A new broadband terahertz CMOS low-noise amplifier

Abstract

The present invention discloses a novel broadband terahertz CMOS low-noise amplifier, belonging to the field of integrated circuit technology. The invention comprises a bias device, an on-chip transformer, a transformer with an equivalent low coupling coefficient in a T-shaped inductor structure, and an operational amplifier. The bias device is used for feeding power and serves as the input end of the amplifier circuit for power supply. The on-chip transformer is used to increase gain, expand the tuning range, and reduce power consumption. The transformer with an equivalent low coupling coefficient in the T-shaped inductor structure functions equivalently to the on-chip transformer and is used to further reduce the insertion loss of the matching network and increase the circuit gain. The operational amplifier is used for impedance transformation. The bias device is connected to the operational amplifier. The on-chip transformer is connected to the operational amplifier. The operational amplifier is connected to the transformer with an equivalent low coupling coefficient in the T-shaped inductor structure.

Description

Technical Field

[0001] The present invention relates to the technical field of integrated circuits, and in particular to a novel broadband terahertz CMOS low-noise amplifier. Background Art

[0002] A low-noise amplifier (LNA) is an amplifier with a very low noise figure. It is commonly used as a high-frequency or intermediate-frequency preamplifier in various radio receivers, as well as in the amplification circuits of highly sensitive electronic detection equipment. When amplifying weak signals, the amplifier's own noise can significantly interfere with the signal, so it is desirable to reduce this noise to improve the output signal-to-noise ratio.

[0003] Traditional low-noise amplifiers (LNAs) used in communications systems have narrow bandwidths and low frequencies, while terahertz LNAs require wide bandwidths and high frequencies, making their design significantly more challenging. Traditional terahertz LNAs typically employ a sampling transmission line structure and are single-ended. This structure suffers from low gain and a large footprint. Furthermore, traditional terahertz LNAs typically utilize SiGe technology, which is a disadvantage in terms of high cost.

[0004] Low-noise amplifiers based on transmission line structures using SiGe technology typically require transmission lines with lengths approaching 1 / 4 to 1 / 2 wavelengths. This length of transmission line requires a surface area three to four times that of an inductor or transformer with equivalent matching performance. Therefore, the area of ​​a low-noise amplifier based on transmission line matching is much larger than that of an inductor-matched low-noise amplifier. Furthermore, the Q factor of the transmission line is generally less than 5, sometimes as low as 2, which reduces the gain of the low-noise amplifier based on transmission line matching.

[0005] For broadband low-noise amplifiers, a transformer with a low coupling coefficient is required. However, a transformer with a low coupling coefficient will lead to a relatively higher insertion loss. Therefore, this design proposes an equivalent low-coupling-coefficient transformer based on a T-type inductor structure to increase the gain. Summary of the Invention

[0006] The object of the present invention is to provide a novel broadband terahertz CMOS low-noise amplifier to solve the problems raised in the above background technology.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions: a novel broadband terahertz CMOS low-noise amplifier, the amplifier comprising a bias device, an on-chip transformer, a transformer with an equivalent low coupling coefficient of a T-type inductor structure, and an operational amplifier;

[0008] According to the above technical solution, the bias device is used for feeding power and serves as the input end of the amplifier circuit for power supply; the on-chip transformer is used to increase gain, expand tuning range and reduce power consumption; the T-shaped inductor structure with an equivalent low coupling coefficient transformer has the same function as the on-chip transformer and is used to further reduce the insertion loss of the matching network and increase the circuit gain; the operational amplifier is used for impedance transformation;

[0009] According to the above technical solution, the bias device is connected to the operational amplifier; the on-chip transformer is connected to the operational amplifier; and the operational amplifier is connected to a transformer with an equivalent low coupling coefficient of a T-shaped inductor structure.

[0010] According to the above technical solution, the on-chip transformer includes a primary coil and a secondary coil;

[0011] According to the above technical solution, the primary coil and the secondary coil are connected in parallel on the same side.

[0012] According to the above technical solution, the voltage of the on-chip transformer is calculated as follows:

[0013] V1=jωL1I1+jωMI2

[0014] Where V1 is the voltage of the on-chip transformer; L1 is the inductance of the primary coil; I1 is the current of the primary coil; I2 is the current of the secondary coil; M is the mutual inductance coefficient between the primary coil and the secondary coil; j is the imaginary unit; and ω is the angular velocity.

[0015] According to the above technical solution, the voltage of the equivalent low coupling coefficient transformer of the T-type inductor structure is calculated as follows:

[0016] V2=jω(L1-M)I1+jωM(I1+I2)=jωL1I1+jωMI2

[0017] Wherein, V2 is the equivalent voltage of the transformer with an equivalent low coupling coefficient of the T-type inductor structure.

[0018] Because V1 = jωL1I1 + jωMI2 = V2, it can provide an equivalent voltage. Therefore, the equivalent low-coupling-coefficient transformer of the T-type inductor structure can provide an equivalent effect to the on-chip transformer and can be replaced.

[0019] According to the above technical solution, the coupling coefficient of the equivalent low-coupling-coefficient transformer of the T-shaped inductor structure ranges from 0.2 to 0.95, which is a variable that can be flexibly designed.

[0020] Therefore, the on-chip transformer equivalent circuit and the on-chip transformer T-type matching structure circuit are equivalent. Therefore, it can be seen that the T-type inductor of the equivalent transformer has the same function as the traditional on-chip transformer. At the same time, it overcomes the defect of large coupling capacitance between the primary and secondary coils of the traditional transformer, thereby greatly improving the self-resonant frequency of the T-type inductor of the equivalent transformer. The large coupling coefficient between the primary and secondary coils of the traditional transformer cannot be designed separately and is a parasitic parameter parasitic on the primary and secondary coils. The coupling coefficient of the T-type inductor of the equivalent transformer (usually the coupling coefficient k ranges from 0.5 to 0.95, while the coupling coefficient of the T-type inductor of the equivalent transformer can range from 0.2 to 0.95) is a variable that can be flexibly designed, and therefore can be flexibly applied to the circuit design of broadband terahertz CMOS low-noise amplifiers.

[0021] According to the above technical solution, the inductance Q value of the transformer with an equivalent low coupling coefficient of the T-shaped inductor structure is greater than 10 and less than 20.

[0022] Inductance is a property of a conductor, measured as the ratio of the electromotive force (EMF) or voltage induced in the conductor to the rate of change of the current that produces this voltage. A steady current produces a stable magnetic field, while a changing current (AC) or fluctuating DC produces a changing magnetic field. This changing magnetic field, in turn, induces an electromotive force in the conductor within this field. The magnitude of the induced EMF is proportional to the rate of change of the current, and the proportionality factor is called inductance.

[0023] Inductance is a property of a closed circuit, generally divided into self-inductance and mutual inductance. That is, when the current through a closed circuit changes, an electromotive force will appear to resist the change in current. This inductance is called self-inductance and is a property of the closed circuit itself. If the current in one closed circuit changes, an electromotive force is generated in the other closed circuit due to induction. This inductance is called mutual inductance.

[0024] When two inductors are close to each other, the change in the magnetic field of one inductor will affect the other inductor. This influence is mutual inductance, and the magnitude of the mutual inductance depends on the self-inductance of the inductor and the degree of coupling between the two inductors.

[0025] The inductor Q value, also known as the quality factor of the inductor, is the main parameter for measuring inductor components. It refers to the ratio of the inductive reactance to its equivalent loss resistance when the inductor operates under an AC voltage of a certain frequency. The higher the Q value of the inductor, the smaller its loss and the higher its efficiency.

[0026] However, for low-noise amplifiers based on transmission line structures using SiGe technology, the Q value of the transmission line is generally less than 5, or even as low as around 2, which will reduce the gain of the low-noise amplifier based on the transmission line; therefore, after increasing the Q value of the inductor, the efficiency can be fully improved. Therefore, this design proposes an equivalent low-coupling coefficient transformer based on a T-type inductor structure. Compared with the Q value of the transmission line, the Q value of the on-chip inductor is generally more than 10, and the maximum can be close to 20. The equivalent low-coupling coefficient transformer of the T-type inductor structure is different from the electromagnetic field coupling of the transformer. Its direct connection characteristics can reduce the insertion loss of its matching network.

[0027] The quality factor describes the ratio of a circuit's energy storage to its energy consumption per cycle. The product of the frequency band and the quality factor equals the circuit's resonant frequency. Therefore, while maintaining resonance, the quality factor and the width of the passband are in conflict. Therefore, a higher quality factor isn't always better; it also depends on the required frequency band.

[0028] In frequency selection circuits (selecting a certain frequency), wave blocking circuits (blocking a certain frequency), absorption circuits (attenuating a certain frequency), and wave trap circuits (removing a certain frequency), a certain frequency f is used or removed. In this case, the larger the Q value, the better. This is because the frequency f of the resonant circuit is used. When the LC parallel resonant circuit resonates, the circuit impedance is maximum, which is equivalent to an open circuit, so that the frequency signal of frequency f cannot pass through, achieving the purpose of blocking this signal. When the LC series resonant circuit resonates, the impedance is minimum, which is equivalent to a short circuit. At this time, the frequency of frequency f can easily pass through, while other signal frequencies are blocked, thus achieving the purpose of frequency selection.

[0029] In this design, the T-shaped inductor structure's equivalent low-coupling transformer differs from the transformer's electromagnetic field coupling. Its direct connection reduces insertion loss in the matching network. Compared to traditional transformers, the T-shaped inductor structure's equivalent low-coupling transformer maintains a self-resonant frequency greater than 200 GHz even when its single inductance reaches 100 pH, making it suitable for terahertz circuit design.

[0030] Terahertz waves refer to electromagnetic waves with a frequency range of 0.1 to 10 THz (wavelength of 3000 to 30 μm). They coincide with millimeter waves in the long wave band and with infrared light in the short wave band. They are the transition zone from macroscopic classical theory to microscopic quantum theory, and also the transition zone from electronics to photonics. They are called the "terahertz gap" of the electromagnetic spectrum.

[0031] Terahertz waves cover the characteristic spectra of semiconductors, plasmas, organisms, and biomacromolecules. Utilizing this frequency band can deepen and expand our understanding of fundamental scientific issues in physics, chemistry, astronomy, informatics, and life sciences. Terahertz technology has broad applications in radar, remote sensing, homeland security and counterterrorism, highly secure data communications and transmission, atmospheric and environmental monitoring, real-time bioinformatics extraction, and medical diagnostics.

[0032] Terahertz communication can achieve wireless transmission speeds of 10 GB / s, particularly for satellite communications. Because the near-vacuum state of outer space eliminates the effects of moisture, this technology is hundreds to over a thousand times faster than current ultra-wideband technology. This enables terahertz communication to achieve highly secure satellite communications at extremely high bandwidths. This invention can be applied to terahertz amplifier circuits, providing significant benefits to the national economy and security.

[0033] According to the above technical solution, when the single inductance value in the transformer with an equivalent low coupling coefficient of the T-shaped inductor structure reaches 100pH, the self-resonant frequency is greater than 200 GHz.

[0034] According to the above technical solution, in the amplifier, the input and output stages use traditional on-chip transformers to convert single-ended signals into differential signals.

[0035] According to the above technical solution, high-frequency inductors can form a matching network together with capacitors in the circuit to eliminate the impedance mismatch between the device and the transmission line and reduce reflection and loss; they can also form an LC filter together with capacitors to filter out some unwanted frequency components to prevent interference with the operation of the device; in active RF circuits such as PA, they can isolate the RF signal from the DC bias and DC power supply; together with capacitors, they form an LC oscillation circuit as the oscillation source of the VCO; they can also form an LC balun together with capacitors to realize the conversion between single-ended RF signals and differential signals.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] 1. The present invention utilizes a T-type inductor structure to effectively improve the inductor Q value. Moreover, the equivalent low coupling coefficient transformer of the T-type inductor structure is different from the electromagnetic field coupling of the transformer. Its direct connection characteristic can reduce the insertion loss of its matching network, thereby improving the circuit gain.

[0038] 2. The equivalent low-coupling-coefficient transformer with a T-shaped inductor structure of the present invention has a self-resonant frequency greater than 200 GHz when its single inductance reaches 100 pH. However, when the primary and secondary inductances of a conventional transformer approach 100 pH, the self-resonant frequency of the transformer will be reduced to less than 150 GHz. Therefore, the present invention can be used in terahertz amplifier circuits.

[0039] 3. The low-coupling-coefficient equivalent transformer with a T-shaped inductor structure of the present invention has equivalent functionality to a conventional on-chip transformer. It also overcomes the drawback of the large coupling capacitance between the primary and secondary coils of conventional transformers, thereby significantly increasing the self-resonant frequency of the T-shaped inductor of the equivalent transformer.

[0040] 4. The coupling coefficient of the equivalent low-coupling-coefficient transformer with a T-type inductor structure of the present invention can range from 0.2 to 0.95 and can be flexibly designed. In contrast, the large coupling coefficient between the primary and secondary coils of a conventional transformer cannot be designed independently and is a parasitic parameter of the primary and secondary coils. Therefore, the present invention is more complete and comprehensive.

[0041] 5. The present invention can be applied to the design of terahertz circuits. Terahertz communication can perform highly secure satellite communication with extremely high bandwidth. Moreover, since terahertz energy is very small and will not cause damage to matter, the present invention can provide a basis for terahertz circuit design. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0043] Figure 1 This is a circuit diagram of a novel broadband terahertz CMOS low-noise amplifier of the present invention;

[0044] Figure 2 This is a layout of a T-type inductor of a novel broadband terahertz CMOS low-noise amplifier of the present invention;

[0045] Figure 3 This is a schematic diagram of an on-chip transformer of a novel broadband terahertz CMOS low-noise amplifier of the present invention;

[0046] Figure 4 This is a schematic diagram of an equivalent low-coupling-coefficient transformer of a T-shaped inductor structure of a novel broadband terahertz CMOS low-noise amplifier of the present invention. DETAILED DESCRIPTION

[0047] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0048] See also Figure 1-4 , the present invention provides a technical solution: Figure 1As shown, a novel broadband terahertz CMOS low-noise amplifier includes a bias tee, an on-chip transformer, an equivalent low-coupling-coefficient transformer of a T-type inductor structure, and an operational amplifier.

[0049] The bias tee is used for feeding power and serves as the input end of the amplifier circuit for power supply; the on-chip transformer is used to increase gain, expand tuning range and reduce power consumption; the T-shaped inductor structure with an equivalent low coupling coefficient transformer has the same function as the on-chip transformer and is used to further reduce the insertion loss of the matching network and increase the circuit gain; the operational amplifier is used for impedance transformation;

[0050] The bias device is connected to the operational amplifier; the on-chip transformer is connected to the operational amplifier; and the operational amplifier is connected to a transformer with an equivalent low coupling coefficient of a T-shaped inductor structure.

[0051] The on-chip transformer includes a primary coil and a secondary coil;

[0052] The primary coil and the secondary coil are connected in parallel on the same side.

[0053] The voltage of the on-chip transformer is calculated as follows:

[0054] V1=jωL1I1+jωMI2

[0055] Where V1 is the voltage of the on-chip transformer; L1 is the inductance of the primary coil; I1 is the current of the primary coil; I2 is the current of the secondary coil; M is the mutual inductance coefficient between the primary coil and the secondary coil; j is the imaginary unit; and ω is the angular velocity.

[0056] The voltage calculation method of the equivalent low coupling coefficient transformer of the T-type inductor structure is as follows:

[0057] V2=jω(L1-M)I1+jωM(I1+I2)=jωL1I1+jωMI2

[0058] Wherein, V2 is the equivalent voltage of the transformer with an equivalent low coupling coefficient of the T-type inductor structure.

[0059] The coupling coefficient of the equivalent low-coupling-coefficient transformer of the T-shaped inductor structure ranges from 0.2 to 0.95, and is a variable that can be flexibly designed.

[0060] The inductance Q value of the transformer with an equivalent low coupling coefficient of the T-shaped inductor structure is greater than 10 and less than 20.

[0061] When the single inductance value of the transformer with an equivalent low coupling coefficient of the T-shaped inductor structure reaches 100 pH, the self-resonant frequency is greater than 200 GHz.

[0062] In this amplifier, the input and output stages use conventional on-chip transformers to convert single-ended signals into differential signals.

[0063] In this embodiment:

[0064] A transformer with an equivalent low coupling coefficient and an on-chip transformer with a T-type inductor structure are provided, and voltage calculations are performed on the transformers under the two structures;

[0065] The on-chip transformer includes a primary coil and a secondary coil;

[0066] The primary coil and the secondary coil are connected in parallel on the same side.

[0067] The voltage of the on-chip transformer is calculated as follows:

[0068] V1=jωL1I1+jωMI2

[0069] Where V1 is the voltage of the on-chip transformer; L1 is the inductance of the primary coil; I1 is the current of the primary coil; I2 is the current of the secondary coil; M is the mutual inductance coefficient between the primary coil and the secondary coil; j is the imaginary unit; and ω is the angular velocity.

[0070] The voltage of the equivalent low coupling coefficient transformer of the T-type inductor structure is calculated as follows:

[0071] V2=jω(L1-M)I1+jωM(I1+I2)=jωL1I1+jωMI2

[0072] Wherein, V2 is the equivalent voltage of the transformer with an equivalent low coupling coefficient of the T-type inductor structure;

[0073] Therefore, it can be concluded that V1=jωL1I1+jωMI2=V2;

[0074] It can be seen that the on-chip transformer equivalent circuit and the equivalent low-coupling-coefficient transformer circuit of the T-type inductor structure are equivalent, that is, the T-type inductor of the equivalent transformer has the same function as the traditional on-chip transformer. Therefore, it is applied to the circuit design of broadband terahertz CMOS low-noise amplifier.

[0075] The coupling coefficient in the transformer with an equivalent low coupling coefficient of the T-type inductor structure is set to 0.5; the inductance Q value in the transformer with an equivalent low coupling coefficient of the T-type inductor structure is 15; and when the single inductance value in the transformer with an equivalent low coupling coefficient of the T-type inductor structure reaches 100pH, the self-resonant frequency is greater than 200GHz.

[0076] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0077] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A novel broadband terahertz CMOS low-noise amplifier, characterized by: The amplifier includes a bias device, an on-chip transformer, an equivalent low-coupling-coefficient transformer of a T-type inductor structure, and an operational amplifier; The bias device is used for feeding power and serves as the input end of the amplifier circuit for power supply; The on-chip transformer is used to increase gain, expand tuning range and reduce power consumption; the T-shaped inductor structure with an equivalent low coupling coefficient transformer is equivalent to the on-chip transformer and is used to further reduce the insertion loss of the matching network and increase the circuit gain; the operational amplifier is used to perform impedance transformation; The bias device is connected to an operational amplifier; the on-chip transformer is connected to the operational amplifier; the operational amplifier is connected to a transformer with an equivalent low coupling coefficient of a T-type inductor structure; The on-chip transformer includes a primary coil and a secondary coil; The T-type inductor structure refers to the inductance values ​​of 、 The two inductors, the mutual inductance of the primary coil and the secondary coil form a T-shaped structure, where Refers to the inductance of the primary coil; Refers to the inductance of the secondary coil; Refers to the mutual inductance between the primary coil and the secondary coil.

2. The novel broadband terahertz CMOS low-noise amplifier according to claim 1, characterized in that: The primary coil and the secondary coil are connected in parallel on the same side.

3. The novel broadband terahertz CMOS low-noise amplifier according to claim 2, characterized in that: The voltage of the on-chip transformer is calculated as follows: ； in, is the voltage of the on-chip transformer; is the current of the primary coil; is the current of the secondary coil; is an imaginary unit; is the angular velocity.

4. The novel broadband terahertz CMOS low-noise amplifier according to claim 3, characterized in that: The voltage calculation method of the equivalent low coupling coefficient transformer of the T-type inductor structure is as follows: ； in, It is the equivalent voltage of the transformer with low coupling coefficient and T-type inductor structure.

5. The novel broadband terahertz CMOS low-noise amplifier according to claim 1, characterized in that: The coupling coefficient of the transformer with an equivalent low coupling coefficient of the T-type inductor structure ranges from 0.2 to 0.95, which is a variable for flexible design.

6. The novel broadband terahertz CMOS low-noise amplifier according to claim 1, characterized in that: The inductance Q value of the transformer with an equivalent low coupling coefficient of the T-shaped inductor structure is greater than 10 and less than 20.

7. The novel broadband terahertz CMOS low-noise amplifier according to claim 1, characterized in that: When the single inductance value of the transformer with an equivalent low coupling coefficient of the T-shaped inductor structure reaches 100 pH, the self-resonant frequency is greater than 200 GHz.

8. The novel broadband terahertz CMOS low-noise amplifier according to claim 1, characterized in that: In this amplifier, the input and output stages use conventional on-chip transformers to convert single-ended signals into differential signals.

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