CN216313076U - Circuit for eliminating electromagnetic interference signal leaked by transmitter - Google Patents
Circuit for eliminating electromagnetic interference signal leaked by transmitter Download PDFInfo
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- CN216313076U CN216313076U CN202122361308.7U CN202122361308U CN216313076U CN 216313076 U CN216313076 U CN 216313076U CN 202122361308 U CN202122361308 U CN 202122361308U CN 216313076 U CN216313076 U CN 216313076U
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Abstract
The utility model discloses a circuit for eliminating electromagnetic interference signals leaked by a transmitter, which comprises a sampling module, an adjusting module and a feedback module. The sampling module is used for directly coupling the transmitter to obtain a reference signal, and the adjusting module adjusts the reference signal to generate a cancellation signal with equal amplitude and opposite phase with the noise signal. The feedback module generates a feedback signal according to the relevance of the receiving signal and the cancellation signal, and further adjusts the cancellation signal. The circuit is connected between the transmitting antenna and the low-noise amplifier of the system, has a simple structure, and is convenient to integrate with the low-noise amplifier.
Description
Technical Field
The utility model belongs to the technical field of electromagnetic fields, relates to a cancellation circuit for anti-electromagnetic interference signals, and particularly relates to a circuit for eliminating electromagnetic interference signals leaked by a transmitter.
Background
In an environment of strong electromagnetic leakage, there is a leakage signal from the transmitter in addition to the signal from the target for the receiver. The leakage of electromagnetic interference signals has the following mechanism: (1) coupling through a substrate of a chip; (2) coupling caused by chip-antenna interconnects; (3) mutual coupling between the transmitting and receiving antennas. For a compact transmit receive type module: the isolation between transmitter and receiver can be reasonably set to 30dB, assuming a transmitter output power of 10dBm, then-20 dBm of signal power is received at the input of the receiver. In this case, the power of the interference signal of the electromagnetic leakage may be several orders of magnitude higher than the power of the received target signal. High power electromagnetic interference signals limit the linearity and resolution of the receiver of the ADC, resulting in increased circuit area and increased power consumption.
Therefore, it is of great significance to shield or eliminate electromagnetic interference signals between the transmitter and the receiver. Common emi cancellation circuits can be divided into passive circuits and active circuits. The passive circuit has high linearity when electromagnetic interference signals are counteracted, and the influence on the performance of the receiver is small. The main disadvantage is that the size and power consumption are too large to be integrated in a large-capacity CMOS. The active circuit has more flexibility and smaller occupied area, and can be easily integrated in batch CMOS. However, receiver performance may be degraded due to noise and distortion of the active devices. There are several different options for the location of the emi cancellation circuit in the receiver chain. Such as directly after the antenna, after a Low Noise Amplifier (LNA), after baseband down conversion. These solutions have respective advantages and disadvantages: close to the antenna can reduce the linearity requirements and thus reduce power consumption, but at the same time also increases the Noise Figure (NF), compared to a connection close to the baseband which has little effect on the NF, but before the cancellation point all modules need a high linearity to process the received signal and the overflow without compression, which means a higher power consumption. It is more challenging than the way that the vanishing point is behind the rf antenna.
Disclosure of Invention
In view of the deficiencies of the prior art, the present invention provides a circuit for eliminating the electromagnetic interference signal leaked by the transmitter, which correlates the signal on the receiving link with the sampled signal of the transmitted signal based on the known condition of the transmitted signal at the receiving end, then adjusts the delay of the sampled signal to match the delay of the leaked electromagnetic interference signal, then cancels the overflow using the superposition result of the two signals, and cancels the electromagnetic interference after the receiving antenna and before the low noise amplifier.
A circuit for eliminating leakage electromagnetic interference signals of a transmitter comprises a sampling module, a regulating module and a feedback module.
The sampling module includes a quadrature coupler. The adjusting module comprises an I-path adjustable amplifier, a Q-path adjustable amplifier and a transformer. The feedback module includes a first adder, a second adder, and an integrator.
The input end of the orthogonal coupler is connected with the output end of the transmitter, and the output end of the orthogonal coupler is connected with the input ends of the I-path adjustable amplifier and the Q-path adjustable amplifier. The output ends of the I-path adjustable amplifier and the Q-path adjustable amplifier are connected with the primary coil of the transformer. The input end of the first adder is connected with the secondary coil of the transformer, and the output end of the first adder is connected with the output end of the transmitting antenna. The input end of the second adder is connected with the output end of the transmitting antenna and the secondary coil of the transformer, and the output end of the second adder is connected with the input end of the integrator. The output end of the integrator is connected with the input end of the first adder.
Preferably, the sampling module further comprises an antenna amplifier, an input end of the antenna amplifier is connected with an output end of the transmitting antenna, and an output end of the antenna amplifier is connected with an output end of the first adder.
Preferably, the quadrature coupler and the antenna amplifier are coupled to the transmitter and the antenna amplifier, respectively.
The sampling module is coupled with the output end of the transmitter and the output end of the transmitting antenna respectively to obtain a reference signal and a receiving signal, wherein the receiving signal comprises an interference signal caused by electromagnetic leakage. The reference signal is adjusted by the I-path adjustable amplifier and the Q-path adjustable amplifier respectively and then input into the transformer for superposition, and the output signal of the transformer is adjusted by the feedback module to generate a cancellation signal with the same amplitude and opposite phase with the interference signal. An integrator in the feedback module and a second adder compare the output signal and the received signal of the transformer, and the first adder adjusts the amplitude of the output signal of the transformer according to the output of the integrator. When the input signal of the integrator is zero, the output signal is constant, the feedback module stops working when reaching a steady state, and the interference signal in the received signal is eliminated.
The utility model has the following beneficial effects:
1. the cancellation circuit is connected to the front end of the low-noise amplifier in the whole receiver chain and the rear end of the receiving antenna, and the electromagnetic interference signals are cancelled at the position, so that the saturation of the rear end circuit can be avoided.
2. The adjustable gain amplifier controlled by the switch realizes the adjustment of the amplitude and the phase of the sampling signal, and the adjustable gain amplifier adopting the digital switch can realize the continuous adjustment of the amplitude of the sampling signal.
3. The correlation of the adjusted sampled signal with the interference signal can be determined for use with an integrator. Whether the interference signal is cancelled is judged mainly by integrating the superposed signals.
Drawings
FIG. 1 is a schematic diagram of an embodiment cancellation circuit;
FIG. 2 is a schematic diagram of negative feedback regulation in a cancellation circuit;
FIG. 3 is a flow chart of negative feedback regulation in the cancellation circuit.
Detailed Description
The utility model is further explained below with reference to the drawings;
as shown in FIG. 1, a circuit for eliminating a leakage EMI signal of a transmitter includes a sampling module, a regulating module and a feedback module.
The sampling module comprises a quadrature coupler 4 and an antenna amplifier. The adjustable amplifier 5 comprises an adjustable amplifier 5 of the adjusting module and a transformer 6, wherein the adjustable amplifier 5 is divided into an adjustable amplifier of an I path and an adjustable amplifier of a Q path. The feedback module comprises a first adder 2, a second adder 1 and an integrator 3.
The input end of the quadrature coupler 4 is coupled with the output end of the transmitter, and the output end is connected with the input ends of the I-path adjustable amplifier and the Q-path adjustable amplifier. The output ends of the I-path adjustable amplifier and the Q-path adjustable amplifier are connected with the primary coil of the transformer 6. The input of the first adder 2 is connected to the secondary winding of the transformer 6, and the output is connected to the output of the antenna amplifier. The input end of the antenna amplifier is connected with the output end of the transmitting antenna. The second adder 1 has an input connected to the input of the output of the antenna amplifier and to the secondary winding of the transformer 6 and an output connected to the input of the integrator 3. An output of the integrator 3 is connected to an input of the first adder 2.
The quadrature coupler 4 couples the input signal into two paths of quadrature signals with phase difference of 90 ° and equal amplitude, respectively adjusts the amplitude through the I-path adjustable amplifier and the Q-path adjustable amplifier, and controls the amplitude and phase of the signal through superposition of the transformer 6. The negative feedback circuit of the integrator 3 and the first adder 2, the second adder 1 and the integrator performing correlation between the reference signal and the received signal, the first adder 2 scaling the cancellation signal according to the correlation output. Due to the integrator 3 in the loop, a steady state is reached when the integrator input is zero and the output is constant, which means that the received and transmitted signals are uncorrelated and the interfering signals are suppressed.
Claims (3)
1. A circuit for canceling a transmitter leakage emi signal, comprising: the device comprises a sampling module, a regulating module and a feedback module;
the sampling module comprises a quadrature coupler; the adjusting module comprises an I-path adjustable amplifier, a Q-path adjustable amplifier and a transformer; the feedback module comprises a first adder, a second adder and an integrator;
the input end of the orthogonal coupler is connected with the output end of the transmitter, and the output end of the orthogonal coupler is connected with the input ends of the I-path adjustable amplifier and the Q-path adjustable amplifier; the output ends of the I-path adjustable amplifier and the Q-path adjustable amplifier are connected with a primary coil of the transformer; the input end of the first adder is connected with the secondary coil of the transformer, and the output end of the first adder is connected with the output end of the transmitting antenna; the input end of the second adder is connected with the output end of the transmitting antenna and the secondary coil of the transformer, and the output end of the second adder is connected with the input end of the integrator; the output end of the integrator is connected with the input end of the first adder.
2. A circuit for canceling a transmitter leakage emi signal as recited in claim 1, wherein: the sampling module further comprises an antenna amplifier, the input end of the antenna amplifier is connected with the output end of the transmitting antenna, and the output end of the antenna amplifier is connected with the output end of the first adder.
3. A circuit for canceling a transmitter leakage emi signal as recited in claim 1, wherein: the orthogonal coupler and the antenna amplifier are respectively coupled with the transmitter and the antenna amplifier.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202122361308.7U CN216313076U (en) | 2021-09-28 | 2021-09-28 | Circuit for eliminating electromagnetic interference signal leaked by transmitter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202122361308.7U CN216313076U (en) | 2021-09-28 | 2021-09-28 | Circuit for eliminating electromagnetic interference signal leaked by transmitter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN216313076U true CN216313076U (en) | 2022-04-15 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202122361308.7U Active CN216313076U (en) | 2021-09-28 | 2021-09-28 | Circuit for eliminating electromagnetic interference signal leaked by transmitter |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN216313076U (en) |
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2021
- 2021-09-28 CN CN202122361308.7U patent/CN216313076U/en active Active
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