JP2004159102A - High-frequency power amplifier circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-frequency power amplifier circuit by which high efficiency is obtained while securing a wide dynamic range of the high-frequency output power. <P>SOLUTION: The high-frequency power amplifier circuit comprises: a preamplifier circuit amplifying the inputted high frequency signal to a specified level; a first output circuit outputting the output signal from the preamplifier circuit to an antenna; a second output circuit amplifying the output signal from the preamplifier circuit to the specified level to output to the antenna; a switch circuit selectively using one of the first output circuit and the second output circuit in accordance with the high-frequency output level outputted from the antenna; and a phase correction circuit inserted in the preceding stage of the second output circuit and correcting the phase of a signal inputted to the second output circuit. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a high-frequency power amplifier circuit that is most suitable for being incorporated in a mobile communication device such as a mobile communication terminal.
[0002]
[Prior art]
For example, a high-frequency power amplifier circuit incorporated in a portable communication terminal or the like generally has a two-stage circuit configuration including a preamplifier circuit and a final-stage amplifier circuit. The inter-stage circuit between the final-stage amplifier circuits is provided with an inter-stage matching circuit for obtaining desired characteristics. Then, the impedance of the interstage coupling circuit is controlled to optimize the efficiency (for example, see Patent Document 1).
[0003]
Further, the preamplifier circuit is provided with a pre-stage bias circuit for supplying a direct current. It is known that the high-frequency power output from the high-frequency power amplifier circuit is varied by variably controlling the bias current or the bias voltage of the pre-stage bias circuit.
[0004]
[Patent Document]
JP 2001-16053 A [0005]
[Problems to be solved by the invention]
However, in the above-described high-frequency power amplifier circuit, when controlling the output power output from the antenna, the output power is output from the high-frequency power amplifier circuit because only the amplification of the preamplifier circuit is adjusted by adjusting the pre-stage bias circuit. There has been a problem that high-frequency power cannot be varied over a wide range.
[0006]
For this reason, for example, even in the case where the distance to the base station is short and the high-frequency power output from the antenna is small, in the high-frequency power amplifier circuit having the two-stage circuit configuration described above, the final-stage amplifier circuit has a small output. In this case, the operation is inefficient, and there is a problem that wasteful power is consumed. Therefore, when such a high-frequency power amplifier circuit is applied to a mobile communication terminal or the like, it is necessary to increase the size of a battery to be operable for a long period of time, which has been a serious problem in downsizing the mobile communication terminal. .
[0007]
Therefore, when the high frequency power output from the antenna 2 is small as shown in FIG. 1, the inventor outputs the output of the preamplifier circuit 5 directly from the antenna without passing through the final-stage amplifier circuit 6, while outputting the output from the antenna 2 When the high-frequency power to be supplied is large, the high-frequency power amplifier circuit 1 of the RF switch switching type that outputs the signal from the antenna 2 through the final-stage amplifier circuit 6 is devised.
[0008]
However, when such a circuit system is applied, the output circuits of the preamplifier circuit 5 and the output circuit of the final-stage amplifier circuit 6 are inserted through the delay lines 8a and 8b so that the output circuits are high-frequency. Need to be separated. Further, it is necessary to match impedances on the input side and the output side of the final-stage amplifier circuit 6 through the matching circuits 7c and 7d.
[0009]
Then, there arises a problem that the phase of the signal output from the preamplifier circuit 5 and the phase of the signal output from the final-stage amplifier circuit 6 are different from each other at the antenna end 9. For example, as shown in FIG. 1, the phase is delayed by 225 degrees in the final stage amplifier circuit 6 including the matching circuits 7c and 7d, and further, the phase is delayed by 84 degrees in the delay line 8a.
On the other hand, the output of the preamplifier circuit 5 is output from the antenna 2 with a phase delayed by 69 degrees by the delay line 8b interposed between the RF switch 3 and the antenna 2. Therefore, the phase difference at the antenna end 9 is [−225−84 − (− 64) = − 245 degrees], that is, 115 degrees. Therefore, when the RF switch 3 is switched, the phase of the high-frequency signal output from the antenna changes significantly. Therefore, there is a problem that the carrier synchronization used for channel estimation on the base station side is undesirably affected.
[0010]
The present invention has been made in consideration of the above-described problems, and an object of the present invention is to provide a high-frequency power amplifier circuit that can obtain high efficiency while securing a wide dynamic range of high-frequency output power. is there.
[0011]
[Means for Solving the Problems]
To achieve the above object, according to the high frequency power amplifier circuit of the present invention, a preamplifier circuit for amplifying an input high frequency signal to a predetermined level, and an output signal of the preamplifier circuit A first output circuit for outputting a signal to an antenna, a second output circuit for amplifying an output signal of the preamplifier circuit to a predetermined level and outputting the amplified signal to the antenna, and a high-frequency output level output from the antenna. A switch circuit for selectively using one of the first output circuit and the second output circuit, and a switch circuit interposed at a stage preceding the second output circuit and input to the second output circuit. A phase correction circuit for correcting the phase.
[0012]
Preferably, the phase correction circuit is configured as a lumped constant circuit including an inductor and a capacitor and / or a distributed constant circuit including a linear conductor formed on a substrate.
Therefore, according to the present invention, it is possible to provide a high-frequency power amplifier circuit that can obtain high efficiency while securing a wide dynamic range of high-frequency output power.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a high frequency power amplifier circuit according to the present invention will be described with reference to the drawings.
FIG. 2 is a diagram illustrating a schematic configuration of a high-frequency power amplifier circuit according to one embodiment of the present invention. The high-frequency power amplifier circuit 1 includes a final-stage amplifier circuit 6 that further amplifies the output signal of the preamplifier circuit 5 and outputs the signal to the antenna 2, and a final-stage amplifier circuit according to the level of the high-frequency power output from the antenna 2. An output-side RF switch 3 b for outputting either the output signal of the antenna 6 or the output signal of the preamplifier circuit 5 from the antenna 2 is provided.
[0014]
On the output side of the preamplifier circuit 5, it is selected whether the output signal is sent to the bypass circuit (first circuit) 10 or the final-stage amplifier circuit (second circuit) 6 for sending the output signal to the antenna 2. An input-side RF switch 3a is provided.
These RF switches 3a and 3b are switched in pairs, and when a signal having a large output level is required from the antenna 2, the RF switches 3a and 3b are switched to the final stage amplifier circuit 6 side. When a signal having a small output level is required from the antenna 2, the RF switches 3a and 3b are switched to the bypass circuit 10 to directly output the output of the preamplifier circuit 5 from the antenna 2 without passing through the final-stage amplifier circuit 6. It is configured as follows.
[0015]
A feature of the present invention in the high-frequency power amplifier circuit 1 configured as described above is that the phase correction circuit 11 is interposed in the preceding stage of the final-stage amplifier circuit 6 and the output power of the preamplifier circuit 5 is further amplified. The configuration is such that high efficiency is maintained without causing a difference between the phase of the output signal of the final-stage amplifier circuit 6 and the phase of the output signal of the output of the preamplifier circuit 5 directly output from the antenna 2.
[0016]
Although not shown, the phase correction circuit 11 may be a lumped constant circuit combining an inductor and a capacitor, a distributed constant circuit formed of a strip line provided on a substrate, or a combination of the distributed constant circuit and the lumped constant circuit. Be composed. Incidentally, as shown in FIG. 2, the phase correction circuit 11 configured by combining a distributed constant circuit and a lumped constant circuit is desirable because its occupied area can be reduced.
[0017]
Now, in the high-frequency power amplifier circuit 1 configured as described above, when the high-frequency output level output from the antenna 2 is smaller than a predetermined reference level and the output of the preamplifier circuit 5 is directly output from the antenna 2, As described above, the switching control unit 4 switches the RF switches 3a and 3b to the bypass circuit 10 side, respectively.
Then, the high-frequency signal input to the high-frequency power amplifier circuit 1 is converted by the matching circuit 7 a so as to match the input impedance of the pre-amplifier circuit 5 and is provided to the pre-amplifier circuit 5. The high-frequency signal amplified by the preamplifier circuit 5 is subjected to output impedance matching of the preamplifier circuit 5 by a matching circuit 7b, and is supplied to the input-side RF switch 3a.
[0018]
The input side RF switch 3a and the output side RF switch 3b are switched to the bypass circuit 10 side by the switching control unit 4 so that the output of the preamplifier circuit 5 is directly output from the antenna 2 as described above. Thus, the output signal of the preamplifier circuit 5 is radiated from the antenna 2.
On the other hand, when the high-frequency output level output from the antenna 2 is higher than a predetermined reference level and the output signal of the preamplifier circuit 5 needs to be further amplified by the final-stage amplifier circuit 6, as described above, the switching controller 4 switches the RF switches 3a and 3b to the final stage amplifier circuit 6 side.
[0019]
Then, the high-frequency signal input to the high-frequency power amplifier circuit 1 is provided to the final-stage amplifier circuit 6 via the pre-amplifier circuit 5, the matching circuit 7b, and the input-side RF switch 3a. Incidentally, matching circuits 7c and 7d are provided on the input side and the output side of the final-stage amplifier circuit 6, respectively, so that the efficiency of the final-stage amplifier circuit 6 is adjusted to be optimal.
[0020]
The signal amplified by the final-stage amplifier circuit 6 is matched with the impedance on the antenna side by the matching circuit 7d provided on the output side as described above, and is output to the antenna 2 via the output RF switch 3b. Radiated from
The high-frequency power amplifier circuit 1 configured as described above will be described in more detail with reference to the schematic configuration of the high-frequency power amplifier circuit shown in FIG. In this figure, the phase of a signal input to the high-frequency power amplifier circuit 1 is set to a reference phase of 0 degree.
[0021]
First, when the RF switches 3b and 3a are switched to the bypass circuit 10 side, when the input signal passes through the matching circuit 7a, the preamplifier circuit 5, the matching circuit 7b and the input-side RF switch 3a, the phase of the signal is changed. Becomes a phase advanced by 90 degrees with respect to the input signal. Then, this signal is provided to the antenna 2 via the output side RF switch 3b. That is, the signal input to the high-frequency power amplifier circuit 1 is radiated from the antenna 2 with the phase advanced by 90 degrees.
[0022]
On the other hand, when the input-side RF switch 3a is operated by switching to the final-stage amplifier circuit 6, the signals output via the matching circuits 7a and 7b, the preamplifier circuit 5, and the input-side RF switch 3a are as described above. Thus, the signal is a signal having a phase advanced by 90 degrees with respect to the input signal. Then, this signal is delayed by 135 degrees by the phase correction circuit 11 in the stage before the final-stage amplifier circuit 6. Therefore, the phase of the high-frequency signal output from the phase correction circuit 11 is [+ 90-135 = −45 degrees], that is, a lag phase of 45 degrees with respect to the phase of the input signal (lead phase is positive, lag phase is Negative).
[0023]
Then, the phase of this signal is delayed by 225 degrees by being output through the matching circuit 7c, the final-stage amplifier circuit 6, and the matching circuit 7d. Therefore, a signal delayed by [−45−225 = −270 degrees] with respect to the input signal, that is, a signal advanced by 90 degrees is generated. This signal is radiated from the antenna 2 via the output-side RF switch 3b. Even when the signal is output through the final-stage amplifier circuit 6 as described above, a high-frequency signal having a phase advanced by 90 degrees with respect to the phase of the input signal input to the high-frequency power amplifier circuit 1 is radiated through the antenna 2. You.
[0024]
That is, whether the output signal of the preamplifier circuit 5 is directly output from the antenna 2 or the output signal of the preamplifier circuit 5 is amplified by the final-stage amplifier circuit 6 and then output from the antenna 2, No phase difference occurs.
In the high-frequency power amplifier circuit thus configured, even if the output signal of the preamplifier circuit 5 is directly output from the antenna 2, the output signal of the preamplifier circuit 5 is amplified by the final-stage amplifier circuit 6. Even when the signal is output from the antenna 2, since the phase correction circuit 11 is provided between the final-stage amplifier circuit 6 and the preamplifier circuit 5, a phase difference may occur in the high-frequency signal output from the antenna 2. Absent.
[0025]
Further, since the phase correction circuit 11 is arranged before the final-stage amplifier circuit 6, high efficiency can be maintained without lowering the efficiency. For this reason, even when a circuit system in which the switching of the amplifier circuit according to the high-frequency output level of the high-frequency power amplifier circuit is applied by applying the RF switch 3 is applied, the phase of the output signal does not jump, and A high-efficiency high-frequency power amplifier circuit can be configured while securing a wide dynamic range of output power.
[0026]
Next, a high-frequency power amplifier circuit according to another embodiment of the present invention will be described using the schematic configuration shown in FIG. This different embodiment is different from the above-described embodiment in that, instead of the output-side RF switch 3b, the transmission line 12a, 12b of [1/4] wavelength of the high-frequency signal amplified by the high-frequency power amplifier circuit is used. The signal is output to the antenna 2.
[0027]
When a transmission line of [1/4] wavelength is provided and the input side of the transmission line is grounded, the impedance when the transmission line 12a or the transmission line 12b is viewed from the antenna end 9 can be made infinite. .
For this reason, when the final-stage amplifier circuit 6 is not used, the switching control unit 4 deactivates the final-stage amplifier circuit 6 and switches the input-side RF switch 3a and the bypass RF switch 3c to switch the preamplifier circuit. 5 may be output from the antenna 2. At this time, since the final-stage amplifier circuit 6 is inactive, its output can be regarded as equivalently grounded. Therefore, when the transmission line 12a on the side of the final-stage amplifier circuit 6 is viewed from the antenna end 9 side, the impedance thereof becomes infinite, so that the influence of the final-stage amplifier circuit 6 is eliminated.
[0028]
On the other hand, when the output signal of the preamplifier circuit 5 is amplified by the final-stage amplifier circuit 6, the switching control unit 4 supplies the output signal of the input-side RF switch 3a to the final-stage amplifier circuit 6 via the phase correction circuit 11. The input side RF switch 3a is switched. The switching control unit 4 activates the final-stage amplifier circuit 6 and switches the bypass RF switch 3c to the ground side.
[0029]
Then, when the transmission line 12b connected to the bypass circuit 10 is viewed from the antenna end 9 side, the impedance is infinite and the bypass circuit 10 is not affected.
Thus, according to the high-frequency power amplifier circuit 1 configured as described above, the output signal of the preamplifier circuit 5 can be directly output from the antenna 2 or the output signal of the preamplifier circuit 5 can be output to the final-stage amplifier circuit 6. Even when the signal is amplified by the antenna 2 and output from the antenna 2, the phase correction circuit 11 is provided in the preceding stage in the final-stage amplifier circuit 6, so that no phase difference occurs in the high-frequency signal output from the antenna 2.
[0030]
In addition, since the phase correction circuit 11 is arranged before the final-stage amplifier circuit 6, high efficiency can be maintained without lowering the efficiency. Therefore, even when a circuit system in which the switching of the amplifier circuit according to the high-frequency output level is applied by applying the RF switch is applied, the phase of the signal output from the high-frequency power amplifier circuit does not jump. A high-efficiency high-frequency power amplifier circuit can be configured while securing a wide dynamic range of high-frequency output power.
[0031]
Further, since the output-side RF switch 3b is not provided at the output of the final-stage amplifier circuit 6, an RF switch for passing a large amount of power is not required, and the circuit scale can be reduced.
The present invention is not limited to the above-described embodiments, and can be implemented with various modifications without departing from the scope of the invention.
[0032]
【The invention's effect】
As described above, according to the high-frequency power amplifier circuit according to the present invention, the phase correction circuit is arranged before the final-stage amplifier circuit, and the phase change by the final-stage amplifier circuit is corrected. Regardless of whether the output signal of the preamplifier circuit is output directly from the antenna or the case where the output signal is output from the antenna via the final-stage amplifier circuit, there is no phase difference between the output signals. Practically significant effects such as high efficiency can be maintained without affecting the carrier synchronization used for the channel estimation of the station.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of a conventional high-frequency power amplifier circuit.
FIG. 2 is a diagram showing a schematic configuration of a high-frequency power amplifier circuit according to one embodiment of the present invention.
FIG. 3 is a diagram showing a schematic configuration of a high-frequency power amplifier circuit according to another embodiment of the present invention.
[Explanation of symbols]
2 Antenna 3 RF switch 4 Switching control unit 5 Preamplifier circuit 6 Final amplifier circuit 7 Matching circuit 10 Bypass circuit 11 Phase correction circuit

Claims (2)

A preamplifier circuit for amplifying the input high-frequency signal to a predetermined level,
A first output circuit for outputting an output signal of the preamplifier circuit to an antenna;
A second output circuit that amplifies an output signal of the preamplifier circuit to a predetermined level and outputs the amplified signal to the antenna;
A switch circuit that selectively uses one of the first output circuit and the second output circuit according to a high-frequency output level output from the antenna;
A high-frequency power amplifier circuit, comprising: a phase correction circuit interposed at a stage preceding the second output circuit and correcting the phase of a signal input to the second output circuit. 2. The high-frequency power amplifier circuit according to claim 1, wherein the phase correction circuit comprises a lumped constant circuit composed of an inductor and a capacitor and / or a distributed constant circuit having a linear conductor formed on a substrate.

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