JPH11266169A - Mobile telephone set device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable strict standards regarding a transmitter noise in a reception frequency band to be satisfied, without shortening speech time or using an expensive circuit. SOLUTION: A voltage control type variable tuning filter 3, having a pass band and an attenuation band, is arranged between a modulator 1 and a power amplifier 5. In addition, a controller, which controls this variable tuning filter 3 so that the pass band of the voltage control type variable tuning filter 3 is within a transmission frequency band and the attenuation band is within a reception frequency band, is provided, constituted of a power detector 4, a phase detector 6, a dither generation circuit 7, a control circuit 8, an adder 9 and a sample and hold circuit 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile telephone device, and more particularly to a time division multiple access (TDMA).
The present invention relates to a mobile telephone device used in a mobile communication system based on the n multiple access method or the like.

[0002]

2. Description of the Related Art A generally known mobile telephone is UH
Transmission and reception are performed at different frequencies in an F (Ultra High Frequency) frequency band. As a multiple access system in a mobile communication system using such a mobile telephone, there is, for example, a TDMA system.
The DMA system is, for example, a GSM (Global System for Mobile communication) which is a digital mobile phone system in Europe.
on) Used in the system. TDMA system (G
In the SM system, a strict standard is set for the amount of transmitter noise included in the reception frequency band. As a method for satisfying such a standard, an output unit of a power amplifier of a transmitter of a mobile telephone is used. In addition, a method of using a notch filter having a large Q is known. However,
Such filters are relatively large and
This results in significant insertion loss. To compensate for this insertion loss, the power amplifier must operate at a relatively high output power, so that a relatively large current is drawn from the power supply, usually a battery in the telephone. Therefore, if the capacity of the battery is constant, the talk time of a mobile telephone using such a notch filter is shortened.

Another known type of mobile telephone has a phase locked loop (PLL) connecting a power amplifier with a modulator that produces a signal to be transmitted in the transmit frequency band. Here, the modulation output of the modulator is a phase-sensitive loop phase-sensitive detector (phase-sensitive detector).
The input of the power amplifier is connected to a voltage controlled oscillator (VCO) of a phase locked loop. With this configuration, the wideband noise of the transmission signal supplied to the power amplifier is determined by the phase noise of the voltage controlled oscillator when the loop is locked. By using this, it is possible to reduce transmitter noise included in the reception frequency band. However, a voltage controlled oscillation circuit that operates in the UHF band and has low phase noise is relatively expensive.

[0004]

As described above, in the case of a conventional mobile telephone, if an attempt is made to reduce the transmitter noise included in the reception frequency band, the current consumption increases and the talk time becomes shorter. However, there is a problem that a relatively expensive low phase noise voltage controlled oscillation circuit must be used.

It is an object of the present invention to provide a mobile telephone device capable of satisfying a strict standard for transmitter noise in a receiving frequency band without shortening a talk time or using an expensive circuit. .

[0006]

According to the present invention, there is provided a mobile telephone device comprising: a modulator for generating a transmission signal within a transmission frequency band;
A power amplifier that amplifies a transmission signal and supplies the antenna to an antenna;
A tunable filter disposed between the modulator and the power amplifier and having a passband and an attenuation band; tunable so that the passband is in the transmission frequency band and the attenuation band is in the reception frequency band of the mobile telephone device. A control device for controlling the filter.

[0007] According to the present invention, since there is no need for an element that causes insertion loss to the output of the power amplifier, the talk time is hardly affected. Also, since a relatively simple and inexpensive circuit such as a tunable filter is used,
Has little effect on the cost of the equipment.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a preferred embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a mobile telephone device according to a preferred embodiment of the present invention, and FIG. 2 is a timing chart for explaining the operation of the device shown in FIG.

The mobile telephone apparatus shown in FIG. 1 is used in a standard mobile communication system such as a TDMA system or a GSM system, and uses a UHF frequency band according to the standard of the mobile communication system used. And a modulator 1 for generating a modulated carrier (carrier).
An output of the modulator 1 is supplied to an input of a voltage-controlled tunable filter 3 via a preamplifier 2. The output of the voltage-controlled tunable filter 3 is connected via a power detector 4 to an input of a power amplifier 5. The transmission signal output from the power amplifier 5 is supplied to an antenna (not shown).

The power detector 4 detects the output power of the voltage control type tunable filter 3, and the detection output (power detection value) is connected to the first input of the phase detector 6. . The phase detector 6 may be constituted by, for example, a multiplier. The output of the dither generation circuit 7 is connected to the second input of the phase detector 6. The dither generation circuit 7 will be described later. The output of the phase detector 6 is connected to the input of the control circuit 8. Here, the control circuit 8 is composed of, for example, an operational amplifier (operational amplifier: OP amplifier). One input of the operational amplifier is an input of the control circuit 8, and the other input is a voltage control type variable amplifier. It is connected to a reference voltage power supply (not shown) for supplying a reference voltage corresponding to the maximum output power of the tuning filter 3. Such a control circuit 8 functions as a comparator. An adder 9 for adding the output signal of the dither generation circuit 7 and the output signal of the control circuit 8 is provided. The output of the adder 9 is supplied via a sample / hold circuit 10 to a voltage-controlled variable tuning filter. 3 is connected to the tuning voltage input terminal.

Next, the operation of the mobile telephone device will be described. Since this mobile telephone device is assumed to be used in a TDMA system, it performs intermittent transmission. Here, a period during which transmission is actually performed from the antenna is called a transmission slot.

In the timing chart shown in FIG.
The waveform A shows the envelope of the output signal of the preamplifier 2, and the waveform B shows the envelope of the output signal of the power amplifier 5 during the transmission slot. Where the transmission slot is
This is a period between time t2 and time t3. Waveform C shows the filter calibration period between time t1 and time t2 prior to the transmission slot. Note that a waveform D indicates a transition of a signal at the control input 11 of the sample / hold circuit 10.

During normal operation of the device, the power amplifier 5 is initially deactivated when transmitting signals so that it is not affected by power supply transients caused by switching on the preamplifier 2, Circuits in the modulator 1 and other places can be stabilized. In the initialization stage of the transmission sequence starting from time t1 in FIG. 2, a signal represented by a waveform D is supplied to a control input 11 of a sample / hold circuit 10, which is a holding circuit, thereby holding the sample / hold circuit. The (hold) function is prohibited, and the output of the adder 9 is supplied directly to the tuning voltage input section of the voltage control type variable tuning filter 3.

The dither generator 7 can be embodied, for example, as a properly controlled counter or a digital-to-analog converter (DAC) connected to the output of a microprocessor, known as a so-called dither signal. Generates a fluctuating voltage. The amplitude of the generated fluctuating voltage tunes the tuning of the voltage-controlled variable tuning filter 3 to a required tuning frequency region, that is, a frequency in a frequency band including the transmission signal from the preamplifier 2. By "dithered" the output voltage of the dither generation circuit 7 between two adjacent values, the voltage-controlled tunable filter 3 is tuned between two adjacent reject values.

The voltage-controlled tunable filter 3 preferably has a pass band large enough to pass the transmission signal from the preamplifier 2, and outside the pass band, the frequency band in the reception frequency band of the device. The noise caused by the output of the power amplifier 5 has an attenuation degree that satisfies a required standard;
It is a bandpass (bandpass) filter. Alternatively,
It is also possible to use other types of filters, such as high-pass filters.

When the pass band of the voltage-controlled tunable filter 3 is switched at small intervals between two center frequencies, the power is supplied from the modulator 1 and the preamplifier 2 to the power detector 4 by the voltage-controlled tunable filter 3. The amount of power changes. Therefore, the output of the power detector 4 is a fluctuating voltage, and its phase fluctuation with respect to the output signal of the dither generation circuit 7 is whether the transmission signal is above or below the pass band of the voltage-controlled tunable filter 3. It depends on what. For example, when the frequency of the transmission signal is lower than both the first pass band and the second pass band on the higher frequency side than the first pass band, the voltage-controlled tunable filter 3
Is switched from the first pass band to the second pass band, the output of the power detector 4 decreases. On the other hand, when the frequency of the transmission signal is higher than the first and second pass bands, the output signal of the power detector 4 increases by switching from the first pass band to the second pass band. Therefore, the output of the phase detector 6 outputs a signal whose polarity and absolute value depend on the polarity and absolute value of the difference between the transmission frequency band and the pass band of the filter.

The control circuit 8 compares the output of the phase detector 6 with a reference value corresponding to the maximum output of the voltage control type voltage tuning filter 3 when correctly tuned. Therefore, the control circuit 8 generates an error signal, and this error signal is added to the signal from the dither generation circuit 7 to tune the voltage control type variable tuning filter 3 toward the transmission frequency band. This arrangement functions as a servo feedback arrangement that locks the pass band of the voltage control type tunable filter 3 with respect to the transmission frequency band of the transmission signal from the modulator 1.

When the control circuit 8 detects that the output power of the voltage control type variable tuning filter 3 has a predetermined value, the sample / hold circuit 10 is enabled at time t2, and the sample / hold circuit 10 The correct value is sampled and held, which is then supplied to a voltage controlled tunable filter 3. Therefore, the pass band of the filter is locked to the transmission frequency band. Subsequently, the power amplifier 5 enters an operating state, for example, at time t2 shown in FIG.
At such a predetermined time, transmission can be started.

[0019]

As described above, according to the present invention, a tunable filter having a pass band and an attenuation band is provided, and the pass band of the tunable filter is in the transmission frequency band and the attenuation band is in the reception frequency band. And a control device for controlling the tunable filter, the transmitter noise in the receiver frequency band with little effect on talk time and little on the cost of the device. This has the effect of reducing noise.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a mobile telephone device according to a preferred embodiment of the present invention.

FIG. 2 is a timing chart for explaining the operation of the apparatus shown in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Modulator 2 Preamplifier 3 Voltage control type variable tuning filter 4 Power detector 5 Power amplifier 6 Phase detector 7 Dither generation circuit 8 Control circuit 9 Adder 10 Sample / hold circuit 11 Control input

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H03L 7/06 H04B 7/24 G H04B 7/24 H03L 7/06 E

Claims (8)

[Claims] 1. A mobile telephone device, comprising: a modulator that generates a transmission signal within a transmission frequency band; a power amplifier that amplifies the transmission signal and supplies the antenna to an antenna; A tunable filter disposed between the tunable filters and having a pass band and an attenuation band; andthe tunable filter so that the pass band is in the transmission frequency band and the attenuation band is in the reception frequency band of the mobile telephone device. A control device for controlling the mobile telephone device. 2. The mobile telephone device according to claim 1, wherein said tunable filter is a tunable bandpass filter. 3. The mobile telephone device according to claim 1, wherein said tunable filter is of a voltage control type. 4. A control device comprising: a power detector connected to an output of the tunable filter; and a tuning control voltage applied to the tunable filter, wherein a predetermined power is detected by the power detector. 4. The mobile telephone device according to claim 3, further comprising: a control loop for changing the mobile telephone device. 5. A signal generator, wherein the control loop generates a fluctuating voltage for application to the tunable filter;
The mobile telephone device according to claim 4, further comprising a feedback circuit having an input connected to the power detector and an output superimposed on the fluctuating voltage. 6. A feedback circuit comprising: a multiplier having inputs connected to the power detector and the signal generator; and a comparator for comparing an output of the multiplier with a reference level corresponding to the predetermined power. The mobile telephone device according to claim 5, comprising: 7. The mobile telephone device according to claim 3, further comprising a holding circuit that holds the tuning control voltage following the tuning of the variable tuning filter. 8. The mobile telephone device according to claim 1, wherein the control device is configured to disable the power amplifier until the tuning of the tunable filter is completed.