A compact, low-noise frequency converter receiver circuit

Abstract

This invention relates to the field of communication technology and discloses a compact, low-noise frequency conversion receiver circuit. Addressing the problem of increased area and power consumption caused by the need for large-area filters or IQ generation circuits in existing RF receiver front-end circuits for image noise suppression, this invention proposes a receiver architecture using a 3-coil transformer before the mixer. The transformer is implemented in an 8-shape, filtering out image noise and reducing the circuit's noise figure without increasing area or complexity. Therefore, this patent aims to achieve lower noise in the frequency conversion receiver by optimizing the circuit architecture and using a carefully designed 8-shaped inductor in the 3-coil transformer before the mixer, avoiding the drawbacks of traditional image suppression receivers that require IQ mixing or large on-chip bandpass filters, thereby improving the overall performance of the receiver.

Description

Technical Field

[0001] This invention relates to the field of communication technology, and in particular to a compact, low-noise frequency converter receiver circuit. Background Technology

[0002] Modern wireless communication systems (such as 5G, satellite communication, and radar) have an urgent need for broadband, low-noise, and high-sensitivity receivers. Traditional frequency conversion receivers suffer significant noise figure degradation in wide-band, high-frequency applications (such as millimeter waves and terahertz), especially due to image noise, which further worsens the noise figure compared to unconverted receivers, making it difficult to meet the requirements of high dynamic range signal processing.

[0003] Existing methods for addressing image noise primarily employ two approaches. First, IQ mixing generates a 90° phase difference at the local oscillator port, suppressing image noise in the converted intermediate frequency (IF) signal. Second, an on-chip image suppression filter is added after the low-noise amplifier (LNA) and before the mixer to suppress image noise. Both methods have their own limitations. IQ mixing requires an IQ mixer and quadrature signal generation circuitry, increasing chip power consumption and area, thus raising design complexity. On-chip filters, on the other hand, occupy a significant area, and their insertion loss partially offsets the noise figure reduction benefits of image noise suppression. Summary of the Invention

[0004] The present invention provides a compact, low-noise frequency converter receiver circuit, which aims to solve at least one of the above-mentioned technical problems.

[0005] To achieve the above objectives, the present invention provides a compact low-noise frequency converter receiver circuit, comprising:

[0006] Primary LNA, secondary LNA, and mixer;

[0007] The secondary LNA and the mixer are provided with a 3-coil mirror noise suppression transformer, which includes mutually coupled L1 inductor, L2 inductor and L3 inductor.

[0008] Wherein, the L1 inductor is connected to the output terminal of the secondary LNA, the L2 inductor is connected to the input terminal of the mixer, and the L3 inductor is connected to the terminating capacitor Ci;

[0009] Specifically, the L1 inductor, the L2 inductor, and the coupling coefficient between the L1 and L2 inductors are configured to convert the input impedance of the mixer into the conjugate impedance of the secondary LNA output impedance at the operating frequency of the secondary LNA; the coupled resonant cavity formed by the L1 inductor, the L3 inductor, and the terminating capacitor Ci is configured to make the impedance of the secondary LNA towards the 3-coil mirror noise suppression transformer close to the value of 0 at the frequency of the mirror signal; the L3 inductor is configured to be an "8" shaped inductor, and the "8" shaped inductor makes the coupling coefficient between the L2 and L3 inductors set to the value of 0.

[0010] Optionally, an input matching circuit is provided between the primary LNA and the RF input terminal.

[0011] Optionally, an interstage matching balun is provided between the primary LNA and the secondary LNA. The interstage matching balun is configured to convert single-ended signals into differential signals to achieve conjugate matching between the primary LNA and the secondary LNA.

[0012] Optionally, an interstage capacitor is provided between the primary LNA and the secondary LNA, with the first end of the interstage capacitor connected to the output terminal of the primary LNA and the second end of the interstage capacitor connected to the input terminal of the secondary LNA.

[0013] Optionally, the first input terminal of the 3-coil mirror noise suppression transformer is connected to the output terminal of the secondary LNA, and the second input terminal of the 3-coil mirror noise suppression transformer is grounded, so that the 3-coil mirror noise suppression transformer converts the single-ended signal into a differential signal.

[0014] Optionally, in the coupled resonant cavity formed by the L1 inductor, the L3 inductor, and the terminating capacitor Ci, noise at the mirror frequency flows into the terminating capacitor Ci, thus preventing the mixer from being affected by noise and causing the noise figure of the receiving circuit to deteriorate.

[0015] Optionally, the upper half of the figure-eight inductor used in the L3 inductor is inside the multi-turn coil of the L1 inductor, so that the time-varying magnetic field in the L3 inductor passes through the overlapping part of the L3 and L1 inductors, forming the coupling coefficient between the L1 and L3 inductors.

[0016] Optionally, the figure-eight shaped inductor used in the L3 inductor is entirely inside the L2 inductor, so that the time-varying magnetic field inside the L3 inductor passes through the overlapping part of the L3 and L2 inductors, forming the coupling coefficient between the L2 and L3 inductors.

[0017] Optionally, when the figure-eight inductor used in the L3 inductor is entirely inside the L2 inductor, the magnetic flux generated by the upper and lower halves of the figure-eight inductor is the same in magnitude but opposite in direction, so that the coupling coefficient between the L2 and L3 inductors is 0.

[0018] Optionally, an intermediate frequency amplifier is provided between the mixer and the intermediate frequency input terminal.

[0019] The beneficial effects of this invention are as follows: It proposes a compact, low-noise frequency conversion receiver circuit. Addressing the problem of increased area and power consumption caused by the need for large-area filters or IQ generation circuits in existing RF receiver front-end circuits for image noise suppression, this invention proposes a receiver architecture using a 3-coil transformer before the mixer. The transformer is implemented in an 8-shape, filtering out image noise and reducing the circuit's noise figure without increasing area or complexity. Therefore, this patent aims to optimize the circuit architecture by carefully designing the 3-coil transformer before the mixer to use an 8-shaped inductor (or 8-shaped transformer), avoiding the drawbacks of traditional image suppression receivers that require IQ mixing or large on-chip bandpass filters, thus achieving lower noise in the frequency conversion receiver and improving the overall performance of the receiver. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the compact low-noise frequency converter receiver circuit of the present invention;

[0021] Figure 2 This is a schematic diagram of one of the three-coil mirror noise suppression transformers of the present invention;

[0022] Figure 3 This is a second schematic diagram of the three-coil mirror noise suppression transformer of the present invention;

[0023] Figure 4 This is a third schematic diagram of the three-coil mirror noise suppression transformer of the present invention;

[0024] Figure 5 This is a schematic diagram showing the relationship between the impedance Z21 parameter and frequency in this invention;

[0025] Figure 6 Simulation diagrams of the noise figure for a receiver using a 3-coil mirror noise suppression transformer and a conventional receiver are provided.

[0026] Figure 7 This is one actual circuit diagram of the compact low-noise frequency converter receiver circuit of the present invention;

[0027] Figure 8This is a second actual circuit diagram of the compact low-noise frequency converter receiver circuit of the present invention. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0029] like Figure 1 As shown, this embodiment of the invention provides a compact low-noise frequency converter receiver circuit, including: a first-stage LNA, a second-stage LNA, and a mixer;

[0030] The secondary LNA and the mixer are provided with a 3-coil mirror noise suppression transformer, which includes mutually coupled L1 inductor, L2 inductor and L3 inductor.

[0031] Wherein, the L1 inductor is connected to the output terminal of the secondary LNA, the L2 inductor is connected to the input terminal of the mixer, and the L3 inductor is connected to the terminating capacitor Ci;

[0032] Specifically, the L1 inductor, the L2 inductor, and the coupling coefficient between the L1 and L2 inductors are configured to convert the input impedance of the mixer into the conjugate impedance of the secondary LNA output impedance at the operating frequency of the secondary LNA; the coupled resonant cavity formed by the L1 inductor, the L3 inductor, and the terminating capacitor Ci is configured to make the impedance of the secondary LNA towards the 3-coil mirror noise suppression transformer close to the value of 0 at the frequency of the mirror signal; the L3 inductor is configured to be an "8" shaped inductor, and the "8" shaped inductor makes the coupling coefficient between the L2 and L3 inductors set to the value of 0.

[0033] In a preferred embodiment, an input matching circuit is provided between the primary LNA and the radio frequency input terminal.

[0034] In a preferred embodiment, an interstage matching balun is provided between the primary LNA and the secondary LNA. The interstage matching balun is configured to convert single-ended signals into differential signals to achieve conjugate matching between the primary LNA and the secondary LNA.

[0035] In a preferred embodiment, an interstage capacitor is provided between the primary LNA and the secondary LNA, with the first end of the interstage capacitor connected to the output terminal of the primary LNA and the second end of the interstage capacitor connected to the input terminal of the secondary LNA.

[0036] In a preferred embodiment, the first input terminal of the 3-coil mirror noise suppression transformer is connected to the output terminal of the secondary LNA, and the second input terminal of the 3-coil mirror noise suppression transformer is grounded, so that the 3-coil mirror noise suppression transformer converts the single-ended signal into a differential signal.

[0037] In a preferred embodiment, in the coupled resonant cavity formed by the L1 inductor, the L3 inductor, and the terminating capacitor Ci, noise at the mirror frequency flows into the terminating capacitor Ci, thus preventing the mixer from being affected by noise and causing the noise figure of the receiving circuit to deteriorate.

[0038] In a preferred embodiment, the upper half of the figure-eight inductor used in the L3 inductor is inside the multi-turn coil of the L1 inductor, so that the time-varying magnetic field in the L3 inductor passes through the overlapping part of the L3 and L1 inductors, forming the coupling coefficient between the L1 and L3 inductors.

[0039] In a preferred embodiment, the figure-eight shaped inductor used in the L3 inductor is entirely inside the L2 inductor, so that the time-varying magnetic field inside the L3 inductor passes through the overlapping part of the L3 and L2 inductors, forming the coupling coefficient between the L2 and L3 inductors.

[0040] In a preferred embodiment, when the figure-eight inductor used in the L3 inductor is entirely inside the L2 inductor, the magnetic flux generated by the upper and lower halves of the figure-eight inductor is the same in magnitude but opposite in direction, so that the coupling coefficient between the L2 and L3 inductors is 0.

[0041] In a preferred embodiment, an intermediate frequency amplifier is provided between the mixer and the intermediate frequency input terminal.

[0042] Therefore, this invention proposes a compact, low-noise frequency converter receiver circuit. The key technical point lies in the use of a transformer matching network before the mixer in the receiver system. This transformer is a three-coil transformer, and the third coil of the transformer is an 8-shaped inductor. Through the reasonable design of the figure-8 inductor, the coupling coefficient k12 of the inductor is chosen to maximize the receiver link gain, k23 is 0, and k13 ensures that the impedance looking inward from the three-coil transformer is minimal at the image frequency, thus filtering out image noise.

[0043] Furthermore, while maintaining the same chip area, a three-coil transformer before the mixer filters out noise at the image frequency without affecting the RF signal and receiver channel gain, thus reducing the receiver's noise figure. Addressing the issue of increased area and power consumption caused by the need for large-area filters or IQ generation circuits in existing RF receiver front-end circuits for image noise suppression, a receiver architecture using a three-coil transformer before the mixer is proposed. The transformer is implemented in an 8-shape, filtering out image noise and reducing the circuit's noise figure without increasing area or complexity.

[0044] It should be noted that the purpose of this invention is to realize a compact, low-noise frequency conversion receiver. The receiver takes the input signal through a first-stage LNA and converts the single-ended signal into a differential signal through an inter-stage matched balun between the first and second-stage LNAs. Furthermore, it achieves conjugate matching between the two stages, ensuring bandwidth and gain. Between the second-stage LNA and the mixer, this invention employs the following... Figure 1 The diagram shows a 3-coil mirror noise suppression transformer. It is formed by the mutual coupling of three inductors: inductor L1 is connected to the output of the secondary LNA, inductor L2 is connected to the input of the mixer, and inductor L3 is connected to a terminating capacitor Ci.

[0045] First, consider inductors L1 and L2. The coupling coefficient of these two inductors is k12. To minimize losses from the secondary LNA to the mixer, L1, L2, and k12 convert the mixer's input impedance to the conjugate impedance of the secondary LNA's output impedance at the LNA's operating frequency. Next, consider the coupling between L1 and L3. The coupled resonant cavity formed by L1, L3, and Ci ensures that the impedance seen by the secondary LNA to the transformer is close to 0 at the frequency of the image signal. Noise at the image frequency flows into capacitor Ci instead of entering the mixer, thus preventing noise degradation in the receiving circuit. For the coupling between L2 and L3, to prevent thermal noise from L3 from being coupled into L2 (i.e., into the mixer), the coupling coefficient k23 will be 0. This near-zero coupling coefficient is achieved by setting L3 as an "8"-shaped inductor.

[0046] Specifically, in this embodiment, the layout of the figure-eight inductor is as follows: Figure 2 As shown. L1 and L2 are connected to the output of the pre-amplifier (LNA) and the input of the post-amplifier (MJT), respectively, and L3 is connected to capacitor Ci. First, let's analyze L1 and L3. Figure 3 Retaining only L1 and L3 of the three-coil inductors, with the upper half of L3's coil inside the multi-turn coil of L1, means that the time-varying magnetic field within the L3 inductor will also pass through the overlapping portion of L3 and L1. Assuming the magnetic flux in this portion is perpendicular to the plane of the image and pointing inwards, the magnetic flux is as follows... Figure 3As shown, this results in the coupling coefficient k13 between L1 and L3. Next, we analyze L2 and L3... Figure 4 Retaining only L2 and L3, with the entire L3 coil inside the L2 coil, means that the time-varying magnetic field within the L3 inductor will also pass through the overlapping portion of L3 and L2. Assuming the magnetic flux in this portion is perpendicular to the plane of the image and pointing inwards, and considering that the upper and lower parts of the figure-eight L3 generate magnetic flux in opposite directions, it's like... Figure 4 As shown, both sets of opposite magnetic fluxes are inside L2, so the induced currents in L2 cancel each other out, resulting in a coupling coefficient k23 of 0 between L2 and L3. The coupling relationship between L1 and L2 is the same as that of a normal transformer, and will not be explained in detail here.

[0047] Figure 5 The diagram illustrates the relationship between the impedance Z21 parameter and frequency of a 3-coil transformer. It shows that the designed transformer exhibits a significantly low Z21 value at the image frequency, indicating a very low input impedance at this frequency. Therefore, noise at the image frequency will flow into the Ci port instead of being superimposed at the mixer. At the operating frequency, Z21 maintains a suitable value, ensuring sufficient gain for the circuit. Figure 6 The simulation diagrams of the noise figure of the receiver using a 3-coil inductor and the noise figure of a conventional receiver show that the noise figure of the present invention is significantly reduced within the same frequency band, thus achieving the purpose of the invention.

[0048] In a preferred embodiment, the present invention provides actual circuit diagrams for two compact low-noise frequency converter receiver circuits, such as... Figure 7 and Figure 8 As shown. Among them, Figure 7 The circuit diagram shown has been described in detail above and will not be repeated here. Figure 8 In the circuit diagram shown, both the primary and secondary LNAs are single-ended circuits. In addition to performing impedance matching functions for the LNA and mixer, the 3-coil transformer also performs the single-ended to differential balun function.

[0049] Therefore, this invention addresses the problem of increased area and power consumption caused by the need for large-area filters or IQ generation circuits in existing RF receiver front-end circuits to suppress image noise. It proposes a receiver architecture that uses a 3-coil transformer before the mixer, wherein the transformer is implemented in an 8-shape. This eliminates image noise and reduces the noise figure of the circuit without increasing the area and complexity.

[0050] It is understood that in the description of this specification, references to terms such as "one embodiment," "another embodiment," "other embodiments," or "first embodiment to Nth embodiment," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0051] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or system. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or system that includes that element.

[0052] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A compact, low-noise frequency converter receiver circuit, characterized in that, include: Primary LNA, secondary LNA, and mixer; The secondary LNA and the mixer are provided with a 3-coil mirror noise suppression transformer, which includes mutually coupled L1 inductor, L2 inductor and L3 inductor. Wherein, the L1 inductor is connected to the output terminal of the secondary LNA, the L2 inductor is connected to the input terminal of the mixer, and the L3 inductor is connected to the terminating capacitor Ci; Specifically, the L1 inductor, the L2 inductor, and the coupling coefficient between the L1 and L2 inductors are configured to convert the input impedance of the mixer into the conjugate impedance of the secondary LNA output impedance at the operating frequency of the secondary LNA; the coupled resonant cavity formed by the L1 inductor, the L3 inductor, and the terminating capacitor Ci is configured to make the impedance of the secondary LNA towards the 3-coil mirror noise suppression transformer close to 0 at the frequency of the mirror signal; the L3 inductor is configured to be an "8" shaped inductor, and the "8" shaped inductor makes the coupling coefficient between the L2 and L3 inductors set to 0.

2. The compact low-noise frequency converter receiver circuit as described in claim 1, characterized in that, An input matching circuit is provided between the primary LNA and the RF input terminal.

3. The compact low-noise frequency converter receiver circuit as described in claim 1, characterized in that, An interstage matching balun is provided between the primary LNA and the secondary LNA. The interstage matching balun is configured to convert single-ended signals into differential signals to achieve conjugate matching between the primary LNA and the secondary LNA.

4. The compact low-noise frequency converter receiver circuit as described in claim 1, characterized in that, An interstage capacitor is provided between the primary LNA and the secondary LNA. The first end of the interstage capacitor is connected to the output terminal of the primary LNA, and the second end of the interstage capacitor is connected to the input terminal of the secondary LNA.

5. The compact low-noise frequency converter receiver circuit as described in claim 4, characterized in that, The first input terminal of the 3-coil mirror noise suppression transformer is connected to the output terminal of the secondary LNA, and the second input terminal of the 3-coil mirror noise suppression transformer is grounded, so that the 3-coil mirror noise suppression transformer converts the single-ended signal into a differential signal.

6. The compact low-noise frequency converter receiver circuit as described in claim 1, characterized in that, In the coupled resonant cavity formed by the L1 inductor, the L3 inductor, and the terminating capacitor Ci, noise at the mirror frequency flows into the terminating capacitor Ci, thus preventing the mixer from being affected by noise and causing the noise figure of the receiving circuit to deteriorate.

7. The compact low-noise frequency converter receiver circuit as described in claim 1, characterized in that, The upper half of the figure-eight inductor used in the L3 inductor is inside the multi-turn coil of the L1 inductor, so that the time-varying magnetic field in the L3 inductor passes through the overlapping part of the L3 and L1 inductors, forming the coupling coefficient between the L1 and L3 inductors.

8. The compact low-noise frequency converter receiver circuit as described in claim 1, characterized in that, The L3 inductor uses an "8"-shaped inductor that is entirely inside the L2 inductor, so that the time-varying magnetic field inside the L3 inductor passes through the overlapping part of the L3 and L2 inductors, forming the coupling coefficient between the L2 and L3 inductors.

9. The compact low-noise frequency converter receiver circuit as described in claim 8, characterized in that, When the figure-eight inductor used in the L3 inductor is entirely inside the L2 inductor, the magnetic flux generated by the upper and lower halves of the figure-eight inductor is the same in magnitude but opposite in direction, so that the coupling coefficient between the L2 and L3 inductors is 0.

10. The compact low-noise frequency converter receiver circuit as described in claim 1, characterized in that, An intermediate frequency amplifier is provided between the mixer and the intermediate frequency input terminal.

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