KR0129849B1 - Low noise block - Google Patents

Abstract

A dependent booster of a cellular phone prevents a deterioration of an intermodulation characteristic owing to double serial disposition of LNA when a body is connected to a booster, and removes a communication impossible state at a position near the base station. The control device of a low-noise receiving very high frequency amplifier of a dependent booster includes: a duplex filter(11) connected to a input duplex filter(23) via a RF cable; a receiving amplifier(12) for amplifying an output signal of the filter(11), and transmitting it to a center frequency part(I/F)(13); a center frequency part(13) for converting an amplified RF of the receiving amplifier(LNA)(12) to a center frequency(IF), and outputting a signal(RSSI) to a CPU(14); a center controller(16) for integrating CPU(15) with analog/digital converter(A/D)(14) as one body; an input part duplex filter(23) for a separation of a receiving/transmitting frequency; an output side filter(24) connected to an external antenna(30); a transistor(TR) for performing a switching function to control the receiving amplifier(22); a switch(21) connected to the CPU(15) and a control line; and a dependent booster(20) having an input part duplex filter(23) of a booster.

Description

Low Noise Receiving Ultrasonic Amplifier Control Device of Dependent Booster for Improving Intermodulation Characteristics of Mobile Phone

1 is a connection diagram of a main body and a slave booster of a conventional portable telephone.

2 is a block diagram of a low noise receiving ultra-high amplifier control device of a slave booster for improving the iterative modulation characteristics of the portable telephone of the present invention.

3 is a flowchart illustrating a method of controlling a low noise receiving ultra short amplifier of a slave booster for improving the iterative modulation characteristic of the portable telephone of the present invention.

The present invention relates to a booster (Booster) of the portable telephone, particularly in the configuration of a 3watt booster used for car phone level calls when the portable telephone is mounted in a vehicle, the portable telephone body and the high frequency ( It can be divided into a stand-alone booster that has a completely independent RF path and a slave booster that shares a high-frequency (RF) path with a mobile phone main body. This is to eliminate the decrease of reception sensitivity and the inability to receive due to the problem. Therefore, it is possible to solve the problem caused by the duplication of LNA, which is used for the purpose of improving the reception sensitivity even if it is not necessarily a mobile phone. It is about a device.

A connection diagram of a main body of a conventional portable telephone and a slave booster is shown in FIG. 1, which includes a main body 10 including a transmission amplifier 1, a filter 2, and a reception amplifier 3; Input side duplex filter (4) for separation of transmission and reception frequencies, output side filter (6) connected to external antenna (30), and transmission power from main body (10) for amplifying car phone level A transmission amplifier 5 and an output control unit 8 for controlling the same, and a reception amplifier unit 7 for compensating for the loss of the received signal by each filter and the connection cable, are connected to the main body by a connection cable. It consists of a slave booster 20 is connected to 10).

In the above configuration, the overall characteristics of the transmitter / receiver are greatly improved, but the intermodulation characteristics of the receiver are degraded.

For example, suppose that a situation in which (fo + Δf) and (fo + 2Δf) are simultaneously input to the receiving amplifier input of the receiver when the signal that the user wants to receive is called fo. Due to the non-linearity of the amplifier, each signal generates harmonics, where the intermodulation is the second harmonic of (fo + Δf), that is, (fo + 2Δf) and another input signal (fo +). The output due to the difference of 2Δf) becomes fo.

In other words,

(2fo + 2 △ f)-(fo + 2 △ f) = fo

Becomes

In other words, if two signals ((fo + Δf) and (fo + 2Δf)) that are not received at all by the receiver are applied to the receiver at the same time, they will be received. In the case of the configuration as shown in Fig. 1, it is obvious that the characteristics of the reception amplifier are deteriorated since the reception amplifier is doubled.

In other words, when the mobile phone is actually used, several people are simultaneously talking to several wireless channels within a range of one base station, which means that a plurality of signals that the user does not want are simultaneously received at the receiving part of the mobile phone.

In this case, if the strength of the various signals is below a certain threshold level, there is no big problem, but if it is above the threshold level, the magnetic frequency generated by the unwanted signal disturbs the magnetic frequency that is actually received. there was.

That is, when the main body is connected to the booster, as described above, deterioration of the intermodulation characteristics due to the double serial arrangement of the LNA is inevitable, and in particular, when the user is in close proximity to the base station, a call interruption state often occurs.

The present invention is to solve the above-mentioned problems, characterized in that the central processing unit of the main body monitors the strength of the received signal at all times, but limits the operation of the booster receiving amplifier when the strength is above a certain limit. It is to improve the call characteristics.

When described in detail with reference to the drawings, the block diagram of the low noise receiving ultra-high amplifier control device of the slave booster for improving the intermodulation characteristics of the present invention portable phone can be shown as shown in Figure 2, high frequency cable (RF CABLE) By receiving the amplification of the duplex filter 11 on the main body side and the signal output from the filter 11 connected to the input unit duplex filter 23 on the booster side by the intermediate frequency (I / F) unit 13 The reception amplifier 12 and the high frequency RF amplified by the reception amplifier 12 are converted to an intermediate frequency IF, and the received signal strength indicator (RSSI) or less' And an intermediate frequency unit 13 for outputting a signal of RSSI 'to the central control unit 14, and a central processing unit (CPU) 15 for controlling the switching unit 21 connected by control lines. Digital converter (hereinafter referred to as 'A / D') 14 is integrated The body 10 and made to a central control unit 16; Booster-side input part duplex filter 23 for separation of transmit and receive frequencies, output-side filter 24 connected to external antenna 30, and transistors for switching control for receiving amplifier 22 (TR) It is composed of a sub-booster 20 including a switching unit 21 and the input side duplex filter 23 of the booster is connected to the central processing unit 15 of the main body 10 by a control line and controlled. .

That is, the switching is controlled by the low noise ultra-low frequency amplifier (hereinafter referred to as 'LNA') 22 of the slave booster 20 and the central processing unit 15 of the main body 10 to supply power to the LNA 22. A / D unit 14 for monitoring the RSSI by the transistor TR, bias resistor R, and the central processing unit 15, and a receiving I / F unit of the main body 10 generating the RSSI ( 13) and the central processing unit (15).

When the main body 10 is connected to the subordinate booster 20, as described above, although there are differences depending on the degree of non-linearity of the LNA 22, two signals (fo + Δf and fo which are undesirable in a test under laboratory conditions) Data demodulation failed in the data channel when the intensity of + 2Δf) was about -20 dBm. In other words, the call was impossible.

At this time, when the power applied to the LNA 22 of the subordinate booster 20 is shut down, the LNA 22 no longer operates as an amplifier and only a part of a signal due to conduction is transmitted. The operating mode was changed, and the attenuation was about 50 dB under laboratory conditions.

In other words, shutting down the LNA power supply of the slave booster has the same effect as improving the intermodulation characteristic by 50dB.

Now, in relation to the test conditions and the flow chart, first, when power is applied to the main body and the booster, the central processing unit sets the control terminal to 'high', and this 'high' level signal is transmitted through the resistor R to the selector and the emitter of the TR. After the power is turned on, the power is normally supplied to the LNA, and then the RSSI signal generated by the I / F part of the main unit is read by the A / D convertor, and the A / D value is -30dBm or more. Has a problem at -20dBm, but considers margin of 10dB), and if it is not abnormal, it keeps monitoring, and if it is abnormal, it determines that there is a problem, and switches the control terminal from 'high' to 'low'. And the TR 'off' between the collector and emitter to cut off the power to the LNA, allowing the LNA to operate in attenuation mode.

For example, if the initial RSSI value corresponds to -28 dBm, the A / D value of the RSSI changes to -78 dBm in attenuation mode (because 50 dB attenuation).

The CPU then checks the RSSI again to see if it is below -90dBm (-30dBm -50dBm = -80dBm or 10dB for a spare). It maintains state, and if it is below, it judges that it has exited the area and controls the control terminal from 'low' to 'high' to return to the initial state and repeat the loop constantly.

Referring to the operation sequence described above in detail with reference to the drawings, the operation flowchart of the low noise receiving ultra-short amplifier control method of the slave booster for improving the intermodulation characteristics of the portable telephone of the present invention is shown as shown in FIG. RSSI A / D value at -30dBm input, Y is called RSSI A / D value at -90dBm input, and RSSI value is compared with X value (step SI). If the RSSI value is not large, the LNA of the booster is 'off' (step S2). Then, the magnitude of the RSSI value and the Y value is compared (step S3), and if the RSSI value is small, the process returns to step S2. If the RSSI value is not small, the LNA of the booster is turned 'on', and then the step of returning to the first step is sequentially repeated.

As described above, according to the present invention, a receiver having a poor intermodulation characteristic, that is, an intermodulation characteristic is also improved according to the flowchart of the present invention, as the performance of the simple booster and the low-cost dependent booster is improved to more than the independent booster. In this case, not only all problems caused by the intermodulation characteristics can be solved but also it is very useful because it can eliminate the improvement and interference of the voice quality due to the improvement of the intermodulation characteristics.

Claims (2)

A main frequency duplex filter 11 connected to the booster side duplex filter 23 on the booster side and a signal output from the filter 11 are amplified by a high frequency cable RF band. / F) converts the receiving amplifier (LNA) 12 and the high frequency RF amplified by the receiving amplifier 12 to the intermediate frequency (IF) and outputs the corresponding received signal strength An intermediate frequency unit 13 for outputting the RSSI signal to the central control unit 14, a central processing unit (CPU) 15 for controlling the switching unit 21 connected by a control line, and an analog / digital converter ( A main body 10 including a central control unit 16 in which an A / D) 14 is integrated; Booster-side input part duplex filter 23 for separation of transmit and receive frequencies, output-side filter 24 connected to external antenna 30, and transistors for switching control for receiving amplifier 22 (TR) Consisting of a sub booster 20 including a switching unit 21 connected to the central processing unit 15 of the main body 10 by a control line and controlled, and an input side duplex filter 23 of the booster. Low noise receiver ultra-amplifier control device of subordinate booster for improving the INTERMODULATION characteristics. The control terminal of claim 1, wherein the central processing unit 15 sets the control terminal to 'high' when power is applied to the main body 10 and the slave booster 20, and the 'high' level signal is a bias resistor (R). After connecting the collector and the emitter of the transistor TR through the power supply to the LNA 12 normally, the RSSI signal generated by the I / F unit of the main body is read into the A / D 14, and A / D (14) is monitored for more than -30dBm, and if it is not abnormal, it keeps monitoring, and if it is abnormal, it determines that there is a problem, and switches the control terminal from 'high' to 'low' ), Disconnect the power supply to the LNA 14 so that the LNA 14 operates in the attenuation mode, and then check the RSSI again to see if it is below -90 dBm, and if it is not below -90 dBm, there is still no problem. If it is less than In order to improve the INTERMODULATION characteristic of the mobile telephone, it has been programmed to repeat the loop constantly by returning to the initial state by controlling the control terminal from 'low' to 'high' state. Low-noise ultra-short amplifier control device of slave booster.