Terahertz low-noise amplifier
By adopting interleaved tuning technology and transconductance enhancement technology in terahertz broadband low-noise amplifiers, the problems of insufficient gain, limited bandwidth coverage and poor noise performance in the prior art are solved, and a high gain, broadband coverage and low noise amplifier design is achieved.
Patent Information
- Application Number
- CN202510123809.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-26
- Publication Date
- 2025-05-23
AI Technical Summary
Existing terahertz broadband low-noise amplifiers have problems such as insufficient gain, limited bandwidth coverage, serious signal transmission loss and prominent parasitic effects, which are difficult to meet the needs of high gain, stability and broadband coverage.
Using interlaced tuning technology and transconductance enhancement technology, the improved transformer coupled transconductance enhancement structure is introduced into the co-radio-coordinated amplification unit, and the interstage matching unit is used to consist of transformers and capacitors, so as to achieve the staggered distribution of gain frequency points of amplifiers at each stage and expand the overall bandwidth.
It significantly improves the gain, bandwidth coverage, noise performance and stability of broadband amplifiers, solves the problems of insufficient gain, limited bandwidth and poor noise performance, and realizes an efficient, stable and superior amplifier design.
Smart Images
Figure CN120034129A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of terahertz technology, and in particular to a terahertz low-noise amplifier. Background Art
[0002] In recent years, as low-frequency spectrum resources are increasingly exhausted, the terahertz band has gradually become a research hotspot, showing great application potential in the fields of communications, imaging, and sensing. In the receiver system, the terahertz broadband low-noise amplifier is a key component that needs to have high gain and broadband coverage to effectively improve signal quality and reduce the noise impact of the subsequent modules. However, since the terahertz frequency is close to the characteristic frequency of the transistor, the gain performance of the amplifier is generally limited.
[0003] In order to improve the gain of terahertz broadband low-noise amplifiers, the existing technology usually adopts a multi-stage amplifier cascade method. However, this solution has significant defects, including poor circuit stability and the inter-stage matching between each stage of amplifiers is often narrow-band, making it difficult to achieve broadband coverage. At the same time, the gain performance of this design is easily affected by process deviations, resulting in the amplifier performance in actual applications being difficult to meet the requirements of high gain and high stability.
[0004] To solve the above problems, some existing research has improved the design of the inter-stage matching network, such as optimizing the inductor and capacitor parameters, to achieve a wider band inter-stage matching characteristic, thereby improving the stability of the gain in a wide frequency range. However, this method can only reduce the process deviation problem of the gain to a certain extent, and the overall stability and gain performance of the circuit still have a large room for improvement, and the signal transmission loss and the instability caused by the multi-band coverage design have not been completely solved.
[0005] In addition, although the current terahertz amplifiers based on III-V semiconductor materials (such as GaAs and InP) have good high-frequency performance, their processes are complex, the manufacturing cost is high, and it is difficult to achieve high integration with digital circuits, which is not suitable for low-cost and large-scale mass production needs. In contrast, amplifiers based on SiGe technology have the advantages of low cost, strong process compatibility and high integration, and are more suitable for large-scale applications. However, the broadband performance of SiGe amplifiers in the terahertz frequency band is still limited, with problems such as insufficient gain, limited bandwidth coverage and large signal loss. At the same time, parasitic effects and frequency selectivity issues further limit their performance in practical applications. Summary of the invention
[0006] In order to solve the problems existing in the above-mentioned prior art, the present invention provides a terahertz low noise amplifier, which solves the problems of insufficient gain, limited bandwidth coverage, serious signal transmission loss and prominent parasitic effects in the prior art, so as to meet the actual application needs of the terahertz frequency band and realize a terahertz broadband low noise amplifier with high gain, high stability and broadband coverage.
[0007] A terahertz low-noise amplifier comprises an input matching unit, a cascode amplification unit and an output matching unit connected in sequence, wherein the cascode amplification unit has multiple stages, and two adjacent stages of the cascode amplification units are connected to each other through an inter-stage matching unit, and the inter-stage matching unit is composed of a combination of a transformer and a capacitor.
[0008] Furthermore, the input matching unit, inter-stage matching unit and output matching unit are tuned to different center frequencies based on the staggered tuning principle, so that the gain frequency points of each cascode amplifier unit are staggered, avoiding the problem of excessive concentration or excessive overlap of gain frequency points.
[0009] The interleaved tuning technology is used to expand the overall bandwidth by dispersing the matching gain peaks of the cascode units at different frequencies. This method avoids the bandwidth limitation problem caused by all gain peaks being concentrated at the same frequency by accurately adjusting the resonance points at each level, thereby achieving a more uniform spectral distribution of the gain. As a result, not only the bandwidth performance of the system is improved, but also the gain flatness of the circuit is improved to a certain extent, so that it exhibits better stability and transmission efficiency within a wide bandwidth. This technology is particularly suitable for RF and high-speed communication systems with high bandwidth and high gain requirements.
[0010] Furthermore, the common emitter common base amplifier unit adopts an improved transformer coupled transconductance enhancement structure, and the improved transformer coupled transconductance enhancement structure includes a common base tube, and the base of the common base tube is connected in series with a capacitor C g , the capacitor C g Less than 100fF.
[0011] Furthermore, the compositive emitter and compositive base amplification unit comprises a compositive base tube M 1 And common base tube M 3 The first compositive compositive subunit and the compositive base tube M 2 And common base tube M 4 The second cascode subunit is composed of the common emitter and the common base tube M in the first cascode subunit. 1 Collector and common base tube M 3 The emitters are connected with mutual coupling inductance Ls, and the base tube M 3 The base of g and mutual coupling inductance L gThe first cascode subunit and the second cascode subunit have the same structure and are symmetrically arranged, M 1 With M 2 The base of M is the input. 3 With M 4 The collector of is the output.
[0012] The transconductance enhancement structure is used to construct negative feedback between the base and the emitter, increasing the voltage swing between the base and the emitter, thereby increasing the equivalent transconductance. This is mainly achieved through the inductance L between the source of the common emitter tube and the common base tube. s Coupling voltage to the base inductance L of the common base tube g Compared with the traditional transformer coupling structure, this adopts an improved structure, in which a capacitor C of tens of fF is connected in series with the base of the common base tube. g , which weakens the transformer's low-frequency feedback effect and effectively improves the stability of the low frequency. Transformer coupling introduces a feedback path. The stability of the circuit at low frequency is relatively poor, and the transformer's coupling coefficient is higher at low frequency. That is to say, the strong coupling introduced by the transformer at low frequency will make the circuit more unstable. Connect a small capacitor C in series with the base. g , which can isolate the coupling effect of low-frequency signals, thereby reducing the gain of the feedback loop in the low-frequency band and improving the low-frequency stability. At the same time, in the high-frequency band required for the circuit to work, the signal gain will not be significantly attenuated due to the weakened isolation effect of the capacitor. Therefore, this design not only solves the stability problem in the low-frequency band, but also ensures the normal gain in the high-frequency band.
[0013] Furthermore, the cascode amplifier unit has five stages, and a first inter-stage matching unit, a second inter-stage matching unit, a third inter-stage matching unit, and a fourth inter-stage matching unit are sequentially arranged between each stage of the cascode amplifier unit.
[0014] Furthermore, the input matching unit and the output matching unit adopt a combination structure of a self-shielding balun and a DC blocking capacitor.
[0015] The beneficial effects of the present invention include:
[0016] The present invention innovatively solves the problems of insufficient gain, limited bandwidth coverage, poor noise performance and poor circuit stability of existing broadband amplifiers by combining transconductance enhancement technology and interleaved tuning technology.
[0017] Transconductance enhancement technology improves the equivalent transconductance by introducing negative feedback between the base and emitter of the transistor, significantly improving gain and reducing noise without increasing power consumption, while optimizing the low-gain performance of the common-base amplifier. The improved transformer coupling design further enhances low-frequency stability and maintains high gain performance in the high-frequency range, improving the overall stability and consistency of the circuit. Interleaved tuning technology achieves uniform gain coverage in a wide frequency range by staggering the maximum gain frequency points of multi-stage amplifiers, improves bandwidth flatness, and effectively reduces the impact of inter-stage interference and parasitic effects. The combined application of these two technologies significantly improves the gain, bandwidth coverage, noise performance and stability of broadband amplifiers, providing an efficient, stable and high-performance solution for the practical application of broadband amplifiers. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 This is a module diagram of a terahertz low-noise amplifier involved in an embodiment of the present application.
[0019] Figure 2 This is a circuit structure diagram of a terahertz low noise amplifier involved in an embodiment of the present application.
[0020] Figure 3 It is a schematic diagram of an improved transformer-coupled transconductance enhancement structure involved in an embodiment of the present application.
[0021] Figure 4 This is a terahertz low-noise amplifier layout involved in an embodiment of the present application.
[0022] Figure 5 This is a measured S parameter diagram of a terahertz low noise amplifier involved in an embodiment of the present application.
[0023] Figure 6 This is a diagram of the measured noise coefficient of a terahertz low-noise amplifier involved in an embodiment of the present application. DETAILED DESCRIPTION
[0024] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.
[0025] Example 1
[0026] A terahertz low noise amplifier, such as Figure 1 As shown, it includes an input matching unit, a cascode amplifier unit, a first interstage matching unit, a second interstage matching unit, a third interstage matching unit, a fourth interstage matching unit and an output matching unit. As shown in the schematic diagram, after the RF signal enters from the input end, it passes through the input matching unit, the cascode amplifier unit, the first interstage matching unit, the cascode amplifier unit, the second interstage matching unit, the cascode amplifier unit, the third interstage matching unit, the cascode amplifier unit, the fourth interstage matching unit, and the cascode amplifier unit in sequence, and then reaches the output matching unit.
[0027] like Figure 2 As shown in FIG. 1 , the circuit topology mainly consists of an input matching unit, a five-stage cascode amplifier unit, four groups of interstage matching units and an output matching unit. The input matching unit adopts a combination structure of a self-shielded balun and a DC-blocking capacitor to complete the impedance matching from the RF input GSG to the input of the first-stage cascode amplifier unit. The self-shielded balun can not only achieve impedance matching efficiently, but also significantly reduce the energy loss caused by RF signal leakage, further improving the circuit performance. The cascode amplifier unit is designed based on an improved transformer-coupled transconductance enhancement structure. This structure not only significantly improves the gain of the amplifier unit, but also effectively enhances the low-frequency stability, ensuring the reliability and performance consistency of the circuit. The interstage matching unit is composed of a combination of a transformer and a capacitor, which is used for matching and signal transmission between the first to fifth stage amplifier units, ensuring efficient coupling and energy transfer between each stage. The output matching unit is also composed of a self-shielded balun and a DC-blocking capacitor to achieve impedance matching from the output of the last stage cascode amplifier unit to the RF output GSG. The use of the self-shielded balun not only further optimizes the matching effect, but also effectively reduces the signal loss caused by RF leakage. In addition, in order to expand the bandwidth, the entire amplifier adopts a design strategy in which the gain peak of the multi-stage common emitter and common base amplifier unit is matched at different frequencies. Through the above structural optimization design, the circuit performs well in gain improvement, bandwidth expansion, low-frequency stability and RF loss control, and has good comprehensive performance and practical value.
[0028] Figure 3 It is a common emitter and base amplifier unit designed based on an improved transformer-coupled transconductance enhancement structure. It consists of two groups of common emitter and base structures, respectively composed of M 1 and M 3 The first cascode unit composed of M 2 and M 4 The second common emitter common base unit, the mutual coupling inductance L existing in the common emitter common base tube base and emitter of the common emitter common base structure g With L s , and the common base tube capacitance C g . There is M 1 With M2 The base of M is the input. 3 With M 4 The collector of is the output.
[0029] The principle of the transconductance enhancement structure is to build negative feedback between the base and the emitter, increase the voltage swing between the base and the emitter, and thus increase the equivalent transconductance. This is mainly achieved through the inductance L between the source of the common emitter tube and the common base tube. s Coupling voltage to the base inductance L of the common base tube g Compared with the traditional transformer coupling structure, this design adopts an improved structure, in which a capacitor C of tens of fF is connected in series with the base of the common base tube. g , which weakens the transformer's low-frequency feedback effect and effectively improves the stability of the low frequency. Transformer coupling introduces a feedback path. The stability of the circuit at low frequency is relatively poor, and the transformer's coupling coefficient is higher at low frequency. That is to say, the strong coupling introduced by the transformer at low frequency will make the circuit more unstable. Connect a small capacitor C in series with the base. g , which can isolate the coupling effect of low-frequency signals, thereby reducing the gain of the feedback loop in the low-frequency band and improving the low-frequency stability. At the same time, in the high-frequency band required for the circuit to work, the signal gain will not be significantly attenuated due to the weakened isolation effect of the capacitor. Therefore, this design not only solves the stability problem in the low-frequency band, but also ensures the normal gain in the high-frequency band.
[0030] Interleaved tuning technology achieves the purpose of expanding the overall bandwidth by dispersing the matching gain peaks of the cascode units at different frequencies. This method avoids the bandwidth limitation problem caused by all gain peaks being concentrated at the same frequency by accurately adjusting the resonance points at each level, thereby achieving a more uniform spectral distribution of the gain. As a result, not only the bandwidth performance of the system is improved, but also the gain flatness of the circuit is improved to a certain extent, so that it exhibits better stability and transmission efficiency within a wide bandwidth. This technology is particularly suitable for RF and high-speed communication systems with high bandwidth and high gain requirements.
[0031] The final design layout is as follows Figure 4 As shown in the figure, the chip is 1mm long, 0.8mm wide and has an area of 0.8mm2. In order to eliminate the adverse effects of static electricity on the LNA chip, ESD is added to the four corners of the chip and the base feed pad. In order to ensure a good grounding effect for the entire chip, a ground pad is added between the feed pads.
[0032] The final test results are as follows Figure 5-6As shown, the designed LNA is stable over the entire frequency band. Within 170-230GHz, the noise figure is 11.2-15dB, the gain range is 18.6-23.2dB, and the S22 is basically less than -5dB. From the simulation results, it can be obtained that the 6dB gain band is approximately 170-230GHz, and the bandwidth is approximately 60GHz.
[0033] The above-mentioned embodiments only express the specific implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the protection scope of the present application. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the technical solution concept of the present application, and these all belong to the protection scope of the present application.
Claims
1. A terahertz low noise amplifier, characterized in that: It comprises an input matching unit, a cascode amplification unit and an output matching unit connected in sequence. The cascode amplification unit has multiple stages. Two adjacent cascode amplification units are connected to each other through an inter-stage matching unit. The inter-stage matching unit is composed of a transformer and a capacitor.
2. A terahertz low noise amplifier according to claim 1, characterized in that: The input matching unit, the inter-stage matching unit and the output matching unit are tuned to different center frequencies based on the staggered tuning principle, so that the gain frequency points of each cascode amplification unit are staggered.
3. The terahertz low noise amplifier according to claim 1, characterized in that: The common-emitter common-base amplifier unit adopts an improved transformer-coupled transconductance enhancement structure, which includes a common-base tube, the base of which is connected in series with a capacitor C g , the capacitor C g Less than 100fF.
4. A terahertz low noise amplifier according to claim 3, characterized in that: The cascode amplifier unit comprises a first cascode subunit consisting of a cascode tube M1 and a cascode tube M3 and a second cascode subunit consisting of a cascode tube M2 and a cascode tube M4. In the first cascode subunit, a mutual coupling inductor Ls is connected between the collector of the cascode tube M1 and the emitter of the cascode tube M3, and a capacitor C is connected to the base of the cascode tube M3 in sequence. g and mutual coupling inductance L g The first cascode subunit and the second cascode subunit have the same structure and are symmetrically arranged, the bases of M1 and M2 are inputs, and the collectors of M3 and M4 are outputs.
5. The terahertz low noise amplifier according to claim 1, characterized in that: The cascode amplifier unit has five stages, and a first inter-stage matching unit, a second inter-stage matching unit, a third inter-stage matching unit, and a fourth inter-stage matching unit are sequentially arranged between the cascode amplifier units.
6. The terahertz low noise amplifier according to claim 1, characterized in that: The input matching unit and the output matching unit adopt a combined structure of a self-shielding balun and a DC-isolating capacitor.