Multistage cascaded amplifier circuit and system

Abstract

The invention provides a multi-stage cascaded amplifier circuit and system. A load of each cascaded single-stage amplifier in the circuit comprises a first inductor, an adjustable capacitor and an adjustable resistor which are connected in parallel; the adjustable resistor is used for adjusting gain; the first single-stage amplifier is tuned to a frequency point lower limit value of a preset working frequency range, and the second single-stage amplifier is tuned to a frequency point upper limit value; other single-stage amplifiers are tuned to a first frequency point; wherein the first frequency point is a frequency point between the frequency point lower limit value and the frequency point upper limit value. In the circuit, a load of each single-stage amplifier comprises a first inductor, an adjustable capacitor and an adjustable resistor which are connected in parallel, the capacitor in the load of each single-stage amplifier is set to be the adjustable capacitor, and the resistor is set to be the adjustable resistor, so that the purposes that the resonance point of the single-stage amplifier is adjustable and the gain is adjustable can be achieved; a plurality of single-stage amplifiers are cascaded, so that each single-stage amplifier resonates at different frequency points, and the purpose of broadband is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of integrated circuits, and in particular to a multi-stage cascade amplifier circuit and system. Background Art

[0002] In a general receiver RF link with high gain requirements, there will be multi-stage amplifiers including LNA (Low Noise Amplifier). The load of the amplifier is usually a parallel LCR link. LC tank has the characteristics of narrowband. Multi-stage amplifiers are cascaded, and the load LC tank resonates at the same operating frequency, which will have a narrower bandwidth than a single-stage amplifier. Such a structure often cannot meet the technical indicators of broadband. In related technologies, in order to increase the bandwidth, a low-Q resistor is usually connected in parallel to the load LC to achieve the purpose of broadband, but this is at the expense of gain; or broadband can be achieved through multi-stage transformer coupling, but this method consumes a large chip area. In summary, when the bandwidth requirements of the link are high, the related technology lacks an effective solution. Summary of the invention

[0003] The object of the present invention is to provide a multi-stage cascade amplifier circuit and system to achieve the purpose of broadband.

[0004] The present invention provides a multi-stage cascade amplifier circuit, in which a plurality of single-stage amplifiers are cascaded; the load of each single-stage amplifier comprises a first inductor, an adjustable capacitor and an adjustable resistor connected in parallel with each other; the adjustable resistor is used to adjust the gain; wherein, among the plurality of single-stage amplifiers, the first single-stage amplifier is tuned to a frequency lower limit value of a preset working frequency range, and the second single-stage amplifier is tuned to a frequency upper limit value of the preset working frequency range; each of the other single-stage amplifiers except the first single-stage amplifier and the second single-stage amplifier is tuned to a first frequency point; wherein the first frequency point is a frequency point between the frequency lower limit value and the frequency upper limit value.

[0005] Furthermore, among the multiple single-stage amplifiers, the first-stage single-stage amplifier is a low-noise amplifier.

[0006] Furthermore, each of the single-stage amplifiers except the first-stage single-stage amplifier is a radio frequency amplifier.

[0007] Furthermore, the first frequency points corresponding to each other single-stage amplifier are different.

[0008] Furthermore, the first frequency points corresponding to each other single-stage amplifier are evenly distributed within the frequency lower limit value and the frequency upper limit value.

[0009] Furthermore, for each single-stage amplifier, the operating frequency of the single-stage amplifier is adjusted by adjusting the adjustable capacitor in the single-stage amplifier.

[0010] Furthermore, for each single-stage amplifier, the gain of the single-stage amplifier is adjusted by adjusting an adjustable resistor in the single-stage amplifier.

[0011] Furthermore, by adjusting the gain of each single-stage amplifier, the overall gain of the amplifier circuit within a preset operating frequency range is adjusted.

[0012] Furthermore, the gain flatness of the overall gain of the amplifier circuit within a preset operating frequency range satisfies a preset flatness threshold.

[0013] The present invention provides a multi-stage cascade amplifier system, which includes any one of the multi-stage cascade amplifier circuits described above.

[0014] The multi-stage cascade amplifier circuit and system provided by the present invention have multiple single-stage amplifiers cascaded in the amplifier circuit; the load of each single-stage amplifier includes a first inductor, an adjustable capacitor and an adjustable resistor connected in parallel; the adjustable resistor is used to adjust the gain; wherein, among the multiple single-stage amplifiers, the first single-stage amplifier is tuned to the lower limit value of the frequency point of the preset working frequency range, and the second single-stage amplifier is tuned to the upper limit value of the frequency point of the preset working frequency range; each single-stage amplifier other than the first single-stage amplifier and the second single-stage amplifier is tuned to the first frequency point; wherein the first frequency point is a frequency point between the lower limit value of the frequency point and the upper limit value of the frequency point. In the circuit, the load of each single-stage amplifier includes a first inductor, an adjustable capacitor and an adjustable resistor connected in parallel with each other. By setting the capacitor in the load of each single-stage amplifier as an adjustable capacitor and the resistor as an adjustable resistor, the purpose of adjustable resonance point and adjustable gain of the single-stage amplifier can be achieved. By cascading multiple single-stage amplifiers, each single-stage amplifier resonates at different frequencies, thereby achieving the purpose of broadband. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 A schematic diagram of a multi-stage cascade amplifier circuit provided by an embodiment of the present invention;

[0017] Figure 2 A schematic diagram of an internal circuit structure of a single-stage amplifier provided by an embodiment of the present invention;

[0018] Figure 3A schematic diagram of a multi-stage cascade amplifier circuit provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0019] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] In the related art, when the bandwidth requirement of the link is high, no effective solution has been proposed. Based on this, an embodiment of the present invention provides a multi-stage cascade amplifier circuit and system. This technology can be applied to applications where the link needs to meet different bandwidth requirements.

[0021] To facilitate understanding of this embodiment, a multi-stage cascade amplifier circuit disclosed in an embodiment of the present invention is first introduced. Figure 1 As shown, a plurality of single-stage amplifiers 10 are cascaded in the circuit; the load of each single-stage amplifier 10 includes a first inductor L, an adjustable capacitor C and an adjustable resistor R connected in parallel with each other; the adjustable resistor R is used to adjust the gain; wherein, among the plurality of single-stage amplifiers 10, the first single-stage amplifier is tuned to the lower frequency limit value of the preset working frequency range, and the second single-stage amplifier is tuned to the upper frequency limit value of the preset working frequency range; each of the other single-stage amplifiers except the first single-stage amplifier and the second single-stage amplifier is tuned to the first frequency point; wherein the first frequency point is a frequency point between the lower frequency limit value and the upper frequency limit value.

[0022] The first single-stage amplifier can be any single-stage amplifier among the multiple single-stage amplifiers 10; the second single-stage amplifier can be any single-stage amplifier among the multiple single-stage amplifiers 10 except the first single-stage amplifier; the preset operating frequency range can be set according to actual needs, and the preset operating frequency range can be a wider frequency range or a narrower frequency range; the lower frequency limit can be understood as the minimum frequency value of the preset operating frequency range; the upper frequency limit can be understood as the maximum frequency value of the preset operating frequency range; in actual implementation, the amplifier circuit can be composed of multiple single-stage amplifiers 10 cascaded together, and the internal circuit structure of each single-stage amplifier 10 is usually different, and needs to be designed according to the relevant design indicators of the link. For easy understanding, see Figure 2 A schematic diagram of the internal circuit structure of a single-stage amplifier is shown, wherein the load is the first inductor L, the adjustable capacitor C and the adjustable resistor R connected in parallel with each other in this embodiment; the first circuit modules in different single-stage amplifiers 10 can be designed separately according to different design indicators, for example, the first circuit module can be composed of a bias circuit and a power switch tube, etc.

[0023] The load of each single-stage amplifier 10 includes a first inductor L, an adjustable capacitor C and an adjustable resistor R which are all connected in parallel with each other. The first inductor L in each single-stage amplifier 10 may be the same or different; the adjustable capacitor C and the adjustable resistor R in each single-stage amplifier 10 may be adjusted separately; in actual implementation, the resonance point of each single-stage amplifier 10 can be changed by adjusting the adjustable capacitor C of each single-stage amplifier 10. Specifically, according to the preset operating frequency range obtained, the first single-stage amplifier can be made to resonate at the lower limit value of the frequency point by adjusting the adjustable capacitor of the first single-stage amplifier, and the second single-stage amplifier can be made to resonate at the upper limit value of the frequency point by adjusting the adjustable capacitor of the second single-stage amplifier; for each single-stage amplifier other than the first single-stage amplifier and the second single-stage amplifier, the adjustable capacitor of each other single-stage amplifier can be adjusted respectively so that each other single-stage amplifier resonates at the first frequency point corresponding to each other, and the first frequency point can be any frequency point between the lower limit value of the frequency point and the upper limit value of the frequency point. The first frequency points corresponding to each other single-stage amplifier may be the same or different.

[0024] In the above-mentioned multi-stage cascade amplifier circuit, the load of each single-stage amplifier includes a first inductor, an adjustable capacitor and an adjustable resistor connected in parallel with each other. By setting the capacitor in the load of each single-stage amplifier to an adjustable capacitor and setting the resistor to an adjustable resistor, the purpose of adjustable resonance point and adjustable gain of the single-stage amplifier can be achieved. By cascading multiple single-stage amplifiers, each single-stage amplifier resonates at a different frequency point, thereby achieving the purpose of broadband.

[0025] Furthermore, among the multiple single-stage amplifiers, the first-stage single-stage amplifier is a low-noise amplifier. The low-noise amplifier is a linear amplifier for amplifying low signals, and has the characteristics of high amplification, high gain, and low noise coefficient, and can effectively suppress the influence of external noise. In actual implementation, the low-noise amplifier is used as the first-stage single-stage amplifier, which can realize the amplification function under low noise, and can improve the power of the input signal while suppressing noise interference.

[0026] Furthermore, each single-stage amplifier except the first-stage single-stage amplifier is a radio frequency amplifier. A radio frequency amplifier is a device for amplifying high-frequency signals, which can increase the amplitude of high-frequency signals, thereby enhancing the transmission distance and quality of the signal; in this embodiment, except for the first-stage single-stage amplifier selecting a low-noise amplifier, each other single-stage amplifier can select a radio frequency amplifier, and the internal circuit structure of each radio frequency amplifier is usually different.

[0027] Furthermore, the first frequency points corresponding to each other single-stage amplifier are different. In order to make the overall gain of the multi-stage cascade amplifier circuit present a better flatness in the entire preset operating frequency range, the first frequency points corresponding to each other single-stage amplifier except the first single-stage amplifier and the second single-stage amplifier can be dispersed, that is, the first frequency points corresponding to each other single-stage amplifier are different.

[0028] Furthermore, the first frequency points corresponding to each other single-stage amplifier are evenly distributed within the frequency lower limit and the frequency upper limit. In order to make the overall gain of the multi-stage cascade amplifier circuit present better flatness in the entire preset operating frequency range, the first frequency points corresponding to each other single-stage amplifier except the first single-stage amplifier and the second single-stage amplifier can be evenly dispersed.

[0029] Furthermore, for each single-stage amplifier, the operating frequency of the single-stage amplifier is adjusted by adjusting the adjustable capacitor in the single-stage amplifier; the gain of the single-stage amplifier is adjusted by adjusting the adjustable resistor in the single-stage amplifier. By adjusting the gain of each single-stage amplifier, the overall gain of the amplifier circuit within a preset operating frequency range is adjusted.

[0030] See also Figure 3 A schematic diagram of a multi-stage cascade amplifier circuit is shown. The amplifier circuit takes a three-stage cascade including a low noise amplifier LNA as an example, and includes: a low noise amplifier LNA, a first-stage RF amplifier AMP1 and a second-stage RF amplifier AMP2. The load capacitance of each stage of the amplifier is adjustable. The resonance point of each stage of the amplifier can be changed by adjusting the capacitance value of the capacitor. For example, the low noise amplifier LNA is resonated at the lower limit value of the frequency point in the preset working frequency range, and the first-stage RF amplifier AMP1 is resonated at the upper limit value of the frequency point in the preset working frequency range. In this way, after the first two stages are cascaded, the gain will appear in a double peak shape. Then, the second-stage RF amplifier AMP2 is resonated at the center frequency point. The center frequency point can be obtained by adding and averaging the lower limit value and the upper limit value of the frequency point, so as to make up for the insufficient gain of the center frequency point. In this way, after the three-stage cascade, the overall gain of the amplifier circuit will present a state with good flatness within the entire preset working frequency range.

[0031] In the case of two-stage cascade or multi-stage cascade, the bandwidth can also be improved by adjusting the resonance point of each stage of the amplifier. Although this adjustment staggers the peak point of the gain of each stage of the amplifier and will reduce the gain to a certain extent, since the single-stage gain of each single-stage amplifier can be freely adjusted, the high gain after cascading can be achieved by increasing the gain of each stage of the amplifier. At the same time, the adjustable single-stage gain can also increase the robustness of the circuit. For example, when temperature or batch fluctuations affect the bandwidth of the cascade, the resonance point and gain of each stage of the amplifier can be adjusted to readjust to a state where both the gain and bandwidth meet the design specifications.

[0032] Figure 3 In the case of high bandwidth requirements for links, the resonance points of the multi-stage amplifiers can be adjusted to different frequency points. For example, the low noise amplifier LNA is resonated at the frequency point f0, and the first-stage RF amplifier AMP1 is tuned to the frequency point f2. The gain response after the two-stage cascade is double-peaked, and a pit appears at the center frequency point f1. The second-stage RF amplifier AMP2 is tuned to f1 to make up for the insufficient gain at the center frequency point. The gain flatness after the three-stage cascade is better. If the signal bandwidth of the working mode is narrow, the resonance point of each stage of the amplifier can be adjusted to the same point. In addition, the load resistor of each stage is an adjustable resistor. If the gain of a certain stage is too high or too low, resulting in a narrow bandwidth and poor flatness, for example, the gain at the high frequency point f2 becomes low, the gain of the first-stage RF amplifier AMP1 can be raised by adjusting the load adjustable resistor of the first-stage RF amplifier AMP1, thereby adjusting the bandwidth of the cascade.

[0033] Furthermore, the gain flatness of the overall gain of the amplifier circuit within the preset operating frequency range satisfies a preset flatness threshold. The gain flatness can be understood as the value of the gain "dramatic increase" and "rapid decrease" within the preset operating frequency range, measured in decibels (dB); the flatness threshold can be set according to actual needs. When the above gain flatness satisfies the preset flatness threshold, it can be considered that the gain flatness of the overall gain of the amplifier circuit within the preset operating frequency range is good and can meet the preset flatness design requirements.

[0034] The above-mentioned multi-stage cascade amplifier circuit achieves the purpose of adjustable single-stage resonance point and adjustable gain by making the load capacitance of each single-stage amplifier into an adjustable capacitance matrix and the load resistance into an adjustable resistance matrix. Then, the multi-stage amplifiers are cascaded so that each stage of the amplifier resonates at a different frequency point, thereby achieving the purpose of broadband.

[0035] An embodiment of the present invention further provides a multi-stage cascade amplifier system, the system comprising any of the multi-stage cascade amplifier circuits described above.

[0036] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0037] In addition, each functional unit in the embodiments provided in the present disclosure may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0038] It should be noted that similar numbers and letters represent similar items in the following figures. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description and are not to be understood as indicating or implying relative importance.

[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multi-stage cascade amplifier circuit, characterized in that: The amplifier circuit has a plurality of single-stage amplifiers cascaded in series; the load of each single-stage amplifier includes a first inductor, an adjustable capacitor and an adjustable resistor connected in parallel with each other; the adjustable resistor is used to adjust the gain; Among the multiple single-stage amplifiers, the first single-stage amplifier is tuned to the lower frequency limit of the preset operating frequency range, and the second single-stage amplifier is tuned to the upper frequency limit of the preset operating frequency range; each single-stage amplifier except the first single-stage amplifier and the second single-stage amplifier is tuned to a first frequency point; wherein the first frequency point is a frequency point between the lower frequency limit value and the upper frequency limit value.

2. The amplifier circuit according to claim 1, characterized in that Among the multiple single-stage amplifiers, the single-stage amplifier of the first stage is a low-noise amplifier.

3. The amplifier circuit according to claim 2, characterized in that Each of the other single-stage amplifiers except the first-stage single-stage amplifier is a radio frequency amplifier.

4. The amplifier circuit according to claim 1, characterized in that The first frequency points corresponding to each of the other single-stage amplifiers are different.

5. The amplifier circuit according to claim 1, characterized in that The first frequency points corresponding to each other single-stage amplifier are evenly distributed within the frequency lower limit value and the frequency upper limit value.

6. The amplifier circuit according to claim 1, characterized in that For each single-stage amplifier, the operating frequency of the single-stage amplifier is adjusted by adjusting the adjustable capacitor in the single-stage amplifier.

7. The amplifier circuit according to claim 1, characterized in that For each single-stage amplifier, the gain of the single-stage amplifier is adjusted by adjusting the adjustable resistor in the single-stage amplifier.

8. The amplifier circuit according to claim 1, characterized in that By adjusting the gain of each of the single-stage amplifiers, the overall gain of the amplifier circuit within the preset operating frequency range is adjusted.

9. The amplifier circuit according to claim 1, characterized in that The gain flatness of the overall gain of the amplifier circuit within the preset operating frequency range meets a preset flatness threshold.

10. A multi-stage cascade amplifier system, characterized in that: The system comprises the multi-stage cascaded amplifier circuit according to any one of claims 1-9.

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