CN108964621A - Filtering framework is strengthened in a kind of radio-frequency power amplifier and its matching - Google Patents

Abstract

The invention provides a radio frequency power amplifier and its matching enhanced filter architecture. The architecture includes: an input inductor, one end of which is connected to the radio frequency signal input end; a first trap circuit, one end of which is connected to the other end of the input inductor and one end of the band-stop circuit, and the other end is connected to the power ground; the band-stop circuit, in addition One end is connected to one end of the second trap circuit and one end of the band-pass circuit; the other end of the second trap circuit is connected to the power ground; the other end of the band-pass circuit is connected to the radio frequency signal output end. The invention greatly reduces the design difficulty of the front end of the power amplifier, provides a harmonic suppression capability of more than 50dbc at 1.4GHz-3.8GHz, and provides a half-wave suppression capability of more than 10dbc at 350MHz-450MHz, and at the same time, the in-band insertion loss is lower than 1.7db.

Description

A radio frequency power amplifier and its matching enhanced filtering architecture

technical field

The invention relates to the field of radio frequency power amplifiers, in particular to a radio frequency power amplifier and a matching enhanced filtering architecture thereof.

Background technique

With the development of communication technology, the requirements for RF power amplifiers are getting higher and higher. Taking NB-IoT RF power amplifier as an example, NB-IoT (Narrow Band Internet of Things, narrowband Internet of Things) is an important branch of the Internet of Everything. NB-IoT is built on a cellular network and consumes only about 180KHz of bandwidth, and can be directly deployed on a GSM network (Global System for Mobile Communications, Global System for Mobile Communications), a UMTS network (Universal Mobile Telecommunications System, Universal Mobile Communications System) or an LTE network (LongTerm Evolution, long-term evolution) to reduce deployment costs and achieve smooth upgrades.

NB-IoT is an emerging technology in the IoT field, which supports cellular data connections of low-power devices in wide area networks, also known as low-power wide area networks (LPWAN). NB-IoT supports efficient connection of devices with long standby time and high network connection requirements. It is said that NB-IoT device battery life can be improved by at least 10 years, while also providing very comprehensive indoor cellular data connection coverage. In NB-IoT RF power amplifiers, harmonic suppression generally starts at 1.4GHz, and there is also a need for suppression of high-order harmonics.

In the traditional 2G communication system, the harmonic suppression of the low frequency of the NB-IoT RF power amplifier only needs to start from 1.6GHz. The new-generation NB-IoT radio frequency communication system requires harmonic suppression starting from 1.4GHz, and additionally requires the addition of 350MHz-460MHz 10dbc half-wave suppression, which greatly increases the difficulty of research and development of the NB-IoT RF power amplifier front-end.

Traditional filter matching networks often add a specific notch circuit to enhance filtering after matching to 50 ohms, which will also increase additional RF link loss and NB-IoT RF power amplifier development costs.

Contents of the invention

An embodiment of the present invention provides a matching enhanced filtering architecture of a radio frequency power amplifier, including:

Input inductance, one end is connected to the radio frequency signal input end;

A first trap circuit, one end of which is connected to the other end of the input inductance and one end of the band-stop circuit, and the other end is connected to the power ground;

The other end of the band-stop circuit is connected to one end of the second trap circuit and one end of the band-pass circuit;

The other end of the second trap circuit is connected to the power ground;

A band-pass circuit, and the other end is connected to the radio frequency signal output end.

Further, the first trap circuit includes a second capacitor and a second inductor connected in series.

Further, the band stop circuit includes a third capacitor and a third inductor connected in parallel.

Further, the second trap circuit includes a fourth capacitor and a fourth inductor connected in series.

Further, the bandpass circuit includes a fifth inductor and a fifth capacitor connected in series.

Further, the input inductor, the second capacitor, the second inductor, the third inductor, the third capacitor, the fourth capacitor, and the fourth inductor match the impedance of the radio frequency signal output end to 50 ohms.

Further, the frequencies of the first notch circuit and the second notch circuit are different.

Further, the bandpass circuit resonates at the main frequency.

Further, the architecture provides a harmonic suppression exceeding 50dbc at a frequency of 1.4GHz-3.8GHz, and a half-wave suppression exceeding 10dbc at a frequency of 350MHz-450MHz; the in-band insertion loss of the architecture is less than 1.7db.

An embodiment of the present invention also provides a radio frequency power amplifier, including the matching enhanced filtering architecture of the radio frequency power amplifier described above.

The technical solution provided by the embodiments of the present invention greatly reduces the design difficulty of the RF power amplifier front end, provides a harmonic suppression capability of more than 50dbc at 1.4GHz-3.8GHz, and provides a half-wave suppression capability of more than 10dbc at 350MHz-450MHz. The interpolation loss is lower than 1.7db.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings that need to be used in the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those skilled in the art, other drawings can also be obtained based on these drawings without creative effort.

FIG. 1 is a schematic diagram of the composition of a traditional matching enhanced filtering architecture of a radio frequency power amplifier;

Fig. 2 is a schematic composition diagram of a matching enhanced filtering architecture of a radio frequency power amplifier provided by an embodiment of the present invention;

FIG. 3 is a schematic diagram of the suppression effect of the matched enhanced filtering architecture of FIG. 1;

Fig. 4 is a schematic diagram of the suppressing effect of the matching enhanced filtering architecture in Fig. 2;

Fig. 5 is a radio frequency power amplifier provided by an embodiment of the present invention.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention more clear, the specific implementation manners of the technical solutions of the present invention will be described in more detail and clearly below in conjunction with the drawings and embodiments. However, the specific embodiments and examples described below are for the purpose of illustration only, rather than limiting the present invention. It only contains a part of the embodiments of the present invention, but not all of them. Other embodiments obtained by those skilled in the art through various changes of the present invention all belong to the protection scope of the present invention.

It should be understood that although the terms first, second, third, etc. may be used herein to describe various elements or components, these elements or components should not be limited by these terms. These terms are only used to distinguish one element or component from another element or component. Therefore, a first element or component discussed below may be referred to as a second element or a second component without departing from the scope of the present invention.

FIG. 1 is a schematic diagram of composition of a traditional matching enhanced filtering architecture of a radio frequency power amplifier. As shown in Figure 1, in the traditional solution, the RF signal is input from the input terminal, and the impedance is matched to 50 ohms through several matching components L1, C1, L4, L2, C2, and L5, where C1, L4, C2, and L5 are respectively Designed as two trap circuits of different frequencies, one designed to suppress third and fourth harmonics and the other to suppress high frequency harmonics. L3 and C3 are band stop circuits designed for 350MHz-450MHz, and C4 is a DC blocking capacitor.

FIG. 3 is a schematic diagram of suppression effect of the matched enhanced filter architecture in FIG. 1 . As shown in Figure 3, m1-m11 is the harmonic suppression effect of each frequency. When the frequency is 350MHz, the half-wave suppression m1=-13.714db. When the frequency is 460MHz, the half-wave suppression m2=-24.171db. When the frequency is 700MHz, the full-wave suppression m3=-1.867db. When the frequency is 915MHz, the full-wave suppression m4=-1.678db. When the frequency is 1.400GHz, the second harmonic suppression m6=-52.278db. When the frequency is 1.830GHz, the second harmonic suppression m7=-39.691db. When the frequency is 2.100GHz, the third harmonic suppression m8=-42.803db. When the frequency is 2.750GHz, the third harmonic suppression m9=-63.458db. When the frequency is 2.400GHz, the fourth harmonic suppression m10=-48.619db. When the frequency is 3.800GHz, the fourth harmonic suppression m11=-46.905db.

It can be seen that the traditional architecture can provide a suppression capability of about 40-50dbc, a half-wave suppression capability of more than 10dbc, and the in-band insertion loss is about 1.7-1.9db.

FIG. 2 is a schematic diagram of a matched enhanced filtering architecture of a radio frequency power amplifier provided by an embodiment of the present invention. The architecture includes an input inductor L1, a first trap circuit, a band-stop circuit, a second trap circuit, and a band-pass circuit.

One end of the input inductor L1 is connected to the radio frequency signal input end P1. One end of the first trap circuit is connected to the other end of the input inductor L1 and one end of the band-stop circuit, and the other end is connected to the power ground. The other end of the band-stop circuit is connected to one end of the second trap circuit and one end of the band-pass circuit. The other end of the second notch circuit is connected to the power ground. The other end of the bandpass circuit is connected to the radio frequency signal output end.

The first trap circuit includes a second capacitor C2 and a second inductor L2 connected in series. One end of the second capacitor C2 is connected to the connection point of the input inductor L1 and the band-stop circuit, the other end of the second capacitor C2 is connected to one end of the second inductor L2, and the other end of the second inductor L2 is connected to the power ground. The band stop circuit includes a third capacitor C3 and a third inductor L3 connected in parallel. The second trap circuit includes a fourth capacitor C4 and a fourth inductor L4 connected in series. One end of the fourth capacitor C4 is connected to the connection point of the band-stop circuit and the band-pass circuit, the other end is connected to one end of the fourth inductor L4, and the other end of the fourth inductor L4 is connected to the power ground. The band-pass circuit includes a fifth inductor L5 and a fifth capacitor C5 connected in series. One end of the fifth inductor L5 is connected to the connection point of the band-stop circuit and the second trap circuit, the other end is connected to one end of the fifth capacitor C5, and the other end of the fifth capacitor C5 is connected to the radio frequency signal output end.

The input inductor L1, the second capacitor C2, the second inductor L2, the third inductor L3, the third capacitor C3, the fourth capacitor C4, and the fourth inductor L4 match the impedance of the output end of the radio frequency signal to 50 ohms.

The first notch circuit and the second notch circuit have different frequencies. The bandpass circuit resonates at the dominant frequency. The fifth capacitor C5 also serves as a DC blocking capacitor.

FIG. 4 is a schematic diagram of the suppressing effect of the matched enhanced filtering architecture in FIG. 2 . As shown in Figure 4, m1-m11 is the harmonic suppression effect of each frequency. When the frequency is 350MHz, the half-wave suppression m1=-19.079db. When the frequency is 460MHz, the half-wave suppression m2=-13.760db. When the frequency is 700MHz, the full-wave suppression m3=-1.696db. When the frequency is 915MHz, the full-wave suppression m4=-1.667db. When the frequency is 1.4GHz, the second harmonic suppression m6=-64.657db. When the frequency is 1.830GHz, the second harmonic suppression m7=-53.880db. When the frequency is 2.100GHz, the third harmonic suppression m8=-51.796db. When the frequency is 2.750GHz, the third harmonic suppression m9=-57.595db. When the frequency is 2.400GHz, the fourth harmonic suppression m10=-53.021db. When the frequency is 3.800GHz, the fourth harmonic suppression m11=-51.718db.

The architecture provides over 50dbc of harmonic rejection at 1.4GHz-3.8GHz and over 10dbc of half-wave rejection at 350MHz-450MHz. The in-band insertion loss of the architecture is less than 1.7db. superior to traditional architectures.

Output matching in RF power amplifiers is the key to directly determine the performance of RF power amplifiers. Using this matching enhanced filtering structure filters out excess spurs, can improve the linearity of the power amplifier, and does not need to use additional filters, which can greatly save the space and cost of the radio frequency front end.

Fig. 5 is a radio frequency power amplifier provided by an embodiment of the present invention. As shown in FIG. 5 , the radio frequency power amplifier 1 includes the matching enhanced filtering architecture of the radio frequency power amplifier described above.

Since the NB-IoT RF power amplifier has high requirements on harmonics, the above-mentioned matching enhanced filter structure is more suitable for use in the NB-IoT RF power amplifier.

It should be noted that the various embodiments described above with reference to the accompanying drawings are only used to illustrate the present invention rather than limit the scope of the present invention. Those of ordinary skill in the art should understand that without departing from the spirit and scope of the present invention Any modifications or equivalent replacements made to the present invention shall fall within the scope of the present invention. Further, words appearing in the singular include the plural and vice versa unless the context otherwise requires. Additionally, all or a portion of any embodiment may be utilized with all or a portion of any other embodiment, unless stated otherwise.

Claims (10)

1. A matching enhanced filtering architecture of a radio frequency power amplifier, comprising: Input inductance, one end is connected to the radio frequency signal input end; A first trap circuit, one end of which is connected to the other end of the input inductance and one end of the band-stop circuit, and the other end is connected to the power ground; The other end of the band-stop circuit is connected to one end of the second trap circuit and one end of the band-pass circuit; The other end of the second trap circuit is connected to the power ground; A band-pass circuit, and the other end is connected to the radio frequency signal output end. 2. The architecture of claim 1, wherein the first trap circuit comprises a second capacitor and a second inductor connected in series. 3. The architecture according to claim 2, wherein the band stop circuit comprises a third capacitor and a third inductor connected in parallel. 4. The architecture according to claim 3, wherein the second trap circuit comprises a fourth capacitor and a fourth inductor connected in series. 5. The architecture according to claim 4, wherein the bandpass circuit comprises a fifth inductor and a fifth capacitor connected in series. 6. The architecture according to claim 5, wherein the input inductance, the second capacitance, the second inductance, the third inductance, the third capacitance, the fourth capacitance, and the fourth inductance match the impedance of the radio frequency signal output terminal to 50 ohms. 7. The architecture of claim 1, wherein the first notch circuit and the second notch circuit are different in frequency. 8. The architecture of claim 1, wherein the bandpass circuit resonates at a dominant frequency. 9. The architecture according to claim 1, wherein the architecture provides harmonic suppression exceeding 50dbc at frequencies of 1.4GHz-3.8GHz, and half-wave suppression exceeding 10dbc at frequencies of 350MHz-450MHz; the in-band of the architecture The insertion loss is less than 1.7db. 10. A radio frequency power amplifier, comprising the matching enhanced filtering architecture of a radio frequency power amplifier according to any one of claims 1 to 9.