Radio-frequency power amplifier output matching circuit
Technical field
The utility model relates to a kind of radio-frequency power amplifier output matching circuit.
Background technology
Radio-frequency power amplifier is the important component part of various transmitting set.In the front stage circuits of transmitter, the RF signal power that modulation oscillator circuit produces is very little, needing through a series of amplification---buffer stage, interstage amplifier section, final power amplifying stage, after obtaining enough radio-frequency powers, just can be fed on antenna and radiate.In order to obtain enough large radio frequency power output, radio-frequency power amplifier must be adopted.
Design of RF Power Amplifier not only pays close attention to power output, power added efficiency; Also pay close attention to its linear characteristic, the harmonic component in output should be little as much as possible, to avoid producing interference to other channels.
Harmonics restraint is the important indicator of Design of RF Power Amplifier, reflects the linear properties of power amplifier.At the wireless communication system in modern times as in the systems such as GSM, CDMA, AB power-like amplifier is higher and the linearity can meet again the requirement of these systems than category-A power amplifier due to power added efficiency, thus is applied widely.But due to the impact of nonlinear distortion, the harmonic distortion of AB power-like amplifier becomes more serious, usually need to add a band pass filter with harmonic inhabitation after power amplifier exports, this just makes system bulk and cost increase.Along with the develop rapidly of IC industry, function integrated in chip module gets more and more, and harmonics restraint problem also becomes more and more serious.Harmonics restraint is one of problem making engineer have a headache most in current radio-frequency (RF) power amplification integrated circuit (IC) design.The harmonic distortion of output matching circuit on power amplifier of power amplifier has important impact, adopts the output matching circuit of low pass or bandpass characteristics can reduce the harmonic distortion of power amplifier.The output matching circuit of radio-frequency (RF) power amplification realizes usually on substrate.But the LC low pass filter matching structure (as shown in Figure 1) of routine, matching capacitance directly arrives ground, can not form " trap " (Trap) to particular harmonic frequency, thus not reach the requirement suppressing specific high order harmonic component.
Common way is on ground capacity C01, go here and there an inductance L 04 (as shown in Figure 2), and specific order harmonic frequency is formed LC series resonance (during resonance, minimum to ground impedance).But the selection of capacitance will meet the requirement of power match.For capacitance choosing larger when, self-resonant frequency due to electric capacity increases along with capacitance and reduces, and after operating frequency exceedes self-resonant frequency, electric capacity presents perception but not capacitive, now LC resonant circuit can not meet series resonance condition, therefore can not form Trap to specific high order harmonic component, filtering performance is deteriorated; Particularly when capacitance is selected very large, self-resonant frequency may drop near secondary or third harmonic frequencies, now this matching structure two, triple-frequency harmonics rejection also can sharply worsen.
Utility model content
For the deficiencies in the prior art, the utility model is intended to provide a kind of radio-frequency power amplifier output matching circuit improving limitation of high harmonics performance.
For achieving the above object, the utility model adopts following technical scheme:
A kind of radio-frequency power amplifier output matching circuit, it comprises inductance L 1, electric capacity C3, inductance L 3 and at least one electric capacity C4;
The output of one radio-frequency power amplifier U1 is successively by inductance L 1, electric capacity C3 and inductance L 3 ground connection; Each electric capacity C4 is in parallel with electric capacity C3 and is connected.
Preferably, radio-frequency power amplifier output matching circuit also comprises at least one inductance L 4, and each inductance L 4 is in parallel with inductance L 3 and is connected.
Preferably, radio-frequency power amplifier output matching circuit also comprises inductance L 6, electric capacity C11, at least one electric capacity C12, inductance L 8, at least one inductance L 9 and capacitance C14;
The output of one radio-frequency power amplifier U2 is successively by inductance L 6, electric capacity C11 and inductance L 8 ground connection; Each electric capacity C12 is in parallel with electric capacity C11 and is connected; Each inductance L 9 is in parallel with inductance L 8 and is connected; Node between inductance L 1 and electric capacity C3 connects one end of capacitance C14, and the other end of capacitance C14 is as the output of output matching circuit; Node between inductance L 6 and electric capacity C11 connects one end of capacitance C14.
Preferably, radio-frequency power amplifier output matching circuit also comprises inductance L 6, inductance L 4, electric capacity C11, at least one electric capacity C12, inductance L 8 and capacitance C14;
The output of one radio-frequency power amplifier U2 is successively by inductance L 6, electric capacity C11 and inductance L 8 ground connection; Each electric capacity C12 is in parallel with electric capacity C11 and is connected; Node between inductance L 1 and electric capacity C3 connects one end of capacitance C14, and the other end of capacitance C14 is as the output of output matching circuit; Node between inductance L 6 and electric capacity C11 connects one end of capacitance C14; One end of inductance L 4 connects the node between electric capacity C3 and inductance L 3, and the other end of inductance L 4 connects the node between electric capacity C11 and inductance L 8.
Preferably, radio-frequency power amplifier output matching circuit also comprises inductance L 2, electric capacity C5, electric capacity C6, inductance L 5, inductance L 15, inductance L 10, electric capacity C7, electric capacity C8 and inductance L 7;
Inductance L 2 is connected between inductance L 1 and electric capacity C14, and inductance L 7 connects and between inductance L 6 and electric capacity C14; Node between inductance L 2 and electric capacity C14, successively by electric capacity C5 and inductance L 5 ground connection, is also connected between inductance L 7 and electric capacity C14 by electric capacity C6, inductance L 15 and electric capacity C8 successively.Node between inductance L 7 and electric capacity C14 is also successively by electric capacity C7 and inductance L 10 ground connection.
Preferably, radio-frequency power amplifier output matching circuit also comprises electric capacity C22, electric capacity C21, inductance L 13 and inductance L 14; The output of radio-frequency power amplifier U1 is also successively by electric capacity C22 and inductance L 13 ground connection.The output of radio-frequency power amplifier U2 is also successively by electric capacity C21 and inductance L 14 ground connection.
Preferably, radio-frequency power amplifier output matching circuit also comprises inductance L 11, electric capacity C33, electric capacity C34, inductance L 12, electric capacity C29 and electric capacity C38; The output of radio-frequency power amplifier U1 is also successively by inductance L 11 and electric capacity C34 ground connection, and electric capacity C33 is in parallel with electric capacity C34 and is connected; Node between inductance L 11 and electric capacity C34 connects a DC power supply VCC.The output of radio-frequency power amplifier U2 is also successively by inductance L 12 and electric capacity C29 ground connection, and electric capacity C38 is in parallel with electric capacity C29 and is connected.
The harmonic suppression effect of above-mentioned utility model is good.
Accompanying drawing explanation
Fig. 1 and Fig. 2 is the structural representation of existing radio-frequency power amplifier output matching network.
Fig. 3 is the circuit diagram of the first better embodiment of the utility model radio-frequency power amplifier output matching circuit.
Fig. 4 is the circuit diagram of the second better embodiment of the utility model radio-frequency power amplifier output matching circuit.
Fig. 5 is the circuit diagram of the 3rd better embodiment of the utility model radio-frequency power amplifier output matching circuit.
Fig. 6 is the circuit diagram of the 4th better embodiment of the utility model radio-frequency power amplifier output matching circuit.
Fig. 7 is the circuit diagram of the 5th better embodiment of the utility model radio-frequency power amplifier output matching circuit.
Embodiment
Below in conjunction with accompanying drawing and embodiment, the utility model is described further:
Refer to Fig. 3, the utility model relates to a kind of radio-frequency power amplifier output matching circuit, and its first better embodiment comprises inductance L 1, electric capacity C3, inductance L 3 and at least one electric capacity C4.
The output of one radio-frequency power amplifier U1 is successively by inductance L 1, electric capacity C3 and inductance L 3 ground connection.Each electric capacity C4 is in parallel with electric capacity C3 and is connected.So, by parallel way, reduce the capacitance of single electric capacity C3 and C4, improve the self-resonant frequency of electric capacity, away from the order harmonic frequency that will suppress, to reach the demand meeting and suppress high order harmonic component.
See Fig. 4, the second better embodiment of radio-frequency power amplifier output matching circuit also comprises at least one inductance L 4, and each inductance L 4 is in parallel with inductance L 3 and is connected, thus inductance Q value can improve further, and harmonic suppression effect can be made better.
See Fig. 5, the 3rd better embodiment of radio-frequency power amplifier output matching circuit also comprises inductance L 6, electric capacity C11, at least one electric capacity C12, inductance L 8, at least one inductance L 9 and capacitance C14 on the basis of the second better embodiment.
The output of one radio-frequency power amplifier U2 is successively by inductance L 6, electric capacity C11 and inductance L 8 ground connection.Each electric capacity C12 is in parallel with electric capacity C11 and is connected.Each inductance L 9 is in parallel with inductance L 8 and is connected.Node between inductance L 1 and electric capacity C3 connects one end of capacitance C14, and the other end of capacitance C14 is as the output of output matching circuit; Node between inductance L 6 and electric capacity C11 connects one end of capacitance C14.
So, this output matching circuit forms a symmetrical structure, makes even-order harmonic harmonic suppression effect better.
See Fig. 6, the 4th better embodiment of radio-frequency power amplifier output matching circuit and the 3rd better embodiment are unlike not comprising inductance L 9.One end of inductance L 4 connects the node between electric capacity C3 and inductance L 3, and the other end of inductance L 4 connects the node between electric capacity C11 and inductance L 8.
Compared with the 3rd better embodiment, because the inductance L 4 of the 3rd better embodiment and inductance L 9 respectively have a node ground connection, therefore can merge two inductance is an inductance L 4, is more conducive to being realized by bonding line on substrate.
So, the inductance value by changing inductance L 8, inductance L 3 and inductance L 4 carrys out the total inductance amount of regulation output match circuit, the suppression to specific high order harmonic component needed for realization.
See Fig. 7, the 5th better embodiment of radio-frequency power amplifier output matching circuit also comprises inductance L 2, electric capacity C5, electric capacity C6, inductance L 5, inductance L 15, inductance L 10, electric capacity C7, electric capacity C8 and inductance L 7 on the basis of the 3rd better embodiment.
Inductance L 2 is connected between inductance L 1 and electric capacity C14, and inductance L 7 is connected between inductance L 6 and electric capacity C14; Node between inductance L 2 and electric capacity C14, successively by electric capacity C5 and inductance L 5 ground connection, is also connected between inductance L 7 and electric capacity C14 by electric capacity C6, inductance L 15 and electric capacity C8 successively.Node between inductance L 7 and electric capacity C14 is also successively by electric capacity C7 and inductance L 10 ground connection.
So, can by configuring the size of each LC series resonant circuit inductance and capacitance, realize the reasonable suppression to the above each harmonic of secondary, this structure has good inhibition to high order harmonic component especially.
In other embodiments, connecting line or cabling can be used to substitute inductance L 15, choose reasonable track lengths width and capacitor element value, good output impedance coupling can be realized, thus realize maximum power transfer.
In the present embodiment, radio-frequency power amplifier output matching circuit also comprises electric capacity C22, electric capacity C21, inductance L 13 and inductance L 14.
The output of radio-frequency power amplifier U1 is also successively by electric capacity C22 and inductance L 13 ground connection.The output of radio-frequency power amplifier U2 is also successively by electric capacity C21 and inductance L 14 ground connection.
The series resonant circuit of electric capacity C22 and inductance L 13 or electric capacity C21 and inductance L 14 formation forms Trap to harmonic wave, improves the efficiency of power amplifier while harmonic inhabitation.So, in order to suppress each harmonic, the inductance of each series resonant circuit of reasonable disposition and capacitance, by the combination of multistage match circuit, realize the suppression to more than secondary and even more high order harmonic component, the first-harmonic after filtering each harmonic is exported by capacitance C14.
In the present embodiment, radio-frequency power amplifier output matching circuit also comprises inductance L 11, electric capacity C33, electric capacity C34, inductance L 12, electric capacity C29 and electric capacity C38.
The output of radio-frequency power amplifier U1 is also successively by inductance L 11 and electric capacity C34 ground connection, and electric capacity C33 is in parallel with electric capacity C34 and is connected; Node between inductance L 11 and electric capacity C34 connects a DC power supply VCC.The output of radio-frequency power amplifier U2 is also successively by inductance L 12 and electric capacity C29 ground connection, and electric capacity C38 is in parallel with electric capacity C29 and is connected.
Above-mentioned output matching circuit adopts symmetrical structure, is significantly increased to power combining efficiency, but conveniently circuit application and modular design, the program adopts single-ended power, is realized the power supply on another road by the inductance on loop.
For a person skilled in the art, according to technical scheme described above and design, other various corresponding change and distortion can be made, and all these change and distortion all should belong within the protection range of the utility model claim.