JP3490815B2 - Transmitter and its temperature compensation method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of temperature compensating a power amplification unit for amplifying a transmission signal to a predetermined transmission output in a transmitter, and a transmitter for implementing the method.

[0002]

2. Description of the Related Art A radio transmitter is used as a transmission system of a mobile communication device such as a mobile phone, and a transmission signal is amplified by a power amplifier to a predetermined output and then wirelessly transmitted via an antenna. . For example, in the conventional transmitter shown in FIG. 3, the first frequency synthesizer unit 2 outputs a carrier signal fixed to a single frequency based on the reference frequency signal from the reference signal generator 1, and the carrier signal is modulated by the modulator. 3 is modulated by the baseband signal to be a transmission signal. Then, the frequency conversion unit 4 uses the second synthesizer unit 5
The transmission signal output from the modulation unit 3 is converted into a frequency corresponding to the transmission channel based on the signal from the power transmission unit, and the transmission signal output from the frequency conversion unit 4 is amplified by the power amplification unit 6 to a predetermined transmission output. After that, the signal is transmitted from the antenna 7.

Here, there is a relationship as shown in FIG. 2 between the transmission output (transmission power) in the power amplification section 6 and the environmental temperature. When the environmental temperature changes, the transmission power also changes,
There is the problem that the transmitted signal cannot be stably amplified to the desired output. Therefore, in the conventional transmitter, a gate bias unit 10 having an arithmetic unit 8 and a thermistor 9 is provided, and the power amplification unit 6 is controlled by the gate bias unit 8 to cancel the change in the environmental temperature and to reduce the power consumption. Stable amplification by the amplification unit 6 was realized. That is,
A power control signal from a baseband unit (not shown) that generates a baseband signal and a control signal corresponding to a temperature change from the thermistor 9 are input to a calculator 8, and the control signal from the calculator 8 is used to generate power. By controlling the amplification unit 6, the positive and negative polarities of the transmission signal amplified by the power amplification unit 6 have predetermined characteristics regardless of the temperature change.

[0004]

However, in the above-mentioned conventional transmitter, it is necessary to provide the thermistor 9 in the gate bias section 10 in order to perform temperature compensation control of the power amplification section 6, and this thermistor 9 is used. There is a problem in that the cost increases and the difficulty in designing the circuit layout increases with the provision thereof. In addition, since the thermistor generally has a non-linear temperature characteristic, desired temperature compensation is achieved within a predetermined temperature range, but desired temperature compensation is performed at temperatures outside this temperature range. In some cases, it could not be achieved, and there was a problem that the reliability in the usage environment was poor.

The present invention has been made in view of the above conventional circumstances, and an object of the present invention is to provide a transmitter and a temperature compensating method for realizing temperature compensation for power amplification of a transmission signal without using a thermistor.

[0006]

To achieve the above object, a transmitter according to claim 1 of the present invention outputs a carrier signal fixed to a single frequency based on a signal from a reference signal generator. In a transmitter including a frequency synthesizer, a modulator that modulates a carrier signal with a baseband signal, and a power amplifier that amplifies the transmission signal output from the modulator to a predetermined transmission output, a reference signal generator is provided. With a temperature compensated oscillator that outputs a constant frequency signal,
The frequency synthesizer outputs a temperature-compensated carrier signal, and the controller controls the power amplifier based on the phase difference information obtained by the frequency synthesizer in comparison with the signal from the reference signal generator, and transmits it. It is characterized by canceling the temperature change that affects the output.

That is, the above frequency synthesizer is
A voltage controlled oscillator that outputs a frequency signal corresponding to a control voltage as a carrier signal, and a phase comparator that detects a phase difference between the output signal from the voltage controlled oscillator and the output signal from the temperature compensation oscillator (reference signal generating unit) And a loop filter for converting the detected phase difference into a voltage and applying it to a voltage-controlled oscillator, and outputting a temperature-compensated carrier signal from the voltage-controlled oscillator. The power amplifier is controlled on the basis of the phase difference voltage from to cancel the temperature change that affects the transmission output.

Here, the frequency of the signal oscillated from the voltage controlled oscillator of the frequency synthesizer changes with the change of the environmental temperature, and the phase difference (that is,
The phase difference voltage obtained by the loop filter) reflects this environmental temperature change. The present invention uses the above-mentioned phase difference voltage in place of a conventional thermistor in order to detect a change in environmental temperature, and controls the power amplifier based on the phase difference voltage to change the environmental temperature. Regardless of this, the power amplification unit amplifies the transmission signal to have a predetermined characteristic.

According to a second aspect of the present invention, the transmitter controls the power supply based on the power control signal from the baseband unit for generating the baseband signal and the phase difference voltage from the loop filter. Control the amplifier,
The output of the transmission signal is controlled while being temperature-compensated. In addition to the above configuration, the transmitter according to claim 3 of the present invention has
Based on a second frequency synthesizer that outputs a plurality of frequency signals for transmission channels based on a signal from the reference signal generator, and a signal from the second frequency synthesizer,
And a frequency conversion unit that frequency-converts the output signal from the modulation unit and outputs the frequency-converted output signal to the power amplification unit, and the transmission signal is converted into a frequency suitable for the transmission channel and transmitted.

The temperature compensating method according to a fourth aspect of the present invention includes a frequency synthesizer for outputting a carrier signal fixed to a single frequency from an oscillator by performing a phase difference control based on a signal from a reference signal generating section, In a transmitter including a modulator that modulates a carrier signal with a baseband signal and a power amplifier that amplifies the transmission signal output from the modulator to a predetermined transmission output, a temperature-compensated reference signal generator is used. Based on the phase difference between this signal and the signal from the oscillator of the frequency synthesizer, the power amplifier is controlled to cancel the temperature change that affects the transmission output. As a result, also in the present invention, the transmission signal is amplified by the power amplification unit so as to have a predetermined characteristic regardless of the change in the environmental temperature.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A transmitter according to an embodiment of the present invention will be described with reference to the drawings. The same parts as those in the conventional example shown in FIG. The transmitter of this embodiment is used as a transmission system of a communication device such as a mobile phone, and FIG. 1 shows a main part of the transmission system.

The transmitter of this embodiment has, as a constituent circuit, a reference signal generating section 1 for outputting a constant frequency signal regardless of changes in environmental temperature, and a single signal based on the reference signal from the reference frequency generating section 1. A first frequency synthesizer unit 12 that outputs a carrier signal fixed to a frequency, a modulator unit 3 that modulates the carrier signal with a baseband signal, and a transmission channel corresponding to a reference frequency signal from a reference frequency generation unit 1 A second synthesizer unit 5 that outputs an arbitrary frequency signal; a frequency converter 4 that converts the transmission signal output from the modulator 3 based on the signal from the second synthesizer unit 5 into a frequency corresponding to the transmission channel; A power amplification unit 6 that amplifies this transmission signal to a predetermined transmission output, an antenna 7 that wirelessly transmits the amplified transmission signal, and temperature compensation control of the power amplification unit 6. And Tobaiasu portion 18, and a.

The first frequency synthesizer 12 of this embodiment
Is a voltage controlled oscillator 13 that outputs a signal having a frequency corresponding to the control voltage; a phase comparator 14 that detects a phase difference between the signal from the voltage controlled oscillator 13 and the reference signal from the reference signal generator 1; The phase difference detected by the comparator 14 is converted into a voltage through the loop filter 15, and the voltage controlled oscillator 13
Applied as a control voltage. The voltage controlled oscillator 13 is a VCO (Voltage Cont) that changes the oscillation frequency together with a control voltage applied using a voltage variable capacitor, for example.
If the ambient temperature is constant, a carrier signal fixed to a single frequency is output to the modulator 3 when a constant control voltage is applied.

That is, in the first frequency synthesizer 12, the signal output from the voltage controlled oscillator 13 is compared with the reference signal of the constant frequency output from the reference signal generator 1, and the voltage caused by the change in the ambient temperature is compared. When the signal output from the controlled oscillator 13 has a phase difference with respect to the reference signal, the control voltage is adjusted to eliminate this phase difference, and the voltage controlled oscillator 13 outputs a carrier signal fixed at a single frequency. ing. The reference signal generator 1 is a temperature-compensated crystal oscillator (TCXO: Temperature Compensated Crystal Oscillator) which is a crystal oscillator whose frequency is stabilized against temperature changes.
It is composed of a CrystalOscilator) and outputs a reference signal with a constant frequency regardless of changes in environmental temperature.

The gate bias unit 18 is an arithmetic unit that receives a power control signal from a baseband unit (not shown) for generating a baseband signal and a phase difference voltage from the loop filter 15 as input, and the baseband unit. The power amplifier 6 is controlled based on the power control signal from the power amplifier 6 and the power amplifier 6 is controlled based on the phase difference voltage from the loop filter 15.
To control. Therefore, the transmission signal is output-controlled based on the power control signal from the baseband unit, and temperature-compensated and controlled based on the phase difference voltage reflecting the environmental temperature change. At 6, the positive polarity and the negative polarity are amplified so as to have predetermined characteristics.

The second synthesizer section 5 has the same structure as the first synthesizer section 12, and the reference frequency generating section 1
A signal with a constant frequency is output based on the reference frequency signal from the, but the frequency of the output signal can be changed by further having a variable frequency divider to change the frequency division number. . Then, by changing the frequency, the frequency conversion unit 4 converts the transmission signal output from the modulation unit 3 into a frequency corresponding to the transmission channel.

According to the transmitter having the above structure, for example, when the loop filter 15 outputs the voltage V1 based on the originally set phase amount at the ambient temperature where the transmitter is normally used, When the environmental temperature changes and the oscillation frequency from the voltage controlled oscillator 13 fluctuates, the phase comparator 14 detects the phase difference between this frequency signal and the reference signal from the reference signal generator 1. Then, the loop filter 15 is also based on the originally set phase amount and the detected phase difference even in the normal use environment temperature.
Outputs a voltage of V1 + ΔV, and the voltage is applied to the voltage controlled oscillator 13 as a control voltage. As a result, the voltage-controlled oscillator 13 outputs a signal of a frequency that cancels the fluctuation of the oscillation frequency, and outputs a carrier signal fixed to a single frequency even when the environmental temperature changes. In the above example, the loop filter 15 sets a certain amount of phase, and the voltage-controlled oscillator 13 outputs a carrier signal having a predetermined frequency changed with respect to the reference signal.
ΔV is a voltage corresponding to the detected phase difference.

The voltage V1 + ΔV from the loop filter 15 is also input to the gate bias unit 18, and the gate bias unit 18 is supplied with the power control signal value and voltage originally input from the baseband unit for amplification control. V1 + △ V
Is compared and calculated, and the temperature compensation control for the environmental temperature change is performed on the power amplification unit 6. That is, the oscillation frequency of the voltage controlled oscillator 13 changes according to the change of the environmental temperature, and the phase difference voltage input from the loop filter 12 to the gate bias unit 18 also changes according to the change of the oscillation frequency. The gate bias unit 18 controls the power amplification unit 6 according to the change in the environmental temperature, and the transmission signal output from the antenna 7 can be amplified in the power amplification unit 6 to have a desired characteristic.

In the above embodiment, the frequency conversion unit 4
Although the transmitter for changing the transmission signal to the frequency corresponding to the transmission channel using the second frequency synthesizer and the second frequency synthesizer is shown, the present invention can be applied to a transmitter having no such frequency changing function. it can. Further, generally, as shown in the above embodiment, the power amplification unit is controlled by the power control signal from the baseband unit, but the present invention can be applied to a transmitter having no such control function. it can.

[0020]

As described above, according to the present invention,
Based on the fact that the frequency of the signal oscillated from the voltage-controlled oscillator of the frequency synthesizer changes with changes in the ambient temperature, it is necessary to detect changes in the ambient temperature with the phase difference voltage of the oscillation frequency obtained by the phase comparator. Therefore, without using a thermistor as in the conventional case, the power amplification unit can be temperature-compensated and controlled, and the transmission signal can be amplified so as to have a predetermined characteristic regardless of changes in the environmental temperature. Further, as a result, by omitting the thermistor, the cost can be reduced, the circuit layout design of the transmitter can be facilitated and the transmitter can be downsized, and the reliability due to the temperature characteristics of the thermistor can be improved. The decrease can be eliminated.

[Brief description of drawings]

FIG. 1 is a configuration diagram illustrating a transmitter according to an exemplary embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an amplification characteristic of the power amplification unit with respect to temperature change.

FIG. 3 is a configuration diagram showing a transmitter according to a conventional example.

[Explanation of symbols]

1 Reference signal generator, 3 modulator, 4 frequency converter, 5 Second frequency synthesizer, 6 power amplifier, 12 First frequency synthesizer, 13 voltage controlled oscillator, 14 Phase comparator, 15 loop filter, 18 gate bias unit (control unit),

Claims (4)

(57) [Claims] 1. A frequency synthesizer for outputting a carrier signal fixed to a single frequency based on a signal from a reference signal generator, a modulator for modulating the carrier signal with a baseband signal, and a transmission output from the modulator. In a transmitter including a power amplification unit that amplifies a signal to a predetermined transmission output, the reference signal generation unit is a temperature-compensated oscillator that outputs a constant frequency signal, and the frequency synthesizer is controlled according to a control voltage. A voltage controlled oscillator that outputs a frequency signal as a carrier signal, a phase comparator that detects a phase difference between the output signal from the voltage controlled oscillator and the output signal from the temperature compensation oscillator, and the detected phase difference is converted into a voltage. And a loop filter applied to the voltage controlled oscillator to output a temperature-compensated carrier signal. Transmitter, wherein a control unit to cancel the temperature change affecting the transmission output by controlling the power amplifier based on the phase difference voltage, with the from. 2. The control unit temperature-compensates and controls the power amplification unit based on the power control signal from the baseband unit that generates a baseband signal and the phase difference voltage from the loop filter. The transmitter according to 1. 3. A second frequency synthesizer for outputting a plurality of frequency signals for transmission channels based on a signal from a reference signal generator, and an output from a modulator based on a signal from the second frequency synthesizer. 3. The transmitter according to claim 1, further comprising: a frequency conversion unit that frequency-converts the signal and outputs the frequency-converted signal to the power amplification unit. 4. A frequency synthesizer for outputting a carrier signal fixed to a single frequency from an oscillator by performing phase difference control based on a signal from a reference signal generator, and a modulator for modulating the carrier signal with a baseband signal. A power amplifier for amplifying the transmission signal output from the modulator to a predetermined transmission output, and a signal from the temperature-compensated reference signal generator and a signal from the frequency synthesizer oscillator. A temperature compensating method for a transmitter, comprising: controlling a power amplification unit based on the phase difference of 1 to cancel a temperature change that affects a transmission output.