A broadband high-gain low-noise amplifier
Through the common source and common gate resistor feedback amplifier structure and buffer stage circuit design, the problem of high gain and low noise coefficient in wide-band matching of low-noise amplifiers is solved, efficient signal amplification and simplified matching network are achieved, and chip cost and area are reduced.
Patent Information
- Application Number
- CN202111600135.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2021-12-24
- Publication Date
- 2025-09-12
- Estimated Expiration
- 2041-12-24
AI Technical Summary
Existing low-noise amplifiers are difficult to achieve both high gain and low noise figure while achieving wideband matching. They also have complex structures and require inductive components and matching networks, which increases chip area and cost.
The cascode resistor feedback amplifier structure is adopted, combined with the buffer stage circuit and the output stage circuit. Through the cascode amplifier and feedback circuit design, high gain and low noise are achieved, the inductor components are eliminated, and the input and output matching networks are simplified.
It achieves high gain and low noise figure in a wide frequency range, reduces chip area and cost, simplifies matching network and improves signal transmission efficiency.
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Figure CN114640313B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of radio frequency signal reception, and in particular to a broadband high-gain low-noise amplifier. Background Art
[0002] With the continuous development of the wireless communications industry, the use of wireless communication devices is becoming increasingly widespread, encompassing fields such as Beidou navigation, healthcare, smart homes, and engineering construction. To meet the needs and demands of diverse applications, mobile terminals are becoming increasingly multifunctional, integrated, and miniaturized. Because different wireless communication standards vary across applications, multiple frequency bands are often required for transmission and reception, making the frequency bandwidth of RF transceivers a key focus of discussion.
[0003] The low-noise amplifier is at the forefront of the global navigation satellite system receiver, and its performance directly affects the performance of the entire receiver. Its main function is to receive high-frequency signals from the antenna and amplify them. Since the received antenna signal is very weak and is affected by the surrounding environment and is particularly susceptible to coverage, the low-noise amplifier is required to have an extremely low noise figure, high gain and good impedance matching.
[0004] Currently, four common low-noise amplifier (LNA) topologies are common-source amplifiers with a parallel resistor at the input, common-gate amplifiers, parallel-series resistor feedback structures, and source-and-inductor common-source amplifiers. The common-source amplifier with a parallel resistor at the input can directly provide a 50-ohm input impedance, achieving broadband, but its gain is only half that of a standard common-source amplifier. Furthermore, the parallel resistor at the input introduces thermal noise equal to the source resistance, resulting in poor noise performance. The common-gate amplifier utilizes the input impedance of the common-gate amplifier to achieve input impedance matching, but its g_m is limited, resulting in poor noise figure, and it requires an inductor. Compared to the first two, the latter two structures are more widely used in LNAs. For example, Ma Yusheng et al. proposed a low-noise amplifier (LNA) for full-band GNSS applications based on a 0.18µm CMOS process. Operating between 1.1 and 1.7GHz, the amplifier achieves system gain greater than 25dB and a noise figure less than 1.75dB. This amplifier utilizes a two-stage structure consisting of a cascode amplifier with source-inductor negative feedback and a common-source amplifier, achieving both high gain and low noise. However, this requires extremely complex input matching, interstage matching, and output matching networks, along with numerous inductive components, significantly increasing chip size and application cost. In 2017, Yang Jing et al. proposed a high-gain, wideband CMOS LNA for Beidou ground receivers using a resistive shunt feedback structure. This amplifier achieves a maximum gain of 15dB and a minimum noise figure of 2.7dB within the 1GHz to 2GHz range. To achieve this wideband performance, the amplifier strikes a compromise between gain and noise figure, resulting in high gain but a high noise figure. Furthermore, the amplifier contains inductive components, requiring an additional input matching network for optimal matching. Summary of the Invention
[0005] To solve the above problems, the main purpose of the present invention is to provide a broadband high-gain low-noise amplifier, which can meet the requirements of high gain and low noise figure while achieving broadband matching, and adopts a design without inductor components to reduce cost and chip area; in addition, its input and output do not require matching network matching, which greatly simplifies application and reduces cost.
[0006] To achieve the above object, the technical solution adopted by the present invention is:
[0007] A broadband high-gain low-noise amplifier comprises: an amplifier stage circuit, a buffer stage circuit, an output stage circuit, and a feedback circuit. The amplifier stage circuit is used to receive an input signal, the output stage circuit is used to connect to a load, the amplifier stage circuit sequentially generates an output signal through the buffer stage circuit and the output stage circuit, and the feedback circuit is used to feed back the output end of the amplifier stage circuit to the input end of the amplifier stage circuit.
[0008] The amplifier stage circuit adopts a common-source common-gate resistor feedback amplifier structure, which includes a common-source common-gate amplifier, a field-effect transistor M1 and a feedback resistor Rf. The gate of the field-effect transistor M1 is used to connect to the input signal, the source of the field-effect transistor M1 is grounded, and the drain of the field-effect transistor M1 is connected to the common-source common-gate amplifier.
[0009] Furthermore, the cascode amplifier includes a field effect transistor M2 and a field effect transistor M3, the drain of the field effect transistor M3 is connected to the drain of the field effect transistor M1, the gate of the field effect transistor M3 is connected to a first bias voltage through a resistor R1, the source of the field effect transistor M3 is connected to the drain of the field effect transistor M2, the gate of the field effect transistor M2 is connected to the gate of the field effect transistor M1, and the source of the field effect transistor M2 is connected to the voltage VDD.
[0010] Furthermore, the buffer stage circuit includes a field effect transistor M4 and a field effect transistor M5, the source of the field effect transistor M4 is grounded, the gate of the field effect transistor M4 and the gate of the field effect transistor M5 are commonly connected to the drain of the field effect transistor M1, the drain of the field effect transistor M4 is connected to the drain of the field effect transistor M5, and the source of the field effect transistor M5 is connected to the voltage VDD.
[0011] Furthermore, the output stage circuit includes a field effect transistor M6, a field effect transistor M7 and a capacitor C5, the drain of the field effect transistor M7 is connected to the voltage VDD, the gate of the field effect transistor M7 is connected to the drain of the field effect transistor M5, the source of the field effect transistor M7 and the drain of the field effect transistor M6 are commonly connected to one end of the capacitor C5, the other end of the capacitor C5 is used to connect to a load, the source of the field effect transistor M6 is grounded, and the gate of the field effect transistor M6 is connected to a second bias voltage.
[0012] Furthermore, the feedback circuit includes a field effect transistor M8 and a field effect transistor M9, the gate of the field effect transistor M9 is connected to the drain of the field effect transistor M3, the source of the field effect transistor M9 and the drain of the field effect transistor M8 are commonly connected to the gate of the field effect transistor M1, the drain of the field effect transistor M9 is connected to the voltage VDD, the source of the field effect transistor M8 is grounded, and the gate of the field effect transistor M8 is connected to a third bias voltage.
[0013] Furthermore, the feedback resistor Rf is connected between the drain and the gate of the field effect transistor M1.
[0014] Furthermore, a resistor R2 is connected between the drain and the gate of the field effect transistor M5.
[0015] Furthermore, the amplifier stage circuit includes a capacitor C1, a capacitor C2, and a capacitor C4, wherein the first end of the capacitor C1 is used to connect to the input signal, the second end of the capacitor C1 and the gate of the field effect transistor M1 are commonly connected to the first end of the capacitor C2, the second end of the capacitor C2 is connected to the gate of the field effect transistor M2, and the capacitor C4 is connected between the gate of the field effect transistor M4 and the drain of the field effect transistor M1.
[0016] Furthermore, the feedback circuit includes a resistor Rm and a capacitor C3, and the source of the field effect transistor M9 is connected to the first end of the capacitor C2 through the resistor Rm and the capacitor C3.
[0017] The beneficial effects of the present invention are:
[0018] The present invention includes: an amplifier stage circuit, a buffer stage circuit, an output stage circuit, and a feedback circuit. The amplifier stage circuit sequentially generates an output signal through the buffer stage circuit and the output stage circuit. The feedback circuit is used to feed the output end of the amplifier stage circuit back to the input end of the amplifier stage circuit. The amplifier stage circuit uses a common-source common-gate amplifier and a field-effect transistor M1, which can provide high gain and low noise. The buffer stage circuit provides a large load for the amplifier stage circuit and also provides a large gain. The output stage circuit can achieve output impedance matching and improve reverse isolation. The feedback circuit can improve the overall gain and noise figure, achieving broadband matching. Therefore, the present invention can achieve high gain and low noise figure while achieving broadband matching, and adopts a design without inductance components to reduce cost and chip area. In addition, its input and output do not require matching networks, which greatly simplifies application and reduces cost. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 It is a circuit diagram of a traditional resistor feedback amplifier structure.
[0020] Figure 2 It is a circuit diagram of the present invention.
[0021] Figure 3 It is the input impedance equivalent circuit diagram of the present invention.
[0022] Figure 4 It is a schematic diagram of the S parameter simulation results of the present invention.
[0023] Figure 5 It is a schematic diagram of the noise factor NF simulation results of the present invention. DETAILED DESCRIPTION
[0024] See also Figure 1 As shown, the traditional resistor feedback amplifier consists of nmosM1 and pmosM2 and feedback resistor R f At the same time, M1 and M2 current are reused, which can achieve greater gain at the same power consumption compared with the homologous amplification structure. Its open-loop gain expression is:
[0025] Gv=(g m1 +g m2 )(r 01 / / r 02 ) (1)
[0026] Where g m1 and g m2 are the effective transconductance of M1 and M2, r 01 With r 02 are the internal resistances of M1 and M2 respectively.
[0027] Its closed-loop gain can be expressed as:
[0028]
[0029] The input impedance is:
[0030]
[0031] Therefore, from formula (3), we can see that the input impedance is affected by the feedback resistor R f The influence is greater when R f When it is larger, to match to 50 ohms, G v The corresponding value must also be large. From formula (1), we can see that a larger g is needed. m1 and g m2 , a larger current is required, however the resistor R f It is usually a few tens of kilo-ohms, so even with a larger G v , the input impedance is also difficult to match to 50 ohms, and broadband coverage cannot be achieved. On the contrary, when R f When the input impedance is very small, in order to achieve input impedance matching to 50 ohms, the gain is small and the noise figure is large. Therefore, there is a great trade-off between gain, noise figure and input matching, and it is difficult to meet them all at the same time.
[0032] See also Figure 2 As shown, the present invention provides a broadband high-gain low-noise amplifier, comprising: an amplifier stage circuit, a buffer stage circuit, an output stage circuit, and a feedback circuit. The amplifier stage circuit is used to receive an input signal, the output stage circuit is used to connect to a load, the amplifier stage circuit generates an output signal through the buffer stage circuit and the output stage circuit in sequence, and the feedback circuit is used to feed back the output end of the amplifier stage circuit to the input end of the amplifier stage circuit.
[0033] The amplifier stage circuit adopts a common-source common-gate resistor feedback amplifier structure, which includes a common-source common-gate amplifier, a field-effect transistor M1 and a feedback resistor Rf. The gate of the field-effect transistor M1 is used to connect to the input signal, the source of the field-effect transistor M1 is grounded, and the drain of the field-effect transistor M1 is connected to the common-source common-gate amplifier.
[0034] Furthermore, the cascode amplifier includes a field effect transistor M2 and a field effect transistor M3, the drain of the field effect transistor M3 is connected to the drain of the field effect transistor M1, the gate of the field effect transistor M3 is connected to a first bias voltage through a resistor R1, the source of the field effect transistor M3 is connected to the drain of the field effect transistor M2, the gate of the field effect transistor M2 is connected to the gate of the field effect transistor M1, and the source of the field effect transistor M2 is connected to the voltage VDD.
[0035] Furthermore, the feedback resistor Rf is connected between the drain and the gate of the field effect transistor M1.
[0036] The second stage is an amplifier circuit, in which a common-source common-gate amplifier and a feedback resistor R are used. f , which can provide high gain and low noise; wherein, the field effect transistor M2 and the field effect transistor M3 constitute a common source and common gate amplifier, which has a higher gain than the traditional resistive feedback amplifier structure, and at the same time, the current of the field effect transistor M1 and the field effect transistor M2 is multiplexed to achieve a greater gain under the same current.
[0037] Its open-loop gain expression is:
[0038] Gv=(g m1 +g m2 )[rx1 / / (r 02 +r 03 )] (4)
[0039] In the above formula, g m1 , g m2 and g m3 are the effective transconductances of M1, M2 and M3, r 01 , r 02 With r 03 They are the internal resistances of M1, M2 and M3 respectively.
[0040] The closed-loop gain can be expressed as:
[0041]
[0042] In order to achieve high gain while meeting input matching, a source-follower amplifier feedback circuit is added, and M9 is a source-follower amplifier to drive the resistor R m , to achieve input impedance matching. Its input impedance can be expressed as:
[0043]
[0044] From formula (6), we can see that its input impedance is composed of the transconductance of the source and the feedback resistance R m and gain, eliminating the need for resistor R f The effect of the resistance R f A larger value can be used to achieve high gain and low noise figure.
[0045] The input impedance analysis is as follows:
[0046] The input impedance equivalent circuit of the present invention is as follows Figure 3 As shown, assuming the input voltage is V in , the input current is I in ,
[0047] This gives the following equation:
[0048] The solution is:
[0049]
[0050] From this we can get the input impedance R in :
[0051]
[0052] Furthermore, the buffer stage circuit includes a field effect transistor M4 and a field effect transistor M5, the source of the field effect transistor M4 is grounded, the gate of the field effect transistor M4 and the gate of the field effect transistor M5 are commonly connected to the drain of the field effect transistor M1, the drain of the field effect transistor M4 is connected to the drain of the field effect transistor M5, and the source of the field effect transistor M5 is connected to the voltage VDD.
[0053] The second stage is a buffer stage amplifier circuit. In the buffer stage amplifier circuit, the field effect transistor M4 and the field effect transistor M5 are two common source amplifiers, forming an inverter amplifier structure, providing a load for the first stage and driving the subsequent stage at the same time to improve the gain of the entire circuit.
[0054] Furthermore, a resistor R2 is connected between the drain and gate of the field effect transistor M5 , and the resistor R2 is reverse biased.
[0055] Furthermore, the output stage circuit includes a field effect transistor M6, a field effect transistor M7 and a capacitor C5, the drain of the field effect transistor M7 is connected to the voltage VDD, the gate of the field effect transistor M7 is connected to the drain of the field effect transistor M5, the source of the field effect transistor M7 and the drain of the field effect transistor M6 are commonly connected to one end of the capacitor C5, the other end of the capacitor C5 is used to connect to a load, the source of the field effect transistor M6 is grounded, and the gate of the field effect transistor M6 is connected to a second bias voltage.
[0056] The third stage is the output stage, wherein the field effect transistor M7 uses a source follower as the output stage of the amplifier to drive a 50 ohm off-chip load. Its output impedance can be expressed as:
[0057]
[0058] Where r 06 is the internal resistance of M6, g m7 is the effective transconductance of M7.
[0059] From formula (7), we can see that the output impedance is given by r 06 With g m7 Joint decision-making, by choosing a suitable g m7 value, the output impedance can be matched to 50 ohms without adding a matching network. In addition, the source follower has a wide bandwidth and a voltage gain of approximately 1.
[0060] Furthermore, the feedback circuit includes a field-effect transistor M8 and a field-effect transistor M9, the gate of the field-effect transistor M9 is connected to the drain of the field-effect transistor M3, the source of the field-effect transistor M9 and the drain of the field-effect transistor M8 are commonly connected to the gate of the field-effect transistor M1, the drain of the field-effect transistor M9 is connected to the voltage VDD, the source of the field-effect transistor M8 is grounded, and the gate of the field-effect transistor M8 is connected to a third bias voltage.
[0061] Furthermore, the amplifier stage circuit includes a capacitor C1, a capacitor C2, and a capacitor C4, wherein the first end of the capacitor C1 is used to connect the input signal, the second end of the capacitor C1 and the gate of the field effect transistor M1 are commonly connected to the first end of the capacitor C2, the second end of the capacitor C2 is connected to the gate of the field effect transistor M2, and the capacitor C4 is connected between the gate of the field effect transistor M4 and the drain of the field effect transistor M1.
[0062] Furthermore, the feedback circuit includes a resistor Rm and a capacitor C3 , and the source of the field effect transistor M9 is connected to the first end of the capacitor C2 via the resistor Rm and the capacitor C3 .
[0063] Reference Figure 2 The present invention mainly consists of an amplifier stage circuit, a buffer stage circuit, an output stage circuit and a feedback circuit; wherein the amplifier stage circuit adopts a common source and common gate resistor feedback and current multiplexing amplifier structure to provide high gain and low noise, and the source follows the amplifier feedback circuit to introduce a resistor R m , aims to eliminate the feedback resistor R f The impact on gain and noise figure, improve the overall gain and noise figure, while the source follows the transconductance of the feedback and the feedback resistor R m The input impedance is determined by the gain, achieving broadband matching. The buffer stage circuit is an inverter amplifier structure, which provides a larger load for the amplifier stage circuit and also provides a larger gain. The output stage circuit adopts a source-follower amplifier output, mainly to achieve output impedance matching and improve reverse isolation.
[0064] Reference Figure 4The present invention can achieve frequency coverage of 1G to 2G without inductor matching, S11 & S22 are less than -10dB, and can achieve good input and output impedance matching. S21 is the gain of the amplifier, which is greater than 20dB. It can be seen from S12 that it has good reverse isolation.
[0065] Reference Figure 5 In the range of 1G to 2GHz, the NF is less than 1.85dB, and the variation in the entire bandwidth is less than 0.1dB, with an extremely low noise figure.
[0066] To address the difficulties of traditional resistive feedback broadband amplifiers in simultaneously meeting gain and noise figure requirements, as well as the complex input-output matching, the present invention employs a current multiplexing and source-followed feedback technology to achieve low noise and high gain while meeting broadband requirements. Furthermore, the present invention employs an inductor-free structure to achieve simultaneous input-output matching, significantly reducing chip area and eliminating the need for input-output matching networks, significantly reducing costs. Specifically:
[0067] First, the cascode amplifier is used as the first stage of the amplifier, which has a higher gain than the traditional resistive feedback amplifier;
[0068] Second, a source-follower feedback technique is added after the parallel resistor feedback amplification to introduce the resistor R m , eliminating the traditional resistor feedback structure affected by the feedback resistor R f The influence of the input impedance matching is achieved without the need for a matching network structure, while achieving high gain while meeting broadband coverage.
[0069] Third, a buffer stage circuit is added to the output of the amplifier stage circuit, and the buffer stage circuit provides a larger load for the first stage amplification and further improves the gain;
[0070] Fourth, the output stage uses a source follower as the output end of the amplifier, and no matching network structure is required to achieve output impedance matching.
[0071] The above embodiments are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary engineering technicians in this field should fall within the scope of protection determined by the claims of the present invention.
Claims
1. A broadband high-gain low-noise amplifier, characterized in that: The invention comprises: an amplifier stage circuit, a buffer stage circuit, an output stage circuit and a feedback circuit, wherein the amplifier stage circuit is used to receive an input signal, the output stage circuit is used to connect to a load, the amplifier stage circuit generates an output signal through the buffer stage circuit and the output stage circuit in sequence, and the feedback circuit is used to feed back the output end of the amplifier stage circuit to the input end of the amplifier stage circuit; The amplifier stage circuit adopts a cascode resistor feedback amplifier structure, which includes a cascode amplifier, a field effect transistor M1 and a feedback resistor Rf. The gate of the field effect transistor M1 is used to connect to the input signal, the source of the field effect transistor M1 is grounded, and the drain of the field effect transistor M1 is connected to the cascode amplifier; The cascode amplifier includes a field effect transistor M2 and a field effect transistor M3, wherein the drain of the field effect transistor M3 is connected to the drain of the field effect transistor M1, the gate of the field effect transistor M3 is connected to a first bias voltage via a resistor R1, the source of the field effect transistor M3 is connected to the drain of the field effect transistor M2, the gate of the field effect transistor M2 is connected to the gate of the field effect transistor M1, and the source of the field effect transistor M2 is connected to a voltage VDD; The feedback circuit includes a field effect transistor M8 and a field effect transistor M9, wherein the gate of the field effect transistor M9 is connected to the drain of the field effect transistor M3, the source of the field effect transistor M9 and the drain of the field effect transistor M8 are commonly connected to the gate of the field effect transistor M1, the drain of the field effect transistor M9 is connected to the connection voltage VDD, the source of the field effect transistor M8 is grounded, and the gate of the field effect transistor M8 is connected to a third bias voltage; The amplifier stage circuit includes a capacitor C1, a capacitor C2, and a capacitor C4, wherein the first end of the capacitor C1 is used to connect to the input signal, the second end of the capacitor C1 and the gate of the field effect transistor M1 are commonly connected to the first end of the capacitor C2, the second end of the capacitor C2 is connected to the gate of the field effect transistor M2, and the capacitor C4 is connected between the gate of the field effect transistor M4 and the drain of the field effect transistor M1; The feedback circuit includes a resistor Rm and a capacitor C3, and the source of the field effect transistor M9 is connected to the first end of the capacitor C2 through the resistor Rm and the capacitor C3.
2. The broadband high-gain low-noise amplifier according to claim 1, wherein: The buffer stage circuit includes a field effect transistor M4 and a field effect transistor M5. The source of the field effect transistor M4 is grounded, the gate of the field effect transistor M4 and the gate of the field effect transistor M5 are commonly connected to the drain of the field effect transistor M1, the drain of the field effect transistor M4 is connected to the drain of the field effect transistor M5, and the source of the field effect transistor M5 is connected to the voltage VDD.
3. The broadband high-gain low-noise amplifier according to claim 2, wherein: The output stage circuit includes a field effect transistor M6, a field effect transistor M7 and a capacitor C5. The drain of the field effect transistor M7 is connected to the voltage VDD. The gate of the field effect transistor M7 is connected to the drain of the field effect transistor M5. The source of the field effect transistor M7 and the drain of the field effect transistor M6 are commonly connected to one end of the capacitor C5. The other end of the capacitor C5 is used to connect to a load. The source of the field effect transistor M6 is grounded, and the gate of the field effect transistor M6 is connected to a second bias voltage.
4. The broadband high-gain low-noise amplifier according to claim 1, wherein: The feedback resistor Rf is connected between the drain and the gate of the field effect transistor M1 .
5. The broadband high-gain low-noise amplifier according to claim 2, wherein: A resistor R2 is connected between the drain and the gate of the field effect transistor M5.
Citation Information
Patent Citations
Variable gain broadband low-noise amplifier
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