JP3382888B2 - Detection output offset control circuit - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention particularly relates to a detection output offset control circuit.

[0002]

2. Description of the Related Art Conventionally, an envelope detection circuit for converting a power component into a voltage component using a diode, a capacitor C and a resistor R is used in a communication device because of its good detection efficiency. The envelope detection circuit uses a half-wave rectified voltage appearing across the resistor R by charging / discharging the capacitor C, and the obtained signal wave is an envelope. In such a detection circuit, if the discharge time constant is not properly set, there is a problem that a part of the signal wave is not reproduced.
This is due to the distortion of the signal wave caused by the fact that the discharge characteristic cannot follow the change of the modulation wave. In order to reduce this distortion, it is necessary to properly select the discharge time constant of the capacitor C and the resistor R. is there.

[0003]

However, the prior art has the following problems. Usually, a detection method using a diode, a capacitor C, and a resistor R as a detection circuit performs voltage detection on an input signal. However, when detecting the detection voltage of a modulated wave having an amplitude variation with respect to an unmodulated wave of constant power, if the slope of the discharge change determined by the time constant CR is not appropriately given, the power of the input signal can be increased efficiently. There is a possibility that it cannot be converted into a voltage component. Therefore, in order to detect correctly, it is necessary to properly set the time constant determined by CR. Further, in a system in which a plurality of users use the same frequency such as CDMA for mobile communication, power control is performed on a signal to be used depending on the positions of the users, and the frequency utilization efficiency is increased. By multiplexing a plurality of signals in order to raise the power level, the power level becomes a waveform in which the magnitude and the fluctuation are large. Therefore, an appropriate time constant CR
However, there is a problem that it is difficult to obtain a stable detection at present.

The present invention has been made in view of the above problems, and an object of the present invention is to use a calculation table generated from information used at the time of modulation or information of a modulation waveform to detect a detection circuit. By offsetting the detected voltage that is output more, it is possible to absorb the deviation of the detected voltage that occurs when the non-modulated wave and the modulated wave are input, and prevent variations in the detected voltage at the output due to the signal input to the detection circuit. The point is to provide a detection output offset control circuit.

[0005]

The present invention has the following constitution in order to solve the above problems. The gist of the invention according to claim 1 is a detection output offset circuit provided in a transmission device for automatically controlling the transmission power to be constant by feeding back the output of the transmission wave. A detection circuit that generates a detection output that indicates the amplitude of the transmission wave, a transmitter that generates the transmission wave, and automatically controls the transmission power of the transmission wave to be constant according to an input feedback value; and the transmitter. The slope of the amplitude of the transmitted wave is obtained from the information indicating the change in the amplitude of the transmitted wave in a unit time, and the slope is compared with a threshold value,
When the slope is equal to or more than the threshold value, an offset value is set, the offset value is added to the detection output, and an offset means for outputting to the transmitter as a feedback value is provided. Exists in the control circuit. The gist of the invention according to claim 2 is that the offset means obtains a slope of the amplitude of the transmission wave by differentiating information representing a change in amplitude of the transmission wave generated in the transmitter within a unit time, Calculation of setting a threshold value according to the detection capability of the detection circuit, comparing the slope with the threshold value, and accumulating and outputting an offset value by the amount that the slope is the threshold value or more within a certain fixed time. The detection output offset control circuit according to claim 1, further comprising: means and addition means for adding the offset value to the detection output. The gist of the invention according to claim 3 is that the calculating means obtains a slope of the amplitude of the transmission wave by differentiating information representing a change in amplitude of the transmission wave generated in the transmitter within a unit time. A calculating means, a threshold calculating means for setting the threshold according to the detection capability of the detection circuit, a comparing means for comparing the inclination with the threshold, and the inclination is equal to or more than the threshold within a certain fixed time. The detection output offset control circuit according to claim 1 or 2, further comprising: an accumulating unit that accumulates and outputs the offset value by the amount. The gist of the invention according to claim 4 is that the detection circuit comprises:
It is an envelope detection circuit, and it exists in the detection output offset control circuit in any one of Claims 1-4 characterized by the above-mentioned. The gist of the invention according to claim 5 is that the offset means sets a preset offset value for each code synthesis pattern of the modulated signal obtained from the transmitter, and the offset value to the detection output. The detection output offset control circuit according to claim 1, further comprising: an addition unit for performing addition. The gist of the invention according to claim 6 resides in the detection output offset control circuit according to any one of claims 1 to 5, wherein the transmitter outputs a transmission wave modulated by a QPSK modulation method. . The gist of the invention according to claim 7 is from claim 1 to claim 1.
The transmission apparatus includes the detection output offset control circuit according to the sixth aspect. The gist of the invention according to claim 8 is,
The communication device includes the detection output offset control circuit according to the sixth aspect. The gist of the invention according to claim 9 is,
6. A CDM including the detection output offset control circuit according to item 6.
A communication device. The gist of the invention according to claim 10 is:
It exists in IC provided with the detection output offset control circuit of Claims 1-6. The gist of the invention according to claim 11 resides in an electric circuit board including the detection output offset control circuit according to claims 1 to 6. The gist of the invention according to claim 12 is a detection output offset method in a transmission device, which automatically controls the transmission power to be constant by feeding back the output of the transmission wave, wherein a detection circuit detects the transmission wave. To generate a detection output that represents the amplitude,
The transmitter generates a transmission wave, and automatically controls the transmission power of the transmission wave to be constant according to the input feedback value, and the offset unit has a unit time of the transmission wave generated in the transmitter. , The slope of the amplitude of the transmitted wave is obtained from the information indicating the change in amplitude, and the slope is compared with a threshold value. Is added and is output to the transmitter as a feedback value.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

-Embodiment 1- The configuration of a first embodiment of the present invention will be described with reference to FIG. As shown in FIG. 1, the configuration of this embodiment is roughly divided into four blocks of a CONT unit 1, an RF unit 2, a distributor 5, and a detection output offset control unit 6, and the detection output offset control unit 6 performs detection. It has a circuit 3 and an offset circuit 4.

As shown in FIG. 2, the CONT shown in FIG.
The unit 1 includes transmission digital signal sequences 201 and 211, serial-parallel converters 202 and 212, I / Q encoders 203 and 213,
Modulators 204 and 214, multipliers 205 and 215, multiplexer 206, filter 207, quadrature modulator 220, ATT2
22, a D / A converter 224, codes 208 and 218, and power controls 209 and 219, and generates a baseband signal serving as a reference of a transmission wave.

As shown in FIG. 3, the RF unit 2 shown in FIG.
Are mainly MIX (mixer) 31, 34, BPF (bandpass filter) 32, 35, AMP (amplifier) 33, 3
6 and has a function of up-converting the baseband signal 1a input from the CONT unit 1 into a frequency band required for transmission and generating a transmission wave.

As shown in FIG. 4, the detection circuit 3 shown in FIG. 1 has a diode 41, a capacitor C42, and a resistor R.
43, a filter 44, which is a circuit for converting the power component of the signal output from the RF unit 2 into a DC component and detecting the DC voltage.

As shown in FIG. 5, the offset circuit 4 shown in FIG. 1 has a calculation table 51, and is a circuit for offsetting the voltage detected by the detection circuit 3. Here, the calculation table 51 has a function of receiving information on the envelope of the transmission wave and converting the offset voltage, or
The CONT unit 1 has a function of receiving information used for baseband signal generation and converting the offset voltage. The CONT unit 1 in FIG. 1 has a function of generating a baseband signal and controlling transmission power by the ATT 222 using the offset-controlled detection voltage as information.

The operation of the circuit shown in FIG.
The description will be made with reference to 10 to 10. The CONT unit 1 in FIG. 1 modulates a transmitted digital signal to generate a baseband signal that serves as a reference for a transmitted wave.

In the present invention, CDMA (Code Div)
Consider a system in which a plurality of users use the same frequency, such as sion multiple access (code division multiple access). In CDMA, the power is adjusted by performing power control on the signal to be used so that the power from the base station is constant depending on the position of the user. In addition, control such as multiplexing a plurality of signals is performed in order to increase the frequency utilization efficiency.

Therefore, referring to FIG. 2, as an example, a two-multiplex CD
A method of generating the MA baseband signal will be described. The transmission digital signal sequences 201 and 211 input to the serial-parallel converters 202 and 212 are QPSK (Quad).
Rature Phase Shift Keyin
If the signal is modulated by a g: four-phase phase shift keying modulation method, it is possible to transmit 2 bits per signal point, so that every 2 bits are input to the I / Q encoders 203 and 213. The I / Q encoders 203 and 213 generate transmission signal points with 2 bits as one code point on the I / Q plane according to the QPSK modulation method. In the case of a CDMA signal, the generated transmission signal points are coded by the modulators 204 and 214, subjected to power control according to the transmission conditions, that is, amplitude value control, and then multiplexed by the multiplexer 206. The transmission signals thus multiplexed are band-limited by a filter (root Nyquist filter) 207, combined by the quadrature modulator 220 with I and Q, and then transmitted by the AT.
Via T222, it is converted into an analog signal by the D / A converter 224, and the base band signal (1a) of the transmission data is transmitted.
Is output as. Here, the ATT 222 is used in realizing an automatic gain control function described later, and controls the amplitude of the entire combined baseband signal. Further, in the CONT section 1, various modulators 204 and 214 can apply various modulations to a signal.

The baseband signal (1a) thus modulated is input to the RF unit 2 in FIG. In the RF unit 2 shown in FIG. 3, the signals up-converted by the mixers 31 and 34 are removed by the BPFs 32 and 35 to eliminate unnecessary waves outside the required band in order to obtain the frequency band and gain required for transmission. The amplifiers 33 and 36 amplify the power.

The RF signal (2a) thus obtained
Is output as a transmission wave, but it is actually difficult to keep the power constant due to the characteristics of the device and temperature fluctuations. Therefore, automatic gain control is used to keep the output power constant. In the automatic gain control, the transmission power value at the output of the RF unit 2 is fed back as information to control the transmission power. As information generating means at that time, a diode 41 and a capacitor C4 as shown in FIG. 4 are used.
2. A method of converting power information into voltage information by using the detection circuit 3 composed of the resistor R43 is generally used. In the detection circuit 3, the diode 41 performs half-wave rectification on the input signal (FIG. 4A) (FIG. 4B).
Charge and discharge by the capacitor C42 and the resistor R43 (see FIG.
(C)) is performed to obtain an envelope. The signal is filtered 4
By passing it through 4, the AC component is removed and the detection capability information (3a) which is a DC voltage is obtained.

However, at this time, a suitable capacitor C4
If the combination of 2 and the resistor R43 is not selected, the converted voltage becomes excessive or insufficient, and efficient detection cannot be performed, making it difficult to detect an accurate voltage. In particular, in a system such as CDMA in which a plurality of users use the same frequency, it is necessary to increase power by performing power control as described above and to multiplex a plurality of signals in order to improve frequency utilization efficiency. Therefore, a modulated wave with a large amplitude fluctuation is handled. In such a case, it is difficult to obtain an appropriate time constant for each signal, and the detected voltage varies. This occurs because the detection voltage is clipped by the smoothing function of the detection circuit 3 in the case of a modulated wave which has a large waveform fluctuation for a short time, resulting in a lack of power and a small detection voltage. .

As described above, if the detected voltage varies, an error occurs in the information fed back, and stable automatic gain control cannot be performed.
Therefore, in order to absorb this variation, the detection output offset control unit 6 in FIG.
The signal output from the F unit 2 is converted into a DC component, and the detected DC voltage is offset-controlled by the offset circuit 4 having the calculation table 51.

Here, as shown in FIG. 10A, the accurate detection voltage detected without excess or deficiency is V1, and the detection voltage of the modulation wave having the same average power as V2 is V2. Figure 10
If an appropriate time constant is not obtained in (b), the detection voltage V2 will take a value lower than V1 as shown in FIG. 10 (c) if sufficient detection is not performed. Therefore, it is necessary to calculate and add a differential voltage for compensating for the voltage of the insufficient portion. Therefore, as shown in the calculation table 51 in FIG. 5, the differential voltage that will be generated after the voltage detection based on the information such as the modulation code, the power control amount, and the baseband signal waveform used for the modulated wave generation in the CONT unit 1. A circuit for calculating is used.

The operation of the calculation table 51 will be described below. A first embodiment will be described. As shown in FIG.
Since the ONT unit 1 generates the combined amplitude of the baseband signal 1a, the CONT unit 1 outputs the envelope information (1b).
Can be obtained. Here, envelope information (1b)
Is amplitude value data in a certain short time Δt. Figure 6
As shown in, the differentiator 63 of the calculation table 51 calculates the slope at a certain time t with respect to the envelope information (1b) obtained from the CONT unit 1. Further, since it is necessary to grasp the characteristics of the detector in advance in order to obtain the offset amount, the threshold calculator 64 causes the detector circuit 3 shown in FIG.
A threshold serving as a criterion for determination is determined from the detection capability information (3a). Here, the signal of the detection capability information (3a) is the envelope signal of the modulation wave signal obtained from the detection circuit, and the signal of FIG.
2 shows a time waveform like x (t). This CONT part 1
From the relationship between the gradient of the envelope information x (t) obtained in step t in a short time Δt and the threshold value, the comparator 65 determines the envelope information obtained from the CONT unit 1 at every time t as shown in FIG. And determine whether or not there is an offset. That is, when the slope is small, that is, when the slope is less than or equal to the threshold value, sufficient detection is performed without power loss, so there is no need to offset the detected voltage, and when the slope is large,
That is, when the slope is equal to or more than the threshold value, it is determined that it is necessary to offset the shortage because a portion of high power is missing due to smoothing at the set time constant and sufficient detection is not performed. The above operation is accumulated for a certain section T to set an offset value. Offset value 5 obtained here
1a is added by the adder 52 (FIG. 5) for each section as shown in FIG. From FIG. 8, the value at a certain time t when there is no offset is Va, whereas after offset, Va + Vb is given.

Specific examples of the offset will be shown below. For example, in the calculation table 51, the following time chart is created by the determination based on the envelope information obtained from the CONT unit 1 and the threshold information based on the detection capability of the detection circuit 3.

[0022]

[Table 1]

According to Table 1, as a determination result at a certain time t, 1 is given when there is an offset and 0 is given when there is no offset, which is accumulated during a certain section T.
That is, in the section T1, since 4 is obtained as the cumulative result, this is converted into a voltage and the offset value in this section is set to 0.6.
Add as V. By performing such an operation for a certain period L1 and converging the voltage value obtained from the detector output to an accurate value, it becomes possible to absorb the variation that occurs during voltage detection.

Second Embodiment As a second embodiment, if there is no power control in the transmission signal and the code for the data is under a certain condition, a fixed calculation table is used.
It is possible to achieve the same effect. Under this condition, the amplitude fluctuation period for each code is constant, so that the amplitude information after multiplexing can be predicted. Therefore, it is considered to use the fixed calculation table 51A (Table 2) depending on the combination of the output codes.

FIG. 9 shows an example of the case of two-code synthesis for the sake of simplicity. A possible combination for two codes is when the chip polarities are the same or different. Here, if the types of chips are considered to be ± 1, they are added at the same chip rate at a certain time t, and they cancel each other out at a different chip rate. This is converted into an offset value for a certain section T, a fixed table is created, and a high voltage portion is missing due to the time constant like V2, and the offset voltage is applied to a state in which electric power cannot be sufficiently taken in, thereby causing variations. Absorb. For example, when the code synthesis patterns are given as A, B, and C for the section T, if the offset values are set in advance as α, β, and γ, respectively, the output will be detected according to the synthesis pattern at the time of output. It is possible to obtain a stable voltage by adding the offset value. That is, the CONT part 1
When A is received as the pattern information, it is possible to obtain the true value V1 by adding α to the detected voltage V2.

Table 2 shows an example of values stored in the fixed calculation table 51A in the case of the present embodiment.

[0027]

[Table 2]

This makes it possible to refer to the value by calculating it in advance and storing it as ROM data having a combination of codes as an address. Since the detection output offset control circuit according to the embodiment is configured as described above, it has the following effects.

The effect of the present invention is that by offset-controlling the detection voltage output from the detection circuit 3, the deviation of the detection voltage generated when the unmodulated wave and the modulated wave are input is absorbed, and the signal input to the detection circuit is absorbed. This is because it is possible to prevent variations in the detected voltage due to the output.

The reason is that the wireless communication device has the modulation system used in the generation of the transmission waveform in the CONT unit 1, and it is possible to use the power control amount and the used code pattern as information. Because.

Also, by verifying the slope of the envelope obtained from the transmission waveform in real time, it is possible to take in power without excess or deficiency and obtain a stable detection voltage.

In the present embodiment, the present invention is not limited to this, and can be applied to a suitable mode for applying the present invention.

Further, the number, position, shape, etc. of the above-mentioned constituent members are not limited to those in the above-mentioned embodiment, and the number, position, shape, etc. suitable for carrying out the present invention can be adopted.

In each figure, the same components are designated by the same reference numerals.

[0035]

Since the present invention is configured as described above, by performing offset control on the detection voltage output from the detection circuit 3, the detection voltage generated when the unmodulated wave and the modulated wave are input can be detected. It becomes possible to absorb variations.
As a result, it is possible to prevent variations in the detection voltage at the output of the signal input to the detection circuit 3 and to obtain a stable detection voltage regardless of the type of the input signal.

[Brief description of drawings]

FIG. 1 is a block diagram showing a system configuration of a first exemplary embodiment of the present invention.

FIG. 2 is a block diagram of an electric circuit showing a configuration of a CONT unit 1 shown in FIG.

FIG. 3 is a block diagram of an electric circuit showing a configuration of an RF unit 2 shown in FIG.

FIG. 4 is an electric circuit diagram showing a circuit configuration of the detection circuit 3 shown in FIG. 1, and (a), (b) and (c) are diagrams showing signal waveforms at respective points.

5 is a block diagram of an electric circuit showing a configuration of an offset circuit 4 shown in FIG.

6 is a block diagram of an electric circuit showing a configuration of a calculation table 51 shown in FIG.

FIG. 7 is a diagram showing a comparison method of a comparator 65 shown in FIG.

FIG. 8 is a diagram showing a comparison between the accumulation result of the accumulator shown in FIG. 6 and the presence / absence of an offset.

FIG. 9 is a diagram showing a configuration of a fixed calculation table 51A according to the second embodiment.

FIG. 10 is a diagram showing a configuration of an offset.

[Explanation of symbols]

1 CONT department 1a Baseband signal 1b Envelope information 2 RF section 2a RF signal 3 Detection circuit 3a Detection capability information 4 offset circuit 4a Feedback signal 5 distributors 5a Distribution signal 5b distribution signal 6 Detection output offset control section 31,34 MIX 32,35 BPF 33,36 AMP 41 diode 42 Capacitor C 43 Resistance R 44 Filter 51 Calculation table 51a Offset value 51A fixed calculation table 52 adder 61 transmitted wave 63 Differentiator 64 threshold calculator 65 comparator 66 accumulator 201, 211 Transmit digital signal sequence 202,212 series-parallel converter 203,213 I / Q encoder 204,214 modulator 205,215 multiplier 206 Multiplexer 207 Filter 208,218 code 209,219 Power Control 220 Quadrature modulator 222 ATT 224 D / A converter

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H04L 27/20 H04B 1/04 H04J 13/00

Claims (12)

(57) [Claims] 1. A detection output offset circuit provided in a transmission device for automatically controlling a transmission power to be constant by feeding back an output of the transmission wave, the detection output offset circuit detecting the transmission wave and determining an amplitude of the transmission wave. A detection circuit that generates a detected detection output, a transmitter that generates a transmission wave and automatically controls the transmission power of the transmission wave to be constant according to an input feedback value, and a transmission generated by the transmitter. The slope of the amplitude of the transmitted wave is obtained from the information indicating the change in amplitude of the wave within a unit time, the slope is compared with a threshold value, and when the slope is equal to or greater than the threshold value, an offset value is set, and the detection is performed. A detection output offset control circuit, comprising: an offset means for adding the offset value to an output and outputting it as a feedback value to the transmitter. 2. The offset means obtains a slope of the amplitude of the transmission wave by differentiating information representing a change in amplitude of the transmission wave generated in the transmitter within a unit time, and the detection circuit of the detection circuit detects the inclination. A threshold value is set according to the capability, the slope is compared with the threshold value, and a calculation unit that accumulates and outputs an offset value by the amount that the slope is equal to or greater than the threshold value within a certain period of time; The detection output offset control circuit according to claim 1, further comprising: an addition unit that adds the offset value to an output. 3. The inclination calculating means for obtaining the inclination of the amplitude of the transmission wave by differentiating the information indicating the change in the amplitude of the transmission wave generated in the transmitter in a unit time, Threshold calculation means for setting the threshold according to the detection capability of the detection circuit, comparison means for comparing the slope and the threshold, offset value by the amount that the slope is equal to or more than the threshold within a certain fixed time 3. The detection output offset control circuit according to claim 1 or 2, further comprising: an accumulator that accumulates and outputs. 4. The detection output offset control circuit according to claim 1, wherein the detection circuit is an envelope detection circuit. 5. The offset means comprises a calculating means for setting a preset offset value for each code synthesis pattern of the modulated signal obtained from the transmitter, and an adding means for adding the offset value to the detection output. The detection output offset control circuit according to claim 1, further comprising: 6. The transmitter according to claim 1, wherein the transmitter outputs a transmission wave modulated by a QPSK modulation method.
5. The detection output offset control circuit according to any one of 5 to 5. 7. A transmitter comprising the detection output offset control circuit according to claim 1. 8. A communication device comprising the detection output offset control circuit according to claim 1. 9. A CDMA communication device comprising the detection output offset control circuit according to claim 1. 10. An IC comprising the detection output offset control circuit according to claim 1. 11. An electric circuit board comprising the detection output offset control circuit according to claim 1. 12. A detection output offset method in a transmission device for automatically controlling the transmission power to be constant by feeding back the output of the transmission wave, wherein the detection circuit detects the transmission wave to express the amplitude. A detection output is generated, the transmitter generates a transmission wave, and automatically controls so that the transmission power of the transmission wave becomes constant according to the input feedback value, and an offset means is generated in the transmitter. Obtain the slope of the amplitude of the transmitted wave from the information indicating the change in the amplitude of the transmitted wave in a unit time, compare the slope with a threshold value, and if the slope is equal to or greater than the threshold value, set an offset value, and A detection output offset control method comprising adding the offset value to a detection output and outputting it as a feedback value to the transmitter.