TW201515384A - Power amplifier - Google Patents

Abstract

A signal level adjustment unit (6) which adjusts the signal level of an RF signal (1) that is an input signal such that the signal level of the RF signal (1) becomes constant, an input-side detector (7) which detects the RF signal the signal level of which has been adjusted by the signal level adjustment unit (6), a signal level adjustment unit (8) which adjusts the signal level of the RF signal attenuated by an attenuator (5) such that the signal level of the RF signal becomes constant, and a feedback-side detector (9) which detects the RF signal the signal level of which has been adjusted by the signal level adjustment unit (8) are provided, and an amplitude comparator (10) detects a difference between the envelope of the RF signal detected by the input-side detector (7) and the envelope of the RF signal detected by the feedback-side detector (9), and outputs a gain control signal for making the difference zero to a main signal variable gain unit (2).

Description

Power amplifier

The present invention relates to a power amplifier on the transmitting side of a wireless terminal such as a mobile phone or WiFi (Wireless Fidelity).

For example, in a transmission device for a wireless terminal such as a mobile phone or WiFi (Wireless Fidelity), it is important to increase the output and increase the efficiency of the power amplifier.

A technology that strives to increase the efficiency of power amplifiers is a distortion correction technique that uses feedback control.

This distortion correction technique is a technique for detecting envelope distortion occurring from a power amplifier and dynamically removing its distortion. In order to make the distortion detection method equal to the signal level of the input signal of the power amplifier and the signal level of the output signal, the signal level of the output signal is adjusted, and the difference between the envelope of the input signal and the envelope of the output signal is detected. A general method for distortion.

Fig. 5 is a view showing a conventional power amplifier configuration diagram.

When the RF signal 101 of the input signal is input, the variable gain unit 102 amplifies or attenuates the RF signal 101 only by the gain of the gain control signal output from the amplitude comparator 109.

The power amplifier 103 amplifies the RF signal amplified or attenuated by the variable gain section 102, and outputs the amplified RF signal 105.

At this time, since the RF signal is distorted by the power amplifier 103, the distortion component 104 overlaps the amplified RF signal 105.

The attenuator 106 attenuates the amplified RF signal 105 in order to match the signal level of the amplified RF signal 105 with the signal level of the RF signal 101, and outputs the attenuated RF signal to the detector 108.

The detector 107 detects the RF signal 101 of the input signal and outputs its RF signal 101 to the amplitude comparator 109.

The detector 108 detects the attenuated RF signal generated by the attenuator 106 and outputs its RF signal to the amplitude comparator 109.

The amplitude comparator 109 detects the difference between the envelope of the RF signal detected by the detector 107 and the envelope of the RF signal detected by the detector 108, and outputs a gain control signal having a differential of zero to the variable gain. Part 102.

For example, since the RF signal is distorted by the power amplifier 103, the envelope of the amplified RF signal 105 becomes lower than the envelope of the RF signal 101, and the gain of the variable gain unit 102 is increased, and the signal level is kept fixed. Compensate for distortion.

On the other hand, since the RF signal is distorted by the power amplifier 103, the envelope of the amplified RF signal 105 becomes higher than the envelope of the RF signal 101, and the gain of the variable gain section 102 is lowered, by maintaining the signal level. Fixed to compensate for distortion.

Here, when the distortion component 104 generated by the power amplifier 103 is modeled as ΔE [dBm], the amount of suppression S of the distortion can be expressed by the following formula (1).

S[dB]=ΔE/(1+A) (1)

In equation (1), the A system loop gain [dB].

The loop gain A, when the signal level of the amplified RF signal 105 is only 1 dB distorted, means the open loop gain of the gain amount [dB] controlled by the feedback loop.

According to the formula (1), when the loop gain A is small, it is understood that a sufficient distortion suppression effect is obtained. Therefore, a sufficient loop gain A must be ensured for all input levels required according to the application requirements.

However, the general detectors 107 and 108 are limited to the linear operation range (detectable range), and when the signal level of the input RF signal is equal to or greater than a certain value, or the signal level of the input RF signal is below a certain value. In the case, the performance as a detector (= detection gain) is significantly deteriorated.

For example, when the output power level is arbitrarily controlled or when a modulated wave having a large instantaneous power fluctuation is processed, the signal amplitude to be controlled greatly fluctuates with time. For example, if the amplifier for the portable terminal is used, the amplitude of the necessary signal amplitude is 30 dB or more. For such a large signal level fluctuation, the detectors 107 and 108 covering the entire linear motion range are designed because of the circuit scale and The increase in power consumption is not practical.

For example, in the following Non-Patent Document 1, in the case where the instantaneous signal level is small, since distortion does not occur in the power amplifier 103, it is considered that the distortion component ΔE can be ignored in the formula (1) (the loop gain is not necessarily required to correspond to the weak input) Under the design idea, reveal the power amplifier of the design loop.

However, in the above design idea, when the design of the feedback is deviated from the ideal, a big problem arises.

As an example to explain this, the level adjustment of the feedback path is assumed to deviate from the ideal value depending on the manufacturing variation and the ambient temperature.

When the amount deviating from the ideal value is assumed to be ΔF, the transfer function of the input and output in the closed circuit is expressed by the following formula (2).

Output power [dBm] = input power [dBm] + G [dB] + ΔE / (1 + A) + ΔF. A/(1+A) (2)

In the formula (2), the total gain [dB] of the G-based variable gain unit 102 and the power amplifier 103.

Equation (2) means that the output power of the power amplifier varies according to the adjustment error ΔF of the feedback path and the loop gain A.

It is assumed that, as assumed in Non-Patent Document 1, when the signal level of the RF signal 101 is small, even if the distortion component 104 of the power amplifier 103 is zero, the loop gain A becomes small due to the fluctuation of the signal level of the RF signal 101, The fourth term (ΔF.A/(1+A)) on the right side of equation (2) produces a gain variation, and the new distortion component 110 adds an RF signal.

[Prior patent documents] [Non-patent document]

[Non-Patent Document 1] S. Kousai, "A 28.3 mW PA-Closed Loop for Linearity and Efficiency Improvement Integrated in a 27.1 dBm WCDMA CMOS Power Amplifier (integrated in 27.1 dB milliwatt wide-band code division multiplexed complementary metal oxide semiconductor power amplifier 28.3 milliwatts of power amplifier closed loop for linearity and efficiency improvement) IEEE J. Solid-State Circuits, vol. 47, no. 12 pp. 2964-2973, Dec. 2012 (Journal of the Institute of Electrical and Electronics Engineers Solid State Circuits, Volume 47, No. 12, No. 2964-2973, December 2012)

Since the conventional power amplifier has the above configuration, since the signal level of the RF signal 101 fluctuates, the loop gain A becomes small, and the gain variation occurs according to the adjustment error ΔF of the feedback path and the loop gain A, the circuit scale and consumption must be sacrificed. The electric power expands the linear motion range (detectable range) of the detectors 107, 108. Or, there is a problem that it is necessary to reduce the signal level (setting range) of the RF signal to which the distortion compensation circuit is applicable.

Since the present invention is formed to solve the above problems, even if the signal level of the input signal to which the distortion compensation circuit is applied is not reduced, the linear operation range of the detector is not enlarged, so that the circuit can be suppressed. The purpose of power amplifiers is to increase the size and power consumption.

According to the power amplifier of the present invention, the variable gain portion for the main signal is provided, and only the gain displayed by the gain control signal amplifies or attenuates the input signal; and the power amplifying portion amplifies the input signal amplified or attenuated by the variable gain portion of the main signal; The attenuator attenuates the input signal amplified by the power amplifying unit; the input side signal level adjusting device adjusts the signal level of the input signal in order to fix the signal level of the input signal before the main signal is amplified or attenuated by the variable gain unit The input side detector detects an input signal for adjusting the signal level by the input side signal level adjusting device; the return side signal level adjusting device adjusts the input signal for fixing the signal level of the input signal attenuated by the attenuator a signal level; a return side detector that detects an input signal that adjusts a signal level by a return side signal level adjusting device; and an amplitude comparator that detects an input signal detected by the input side detector The difference between the envelope and the envelope of the input signal detected by the return side detector is outputted, and a gain control signal having a difference of zero is outputted to the variable gain portion for the main signal.

According to the present invention, the input side signal level adjusting means is provided, and the signal level of the input signal is adjusted in order to fix the signal level of the input signal before the main signal is amplified or attenuated by the variable gain portion; the input side detector detects Adjusting the input signal of the signal level by the input side signal level adjusting device; returning the signal level adjusting device, adjusting the signal level of the input signal for fixing the signal level of the input signal attenuated by the attenuator; and returning side The detector detects an input signal for adjusting the signal level by the return side signal level adjusting means; since the amplitude comparator is configured to detect the envelope of the input signal detected by the input side detector and the input detected by the return side detector The difference between the envelopes of the signals, and outputs a gain control signal that makes the difference to zero to the variable gain portion for the main signal, even if the signal level of the input signal of the distortion compensation circuit is maintained without shrinking It does not enlarge the linear motion range of the detector, but has the effect of suppressing the increase in circuit scale and power consumption.

1‧‧‧RF signal (input signal)

2‧‧‧Variable gain section for main signal

3‧‧‧Power Amplification Department

4‧‧‧Amplified RF signal (amplified input signal)

5‧‧‧Attenuator

6‧‧‧Signal level adjustment unit (input side signal level adjustment device)

6a‧‧‧Input side variable gain section

6b‧‧‧Input side control

7‧‧‧Input side detector

8‧‧‧Signal level adjustment unit (return side signal level adjustment device)

8a‧‧‧Return side variable gain section

8b‧‧‧Return to the side control department

9‧‧‧Return side detector

10‧‧‧Amplitude comparator

21‧‧‧Signal level comparator (control signal conversion device)

22‧‧‧Control signal switch (control signal conversion device)

31‧‧‧Attenuation Control Unit

32‧‧‧Attenuator

101‧‧‧RF signal

102‧‧‧Variable gain section

103‧‧‧Power Amplifier

104‧‧‧ Distortion components

105‧‧‧Amplified RF signal

106‧‧‧Attenuator

107‧‧‧Detector

108‧‧‧Detector

109‧‧‧Amplitude comparator

110‧‧‧ Distortion components

[Fig. 1] Fig. 1 is a view showing a configuration of a power amplifier according to a first embodiment of the present invention; [Fig. 2] (a) showing an input/output characteristic of detectors 107, 108 in a conventional power amplifier; An explanatory diagram showing the input/output characteristics of the input side detector 7 and the return side detector 9 in the first embodiment; [Fig. 3] is a view showing a configuration of a power amplifier according to a second embodiment of the present invention; [Fig. 4] is a view showing a configuration of a power amplifier according to a third embodiment of the present invention; and [Fig. 5] A block diagram of a conventional power amplifier is shown.

[First Embodiment]

Fig. 1 is a view showing the configuration of a power amplifier according to a first embodiment of the present invention.

In the first diagram, the main signal variable gain unit 2 is a variable gain unit that amplifies or attenuates the RF signal 1 of the input signal only by the gain of the gain control signal output from the amplitude comparator 10.

In the first embodiment, although an example in which the input signal is an RF signal is described, it is merely an example, and may be a signal other than the RF signal.

The power amplifying unit 3 is an amplifier that amplifies or attenuates an RF signal that is amplified or attenuated by the main signal variable gain unit with a predetermined gain, and outputs the amplified RF signal 4.

The attenuator 5 is an attenuator that attenuates the RF signal 4 amplified by the power amplifying unit 3 until the signal level of the RF signal 1 before the main signal variable gain unit 2 is amplified or attenuated.

The signal level adjusting unit 6 of the input side signal level adjusting device performs the adjustment of the RF signal in order to fix the signal level of the RF signal 1 before the main signal variable gain unit 2 is amplified or attenuated (for example, -10 dBm). The processing of the signal level of 1.

The input side variable gain unit 6a is a variable gain unit that amplifies or attenuates the RF signal 1 before the main signal variable gain unit 2 is amplified or attenuated under the control of the input side control unit 6b.

The input side control unit 6b is a control circuit that averages the RF signal detected by the input side detector 7, and controls the input side variable gain unit 6a in order to fix the signal level of the averaged RF signal (for example, -10 dBm). Gain.

The input side detector 7 is a detector circuit that detects an RF signal amplified or attenuated by the input side variable gain unit 6a, and outputs the RF signal to the amplitude comparator 10.

The signal level adjusting unit 8 of the return side signal level adjusting means performs a process of adjusting the signal level of the RF signal in order to fix the signal level of the RF signal attenuated by the attenuator 5 (for example, -10 dBm).

The return side variable gain unit 8a is a variable gain unit that amplifies or attenuates the RF signal attenuated by the attenuator 5 under the control of the return side control unit 8b.

The return side control unit 8b averages the RF signal detected by the return side detector 9, and controls the gain of the return side variable gain unit 8a in order to fix the signal level of the averaged RF signal (for example, -10 dBm).

The return side detector 9 is a detection circuit that detects an RF signal amplified or attenuated by the return side variable gain unit 8a, and outputs the RF signal to the amplitude comparator 10.

The amplitude comparator 10 detects the difference between the envelope of the RF signal detected by the input side detector 7 and the envelope of the RF signal detected by the return side detector 9, and outputs a gain control signal having a difference of zero. The variable gain unit 2 is used for the main signal.

In other words, when the envelope of the RF signal detected by the input side detector 7 is higher than the envelope of the RF signal detected by the return side detector 9, the amplitude comparator 10 In order to match these envelopes, a gain control signal for increasing the gain of the main signal variable gain unit 2 is outputted to the main signal variable gain unit 2.

On the other hand, if the envelope of the RF signal detected by the input side detector 7 is lower than the envelope of the RF signal detected by the return side detector 9, the main signal variable gain unit 2 is outputted in order to match these envelopes. The gain control signal of the gain is applied to the variable gain section 2 for the main signal.

Second, explain the action

The main signal variable gain unit 2, when the RF signal 1 is input, only the gain of the gain control signal output from the amplitude comparator 10 described later amplifies or attenuates the RF signal 1 and outputs the amplified or attenuated RF signal to Power amplification unit 3.

When receiving the amplified or attenuated RF signal from the main signal variable gain unit 2, the power amplifying unit 3 amplifies the RF signal only with a predetermined gain set in advance, and outputs the amplified RF signal 4.

When the attenuator 5 receives the amplified RF signal 4 from the power amplifying unit 3, the attenuator 5 attenuates the signal of the RF signal 4 amplified by the power amplifying unit 3 to the RF signal 1 before the main signal variable gain unit 2 is amplified or attenuated. The bit is output, and the attenuated RF signal is output to the signal level adjusting unit 8.

The signal level adjusting unit 6 adjusts the signal level of the RF signal 1 in order to fix the signal level of the RF signal 1 before the main signal variable gain unit is amplified or attenuated (for example, -10 dBm).

In other words, the input side control unit 6b of the signal level adjusting unit 6 averages the RF signal detected by the input side detector 7, and controls the input in order to fix the signal level of the averaged RF signal (for example, -10 dBm). The gain of the side variable gain portion 6a.

The input side variable gain unit 6a of the signal level adjusting unit 6 amplifies or attenuates the RF signal 1 before being amplified or attenuated by the main signal variable gain unit 2 under the control of the input side control unit 6b, and outputs an amplification or The attenuated RF signal is supplied to the input side detector 7.

Therefore, the input side detector 7 detects the RF signal output from the input side variable gain unit 6a, and outputs its RF signal to the amplitude comparator 10, because the signal level adjustment unit 6 adjusts the signal level of the RF signal to be fixed. It is not necessary to enlarge the linear motion range (detectable range) of the input side detector 7.

Here, the display input side control unit 6b averages the RF signal detected by the input side detector 7, and controls the gain of the input side variable gain unit 6a in order to fix the signal level of the averaged RF signal. For example, the RF signal detected by the integrated input side detector 7 may be controlled to increase the gain of the input side variable gain unit 6a in order to fix the signal level of the integrated RF signal.

The signal level adjusting unit 8 adjusts the signal level of the RF signal in order to fix the signal level of the RF signal attenuated by the attenuator 5 (for example, -10 dBm).

In other words, the return-side control unit 8b of the signal level adjusting unit 8 averages the RF signal detected by the return-side detector 9, and controls the return to fix the signal level of the averaged RF signal (for example, -10 dBm). The gain of the side variable gain portion 8a.

The return-side variable gain unit 8a of the signal level adjusting unit 8 amplifies or attenuates the RF signal attenuated by the attenuator 5 under the control of the return-side control unit 8b, and outputs the amplified or attenuated RF signal to the return side detection. 9.

Therefore, the return side detector 9 detects the RF signal output from the return side variable gain unit 8a, and outputs its RF signal to the amplitude comparator 10, because the signal level adjusting unit 8 adjusts the signal level of the RF signal to be fixed. It is not necessary to enlarge the linear motion range (detectable range) of the return side detector 9.

Here, the return-side control unit 8b averages the RF signal detected by the return-side detector 9 and controls the gain of the return-side variable gain unit 8a in order to fix the signal level of the averaged RF signal, but this is only one For example, the RF signal detected by the integrated return side detector 9 may be integrated, and the gain of the return side variable gain unit 8a may be controlled in order to fix the signal level of the integrated RF signal.

The amplitude comparator 10 detects the difference between the envelope of the RF signal detected by the input side detector 7 and the envelope of the RF signal detected by the return side detector 9, and outputs a gain control signal having a difference of zero. The variable gain unit 2 is used for the main signal.

In other words, when the envelope of the RF signal detected by the input side detector 7 is higher than the envelope of the RF signal detected by the return side detector 9 in the amplitude comparator 10, in order to make these envelopes coincide, the output improves the variable of the main signal. The gain control signal of the gain of the gain unit 2 is applied to the variable gain unit 2 for the main signal.

On the other hand, if the envelope of the RF signal detected by the input side detector 7 is lower than the envelope of the RF signal detected by the return side detector 9, the main signal variable gain unit 2 is outputted in order to match these envelopes. The gain control signal of the gain is applied to the variable gain section 2 for the main signal.

Here, Fig. 2 is an explanatory view showing the input/output characteristics of the detector.

In particular, Figure 2(a) shows a conventional power amplifier (electricity of Figure 5) The input and output characteristics of the detectors 107 and 108 in the force amplifier) and the second (b) diagram show the input/output characteristics of the input side detector 7 and the return side detector 9.

For the convenience of explanation, for the signal level (input level or output level) of the RF signal of the variable gain portion 102 of the conventional power amplifier, the a[dB in the second graph (a) is controlled. In the range of ], the RF signal is a modulated wave, assuming that the instantaneous power drop is b [dB] and the peak power rise is c [dB].

At this time, in the conventional power amplifier, since the signal level of the RF signal fluctuates within the range of a [dB], the linear motion range (detectable range) of the detectors 107, 108 must be a + b + c [ dB].

On the other hand, in the first embodiment, the signal level of the RF signal fluctuates within a range of a [dB], because the signal level adjustment sections 6 and 8 adjust the signal level of the RF signal to be fixed, and need not be corresponding. The range of a [dB] fluctuates, and the linear operation range (detectable range) of the input side detector 7 and the return side detector 9 is expanded.

Therefore, the linear operation range (detectable range) of the input side detector 7 and the return side detector 9 is sufficient in the range of b + c [dB] as shown in the second (b) diagram.

Therefore, the power consumption required for the input side detector 7 and the return side detector 9 can be reduced, and the increase in the circuit scale of the input side detector 7 and the return side detector 9 can be suppressed.

Hereinafter, in order to quantitatively explain the effects of the power amplifier of the first embodiment, it is assumed that the design parameters of the respective constituent elements are as follows.

(1) The gain of the main signal variable gain unit 2 is 0 dB when the loop converges (no deformation state).

(2) The gain of the power amplifying unit 3 is 30 dB.

(3) The RF signal 1 of the input signal can be set to an average power of -30 dBm to 0 dBm according to the power control.

(4) The RF signal 1 of the input signal is OFDM (Orthogonal Multi-Frequency Division) modulation, and the instantaneous power varies from the average power in the range of +10 dBm to -10 dBm.

(5) The attenuation amount of the attenuator 5 is -30 dB.

(6) The gain of the input side variable gain unit 6a is controlled so that the output level of the input side detector 7 becomes -10 dBm. However, when the gain is not controlled by the input side control unit 6b, it has a gain of -10 dB.

(7) The gain of the return side variable gain unit 8a is controlled so that the output level of the return side detector 9 becomes -10 dBm. However, when the gain is not controlled by the signal level adjusting unit 8, it has a gain of -10 dB.

When the power amplifier of the first embodiment and the conventional power amplifier are compared, the power amplifier of the first embodiment includes the input side detector 7 and the return side detector described in (6) and (7) above. The output level of 9 controls the function of the fixed value at different points.

Without this function, the input level of the RF signal to the detector changes within an average power of -40dBm to -10dBm. Therefore, if the instantaneous power is changed, the detector must detect the amplitude within a range of 50 dB (-50 dBm to 0 dBm).

Such a wide timing range causes an increase in the circuit scale of the detector and an increase in power consumption.

In the first embodiment, since the input side detector 7 and the return side detector 9 The output level is fixed within -10 dBm, and the timing range necessary for the input side detector 7 and the return side detector 9 can be suppressed to 20 dB (-20 dBm to 0 dBm) of the instantaneous fluctuation portion.

As apparent from the above, according to the first embodiment, the signal level adjusting unit 6 is provided to adjust the RF signal 1 in order to fix the signal level of the RF signal 1 before the main signal is amplified or attenuated by the variable gain unit 2. The input side detector 7 detects the RF signal whose signal level is adjusted by the signal level adjusting unit 6; the signal level adjusting unit 8 adjusts the signal level of the RF signal attenuated by the attenuator 5 to be fixed. The signal level of the RF signal; and the return side detector 9 detect the RF signal whose signal level is adjusted by the signal level adjusting unit 8; since the configuration of the amplitude comparator 10 detects the RF detected by the input side detector 7. The difference between the envelope of the signal and the envelope of the RF signal detected by the return side detector 9 is outputted, and a gain control signal having a difference of zero is outputted to the variable gain portion 2 for the main signal, which is maintained without being reduced. When the signal level of the RF signal of the distortion compensation circuit is applied, the linear operation range (detectable range) of the input side detector 7 and the return side detector 9 is not increased, and the circuit scale and power consumption can be suppressed. Increase effect fruit.

[Second embodiment]

Fig. 3 is a view showing a configuration of a power amplifier according to a second embodiment of the present invention, and the same reference numerals are given to the same or corresponding parts in the drawings, and the description thereof will be omitted.

The signal level comparator 21 performs processing for comparing the RF signal averaged by the input side control unit 6b with a preset threshold value.

Also, the signal level comparator 21, if the averaged RF signal is greater than the critical value If it is high, the following processing is performed: outputting a control signal indicating that the gain control signal output from the amplitude comparator 10 is supplied to the main signal variable gain section 2 to the control signal changeover switch 22, and the averaged RF signal is lower than the critical value. In addition, a control signal to the control signal changeover switch for supplying the fixed gain control signal for the signal level of the RF signal amplified by the power amplifying unit 3 to a predetermined signal level is outputted to the main signal variable gain unit 2. twenty two.

The control signal changeover switch 22 performs a process of outputting a gain control signal output from the amplitude comparator 10 or a fixed gain control signal to the main signal variable gain section 2 based on the control signal output from the signal level comparator 21.

Further, the signal level comparator 21 and the control signal changeover switch 22 constitute a control signal conversion means.

Second, explain the action

However, except for the point at which the signal level comparator 21 and the control signal changeover switch 22 are mounted, since it is the same as the first embodiment described above, the signal level comparator 21 and the control signal changeover switch 22 are mainly explained here. Processing content.

The phenomenon in which the RF signal is distorted by the power amplifying unit 3 occurs when the signal level of the RF signal has a certain level or more, and the signal level of the RF signal does not occur every hour.

Therefore, in this second embodiment, the amplitude comparator 10 manipulates the distortion compensating loop for controlling the gain of the main signal variable gain section 2, and the RF signal is not distorted, in the case where the signal level of the RF signal is limited to a certain size or more. When the signal level is small, a part of the distortion compensation circuit (for example, the amplitude comparator 10, the signal level adjustment unit 8, and the return side detector 9) is stopped, and excess power consumption can be suppressed.

Specifically, it is the same as the following.

The signal level comparator 21 compares the RF signal averaged by the input side control unit 6b with a preset threshold value.

Here, the critical value is, for example, a maximum value in a small signal level in a range in which the signal is not distorted in the power amplifying portion 3, a value which is a fractional percentage to the maximum value thereof, or the like.

When the RF signal averaged by the input side control unit 6b is higher than the critical value (RF signal ≧ threshold value), the RF signal is distorted by the power amplifying unit 3, the output level comparator 10 outputs the output of the display amplitude comparator 10. The gain control signal is supplied to the control signal changeover switch 22 for the control signal of the main signal variable gain section 2.

The control signal changeover switch 22 outputs the gain control signal output from the amplitude comparator 10 to the main signal variable gain unit 2 when receiving the above-described control signal from the amplitude comparator 10.

Therefore, as in the first embodiment described above, the RF signal distortion occurring in the power amplifying portion 3 is compensated.

When the RF signal averaged by the input side control unit 6b is lower than the threshold value (RF signal <critical value), the signal level comparator 21 outputs the display to the power amplifying unit 3 because the RF signal is not distorted by the power amplifying unit 3. The signal control level of the amplified RF signal is a fixed gain control signal of a predetermined signal level, and is supplied to the control signal changeover switch 22 for the control signal of the main signal variable gain section 2.

Here, the fixed gain control signal, for example, assumes that the desired signal level of the amplified RF signal 4 is 20 dB, and the gain of the power amplifying portion 3 is 15 dB. In the case of controlling the main signal, the gain control signal of the gain of the variable gain section 2 is 5 dB.

The control signal changeover switch 22 outputs a fixed gain control signal to the main signal variable gain section 2 when receiving the above control signal from the amplitude comparator 10.

Therefore, when the fixed gain control signal is outputted to the main signal variable gain unit 2 instead of the gain control signal output from the amplitude comparator 10, for example, the amplitude comparator 10, the signal level adjusting unit 8, and the return side are stopped. A part of the distortion compensation circuit of the detector 9 or the like suppresses excessive power consumption.

In the second embodiment, although the display signal level comparator 21 compares the RF signal averaged by the input side control unit 6b with the threshold value, the signal level comparator 21 compares the RF signal averaged by the return side control unit 8b with the critical value. The value is also ok.

In this case, when the fixed gain control signal is outputted to the main signal variable gain unit 2 instead of the gain control signal output from the amplitude comparator 10, the amplitude comparator 10, the signal level adjustment unit 6, and the input side are stopped. A part of the distortion compensation circuit of the detector 7 or the like.

As apparent from the above, according to the second embodiment, in the case where the RF signal detected by the input side detector 7 or the signal level of the RF signal detected by the return side detector 9 is lower than a preset threshold value, Instead of the gain control signal output from the amplitude comparator 10, a fixed gain control signal is outputted to the main signal variable gain unit 2, and a part of the distortion compensation circuit is stopped in a state where the signal level of the RF signal is not distorted is small, so that suppression can be suppressed. The effect of excess power consumption.

[Third embodiment]

Fig. 4 is a view showing a configuration of a power amplifier according to a third embodiment of the present invention, and the same reference numerals are given to the same or corresponding parts in the drawings, and the description thereof will be omitted.

The attenuation amount control unit 31 adjusts the attenuation amount of the attenuator 32 in order to match the gain control signal output from the amplitude comparator 10 with a predetermined reference signal during the adjustment period of the attenuator 32.

The attenuator 32 controls the attenuation amount by the attenuation amount control unit 31, and attenuates the attenuator of the RF signal 4 amplified by the power amplifying unit 3 only by the amount of attenuation.

In the first and second embodiments, the display attenuator 5 attenuates the RF signal amplified by the power amplifying unit 3 to the signal level of the RF signal 1 before the main signal variable gain unit 2 is amplified or attenuated, for example, due to attenuation. The pre-adjustment of the device 5 is insufficient, and there is a case where there is an adjustment error (deviation).

In such a case, even if the attenuator 5 attenuates the RF signal amplified by the power amplifying portion 3, the signal level of the RF signal is not equal to the signal level of the RF signal 1 before the main signal is amplified or attenuated by the variable gain portion 2. .

Therefore, in the third embodiment, the attenuation amount control unit 31 controls the attenuation of the attenuator 32 in order to match the gain control signal output from the amplitude comparator 10 with a preset reference signal during the adjustment period of the adjustment attenuator 32. Decrease.

Specifically, it is the same as the following.

The adjustment period of the attenuator 32 is adjusted, for example, when the power is set or during the standby, the timing of not using the power amplifier or the like is considered.

Further, the reference signal is, for example, a gain indicating the display of the fixed gain control signal (the gain control signal for causing the signal level of the RF signal amplified by the power amplifying unit 3 to be a predetermined signal level) displayed in the second embodiment. With power The signal of the sum of the gains of most of the three.

The attenuation amount control unit 31 controls the attenuation amount of the attenuator 32 in order to match the gain control signal output from the amplitude comparator 10 with a predetermined reference signal during the adjustment period of the adjustment attenuator 32.

In other words, when the gain control signal output from the amplitude comparator 10 is higher than the reference signal (gain control signal ≧ reference signal), the attenuation amount control unit 31 controls the attenuator 32 in the increasing direction in order to match the gain control signal with the reference signal. The amount of attenuation.

On the other hand, if the gain control signal output from the amplitude comparator 10 is lower than the reference signal (gain control signal <reference signal), the attenuation amount of the attenuator 32 is controlled in the decreasing direction in order to make the gain control signal coincide with the reference signal.

When the attenuation amount control unit 31 controls the attenuation amount of the attenuator 32, and the gain control signal output from the amplitude comparator 10 is high in accordance with the reference signal, the adjustment error of the attenuator 32 can be canceled beforehand. That is, the deviation in the input of the amplitude comparator 10 can be corrected.

As described above, the adjustment error ΔF of the feedback path indicated by the equation (2) is made equal to zero, and the instantaneous input power is weakened, and it is possible to avoid the deterioration of the distortion due to the loop control when the loop gain A decreases.

[Fourth embodiment]

In the above-described first to third embodiments, the amplitude comparator 10 is provided to control the distortion compensation control circuit of the gain of the main signal variable gain unit 2, and the input side control unit 6b is provided to control the input side variable gain unit 6a. A control circuit for adjusting the signal level of the gain and a control circuit for adjusting the signal level of the gain of the return-side variable gain unit 8a with the return-side control unit 8b.

In other words, in the first to third embodiments described above, multiple loops are formed in two control loops (a control loop for distortion compensation and a control loop for signal level adjustment).

However, since the two control loops are multiple loops, depending on the conditions, there is a danger that the control loop becomes unstable.

Basically, the response speed of the control loop for distortion compensation is inversely proportional to the bandwidth of the RF signal (modulated signal) that can be compensated for distortion, and must be accelerated as much as possible.

Therefore, in the fourth embodiment, the response speed of the control loop for accelerating the distortion compensation is sufficiently delayed, and the response speed of the control loop for the level adjustment is sufficiently delayed, thereby maintaining the stability of the entire system.

That is, it is preferable that the control circuit for the level adjustment is designed not to respond to the fluctuation speed of the instantaneous power, and to follow the period (usually very late) at which the signal level setting of the RF signal is changed.

Therefore, in the fourth embodiment, for example, by delaying the time constants of the input side control unit 6b and the return side control unit 8b, the response speed of the control circuit for signal level adjustment is higher than that of the control circuit for distortion compensation. Slow.

For the time constant described above, for example, a time constant of a sufficiently delayed phase delay of a control loop for adjusting the signal level of 10 or more is considered.

As described above, by making the response speed of the control circuit for signal level adjustment slower than the response speed of the control circuit for distortion compensation, the bandwidth of the distortion-compensable RF signal (modulation signal) can be maintained while maintaining control. The stability of the loop.

Further, the present invention can be freely combined with the respective embodiments within the scope of the present invention, or any constituent elements of the respective embodiments can be changed, or the respective embodiments can be omitted. Any of the constituent elements in the example.

[Industry use possibility]

In the power amplifier of the transmission device side of the wireless terminal such as a mobile phone or WiFi (Wireless Fidelity), for example, it is suitable for a power amplifier that suppresses the circuit scale of the detector or increases the power consumption.

1‧‧‧RF signal

2‧‧‧Variable gain section for main signal

3‧‧‧Power Amplification Department

4‧‧‧RF signal

5‧‧‧Attenuator

6‧‧‧Signal level adjustment department

6a‧‧‧Input side variable gain section

6b‧‧‧Input side control

7‧‧‧Input side detector

8‧‧‧Signal level adjustment department

8a‧‧‧Return side variable gain section

8b‧‧‧Return to the side control department

9‧‧‧Return side detector

10‧‧‧Amplitude comparator

Claims (6)

An electric power amplifier comprising: a variable gain portion for a main signal, which amplifies or attenuates an input signal only by a gain displayed by a gain control signal; and a power amplifying portion that amplifies an input signal amplified or attenuated by the variable gain portion of the main signal; attenuation And attenuating the input signal amplified by the power amplifying unit; and the input side signal level adjusting means adjusts the signal of the input signal in order to fix the signal level of the input signal before the main signal variable gain unit is amplified or attenuated The input side detector detects an input signal for adjusting the signal level by the input side signal level adjusting device; the return side signal level adjusting device adjusts the signal level of the input signal attenuated by the attenuator, and adjusts a signal level of the input signal; a return side detector for detecting an input signal for adjusting a signal level by the return side signal level adjusting means; and an amplitude comparator for detecting an envelope of the input signal detected by the input side detector The difference between the line and the envelope of the input signal detected by the return side detector described above, and Mission to zero the differential gain control signal to the main signal of the variable gain portion. The power amplifier according to claim 1, wherein the input side signal level adjusting device includes: an input side variable gain unit that amplifies or attenuates an input before the main signal variable gain unit is amplified or attenuated. Signal; The input side control unit controls the gain of the input side variable gain unit to fix the signal level of the input signal on the side of the input side detector; and the return side signal level adjustment means includes: a return side variable gain And amplifying or attenuating the input signal attenuated by the attenuator; and the return-side control unit controls the gain of the return-side variable gain unit in order to fix the signal level of the input signal detected by the return-side detector. The power amplifier according to claim 2, comprising: control signal conversion means, wherein a signal level of the input signal detected by the input side detector or the input signal detected by the return side detector is a preset threshold value When the value is low, a fixed gain control signal is outputted to the main signal variable gain unit instead of the gain control signal output from the amplitude comparator, and the signal level of the input signal amplified by the power amplifying unit is set to a predetermined signal. Level. The power amplifier according to claim 1, wherein the attenuator attenuates an input signal amplified by the power amplifying unit to a signal level of an input signal before amplification or attenuation of the main signal variable gain unit. . The power amplifier according to claim 1, further comprising: an attenuator control unit that controls the above-described attenuator adjustment period in order to match the gain control signal output from the amplitude comparator with a predetermined reference signal The amount of attenuation of the attenuator. An electric amplifier according to claim 2, wherein the The input side control unit controls the response speed of the control circuit for adjusting the signal level of the gain of the input side variable gain unit, and the signal level adjustment for controlling the gain of the return side variable gain unit by the returning side control unit. The response speed of the control loop is slower than the response speed of the control loop for distortion compensation in which the amplitude comparator controls the gain of the variable gain portion for the main signal.