of low insertion loss couplers. The low insertion loss transmit sampler is configured to receive a signal from a transmitter, and further perform sampling on the signal and generate at least one reference sample of the signal. The IQ mixer is configured to adjust phase of the sample by performing phase shifting on the sample. The Time Delay Block with Attenuator is configured to perform attenua-tion on the sample to adjust amplitude of the sample and apply the phase shift on the sample. The amplifier is configured to adjust the amplitude of the signal. The plurality of low insertion loss couplers is configured to inject the generated processed signal at a receiver front end.
BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
[0001] The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawings to reference like features and modules.
[0002] Figure 1 illustrates a block diagram depicting a Ku-band self-interference cancellation circuit for simultaneous transmit and receive systems, according to an implementation of the present invention.
[0003] Figure 2 illustrates a schematic diagram depicting an overall architecture of a simultaneous transmit and receive RADAR systems having a self-interference cancellation circuit, according to an implementation of the present invention.
[0004] Figure 3 illustrates a schematic diagram depicting an IQ mixer, accord-ing to an exemplary implementation of the present invention.
[0005] Figure 4 illustrates a flow chart depicting a method for cancelling signal leakage in simultaneous transmit and receive systems, according to an exemplary implementation of the present invention.
[0006] It should be appreciated by those skilled in the art that any block dia-grams herein represent conceptual views of illustrative systems/platforms embo-dying the principles of the present invention. Similarly, it will be appreciated that any flowcharts, flow diagrams, and the like represent various processes which may be substantially represented in computer readable medium and so executed by a computer or processor, whether or not such computer or processor is explicitly shown.
DETAILED DESCRIPTION
[0007] In the following description, for the purpose of explanation, specific de-tails are set forth in order to provide an understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without these details. One skilled in the art will recognize that embo-diments of the present invention, some of which are described below, may be in-corporated into a number of systems.
[0008] The various embodiments of the present invention provide a Ku-band self-interference cancellation circuit for simultaneous transmit and receive systems and method thereof. Furthermore, connections between components and/or modules within the figures are not intended to be limited to direct connections. Rather, these components and modules may be modified, re-formatted or other-wise changed by intermediary components and modules.
[0009] References in the present invention to “one embodiment” or “an embo-diment” mean that a particular feature, structure, characteristic, or function de-scribed in connection with the embodiment is included in at least one embodiment of the invention. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment.
[0010] In one of the embodiments, a method for cancelling signal leakage in simultaneous transmit and receive systems includes a step of receiving a signal from a transmitter, by a low insertion loss transmit sampler. The method includes a step of performing, by the low insertion loss transmit sampler, sampling on the transmitter signal and generating at least one reference sample of the transmitter signal. The method includes a step of adjusting, by an IQ mixer, phase of the sample by performing phase shifting on the sample. The method includes a step of performing, by a Time Delay Block with Attenuator, attenuation on the sample. The method includes a step of applying, by the Time Delay Block with Attenua-tor, phase shift on the sample and adjusting amplitude of the sample. The method includes a step of performing, by an amplifier, amplitude adjustment of the sam-ple. The method includes a step of injecting, by a plurality of low insertion loss couplers, the above generated processed sample signal at a receiver front end.
[0011] In another implementation, the step of adjusting the phase is for obtain-ing the cancellation for any frequency or a pre-defined frequency band.
[0012] In another implementation, the step of adjusting the amplitude is for obtaining the cancellation for any frequency or a pre-defined frequency band.
[0013] In another implementation, the step of adjusting the phase of the trans-mitter sample by the IQ mixer and/or Time Delay Block with Attenuator, closely to 180° out of phase with respect to a transmit leakage signal.
[0014] In another implementation, the step of adjusting, by the Time Delay Block with Attenuator and/or amplifier, the amplitude of the transmitter sample is to closely match the amplitude of the transmit leakage signal using a combination of the attenuation or by providing amplification or both.
[0015] In another implementation, the step of injecting the processed signal is at the receiver front-end, by using a low insertion loss coupling mechanism.
[0016] In another embodiment, a Ku-band self-interference cancellation circuit for simultaneous transmit and receive systems includes a low insertion loss trans-mit sampler, an IQ mixer, a Time Delay Block with Attenuator, an amplifier, and a plurality of low insertion loss couplers. The low insertion loss transmit sampler is configured to receive a signal from a transmitter, and further perform sampling on the signal and generate at least one reference sample of the signal. The IQ mixer is configured to adjust phase of the sample by performing phase shifting on the sample. The Time Delay Block with Attenuator is configured to perform attenua-tion on the sample to adjust its amplitude and apply the phase shift on the sample. The amplifier is configured to adjust the amplitude of the sample. The plurality of low insertion loss couplers is configured to inject the generated processed sample signal at a receiver front end.
[0017] In another implementation, the IQ mixer is configured to adjust the phase for obtaining the cancellation for any frequency or a pre-defined frequency band.
[0018] In another implementation, the Time Delay Block with Attenuator is configured to adjust the amplitude for obtaining the cancellation for any frequen-cy or a pre-defined frequency band.
[0019] In another implementation, the IQ mixer is configured to adjust the phase of the sample to generate a 180° out of phase signal with respect to a trans-mit leakage signal.
[0020] In another implementation, the Time Delay Block with Attenuator is configured to adjust the amplitude of the sample to closely match the amplitude of the transmit leakage signal using a combination of the attenuation or by providing amplification or both.
[0021] In another implementation, the plurality of low insertion loss couplers is configured to inject the processed sample signal at the receiver front-end, by using a low insertion loss coupling mechanism.
[0022] In another implementation, the circuit is configured to operate in a sin-gle tone frequency and/or in a band limited modulated signal.
[0023] In an exemplary embodiment, the Ku-band self-interference cancella-tion circuit comprising of an adjustable multifunction Time Delay Block with At-tenuator used for introducing attenuation in steps of 0.5dB and time delay in steps of pico seconds.
[0024] In an exemplary embodiment, the Ku-band self-interference cancella-tion circuit can operate for a single tone frequency as well as for a band limited modulated signal.
[0025] In an exemplary embodiment, the Ku-band self-interference cancella-tion circuit internally takes a sample of the transmitted signal as a reference, and it is amplitude and 180° out of phase matched with respect to the leakage signal present at the receive antenna.
[0026] In an exemplary embodiment, the Ku-band self-interference cancella-tion circuit is basically a wideband radio frequency (RF) circuit operating over a frequency range of 14 GHz to 18GHz, which reduces the level of the transmit lea-kage signal inherently present at the receive frontend due to the low transmit to receive isolation for any STAR RADAR systems. If this leakage signal is not can-celled, the receiver gets desensitized. Thus, this cancellation circuitry forms a very important block in the receive frontends as it is expected to protect the receiver from high level transmit leakage.
[0027] Figure 1 illustrates a block diagram depicting a Ku-band self-interference cancellation circuit (100) for simultaneous transmit and receive sys-tems, according to an implementation of the present invention.
[0028] A Ku-band self-interference cancellation circuit (100) for simultaneous transmit and receive systems includes a low insertion loss transmit sampler (102), an IQ mixer (104), a Time Delay Block with Attenuator (106), an amplifier (108), and a plurality of low insertion loss couplers (110).
[0029] In an exemplary embodiment, the self-interference cancellation circuit (100) is a Ku-Band Self Interference Cancellation (SIC) that shows the inherent transmit leakage generated in any simultaneous Transmit and Receive (STAR) RADAR systems, can be cancelled by introducing a phase shifter and an attenua-tor in a feedback path to generate a replica of the leakage signal which is 180 de-grees out of phase and closely matched in amplitude. This generated signal is then injected into a receiver front end to cancel the transmit leakage.
[0030] In an exemplary embodiment, the Ku-band self-interference cancella-tion circuit (100) is designed to work, where in the transmit sample signal is 180 degrees out of phase and closely matched in amplitude to that of leakage signal. This amplitude adjustment of the sampled signal is done by a combination of ap-plying attenuation using a Time Delay Block with Attenuator or by amplifying using an amplifier or both. Similarly, the phase adjustment of the sampled signal is done by a combination of varying phase in coarser steps using a Time Delay Block with Attenuator or by varying phase in finer steps using the IQ mixer (104) or both. The closer the match, the better the cancellation achieved. This present invention can be adapted for other bands of frequencies too.
[0031] In an exemplary embodiment, the Ku-band self-interference cancella-tion circuit (100) is an analog Ku-Band self-interference cancellation (SIC) circuit which is designed to operate over a wideband of frequencies such that, at any par-ticular frequency or band of frequencies, the amplitude and phase of the reference signal can be adjusted for obtaining the best cancellation.
[0032] The low insertion loss transmit sampler (102) is configured to receive a signal from a transmitter. The low insertion loss transmit sampler (102) is confi-gured to perform sampling on the signal and generate at least one reference sample of the signal.
[0033] The IQ mixer (104) is configured to cooperate with the low insertion loss transmit sampler (102) to receive the generated reference sample. The IQ mixer (104) is configured to adjust phase of the sample by performing phase shift-ing on the sample. In an embodiment, the IQ mixer (104) is configured to adjust the phase for obtaining the cancellation for any frequency or a pre-defined fre-quency band. In an exemplary embodiment, the IQ Mixer (104) can introduce phase shift in steps of = 1°.
[0034] The Time Delay Block with Attenuator (106) is configured to cooperate with the IQ mixer (104) to receive the transmit sample signal. The Time Delay Block with Attenuator (106) is configured to introduce attenuation and phase shift on the transmit sample in order to adjust the amplitude and phase of the sample. In an embodiment, the Time Delay Block with Attenuator (106) is configured to adjust the amplitude and phase for obtaining the cancellation for any frequency or a pre-defined frequency band.
[0035] The amplifier (108) is configured to cooperate with the Time Delay Block with Attenuator (106) and is further configured to adjust the amplitude of the transmit sample signal.
[0036] The plurality of low insertion loss couplers (110) is configured to coo-perate with the amplifier (108) to receive the transmit sample signal. The plurality of low insertion loss coupler (110) is configured to inject the generated processed sample signal at a receiver front end, by using a low insertion loss coupling me-chanism.
[0037] Figure 2 illustrates a schematic diagram depicting an overall architecture of a simultaneous transmit and receive RADAR systems (200) having a self-interference cancellation circuit (100), according to an implementation of the present invention.
[0038] In Figure 2, four sections have been illustrated, i.e., a transmitter section (202), a Ku-band self-interference cancellation circuit (100) of Figure 1, a receive section (206), and DC and controls card (212).
[0039] In an embodiment, the transmitter section (202), generates the final transmitter signal (T). This transmitted signal is sampled using a low insertion loss transmit sampler (102) with a coupling factor (C1). In an embodiment, the power amplifier (204) is a Ku-Band power amplifier, which generates the transmitter signal T1.
[0040] In the Ku-band self-interference cancellation circuit (100) section, for any particular frequency, the sampled signal’s amplitude adjustment is achieved using an attenuator element of a Time Delay Block with Attenuator (106) and an amplifier (108),
[0041] In the Ku-band self-interference cancellation circuit (100) section, for any particular frequency, the sampled signal’s phase adjustment is achieved using the combination of time delay element of Time Delay Block with Attenuator (106) and an IQ Mixer (104).
[0042] In an embodiment, the IQ Mixer (104) is used in a unique way. In the conventional use, an IQ mixer (104) is used for converting the signal from one frequency to another frequency. But, in the present invention, the IQ mixer (104) is used as a phase shifter for finer phase adjustment. The input signal (I1, where I1= T1 –C1) is fed to a local-oscillator (LO) port of IQ Mixer (104). The phase shifted signal is obtained at a radio frequency (RF) port of the IQ Mixer (104). The amount of phase shift introduced is a function of the direct current (DC) vol-tages applied at the I & Q ports of the IQ Mixer (104) as shown in Figure 3. Fig-ure 3 illustrates a schematic diagram depicting an IQ mixer, according to an ex-emplary implementation of the present invention. To introduce a phase shift of ?, the voltage to be applied at these ports should be in phase quadrature as in equa-tions (1) and (2), i.e.,
Voltage at the I port = A Cos?……………….. (1)
Voltage at the Q port = A Sin? ……………….. (2)
where, A is the maximum voltage that can be safely applied to the IQ Mixer (104). This method of generating the phase shift has an advantage of obtaining lower phase shift resolution of = 1º.
[0043] In another embodiment, the Time Delay Block with Attenuator (106) is used for dual purposes viz.,
i. applying phase shift in coarser steps in terms of appropriate time delays;
ii. applying the necessary attenuations;
[0044] Based on the controls issued by the DC and controls (212) to the Time Delay Block with Attenuator (106), it introduces attenuation in 0.5dB steps and phase shift will be introduced in terms of time delay. If R is the resolution of the time delay element of the Time Delay Block with Attenuator (106), then,
Phase shift introduced for ‘N’ steps (in deg) = N *Resolution (R) * 360*f … (3)
where, N is the number of steps, f is the operating frequency.
[0045] The output of the Time Delay Block with Attenuator (106) is then given to an amplifier (108) to adjust the amplitude and the final/processed reference sig-nal ‘C’ is now almost equal in amplitude and almost 180º out of phase with re-spect to the transmit leakage signal ‘L’ present at receive frontend (208). If C2 is a coupling factor of the receive coupler, then,
|C| ˜ |L| +C2 and ?C -?L ˜ 180°; Assuming Coupler Phase Shit is 0º ……… (4)
[0046] The signal ‘C’ is injected into the receive front-end (208) and summed with signals ‘S’ + ‘L’ at the front-end to significantly reduce the level of the transmit leakage signal ‘L’ without affecting the system receive signal/ signal of interest (SOI) ‘S’.
where, S: Ku-Band Signal of Interest (SOI) level at the receiver at a frequency f’.
[0047] In an embodiment, the frontend signal summing is achieved using a low insertion loss coupler (110), which degrades the system noise figure only by the insertion loss of the coupler.

[0048] In an embodiment, the receive front-end provides a system gain of G. This difference in the signal levels of L* and L** will be the amount of cancella-tion obtained i.e.,
Cancellation achieved (in dB) = L* (dBm) – L** (dBm) ……. (5)
where, L*—Ku-Band Transmit Leakage signal level at the output of LNA without SIC = L + G
L**—Ku-Band Transmit Leakage signal level at the output of LNA with SIC.
[0049] The amount of cancellation depends on how close the amplitude and phase of the reference signal is matched to the leakage signal. Better the match, higher the cancellation achieved.
[0050] In an embodiment, the Ku-band self-interference cancellation circuit (100) for Simultaneous Transmit and Receive (STAR) Radar Systems (200) is capable of cancelling the transmit leakage signal present at it receive front-end (206) using:
a) Ku-band IQ Mixer/ IQ mixer (104),
b) Ku-band variable delay element with attenuator / Time De-lay Block with Attenuator (106),
c) Ku-band gain block/ Amplifier (108), and
d) Ku-band couplers/ Low Insertion Loss Couplers (102,110) for sampling transmit signal and injecting the processed signal at the receive front-end.

[0051] In an exemplary embodiment, the Ku-band self-interference cancella-tion circuit (100), where the transmit leakage cancellation is done at the receiver frontend (206), i.e., by incorporating a low insertion loss coupling mechanism ahead of a low-noise amplifier (LNA) (210), so that the overall system noise figure is increased only by a value equal to the insertion loss of the coupling mechanism.
S*—Ku-Band Signal of Interest (SOI) level at the output of LNA = S + G
[0052] In an exemplary embodiment, the Ku-band self-interference cancella-tion circuit (100) is capable of operating over a wider frequency band, wherein the amplitude and phase of the transmit sample signal is adjusted for obtaining the best cancellation for any frequency or a defined frequency band.
[0053] In an exemplary embodiment, the phase of the sampled signal is ad-justed to generate a 180° out of phase signal with respect to the transmit leakage signal using a combination of adjusting the phase in coarser steps with an adjusta-ble time delay element of Time Delay Block with Attenuator (106) or with a phase shifter and by adjusting phase in finer steps with the IQ Mixer (104) or both.
[0054] In an exemplary embodiment, the amplitude of the signal is adjusted to closely match the amplitude of the transmit leakage signal using a combination of adjusting the attenuation or by providing amplification or both.
[0055] In an exemplary embodiment, the low insertion loss couplers (102,110) are incorporated to sample a portion of the transmitted Ku-band signal to generate a reference signal; and to inject the processed signal at the receive front-end for cancellation, with minimal effect on the overall system noise figure.
[0056] Figure 4 illustrates a flow chart (400) depicting a method for cancelling signal leakage in simultaneous transmit and receive systems, according to an ex-emplary implementation of the present invention.
[0057] The flow chart starts at a step (402), receiving a signal from a transmit-ter, by a low insertion loss transmit sampler. In an embodiment, a low insertion loss transmit sampler (102) is configured to receive a signal from a transmitter and generating at least one reference sample of the transmitter signal by performing sampling on the transmit signal, as in at a step (404). At step (406) the phase of the transmit sample signal is adjusted by an IQ mixer (104), by performing phase shifting in finer steps on the transmit sample. At a step (408), performing, attenuation and phase shifting on the transmit sample in order to adjust the ampli-tude and phase in coarser steps, by a Time Delay Block with Attenuator (106). At a step (410), the amplitude of the transmit sample signal is adjusted by an amplifi-er (108), by performing amplification of the transmit sample signal. At a step (412), injecting, by a plurality of low insertion loss couplers (110), the generated processed transmit sample signal at a receiver front end.
[0058] It should be noted that the description merely illustrates the principles of the present invention. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present invention. Furthermore, all examples recited herein are principally intended expressly to be only for explanatory pur-poses to help the reader in understanding the principles of the invention and the concepts contributed by the inventor(s) to furthering the art and are to be con-strued as being without limitation to such specifically recited examples and condi-tions. Moreover, all statements herein reciting principles, aspects, and embodi-ments of the invention, as well as specific examples thereof, are intended to en-compass equivalents thereof.
,CLAIMS:
1. A method for cancelling the transmit leakage signal present at a receiver front end in simultaneous transmit and receive systems, said method comprising:
receiving a transmit signal from a transmitter, by a low insertion loss transmit sampler (102);
performing sampling on said transmit signal and generating at least one reference transmit sample of said signal, by said low insertion loss transmit sampler (102);
adjusting phase of said transmit sample signal by performing phase shifting on said transmit sample, by an IQ mixer (104);
performing, phase and amplitude adjustment on said transmit sample signal, by a Time Delay Block with Attenuator (106);
performing, amplitude adjustment on said transmit sample signal, by an amplifier (108); and
injecting, by a plurality of low insertion loss couplers (110), said generated processed transmit signal at a receiver front end.
2. The method as claimed in claim 1, wherein adjusting said phase and am-plitude for obtaining the cancellation for any frequency or a pre-defined frequency band in Ku Band.
3. The method as claimed in claim 1, wherein adjusting, by said Time Delay Block with Attenuator (106) and amplifier (108), the amplitude of said sample for closely matching to the amplitude of the transmit leakage signal using a combina-tion of the attenuation or by providing amplification or both.
4. The method as claimed in claim 1, wherein injecting the processed sample signal at the receiver front-end, by using a low insertion loss coupling mechanism.
5. A Ku-band self-interference cancellation circuit (100) for simultaneous transmit and receive systems, said cancellation circuit (100) comprising:
a low insertion loss transmit sampler (102) configured to receive a signal from a transmitter, said low insertion loss transmit sampler (102) configured to perform sampling on said signal and generate at least one reference sample of said signal;
an IQ mixer (104) configured to cooperate with said low insertion loss transmit sampler (102), said IQ mixer (104) configured to adjust phase of said sample by performing phase shifting on said sample;
a Time Delay Block with Attenuator (106) configured to cooperate with said IQ mixer (104), said Time Delay Block with Attenuator (106) configured to perform attenuation on said sample in order to adjust the amplitude and apply said phase shift on said sample;
an amplifier (108) configured to cooperate with said Time Delay Block with Attenuator (106), said amplifier (108) configured to amplify the said sample in order to adjust the amplitude; and
6. The self-interference cancellation circuit (100) as claimed in claim 5, comprising: a plurality of low insertion loss couplers (110) configured to cooperate with said amplifier (108), said couplers (110) configured to inject said generated processed signal at a receiver front end.
7. The self-interference cancellation circuit (100) as claimed in claim 5, wherein said IQ mixer (104) is configured to adjust said phase for obtaining the cancellation for any frequency or a pre-defined frequency band.
8. The self-interference cancellation circuit (100) as claimed in claim 5, wherein said Time Delay Block with Attenuator (106) is configured to adjust said amplitude for obtaining the cancellation for any frequency or a frequency band.
9. The self-interference cancellation circuit (100) as claimed in claim 5, wherein said IQ mixer (104) is configured to adjust said phase of said sample to generate a nearly 180° out of phase signal with respect to a transmit leakage signal.
10. The self-interference cancellation circuit (100) as claimed in claims 5, wherein said Time Delay Block with Attenuator (106) and amplifier (108) are configured to adjust the amplitude of said sample to closely match the amplitude of the transmit leakage signal using a combination of the attenuation or by provid-ing amplification or both.

11. The self-interference cancellation circuit (100) as claimed in claim 5, wherein the plurality of low insertion loss couplers (110) is configured to inject the processed signal at the receiver front-end, by using a low insertion loss coupling mechanism.
12. The self-interference cancellation circuit (100) as claimed in claim 5, wherein said circuit (100) is configured to operate in a single tone frequency and/or in a band limited modulated signal.