JPS60256231A - Transmission power control circuit - Google Patents

Abstract

PURPOSE:To eliminate the effect of a harmonic by inserting the n-order harmonic rejection filter between a power detecting section and an error amplifier section to simplify the constitution of a transmission power control circuit. CONSTITUTION:A part of an RF signal amplified by a power amplifier 1 is detected by a power detecting section 2, the n-order harmonic is eliminated by the n-order harmonic filter 6 and the detector 3 converts the RF signal to a DC level. The DC level from the detector 3 is fed to an error amplifier section 4, where the level is compared with a reference voltage Vrf, its output is inputted to a power voltage control section 5, which controls a power voltage by the control section 5 and the power voltage of the amplifier section 1 is made to a prescribed voltage. The filter 6 consists of a capacitor and a coil formed on the same printed board to eliminate effectively a harmonic of an RF output from a transmission power control circuit.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to transmission power control 1 used in mobile communication devices, etc.
(This is related to Road 11.

[Prior art]

Conventionally, this type of transmitter has been configured as shown in FIG. 1 in order to control power. The power amplification section 1 amplifies the RF multiplied signal, the power detection section 2 extracts a part of the RF multiplied signal, the detection section 3 converts the RF multiplied signal into DCC level, and the error amplification section 4 compares it with the reference voltage Vrr. , the power of the power amplifier section 1 was controlled by the power supply voltage control circuit 5. Here, the power detection unit 2 obtains part of the power through a coupler or capacitive coupling.

Therefore, if the harmonics in the power amplification section 1 are large, there is a drawback that the harmonics are also converted when the power is converted from the RF signal to the DC level in the detection section 3. Conventionally, as a method to eliminate the above-mentioned drawbacks, methods such as inserting a low-pass filter after the coupler or adding a capacitor in parallel with the diode have been considered.

However, the former has drawbacks such as a large-scale configuration, a large number of parts, which increases costs, and a time required for implementation in small radio devices. Furthermore, the latter method has the disadvantage that desired harmonic components cannot be removed sufficiently.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above drawbacks, provide a transmission power control circuit that has a simple configuration and is not affected by harmonics.

[Structure of the invention]

The transmission power control circuit according to the present invention has a configuration in which a configurable n-th harmonic injection filter is inserted between the power detection section and the error amplification section described above to achieve the above-mentioned [1]. This is to ensure that harmonic components are removed.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

An embodiment of the present invention is shown in FIG.
, the rejection filter 6 removes the n-th harmonic, the detection section 3 converts it to an RF multiplied signal DC level, and the error amplification section 4 converts the DC level and substrate voltage V.
rf and the power supply voltage controller 5 controls the power supply voltage of the power amplifier 1 to obtain a constant output. The rejection filter 6 may be formed by, for example, a coil and a capacitor, or a strip line at the wavelength of the first harmonic may be formed on the printed board 1. It is constructed by forming the

As an example, FIG. 3 shows a case where the power detection section 2 and the harmonic rejection filter 6 are configured on the same plane by a microstrip line. Accurate transmission power control can be performed.

〔Effect of the invention〕

Next, the effects of the present invention will be explained using two drawings. FIG. 4 shows the frequency characteristics of transmission power by a conventional power control circuit, and FIG. 5 shows the frequency characteristics by the control circuit of the present invention.

In conventional control circuits, if there is a fluctuation in harmonic components due to a change in frequency, the transmission power of the fundamental wave changes due to the influence, resulting in uneven frequency characteristics as shown in FIG. On the other hand, having a rejection filter,
In the power control circuit according to the present invention, since harmonic components are reliably removed by the rejection filter, only the fundamental wave component is detected, and a flat frequency characteristic as shown in FIG. 5 is obtained.

As explained above, the present invention has a simple configuration, uses a rejection filter, and removes the n-th harmonic with the rejection filter, making it easy to control transmission power without being affected by harmonics. It is something.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a conventional transmission power control circuit, FIG. 2 is a block diagram showing an embodiment of the present invention, and FIG. 3 is a block diagram showing the power detection section and the nth method shown in FIG. A configuration diagram showing an example in which a harmonic rejection filter and a harmonic rejection filter are configured on the same plane by a microstrip line,
FIG. 4 shows an example of the frequency characteristics of transmission power affected by harmonic components, and FIG. 5 shows an example of the frequency characteristics when the effects of harmonic components are removed by a beam injection filter. l...Power amplification section 2...Power detection section 3...Detection section 4...Error amplification section 5...Power supply voltage control section 6...lKnth harmonic rigidity filter Vrf
...Reference voltage Figure 5 JT'I [whisper jfi

Claims (2)

[Claims] (1) A power detection unit that detects a part of the output power from the power amplification unit, a detection unit that converts the detected power to a DC level, and an error amplification unit that amplifies the difference between the DC level and the reference voltage. and a power supply voltage control unit that controls the power supply voltage to the power amplification unit based on the difference,
A high frequency power control circuit 1 that keeps the output power constant,
A transmission power control circuit characterized in that an n-th harmonic rejection filter is inserted between the power detection section and the wave detection section. (2) The transmission power control circuit according to claim 1, wherein the power detection section and the rejection filter are configured on the same plane by a microstrip line.