A radio phone and method of operating a radio phone.

Radiotelephone, method of use and external amplifier

The present invention relates to a method of using a radiotelephone, wherein the radiotelephone has an external amplifier for receiving, amplifying and transmitting a radio frequency signal, and wherein the received frequency signal is directed to an input amplifier. The invention also relates to a radiotelephone and an external amplifier for implementing this method.

Currently, both car and handheld phones are used in telephone networks. The biggest difference is the higher output power of the car phone and the higher requirements for sensitivity and repeatability. In the present claims, the characteristics of a car phone also refer to the characteristics of a combination of a hand-held telephone and an amplifier, i.e. a booster.

In the prior art, the buffers consist of a synthesizer, a processor and a radio unit in addition to standard radio frequency (RF) components. One example of the complexity of the designs is the so-called serial number sending system, where the booster is a complete car phone without a fixed serial number, or so-called. NAM booster (Number Assignment for Meter). When the phone is connected to a booster, the NAM data, which is a telephone number as an electrical signal to the booster, is then transmitted, which then functions as a telephone and a hand-held telephone is only a control device;

Second, there is a known solution in which the booster comprises two duplex filters (one for the telephone terminal and the other for the antenna terminal) and RF components between them. The advantage of this solution is the simple RF connection, which consists of only one coaxial cable between the booster and the telephone. The disadvantage of this design is that the parameters of the hand-held telephone must be higher than those required by conventional radiotelephone system.

EE 03362 B1 specifications, so the handset due to the booster has to be manufactured with unnecessarily high parameters, which makes it expensive to manufacture.

The technology of known solutions will now be described with reference to FIG. 5 1 illustrates the principle of connecting a hand-held telephone to known amplification devices.

FIG. 1 shows a combination of a hand-held telephone and a known amplifier device. The connection point between the amplifier 1 and the handset 2 is the antenna connector 3 of the handset 2. Instead of the standard antenna, the handset 2 is connected to an amplifier device, i.e. a booster 1, which is also connected to the ANT antenna via duplex filter 6 '. The duplex filter 6 is placed in the receiver circuit RX of the amplifier 1_V preamplifier 4 and transmitter circuit TX_Vgain level 5. A duplex filter 7 of the same type is also located in the handset 2. Duplex filters 6 and 7 separate the transmit and receive frequencies of the amplifier into their respective circuits, where they are amplified accordingly.

During the development of the device, there are difficulties in meeting the requirements for a hand-held telephone. In order to provide the necessary sensitivity, the attenuation caused by the booster duplex filters must be compensated by the amplifier 4. As a result, the signal processing capabilities realized by the combination of booster 1 and handset 2, such as response parameters for distorted signal (high amplitude signal processing, co-modulation, etc.) are impaired, said capabilities being limited mainly by the high frequency parts of the handset. To some extent, the problem has been corrected by increasing the power supply level of the handset (not shown). However, increasing the power consumption of a handheld phone will shorten the battery life of the phone or require the use of more powerful batteries, which is completely contrary to the well-known goals of extending battery life and / or handheld phones.

EE 03362 ΒΙ with small volume and mass. In addition to receiving the received signal, already amplified by an external amplifier, into the input of the radiotelephone, the co-modulation effects in the signal are amplified.

The first part of the present invention relates to a radiotelephone adapted to be connected to an external amplifier comprising a receiving circuit and a transmitting circuit, the receiving circuit having an input amplifier for amplifying an acceptable radio frequency signal. When the radiotelephone is connected to an external amplifier, the corresponding control signal is directed to the radiotelephone to io adjust the gain of the received radio frequency by the input amplifier.

Another aspect of the invention relates to a method of using a radiotelephone having an external amplifier for receiving, amplifying, and transmitting a radio frequency signal from a radiotelephone and a telephone, wherein the received frequency signal is directed to the radiotelephone input amplifier;

An advantage of the present invention is that it provides a combination of a radiotelephone and an external amplifier connected thereto, where co-modulation and noise factor problems encountered in known solutions are limited.

In the following embodiment, embodiments of the present invention will be described in detail with reference to the accompanying drawings, in which: FIG. 1 illustrates a known combination of a hand-held telephone and an amplifier;

FIG. 2 is a block diagram of a combination of a radiotelephone and an amplifier according to the invention,

EE 03362 Bl fig. 3 shows an example schematic diagram of an input amplifier of a radio telephone reception circuit required to implement the invention; and FIG. Figure 4 shows another example of a schematic diagram of an input amplifier of a radiotelephone receiving circuit 5 for implementing the invention.

FIG. 1 is described above. The method and an embodiment of the invention are described in detail below with reference to FIG. 2 to 4, illustrating an embodiment of the invention.

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FIG. 2 shows a schematic diagram of a combination of a radiotelephone and an amplifier according to the invention. The connection between the amplifier 1 and the radiotelephone 2 is a coaxial cable 8 (usually) or an equivalent cable to provide an RF connection. Amplifier 1 has a receiving circuit RX_V (only input amplifier 4 is shown) and TX circuit_V (only power amplifier stage 5 is shown) and a duplex filter 6 consisting of, for example, frequency band filters for separating transmit and receive frequency signals into respective circuits.

When the booster 1 is connected to the radiotelephone 2, the antenna ANT is connected to the booster 1. The control signal OHJ is coupled to the received and amplified radio frequency signal provided by the antenna ANT and controlled by the coaxial cable 8 to the radiotelephone 2, which control signal may be DC voltage or low frequency. The DC signal can be obtained directly from the booster supply voltage or by converting it, for example, with a DC / DC converter. The control of the low frequency control signal can be obtained from the booster supply voltage, for example by means of a DC / AC converter. In the form of a control voltage, the radio telephone 2 receives information that the booster is connected. The control signal OHJ need not be generated in the booster but may be input from an external accessory of the radiotelephone that is connected to the radiotelephone, such as a data adapter or an additional headset. Such a solution

For EE 03362 ΒΙ, the control signal control is not connected to the received radio frequency signal, but is inserted through the connector of the accessory 2 of the radiotelephone.

The radiotelephone also has a duplex filter 7 consisting of, for example, two frequency band filters. The connection between the amplifier 1 and the radiotelephone 2 is usually made by means of a coaxial cable 8, which is switched between the duplex filters 6 and 7. The received and boosted signal in the booster 1 is routed from the duplex filter 7 of the radiotelephone 2 to the RX of the radiotelephone receiver._rwith the first step typically being an input amplifier 9. As mentioned above, the input amplifier stage 9 is controlled or bypassed for the input amplifier io 9. , or its gain is reduced. In the case of a direct-pin or low-frequency voltage control signal OHJ being introduced from booster 1 as in the embodiment described in the patent 15, the radiotelephone must have a filter 10 as shown in FIG. 2 which may be a low-pass filter and coupled to The filter 10 prevents the RF signal from entering the control circuit, but passes a DC or low-frequency voltage control.

FIG. 2, the gain stage 9 is controlled by a control voltage OHJ emitted by the low-pass filter 10. The radio frequency signal received from the gain stage 9 is further directed along the receiving circuit RX_rthat is, through the bandpass filter 11 to the mixer 12, where an intermediate frequency f is added to the RF signal_IF . So the reception chain

RX_r, as well as TX TX_R The use of cordless telephones is well known to those skilled in the art and will not be considered further in this context.

The present invention avoids co-modulation and noise factor problems caused by the use of a single coaxial cable for commonly known solutions. Problems are usually caused by the fact that the cordless telephone amplifier

EE 03362 B1 amplifies the received signal too much (in terms of co-modulation) since it is already pre-amplified by the booster, although both input amplifiers (both the booster and the radiotelephone) are tuned to the desired gain. If the signal is bypassed or lowered by the radio telephone input amplifier while slightly increasing the RX of the boom receiving circuit_r input amplifier 4, then the requirements for co-modulation and noise can be met simultaneously. This type of input amplifier 4 is easy to apply since there is no problem with current consumption.

The use of both a controllable and a skip amplifier is well known in the art. As an example, two different bypass amplifiers used in this solution are described below. The amplifier skip connection can be realized, for example, by diode circuits. These diodes can be connected in series to the input amplifier to minimize current consumption when no booster is used. When using a booster, the DC control signal controls a switch that deflects the signal past the amplifier. In another embodiment, the amplifier can be implemented such that the input RF transistor is operated in key mode, or its operating point is shifted when cooperating with the booster to achieve optimum signal processing.

FIG. 3 is a schematic diagram of a first solution of a skip amplifier. The amplifying element of the amplifier is an RF transistor 13. Here, the switching is realized by means of diodes 14 and 15 and a two-position switch 16, which are supplied with a voltage V_batt. When the radiotelephone is used without a booster, the switch is in position 16 for V_batt reaches resistor 17. In this case, the diode 14 and the transistor 13 conduct the current and the amplifier 9 amplifies the radio frequency signal to the input IN, outputting it to the output OUT. When the control signal OHJ reaches input amplifier 9, switch 16 is moved to another position, resulting in a supply voltage V_batt reaches capacitor 21 and coil 27, whereupon diode 15 begins to conduct current.

The transistor 13 now receives no sup ply voltage and the amplified input signal IN

EE 03362 B1 goes directly to diode 15 to OUT. The connection of the elements 17 to 27 shown in the figure to the amplifier is not described in more detail herein, since their functions are known to those skilled in the art. Since FIG. 3 is intended to illustrate the principle of implementing a skip amplifier, the entire scheme of the amplification is not shown here.

FIG. A transistor 28, when coupled to a booster, operates in key mode. If the radiotelephone is used without a booster, the controlled switch is in the GND (ground) position. Thus, the emitter of the RF transistor 28 is grounded, as a result of which the transistor 28 conducts a current and a radio frequency signal that reaches the amplifier input and is amplified to the output OUT. When the radiotelephone is connected to the booster, the control signal OHJ reaches the control circuit of the switch 29 (not shown), and the switch 29 is switched to a shunt voltage source V_bias. Shear stress

V_bias is powered by V_batt compared to such a value that the voltage between the base of the transistor 28 and the emitter is less than the threshold voltage of the transistor 28, which causes the transistor 28 to turn off and the RF signal from input IN to attenuated to amplifier output OUT. The connection of the elements 31 to 38 shown in the figure to the amplifier is not described in detail herein, since their functions are well known to those skilled in the art. Since FIG. 4 the aim is to illustrate the principle of using a skip amplifier, the entire scheme of the amplifier is not shown in more detail here.

In addition, for example, the low frequency signal OHJ, which controls the amplifier, is received via the RF signal connector of the radiotelephone, the battery charging current of the handset may also be transmitted to the phone (battery) via the same connector (same coaxial cable). To adjust the power of the booster, interruptions of charging current of varying duration can be modulated, which the booster can detect. Such a solution would make it possible to reduce the number of wires since no separate wire is needed for the charging current.

EE 03362 Bl

The present invention avoids the co-modulation and noise factor problems inherent in existing booster and radiotelephone combinations. The invention is not limited to the examples described herein and can be used in various ways within the scope of the accompanying claims. It is conceivable that the external amplifier according to the invention is simply a receiving circuit amplifier or is part of a booster which also has a transmission circuit power amplifier. The scope of the present invention encompasses any novel or combinations thereof, as set forth in more detail herein, or any generalizations made therefrom, whether or not related to the claims of the present invention, or mitigating any or all of the problems associated with the invention. By this means, the Applicant states that new applications based on such features, or subsequent applications based on them, may be formulated during the processing of this application.