JP3504071B2 - Direct conversion receiver - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiver used in a radio used for digital mobile communication or the like, and particularly to controlling a gain in a high frequency band and a gain in a baseband individually by using individual control signals. In addition, the present invention relates to a reception device that prevents deterioration of noise figure characteristics and prevents reception failures.

[0002]

2. Description of the Related Art FIG. 8 shows the structure of a conventional direct conversion receiver. In FIG. 8, the direct conversion receiver is an aerial battle 1 that receives a signal,
A high frequency band gain control amplifier 2 for controlling an output level of a received signal, a phase shifter 3 for obtaining a cos wave and a sin wave from an input local oscillation signal, a reception signal and a local oscillation signal for mixing I, Mixers 4 and 5 for obtaining a Q signal, low-pass filters 6 and 7 for removing unnecessary frequency components from the I and Q signals, and baseband gain control amplifiers 8 and 9 for controlling an output level of an input signal. And A / D converters 11 and 12 for converting analog signals into digital signals
, Digital multipliers 12, 13, 14, 15; digital subtractors 16, 22; digital adder 17; root Nyquist filters 18, 19 for waveform shaping the I and Q baseband signals; An amplitude detection circuit 20 for detecting signal amplitude information, an averaging circuit 21 for averaging processing, and a D / A converter 23 for converting a digital signal into an analog signal.
It consists of and.

In the direct conversion receiver configured as described above, the received signal 24 received by the antenna 1 is output level controlled by the high frequency band gain control amplifier 2 to obtain a signal 25. The signal 25 is input to the mixers 4 and 5, respectively.

Here, when the frequency of the desired wave is f and the frequency of the local oscillation signal 26 is f-fo, it is the adjacent wave whose frequency is f + 2fo that falls into the desired wave band after quadrature demodulation. Therefore, consider the case where there is one adjacent wave of frequency f-2fo in addition to the desired wave. In this case, each signal 25 is represented by the following equation.

[0005]   S (t) = {I (t) cos2πft + Q (t) sin2πft}       + {II (t) cos2π (f-2fo) t + QQ (t) sin2π (f-2fo) t} (1) However, I (t); baseband I signal (desired wave component) Q (t): Baseband Q signal (desired wave component) II (t); Baseband I signal (adjacent wave component) QQ (t); Baseband Q signal (adjacent wave component)

The local oscillation signal 26 is input to the phase shifter 3,
Cos wave 27 and sine wave 28 are output respectively and input to mixers 4 and 5, respectively.

The signal 25 is mixed with the cos wave 27 by the mixer 4 and down-converted to obtain a signal SI (t) 29. The signal SI (t) is expressed by the following equation.

[0008]   SI (t) = {I (t) cos2πft + Q (t) sin2πft} cos2π (f-fo) t         + {II (t) cos2π (f-2fo) t + QQ (t) sin2π (f-2fo) t} cos2π (f-fo) t        = {I (t) cos2πfot + Q (t) sin2πfot} / 2         + {II (t) cos2πfot-QQ (t) sin2πfot} / 2         + {I (t) cos2π (2f-fo) t + Q (t) sin2π (2f-fo) t} / 2         + {II (t) cos2π (2f-3fo) t + QQ (t) sin2π (2f-3fo) t} / 2 (2)

Similarly, the signal 25 is sin by the mixer 5.
Wave 28 mixed and down-converted signal SQ
(t) 30 is obtained. The signal SQ (t) is expressed by the following equation.

[0010]   SQ (t) = {I (t) cos2πft + Q (t) sin2πft} sin2π (f-fo) t         + {II (t) cos2π (f-2fo) t + QQ (t) sin2π (f-2fo) t} sin2π (f-fo) t        = {-I (t) sin2πfot + Q (t) cos2πfot} / 2         + {II (t) sin2πfot + QQ (t) cos2πfot} / 2         + {I (t) sin2π (2f-fo) t + Q (t) cos2π (2f-fo) t} / 2         + {II (t) sin2π (2f-3fo) t + QQ (t) sin2π (2f-3fo) t} / 2 (3)

Next, the signal 29 is input to the analog low-pass filter 6, the unnecessary frequency components are removed, and the signal SSI (t)
You get 31. The signal SSI (t) is expressed by the following equation.

[0012]   SSI (t) = {I (t) cos2πfot + Q (t) sin2πfot} / 2         + {II (t) cos2πfot-QQ (t) sin2πfot} / 2 (4)

Similarly, the signal 30 is input to the analog low-pass filter 7, the unnecessary frequency components are removed, and the signal SSQ
(t) 32 is obtained. The signal SSQ (t) is expressed by the following equation.

[0014]   SSQ (t) = {-I (t) sin2πfot + Q (t) cos2πfot} / 2         + {II (t) sin2πfot + QQ (t) cos2πfot} / 2 (5)

The output levels of the signals 31 and 32 are controlled by the baseband gain control amplifiers 8 and 9, respectively, and the signals 33 and 34 are obtained.

The signal 33 is converted into a digital signal by the A / D converter 10 to obtain a signal DI (nT) 35. Signal DI (n
T) is shown by the following equation.

[0017]   DI (nT) = {I (nT) cos2πfonT + Q (nT) sin2πfonT} / 2         + {II (nT) cos2πfonT-QQ (nT) sin2πfonT} / 2 (6) However, n = 0,1,2, ... T: Sampling period

Similarly, the signal 34 is converted into a digital signal by the A / D converter 11, and the signal DQ (nT) 36 is obtained.
The signal DQ (nT) is expressed by the following equation.

[0019]   DQ (nT) = {-I (nT) sin2πfonT + Q (nT) cos2πfonT} / 2         + {II (nT) sin2πfonT + QQ (nT) cos2πfonT} / 2 (7)

The signal 35 is then sent to the digital multipliers 12, 13
Is multiplied by cos signal 37 and sin signal 38, respectively,
Signals 39 and 40 are obtained respectively. Similarly, signal 36
Are the cos signals by the digital multipliers 14 and 15, respectively.
37 and sin signal 38 are multiplied to obtain signals 41 and 42, respectively.

Next, the signal I1 (nT) 39 and the signal Q2 (nT) 42 are input to the digital subtractor 16 to remove the adjacent wave falling in the desired signal band, and the signal I (nT) 43 is obtained. . Here, in the signals 39 and 42, the desired signal exists as a differential component, but the adjacent wave that falls into the desired signal band exists as an in-phase component, so it is possible to remove the adjacent wave that falls into the desired signal band. It will be possible.

Similarly, the signal Q1 (nT) 40 and the signal I2 (nT) 41 are input to the digital adder 17, and the adjacent wave dropped in the desired signal band is removed to obtain the signal Q (nt) 44. . Here, in the signals 40 and 41, the desired signal exists as an in-phase component, but the adjacent wave that falls into the desired signal band exists as a differential component, so it is possible to remove the adjacent wave that falls into the desired signal band. It will be possible.

Finally, the signal I (nT) 43 and the signal Q (nT) 44 are shaped by the root Nyquist filters 18 and 19, respectively, and adjacent waves outside the desired signal band are removed, so that the baseband I signal 45 respectively. And a baseband Q signal 46 is obtained.

Here, the signals 45 and 46 are the amplitude detection circuit 20.
Is squared and added, and the square root operation is performed to obtain the root Nyquist filter output signal.
47 amplitude information signals are obtained. Next, the signal 47 is averaged by the averaging circuit 21, and a signal 48 is obtained.
The signal 48 is then output by the digital subtractor 22 to the reference signal.
Subtraction with 49 yields signal 50. Finally, signal 50
Is converted into an analog signal by the D / A converter 23, and a control signal 51 is obtained. The control signal 51 controls the gains of the high frequency band gain control amplifier 2 and the base band gain control amplifiers 8 and 9.

[0025]

In the direct conversion receiver having the above-described structure, since the adjacent wave cannot be sufficiently removed by only the analog low-pass filter, the baseband gain control amplifier input signal level is lower than the root Nyquist filter output signal level. It increases by the level of the adjacent wave that remains. Therefore, when the adjacent wave component is much larger than the desired signal component, there is a problem that the baseband gain control amplifier is saturated.

In order to solve such a problem, instead of using the root Nyquist filter output signal from which the adjacent wave is removed, the A / D converter output signal from which the adjacent wave remains is used. There is a method of generating the control signal of the gain control amplifier. However, in the gain control amplifier, generally, when the gain is lowered, the noise figure deteriorates, and when the noise figure characteristic of the high frequency band gain control amplifier deteriorates, the bit error rate characteristic largely deteriorates. Therefore, when this method is used, there is a problem that reception failure occurs when the adjacent wave is very large with respect to the desired signal.

The present invention is to solve such a conventional problem, and controls the baseband gain control amplifier by a control signal generated by the output signal of the A / D converter, and the high frequency band gain control amplifier is root Nyquist. The above problem is solved by controlling with a control signal generated by a filter output signal, and controlling a high frequency band gain control amplifier and a base band gain control amplifier using individual control signals.

[0028]

According to the present invention, a baseband gain control amplifier is controlled by a control signal generated by an A / D converter output signal, and a high frequency band gain amplifier is controlled by a root Nyquist filter output signal. The above problems are solved by controlling the gain control amplifier with a signal and controlling the high-frequency band gain control amplifier and the baseband gain control amplifier using individual control signals.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention is
A direct conversion receiver that offsets the local oscillation frequency in quadrature detection from the received signal frequency and removes the adjacent wave that has dropped to the desired signal band with an image rejection mixer composed of a digital multiplier, digital subtractor, and digital adder. And a direct conversion receiver including a high-frequency band amplifier, a mixer, and a baseband amplifier, wherein the high-frequency band gain and the baseband band gain are individually controlled using individual control signals. The present invention has the effects of preventing the gain control amplifier from saturating and preventing reception failure due to deterioration of the noise figure characteristic of the high frequency band gain control amplifier.

According to a second aspect of the present invention, the high frequency band gain control amplifier is constructed by using an amplifier and a variable attenuator, and the gain control is performed discretely. This is a conversion receiver, and has an effect that the dynamic range can be expanded and gain control can be performed with high accuracy, compared with the invention described in claim 1.

According to a third aspect of the present invention, the high frequency band gain control amplifier is configured by using an amplifier, a fixed attenuator and a switch, and the gain is controlled discretely by switching the amplifier and the fixed attenuator with a switch. The method according to claim 1, wherein
The direct conversion receiver described above has an effect of reducing distortion more than that of the invention described in claim 2.

According to a fourth aspect of the present invention, the gain of the mixer is switched in addition to the gains of the high frequency band amplifier and the base band band amplifier. The direct conversion receiver according to any one of items 3 and 4 has an effect that the dynamic range can be further expanded as compared with the invention according to claim 2.

According to a fifth aspect of the present invention, the image rejection mixer is constituted by a polarity inverter, a multiplexer switch, a digital subtractor and a digital adder. Claim 3,
The direct conversion receiver according to any one of claims 4 and 5 has an effect that the amount of calculation can be further reduced as compared with the invention according to claim 1.

The invention according to claim 6 of the present invention is characterized in that the gain control of the baseband in the baseband amplifier is discretely performed.
The direct conversion receiver according to any one of claims 3, 4, and 5, wherein the dynamic range can be expanded further than that of the invention according to claim 3, and highly accurate gain control can be performed. It has the effect that it can be performed.

The invention according to claim 7 of the present invention is characterized in that the gain control of the mixer is controlled by using a control signal for performing gain control of the baseband in the baseband amplifier. The direct conversion receiver according to any one of claims 5 and 6 has an effect of further reducing distortion as compared with the invention according to claim 4.

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
The configuration of the receiving apparatus according to the embodiment is shown. In FIG. 1, a receiving device includes an antenna 1 for receiving a signal, a high frequency band gain control amplifier 2 for controlling an output level of the received signal, and a phase shift for obtaining a cos wave and a sin wave from an input local oscillation signal. And the mixers 4 and 5 for mixing the received signal characteristic local oscillation signal to obtain I and Q signals, and the I and Q
Low-pass filters 6 and 7 for removing unnecessary frequency components from signals, baseband gain control amplifiers 8 and 9 for controlling output levels for input signals, and A / D conversion for converting analog signals into digital signals Units 10, 11 and digital multipliers 12, 13, 14, 15 and digital subtractor 1
6, 22, 53, a digital adder 17, root Nyquist filters 18, 19 for performing waveform shaping on the I, Q baseband signals, amplitude detection circuits 20, 52 for detecting amplitude information of the input signal, Averaging circuit 21, which performs averaging processing,
53 and D / A for converting digital signals to analog signals
It is composed of converters 23 and 55.

In the direct conversion receiver configured as above, the received signal 24 received by the antenna 1 is output level controlled by the high frequency band gain control amplifier 2 to obtain the signal 25. The signal 25 is input to the mixers 4 and 5, respectively.

Here, if the frequency of the desired wave is f and the frequency of the local oscillation signal 26 is f-fo, the input of the desired wave band after quadrature demodulation is the adjacent wave whose frequency is f + 2fo.
Therefore, consider the case where there is one adjacent wave of frequency f-2fo in addition to the desired wave. In this case, each signal 25 is represented by the following equation.

[0040]   S (t) = {I (t) cos2πft + Q (t) sin2πft}       + {II (t) cos2π (f-2fo) t + QQ (t) sin2π (f-2fo) t} (1) However, I (t); baseband I signal (desired wave component) Q (t): Baseband Q signal (desired wave component) II (t); Baseband I signal (adjacent wave component) QQ (t); Baseband Q signal (adjacent wave component)

The local oscillation signal 26 is input to the phase shifter 3,
Cos wave 27 and sine wave 28 are output respectively and input to mixers 4 and 5, respectively.

The signal 25 is mixed with the cos wave 27 by the mixer 4 and down-converted to obtain a signal SI (t) 29. The signal SI (t) is expressed by the following equation.

[0043]   SI (t) = {I (t) cos2πft + Q (t) sin2πft} cos2π (f-fo) t         + {II (t) cos2π (f-2fo) t + QQ (t) sin2π (f-2fo) t} cos2π (f-fo) t        = {I (t) cos2πfot + Q (t) sin2πfot} / 2         + {II (t) cos2πfot-QQ (t) sin2πfot} / 2         + {I (t) cos2π (2f-fo) t + Q (t) sin2π (2f-fo) t} / 2         + {II (t) cos2π (2f-3fo) t + QQ (t) sin2π (2f-3fo) t} / 2 (2)

Similarly, the signal 25 is sin by the mixer 5.
Wave 28 mixed and down-converted signal SQ
(t) 30 is obtained. The signal SQ (t) is expressed by the following equation.

[0045]   SQ (t) = {I (t) cos2πft + Q (t) sin2πft} sin2π (f-fo) t         + {II (t) cos2π (f-2fo) t + QQ (t) sin2π (f-2fo) t} sin2π (f-fo) t        = {-I (t) sin2πfot + Q (t) cos2πfot} / 2         + {II (t) sin2πfot + QQ (t) cos2πfot} / 2         + {I (t) sin2π (2f-fo) t + Q (t) cos2π (2f-fo) t} / 2         + {II (t) sin2π (2f-3fo) t + QQ (t) sin2π (2f-3fo) t} / 2 (3)

Next, the signal 29 is input to the analog low-pass filter 6, the unnecessary frequency components are removed, and the signal SSI (t)
You get 31. The signal SSI (t) is expressed by the following equation.

[0047]   SSI (t) = {I (t) cos2πfot + Q (t) sin2πfot} / 2         + {II (t) cos2πfot-QQ (t) sin2πfot} / 2 (4)

Similarly, the signal 30 is input to the analog low-pass filter 7, the unnecessary frequency components are removed, and the signal SSQ
(t) 32 is obtained. The signal SSQ (t) is expressed by the following equation.

[0049]   SSQ (t) = {-I (t) sin2πfot + Q (t) cos2πfot} / 2         + {II (t) sin2πfot + QQ (t) cos2πfot} / 2 (5)

The output levels of the signals 31 and 32 are controlled by the baseband gain control amplifiers 8 and 9, respectively, and the signals 33 and 34 are obtained.

The signal 33 is converted into a digital signal by the A / D converter 10, and a signal DI (nT) 35 is obtained. Signal DI (n
T) is shown by the following equation.

[0052]   DI (nT) = {I (nT) cos2πfonT + Q (nT) sin2πfonT} / 2         + {II (nT) cos2πfonT-QQ (nT) sin2πfonT} / 2 (6) However, n = 0,1,2, ... T: Sampling period

Similarly, the signal 34 is converted into a digital signal by the A / D converter 11, and the signal DQ (nT) 36 is obtained.
The signal DQ (nT) is expressed by the following equation.

[0054]   DQ (nT) = {-I (nT) sin2πfonT + Q (nT) cos2πfonT} / 2         + {II (nT) sin2πfonT + QQ (nT) cos2πfonT} / 2 (7)

The signal 35 is then sent to the digital multipliers 12, 13
Is multiplied by cos signal 37 and sin signal 38, respectively,
Signals 39 and 40 are obtained respectively. Similarly, signal 36
Are the cos signals by the digital multipliers 14 and 15, respectively.
37 and sin signal 38 are multiplied to obtain signals 41 and 42, respectively.

Next, the signal I1 (nT) 39 and the signal Q2 (nT) 42 are input to the digital subtractor 16 to remove the adjacent wave dropped in the desired signal band, and the signal I (nT) 43 is obtained. . Here, in the signals 39 and 42, the desired signal exists as a differential component, but the adjacent wave that falls into the desired signal band exists as an in-phase component, so it is possible to remove the adjacent wave that falls into the desired signal band. It will be possible.

Similarly, the signal Q1 (nT) 40 and the signal I2 (nT) 41 are input to the digital adder 17, and the adjacent wave dropped in the desired signal band is removed to obtain the signal Q (nt) 44. . Here, in the signals 40 and 41, the desired signal exists as an in-phase component, but the adjacent wave that falls into the desired signal band exists as a differential component, so it is possible to remove the adjacent wave that falls into the desired signal band. It will be possible.

Finally, the signal I (nT) 43 and the signal Q (nT) 44 are shaped by the root Nyquist filters 18 and 19, respectively, and adjacent waves outside the desired signal band are removed. And a baseband Q signal 46 is obtained.

Here, the signals 35 and 36 are the amplitude detection circuit 52.
Thus, the amplitude information signal of the A / D converter output signal 56 is obtained by squaring, adding, and further calculating the square root. Next, the signal 56 is averaged by the averaging circuit 53 to obtain a signal 57. Then signal 57
Is subtracted from the reference signal 58 by the digital subtractor 54 to obtain a signal 59. Finally, the signal 59 is converted into an analog signal by the D / A converter 55, and the control signal 60 is obtained. The control signal 60 controls the gains of the baseband gain control amplifiers 8 and 9.

Similarly, the signals 45 and 46 are transmitted to the amplitude detection circuit 20.
Is squared and added, and the square root operation is performed to obtain the root Nyquist filter output signal.
47 amplitude information signals are obtained. Next, the signal 47 is averaged by the averaging circuit 21, and a signal 48 is obtained.
The signal 48 is then output by the digital subtractor 22 to the reference signal.
Subtraction with 49 yields signal 50. Finally, signal 50
Is converted into an analog signal by the D / A converter 23, and a control signal 51 is obtained. The control signal 51 controls the gains of the high frequency band gain control amplifier 2 and the base band gain control amplifiers 8 and 9.

As described above, according to the present invention, the baseband gain control amplifier is controlled by the control signal generated by the A / D converter output signal, and the high frequency band gain control amplifier is controlled by the root Nyquist filter output signal. By controlling the high frequency band gain control amplifier and the base band gain control amplifier with separate control signals, the gain control amplifier is prevented from being saturated and the noise figure characteristic of the high frequency band gain control amplifier is deteriorated. Therefore, it is possible to prevent reception failure.

(Second Embodiment) FIG. 2 shows a second embodiment of the present invention.
It is a configuration of a receiving apparatus of the embodiment of. The receiving device of the second embodiment is different from the receiving device of the first embodiment in that the high frequency band gain control amplifier 2 is replaced by an amplifier 61 and a variable attenuator 62.

Here, the members, signals, etc. of the receiving apparatus of the second embodiment corresponding to the members, signals, etc. described in FIG. 1 are assigned the same reference numerals and detailed explanations thereof are omitted.

The operation of the receiving apparatus of the second embodiment will be described with reference to FIG.

The received signal 24 received from the antenna 1 is amplified by the amplifier 61 to obtain the signal 64. Signal 64 is
The level is controlled by the variable attenuator 62, and the signal 25 is obtained.

After that, the procedure until the baseband I signal 21 and the baseband Q signal 22 are obtained is the same as that of the receiving apparatus of the first embodiment.

Further, the baseband gain control amplifier 8,
The generation of the control signal for controlling 9 is the same as that of the receiving device of the first embodiment. The generation of the control signal for controlling the variable attenuator 62 is the same as that of the receiving device of the first embodiment until the signal 50 is obtained. Traffic light 50
Is determined by the determination circuit 63, and the control signal 65 is obtained. The control signal 65 controls the variable attenuator 62. In the configuration of the receiving apparatus according to the second embodiment, the high frequency band gain control amplifier is configured using an amplifier and a variable attenuator, and gain control is performed discretely, so that the receiving apparatus according to the first embodiment. The dynamic range can be expanded further than in the above configuration, and highly accurate gain control can be performed.

(Third Embodiment) FIG. 3 shows a third embodiment of the present invention.
It is a configuration of a receiving apparatus of the embodiment of. The receiving device of the third embodiment is different from the receiving device of the second embodiment in that it includes switches 66, 68, an amplifier 61 and a fixed attenuator 67 instead of the amplifier 61 and the variable attenuator 62. It is in a different configuration.

Here, the members, signals, etc. of the receiving apparatus of the third embodiment corresponding to the members, signals, etc. described in FIG. 1 are assigned the same reference numerals and detailed explanations thereof are omitted.

The received signal 24 received by the antenna 1 is
When the signal is input to the amplifier 61 by the switch 66, it is amplified by the amplifier 61 and the signal 64 is obtained. When the signal is input to the fixed attenuator 67, it is attenuated by the fixed attenuator 67 and the signal 69 is obtained. Switch 68 has signals 64 and 69.
Are switched and output, and a signal 25 is obtained.

After that, the procedure until the baseband I signal 21 and the baseband Q signal 22 are obtained is the same as that of the receiving apparatus of the second embodiment.

The generation of the control signal is the same as that of the receiving device of the second embodiment.

In general, the distortion due to the switch is less than the distortion due to the variable attenuator. In addition, since the fixed attenuator can be configured only by resistors without using a semiconductor element, basically no distortion occurs. Therefore, in the configuration of the receiving device according to the third embodiment, the distortion can be made lower than that of the configuration of the receiving device according to the second embodiment.

As described above, in the configuration of the receiving apparatus according to the third embodiment, the configuration including the switch, the amplifier and the fixed attenuator causes more distortion than the configuration of the receiving apparatus according to the second embodiment. Can be reduced.

(Fourth Embodiment) FIG. 4 shows the configuration of a receiving apparatus according to the fourth embodiment of the present invention. The receiving device of the fourth embodiment is different from the receiving device of the second embodiment in that the mixer gain is switched in addition to the gains of the high frequency band amplifier and the base band amplifier.

Here, the members, signals and the like of the receiver of the fourth embodiment corresponding to the members, signals and the like described in FIG. 2 are assigned the same reference numerals and detailed explanations thereof are omitted.

The operation of the receiving apparatus of the fourth embodiment is shown in FIG.
Will be explained.

It is the same as the receiving apparatus of the second embodiment except that the gains of the mixers 4 and 5 are switched by the control signal 65.

In the configuration of the receiver of the fourth embodiment, the gain of the mixer is switched in addition to the gains of the high-frequency band amplifier and the baseband amplifier, so that the receiver of the second embodiment is configured. The dynamic range can be expanded more than that.

(Fifth Embodiment) FIG. 5 shows a fifth embodiment of the present invention.
It is a configuration of a receiving apparatus of the embodiment of. The receiving device of the fifth embodiment differs from the receiving device of the first embodiment in that instead of the digital multipliers 12, 13, 14, 15 there are polar inverters 70, 71, 72, 73. , Multiplexer switches 74, 75, 76, 77 are provided.

Here, the members, signals and the like of the receiver of the fifth embodiment corresponding to the members, signals and the like described in FIG. 1 are assigned the same reference numerals and detailed explanations thereof are omitted.

The operation of the receiver of the fifth embodiment is shown in FIG.
Will be explained.

The procedure until the signal DI (nT) 35 and the signal DQ (nT) 36 are obtained is the same as that of the receiving apparatus according to the first embodiment.

The polarity of the signal 35 is inverted by the polarity inverters 70 and 71 to obtain the signals 78 and 79, respectively. Similarly,
The polarity of the signal 36 is inverted by the polarity inverters 72 and 73, and the respective signals 80 and 81 are obtained.

Next, the signal 35 and the signal 78 are selectively output by the multiplexer switch 74 in time sequence at the timing of the sampling cycle, and the signal I1 (nT) 39 is obtained. Signal 39
Is given by the following equation.

[0086]   I1 (nT) ＝ DI (nT) ； n = 4k           0 ； n = 4k + 1           -DI (T) ； n = 4k + 2           0 ； n = 4k + 3 (8) However, k = 0, 1, 2, ...

Here, when the signal I1 (nT) is multiplied by cos2πfonT, I1 (nT) cos2πfonT is obtained, but the signal when fo = 1 / 4T (when one cycle of local signal is 4 is oversampling) I1 (nT) cos2πfonT can be transformed as shown in the equation (8). Therefore, the above equation (8) becomes I1 (nT)
Equivalent to multiplying cos2πfonT.

Similarly, the signal 35 and the signal 79, the signal 36 and the signal 80, and the signal 36 and the signal 81 are selected and output in order of time at the sampling cycle timing by the multiplexer switches 75, 76 and 77, respectively, and the signal Q1 ( nT) 40, signal
I2 (nT) 41 and signal Q2 (nT) 42 are obtained. The signals 40, 41 and 42 are respectively expressed by the following equations.

[0089]   Q1 (nT) = 0; n = 4k          DI (nT); n = 4k + 1          0 ； n = 4k + 2         -DI (nT); n = 4k + 3 (9)   I2 (nT) = DQ (nT); n = 4k          0 ； n = 4k + 1         -DQ (nT); n = 4k + 3          0 ； n = 4k + 3 (10)   Q2 (nT) = 0; n = 4k          DQ (nT); n = 4k + 1          0 ； n = 4k + 2         -DQ (nT); n = 4k + 3 (11)

After that, the procedure until the baseband I signal 21 and the baseband Q signal 22 are obtained is the same as that of the receiving apparatus of the second embodiment.

The generation of the control signal is the same as that of the receiving device of the first embodiment.

In the configuration of the receiving apparatus according to the fifth embodiment, the image removing mixer is configured by the polarity reversing device, the multiplexer switch, the digital subtracting device, and the digital adding device without using the digital multiplying device. The amount of calculation can be further reduced as compared with the configuration of the receiving device according to the first embodiment.

(Sixth Embodiment) FIG. 6 shows a sixth embodiment of the present invention.
It is a configuration of a receiving apparatus of the embodiment of. The receiving device of the sixth embodiment is different from the receiving device of the second embodiment in that instead of the gain control amplifiers 8 and 9, switches 82, 83, 84 and 85 and amplifiers 87 and 89 are fixed. Attenuator 86, 88
It has a configuration with.

Here, the members, signals, etc. of the receiving apparatus of the sixth embodiment corresponding to the members, signals, etc. described in FIG. 2 are assigned the same reference numerals and detailed explanations thereof are omitted.

The procedure until the signals 31 and 32 are obtained is the same as that of the receiving apparatus of the second embodiment. The signal 31 is switched by the switch 82 to the amplifier 87 or the fixed attenuator 86. When the signal 31 is input to the amplifier 87, it is amplified by the amplifier 87 and the signal 92 is obtained. When the signal is input to the fixed attenuator 86, it is attenuated by the fixed attenuator 86 and the signal 91 is obtained. switch
84 switches and outputs the signals 91 and 92 to obtain the signal 33.

Similarly, the signal 32 is switched by the switch 83 between input to the amplifier 89 and input to the fixed attenuator 88. The signal 32 is switched to the amplifier 89 or the fixed attenuator 88. When the signal 32 is input to the amplifier 89, it is amplified by the amplifier 89 and the signal 94 is obtained. When the signal is input to the fixed attenuator 88, it is attenuated by the fixed attenuator 88 and the signal 93 is obtained.
The switch 85 switches between the signal 93 and the signal 94 and outputs the signal 34.

After that, the procedure until the baseband I signal 21 and the baseband Q signal 22 are obtained is the same as that of the receiving apparatus of the second embodiment.

The generation of the control signal for controlling the gain in the high frequency band is the same as that of the receiving device of the second embodiment.

The generation of the control signal for controlling the gain in the baseband is the same as that of the receiving apparatus of the second embodiment until the signal 59 is obtained. Signal 59 is
The decision is made by the decision circuit 90, and the signal 95 is obtained. signal
The 95 controls the switches 82, 83, 84, 85.

As described above, in the structure of the receiver of the sixth embodiment, the structure of the switch, the amplifier and the fixed attenuator makes it possible to further improve the structure of the receiver of the third embodiment. The dynamic range can be expanded, and highly accurate gain control can be performed.

(Seventh Embodiment) FIG. 7 shows the configuration of a receiving apparatus according to the seventh embodiment of the present invention. The receiving device of the seventh embodiment is different from the receiving device of the fourth embodiment in that the gain control of the mixer is controlled by using a control signal for performing gain control in the baseband.

Here, the members, signals, etc. of the receiving apparatus of the fourth embodiment corresponding to the members, signals, etc. described in FIG. 2 will be assigned the same reference numerals and detailed description thereof will be omitted.

The operation of the receiving apparatus of the seventh embodiment is shown in FIG.
Will be explained. The receiver is the same as the receiver of the fourth embodiment except that the gains of the mixers 4 and 5 are controlled by using a control signal 60 for controlling the gain of the baseband.

In the configuration of the receiving apparatus of the seventh embodiment, the gain control of the mixer is controlled by using the control signal for performing the gain control of the base band, so that the receiving apparatus of the fourth embodiment is controlled. Distortion can be further reduced as compared with the configuration described above.

[0105]

As is apparent from the description of the above embodiment, the present invention provides a baseband gain control amplifier with an A / D.
Controlled by the control signal generated by the converter output signal, the high frequency band gain control amplifier is controlled by the control signal generated by the root Nyquist filter output signal, and the high frequency band gain control amplifier and the baseband band gain control amplifier are individually controlled. By controlling the gain control amplifier by using, it is possible to prevent the gain control amplifier from being saturated, and to prevent reception failure due to deterioration of the noise figure characteristic of the high frequency band gain control amplifier.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a direct conversion receiver according to a first embodiment of the present invention,

FIG. 2 is a configuration diagram of a direct conversion receiver according to a second embodiment of the present invention,

FIG. 3 is a configuration diagram of a direct conversion receiver according to a third embodiment of the present invention,

FIG. 4 is a configuration diagram of a direct conversion receiver according to a fourth embodiment of the present invention,

FIG. 5 is a configuration diagram of a direct conversion receiver according to a fifth embodiment of the present invention,

FIG. 6 is a configuration diagram of a direct conversion receiver according to a sixth embodiment of the present invention,

FIG. 7 is a configuration diagram of a direct conversion receiver according to a seventh embodiment of the present invention,

FIG. 8 is a configuration diagram of a conventional direct conversion receiver.

[Explanation of symbols]

1 air battle 2 High frequency band gain control amplifier 3 Phase shifter 4,5 mixer 6, 7 Analog low pass filter 8, 9 Baseband gain control amplifier 10, 11 A / D converter 12, 13, 14, 15 Digital Multiplier 16, 22, 54 Digital subtractor 17 Digital adder 18, 19 root Nyquist filter 20, 52 Amplitude information detection circuit 21, 53 Averaging circuit 23, 55 D / A converter 24 Received signal 26 Local oscillation signal 29 Analog I signal 30 analog Q signal 34 Digital I signal 35 Digital Q signal 51, 60 Gain control signal 61, 87, 89 amplifier 62 variable attenuator 63, 90 Judgment circuit 66, 68, 82, 83, 84, 85 switches 67, 86, 88 Fixed attenuator 70, 71, 72, 73 Polarizer 74, 75, 76, 77 multiplexer switches

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References Hiroaki Sudo and 2 others, A Study on Direct Conversion Receiver Using B-449 Digital Image Removal Mixer, Proceedings of IEICE General Conference, Japan , IEICE, March 11, 1996, 449 (58) Fields investigated (Int.Cl. ⁷ , DB name) H04B 1/30

Claims (7)

(57) [Claims] 1. A local oscillation frequency in quadrature detection is offset with respect to a received signal frequency, and an adjacent wave dropped in a desired signal band is removed by an image rejection mixer composed of a digital multiplier, a digital subtractor and a digital adder. In a direct conversion receiver, a high frequency band amplifier, a mixer, and a base band band amplifier are provided, and the high frequency band gain and the base band band gain are
A direct conversion receiver characterized by being individually controlled using individual control signals. 2. The direct conversion receiver according to claim 1, wherein the high frequency band gain control amplifier is configured by using an amplifier and a variable attenuator, and gain control is performed discretely. 3. A process according to claim 1, wherein the high frequency band gain control amplifier using a fixed attenuator and switch the amplifier to configure, and performs discrete gain control by switching the amplifier and a fixed attenuator switch Direct conversion receiver described. 4. The direct conversion according to claim 1, wherein the gain of the mixer is switched in addition to the gains of the high frequency band amplifier and the base band band amplifier. Receiving machine. 5. The image removing mixer comprises a polarity inverter, a multiplexer switch, a digital subtractor, and a digital adder, as claimed in any one of claims 1, 2, 3, and 4. Direct conversion receiver described in. 6. The baseband gain control in the baseband amplifier is discretely performed, claim 1, claim 2, claim 3, claim 4, claim 5.
Direct conversion receiver described in either of the above. 7. The gain control of the mixer is controlled by using a control signal for performing gain control of a baseband in the baseband amplifier. Direct conversion receiver described in either one.