KR20020069915A - Transmitter apparatus for code division mutiple access mobile communication base station - Google Patents

Abstract

PURPOSE: A CDMA mobile communication base station transmitting apparatus is provided to easily estimate an error and improve accuracy and reliability by digitally embodying an AGC(Automatic Gain Control) circuit. CONSTITUTION: A digital processing unit(210) obtains the strength of an inputted digital signal, obtains the strength of a feedback digital signal processed through a feedback path processing unit(230), compares the obtained strength of the inputted digital signal with the obtained strength of the feedback digital signal, obtains an error, and stores the obtained error. An RF(Radio Frequency) processing unit(220) receives I and Q signals from the digital processing unit(210), and up-converts the I and Q signal into an RF for decreasing the change of gain. The feedback path processing unit(230) receives a transmitter output coupling signal from the first directional coupler(226), and down-converts the received transmitter output coupling signal into a baseband signal for synchronizing the gain.

Description

CDMA mobile communication base station transmission equipment {TRANSMITTER APPARATUS FOR CODE DIVISION MUTIPLE ACCESS MOBILE COMMUNICATION BASE STATION}

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a CDMA mobile communication base station transmitter, and more particularly, to digital errors of input and output power of the CDMA mobile base station transmitter. The present invention relates to a CDMA mobile communication base station transmitting apparatus capable of compensating with automatic gain adjustment (hereinafter referred to as AGC) to compensate for a gain change of a transmitter.

1 is a block diagram showing a configuration of a conventional CDMA mobile communication base station transmission apparatus. As shown in FIG. 1, the conventional CDMA mobile communication base station transmission apparatus detects an input signal level of the up converter 100. ), An output level detector 120 for detecting an output signal level of the up converter 100, and a wireless transmitter (TX) AGC circuit 130 for compensating for a change in an output signal received from the output level detector 120. And a second variable attenuator 140 that adjusts the output signal strength of the up-converter 100 and compensates for the amount of change in the output signal according to the temperature change.

2 is an exemplary view showing a configuration of a conventional analog radio transmitter AGC circuit 130. As shown in FIG. 2, a first OP-AMP 131 comparing input levels, an output level, and a control controlled by a processor A second OP-AMP 132 comparing the voltage, a third OP-AMP 133 comparing the output voltage of the first OP-AMP 131 and the output voltage of the second OP-AMP 132, The fourth OP-AMP 134 is integrated.

The operation of the conventional transmission device configured as described above will be described with reference to FIGS. 1 and 2 as follows.

The input level detector 110 converts the RF (Radio Frequency, RF) input coupling signal of the up converter 100 input through the first directional coupler 111 into an analog voltage, The level detector outputs an analog voltage that varies constantly according to the strength of the input RF signal.

Meanwhile, the output level detector 120 converts the RF output coupling signal of the up converter 100 input through the second directional coupler 121 into an analog voltage and uses the level detector to output the strength of the RF signal. Outputs an analog voltage that varies constantly according to

In addition, the second variable attenuator 140 adjusts the output signal strength of the wireless transmitter AGC circuit 130 and the up converter 100, compensates for the output signal variation according to the temperature change, and the upper processor 150 outputs the output signal. The strength of the signal is controlled according to the system characteristics.

Then, the wireless transmitter AGC circuit 130 performs the second variable attenuator 140 with the "wireless transmitter (TX) AGC" voltage of the initial state in order to output an output signal conforming to the system characteristics by the upper processor 150 in the initial state. Control to have the attenuation of the initial state.

If the gain in the up-converter 100 decreases due to a change in the characteristic of the component due to an increase in temperature, the output level change amount "Δoutput", which is the output voltage of the second OP-AMP 132 of FIG. 2, becomes the first OP-AMP of FIG. 131) smaller than the input level change amount " Δ input ", which is an output voltage, " (Δ input-? Output) " becomes a value greater than 0, at which time the control voltage of the second variable attenuator 140 of FIG. The wireless transmitter (TX) AGC "is increased by" (Δ input-Δ output) "above the voltage just before feeding back the AGC loop to compensate for the output level by reducing the attenuation of the second variable attenuator 140 of FIG. do.

When the gain in the up-converter increases due to a decrease in temperature or a change in component characteristics, the output level change amount "Δoutput", which is the output voltage of the second OP-AMP 132 of FIG. 2, outputs the first OP-AMP 131 of FIG. 2. When the input level change amount "Δinput", which is a voltage, becomes larger than "(input -ΔΔ)," becomes smaller than 1, then the control voltage "wireless transmitter TX of the second variable attenuator 140 of FIG. ) AGC "is reduced by" (Δ input-Δ output) "from the voltage just before feeding back the AGC loop to compensate for the output level by increasing the attenuation of the second variable attenuator 140 of FIG. 2.

However, in the conventional transmission apparatus operating as described above, since the input and output level detectors are detectors using analog elements, the output voltages change according to temperature changes.

As a result, when the temperature characteristic of the part itself and the temperature sensor are different, the output compensation of the transmitter may not be corrected, resulting in a change in the input variation and the output variation, thereby causing a difference in the gain of the transmitter. Also, the AGC circuit is also composed of analog devices. There is a problem that the reliability is lower than that of the digital device and is affected by the temperature change.

Accordingly, in view of the above problems, the present invention measures the input and output power of a CDMA mobile base station transmitter in a digital baseband to determine the power strength of the input and output of a transmitter having a digital AGC function that compensates for the gain change of the transmitter. It is an object of the present invention to provide a CDMA mobile communication base station transmitting apparatus capable of compensating for a change in gain of a transmitter by precisely measuring a minimum error in a digital baseband signal region and compensating an error in input and output power strengths with a digital AGC.

1 is a block diagram showing a configuration of a conventional transmission device.

Figure 2 is an exemplary view showing the configuration of a conventional analog AGC circuit.

3 is a block diagram showing the configuration of a CDMA mobile communication base station transmitter according to the present invention.

Figure 4 is an exemplary view showing the configuration of the present invention digital AGC circuit.

*** Explanation of symbols for main parts of drawing ***

210: digital processing unit 211: digital input level detector

212: digital output level detector 213: output controller

214: digital AGC circuit 215: ROM

216: upper processor 220: RF processing unit

221: digital-to-analog converter 222: baseband signal processing unit

223 direct modulator 224 band pass filter

225, 233: amplifier 226: first directional coupler

230: feedback path processor 231: direct demodulator

232: baseband signal processing unit 234: analog-to-digital converter

The present invention for achieving the above object is a digital processing unit for obtaining the strength of the input digital signal, the strength of the feedback digital signal processed by the following feedback path processing unit to compare and then calculate the error and store the digital processing unit, The RF processing unit receives the I and Q signals from the RF signal and directly up-converts them to the RF frequency to reduce the gain change, and receives the transmitter output coupling signal from the first directional coupler of the RF processing unit, and directly downloads it to the baseband signal. And a feedback path processor for converting and matching gain.

The digital processor includes a digital input level detector for measuring the strength of an input signal, a digital output level detector for measuring the strength of a feedback signal of an output signal, an output controller for controlling an output size of a transmission device, and an input and an output signal. It is composed of FPGA (Frield Program Gate Array field programmable gate array, hereinafter referred to as FPGA), which consists of digital AGC circuitry that compares the strength of the transmitter and compensates the gain of the transmission device.

The RF processor includes a digital / analog converter for converting a digital signal into an analog signal, a baseband signal processor for receiving an analog signal from the digital / analog converter and processing the analog baseband signal, and an input from the baseband signal processor. It consists of a direct modulator that upconverts the signal to an RF frequency, and a first directional coupler for feeding back the output of the band pass filter, amplifier and transmitter.

The feedback path processor includes a direct demodulator for downconverting the output of the transmitter to a baseband signal, a baseband signal processor for processing analog baseband signals of the feedback signal, an amplifier, and an analog / digital converter for converting analog signals into digital signals. Characterized in that configured.

Hereinafter, operations and effects of the CDMA mobile communication base station transmitting apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

3 is a circuit diagram showing the configuration of the transmission apparatus of the present invention. The strength of the digital signal input as shown in the drawing is obtained, and the strength of the feedback digital signal processed through the following feedback path processing unit 230 is obtained. The digital processing unit 210 compares the magnitudes of the input and output signals obtained from each other and calculates and stores an error. The digital processing unit 210 receives I and Q signals from the digital processing unit 210 and up-converts them directly to the RF frequency to obtain a gain change. Feedback path processing unit for receiving the transmitter output coupling signal from the RF processing unit 220 for reducing and outputting the first directional coupler 226 of the RF processing unit 220 and directly converting it to a baseband signal, and adjusting the gain ( 230).

The digital processor 210 controls the digital input level detector 211 for measuring the strength of the input signal, the digital output level detector 212 for measuring the strength of the feedback signal of the output signal, and controls the output size of the transmitter. Is composed of an FPGA composed of an output controller 213 and a digital AGC circuit 214 for compensating the gain of the transmission device by comparing the strengths of the input and output signals.

The RF processor 220 may include a digital / analog converter 221 for converting a digital signal into an analog signal, and a baseband signal processor for receiving an analog signal from the digital / analog converter 221 and processing the analog baseband signal. 222, a direct modulator 223 for up-converting the signal received from the baseband signal processor 222 to an RF frequency, a band pass filter 224, an amplifier 225, and outputting the output of the transmitter. It consists of a first directional coupler 226 for.

The feedback path processor 230 includes a direct demodulator 231 for downconverting the output of the transmitter to a baseband signal, a baseband signal processor 232 for processing an analog baseband signal of the feedback signal, an amplifier 233, It is characterized by consisting of an analog-to-digital converter 234 for converting an analog signal into a digital signal.

Referring to Figures 3 and 4 attached to the operation of the present invention configured as described above in detail as follows.

First, the digital input level detector 211 of the digital processing unit 210 obtains the intensity of the input digital signal based on the following equation.

Here, the input I and Q signals are delayed by the time passing through the transmission path and the feedback path and input to the digital input level detector.

Next, the digital output level detector 212 obtains the strength of the feedback digital signal processed through the feedback path processor 230, that is, the intensity of the output signal based on the following equation.

Then, the digital AGC circuit 214 compares the magnitude of the input signal obtained by the input level detector and the output signal obtained by the output level detector, and obtains the compared error value based on the following equation.

Next, the error value obtained above is stored in the ROM 215. Convert to and multiply the original I and Q signals.

Then, obtained from the digital AGC circuit 214 And data representing the one-to-one correspondence between the transmitter and the analog gain are stored in the ROM 215.

The output controller 213 is located in front of the digital AGC circuit 214 and functions to control the base station transmit output strength given by the upper processor 216.

Now, the RF path is configured to control the output signal of the transmitter by directly multiplying the input I and Q signals by the digital gain value given by the upper processor 216.

Thus, digital AGC circuit 214 is implemented using I and Q input signals that have already been digitally controlled to transmit power strength.

Here, the I and Q input signals are controlled by the initial state higher processor 216 of the digital processing unit 210 according to the base station transmission output strength.

As such, the controlled I and Q input signals and the digital AGC circuitry 214 are in the initial state of " A value corresponding to "a value read from ROM 215" Multiply by "

In this case, if the gain of the transmission path and the feedback path is not variable, " = 1 ", and the original I and Q data signals are output as they are.

If the temperature increases and the gain in the transmitter decreases, "Value is reduced so that the d error value, i.e. The value is greater than 0, and the value is greater than 1 in the corresponding ROM table. The value is multiplied by the original I and Q data to compensate for the decrease in gain.

The RF processor 220 directly transmits the baseband signal to the modulator 223 via the digital-to-analog converter 221 and the baseband signal processor 222.

Then, the direct modulator 223 up-converts the baseband signal input from the baseband signal processor 222 to an RF frequency and reduces the gain change generated in the RF path and transmits it to the band pass filter 224.

Next, the first directional coupler 226 transmits the output signal from the band pass filter 224 to the feedback path processor 230, whereby the feedback path processor 230 directly transmits the first signal through the first modulator 231. The transmitter output coupling signal by the directional coupler 226 is directly down converted to a baseband signal.

At this time, the baseband signal processing unit 233 and the amplifier (in order to equalize the gain of the feedback path input signal and the transmitter output signal from the first directional coupler 226 to the analog-to-digital converter 234 of the feedback path processing unit 230). Via 233).

As described in detail above, the present invention is easy to predict the error by implementing the AGC circuit implemented through the conventional analog circuit digitally, and has the effect of improving accuracy and reliability.

In addition, all the circuitry is implemented in an FPGA, which is economical and reduces the size of the transmitter.

Claims (6)

A digital processor which obtains the strength of the input digital signal, compares the strength of the feedback digital signal processed by the following feedback path processor, and then calculates and stores an error; and receives I and Q signals from the digital processor and receives the RF frequency. The RF processing unit is configured to directly up-convert to a gain change to output the gain, and a feedback path processing unit which directly receives the transmitter output coupling signal from the first directional coupler of the RF processing unit, down-converts the baseband signal, and adjusts the gain. CDMA mobile communication base station transmitting apparatus, characterized in that. 2. The digital signal processor of claim 1, wherein the digital processing unit comprises: a digital input level detector for measuring the strength of an input signal, a digital output level detector for measuring the strength of an output signal, and an output controller for controlling the base station transmission output strength given by an upper processor; And an FPGA comprising a digital AGC circuit for compensating a gain of a transmitter by comparing the strengths of the input and output signals from the input and output level detectors. And a ROM storing a one-to-one correspondence relationship with a transmitter analog gain. The RF processor of claim 1, wherein the RF processor comprises: a baseband signal processor configured to process an analog baseband signal through a digital-to-analog converter; and a direct modulator configured to upconvert the baseband signal received from the baseband signal processor to an RF frequency. And an RF path comprising a band pass filter and an amplifier, and a first directional coupler for feeding back the output of the transmitter. 2. The apparatus of claim 1, wherein the feedback path processor includes a direct demodulator for downconverting the output of the transmitter to a baseband signal, a baseband signal processor for processing an analog baseband signal of the feedback signal, an amplifier, and an analog / digital converter. CDMA mobile communication base station transmitting apparatus, characterized in that the configuration. 3. The digital AGC circuit of claim 2, wherein the digital AGC circuit compares the magnitudes of the input and output signals obtained by the level detector. To obtain the error value and the error value If the gain of the transmission path and feedback path is not variable by converting If the original I and Q data signals are output as is, and the temperature increases and the gain in the transmitter decreases, Decrease in value The value is greater than 0 and greater than 1 in the corresponding ROM table. And a value multiplied by the original I and Q data to compensate for a decrease in gain. 4. The apparatus of claim 3, wherein the RF path is configured in such a manner as to control the output signal of the transmitter by multiplying the input I and Q signals by a digital gain value given to a higher processor.