JP2008092021A - Radio communication device, amplifier, and method of controlling amplifier for radio communication device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact direct conversion system radio communication device having a simple configuration that appropriately suppresses a DC offset even under a condition that transmission and reception sections be changed frequently for selective operation. <P>SOLUTION: A switch is provided at the pre-stage of a low-pass filter interposed in the feedback circuit of a baseband amplifier. At a period when the switch sets a reception section to a non-operation state, the transmission of a feedback signal is denied for maintaining a signal level corresponding to the feedback signal by the capacitive element of the low-pass filter, thus shortening settling time in the feedback circuit sharply when the operation of the reception section is restarted for coping with the frequent switching of transmission and reception appropriately. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a direct-conversion wireless communication apparatus in which a transmission unit and a reception unit are configured, for example, as a pair in one structural unit, and either the transmission unit or the reception unit is in operation. The present invention relates to a wireless communication device that functions so that one of the other devices is inactive during a period of time, an amplifier that can be adapted to the wireless communication device, and a method for controlling the amplifier for the wireless communication device.

FIG. 9 is a block diagram showing a QPSK transceiver as a conventional direct conversion wireless communication apparatus. This QPSK transceiver is configured such that a transmission unit 110 and a reception unit 120 are paired with, for example, one structural unit.
The local signal generated by the local oscillator 102 synchronized with the output of the PLL 101 is phase-shifted by the phase shifter 103 so that each phase is shifted by a predetermined amount such as 0 degree, −180 degrees, 90 degrees, and −90 degrees. After being converted into × 2 system signals, the I and Q signals are supplied to the corresponding mixers 111 and 112, and the baseband signals are mixed with the outputs of the local oscillators. Further, the addition circuit 113 adds the values.

The signal added by the adder circuit 113 is amplified by the power amplifier 114 and supplied to the antenna 151 through the transmission / reception switching circuit 140.
On the other hand, a signal wave received by the antenna 151 is supplied to the low noise amplifier 121 through the transmission / reception switching circuit 140 and amplified, and mixed with 2 × 2 local signals by the mixers 122 and 123 of the I and Q systems. Q is converted into each baseband signal of each system, I
, Q After being amplified by the IF amplifiers 124, 125 of each system, the IF amplifiers 124, 125 are amplified.
Comparators 126 and 127 provided corresponding to the respective outputs are compared with predetermined threshold values and reproduced as digital signals.

FIG. 10 is a block diagram showing the configuration of IF amplifier 124 (125) in the QPSK transceiver as the direct-conversion wireless communication apparatus of FIG. Amplifier circuit 10
A feedback circuit 1003 that feeds back the output of 01 to the input side through a low-pass filter (hereinafter referred to as LPF) 1002 (negative feedback) is provided. If LPF1002 has the characteristics of a cut-off frequency f _LPF, only the signal which has passed through the band below the frequency f _LPF is fed back. The feedback signal is subtracted from the input, so that the DC component is suppressed.

FIG. 11 is a diagram illustrating characteristics of the IF amplifier 124 (125) of FIG.
Compared with the heterodyne system, the wireless communication apparatus adopting the direct conversion system does not require an intermediate frequency filter (hereinafter referred to as IF filter), has a feature that the configuration is simplified and the cost is reduced.
However, DC offset due to variations in the transistors constituting the circuit occurs in the signal demodulated by the direct conversion method, and the IF amplifier is saturated in some cases. Therefore, it is important to suppress the DC offset. Become.

As a method of suppressing the DC offset, as described with reference to FIG. 10, there is a method of using an amplifier circuit including a feedback circuit and feeding back and canceling out only the DC component. Although this method can be realized with a relatively small circuit, it is necessary to sufficiently reduce the high-frequency cutoff frequency of the LPF in order to secure a required signal passband, and it takes a long time for the feedback loop to converge. There is a problem of need.

If the application requires bi-directional communication and low power consumption is required, the transmitter (T
X), and during the period when either one of the receivers (RX) is in an operating state, the operation must be switched one by one so that the other is in an inactive state, so that the power of the device must be saved. In the above-described method that requires a long time for the convergence of the circuit, there arises a problem that the operation of the circuit cannot follow such switching.

The AD converter measures the error voltage due to the DC offset, stores the necessary calibration value in the correction table (memory), and supplies it from the DA converter at startup.
A technology that realizes offset suppression and high-speed startup has already been proposed (Patent Document 1).
JP-A-8-256079 (paragraphs 0011 to 0017, FIG. 2)

However, the technique proposed in Patent Document 1 requires a complicated circuit such as an AD converter, a DA converter, and a memory functioning as a correction table, which leaves a problem that the circuit scale increases.
The present invention has been made in view of the above situation, and the DC offset suppression function works properly even under conditions where the transmitter and the receiver are frequently switched and selectively operated. It is another object of the present invention to provide a direct conversion wireless communication device, an amplifier, and a method for controlling the wireless communication device amplifier having a small and simple configuration.

In order to solve the above problems, the present application proposes the following technologies.
(1) A direct conversion wireless communication device including a transmitter and a receiver,
A system controller that outputs a control signal for switching control so that either one of the transmission unit and the reception unit is in an operating state and the other is in a non-operating state;
The receiver is
A mixer that mixes the received signal and the local transmission signal to obtain a baseband signal;
A baseband amplifier disposed after the mixer and amplifying the baseband signal;
With
The baseband amplifier is
A feedback circuit having a low-pass filter for removing a DC offset;
The feedback circuit is
A wireless communication comprising: a switch circuit that cuts off transmission of a feedback signal of the feedback circuit during a predetermined period of a period in which the receiving unit is in a non-operating state according to the control signal output from the system controller apparatus.

In the wireless communication device of (1), the direct conversion method is used to greatly simplify the configuration as compared to the heterodyne method, and either the transmission unit or the reception unit is in an operating state by the system controller. Power is saved because one of them is controlled to be inactive during the period, and the receiving unit is inactive by a switch circuit inserted in the feedback circuit of the baseband amplifier. Since the transmission of the feedback signal of the feedback circuit is interrupted in a predetermined period of the period, the signal level corresponding to the feedback signal accumulated and held in the capacitive element of the low-pass filter is maintained, and when the operation of the receiving circuit is resumed, The settling time of the feedback circuit is greatly shortened, and it is possible to appropriately respond to frequent switching between transmission and reception.

(2) The baseband amplifier further includes a bias switching circuit that switches between an operation state and a non-operation state of the amplification function by controlling supply of a bias voltage.
The switch circuit cuts off the transmission of the feedback signal of the feedback circuit at a timing earlier than the timing at which the bias switching circuit switches the amplification function to the non-operating state, and the bias switching circuit operates the amplification function (1) The wireless communication device according to (1), wherein transmission of a feedback signal of the feedback circuit is started at a timing after a predetermined period of time from the timing of switching to.

In the wireless communication device of (2), particularly in the wireless communication device of (1), the wireless communication device further includes a bias switching circuit that switches between an operating state and a non-operating state of the amplification function by controlling supply of a bias voltage, The circuit disconnects the feedback signal from the feedback circuit at a timing earlier than the timing at which the bias switching circuit switches the amplification function to the non-operating state, and the predetermined period from the timing at which the bias switching circuit switches the amplification function to the operating state. At a later timing, transmission of the feedback signal of the feedback circuit is started. Therefore, the signal level corresponding to the feedback signal is properly stored and held in the capacitive element of the low-pass filter, and the operation of the baseband amplifier is stabilized when the operation of the receiving circuit is resumed.

(3) The wireless communication device according to any one of (1) to (2), wherein the switch circuit is configured by complementary connection of a PMOS transistor, an NMOS, and a transistor.
In the wireless communication device of the above (3), in particular, in the wireless communication device of any one of (1) to (2), the switch circuit is configured by a complementary connection of a PMOS transistor, an NMOS, and a transistor. When the band amplifier is switched to the non-operating state, a feedback signal can be appropriately held, and the feedback signal maintained when the band amplifier is switched to the operating state can be quickly returned to the input side.

(4) The system controller maintains a state in which the switch circuit cuts off a feedback signal of the feedback circuit for a predetermined period after the bias switching circuit switches the amplification function to an active state, The wireless communication apparatus according to any one of (2) to (3), wherein control is performed so as to execute calibration.
In the wireless communication device of (4) above, the operation is stabilized by performing feedback voltage calibration, particularly in the wireless communication device of any one of (2) to (3).

(5) The system controller performs calibration of the baseband amplifier while maintaining the switch circuit in a state for transmitting a feedback signal for a certain period of time, and then sets the switch circuit in a state for interrupting transmission of the feedback signal. The bias switching circuit is controlled to switch between the operating state and the non-operating state of the receiving unit while maintaining the non-calibrating state for a predetermined period, and the calibration is resumed at the timing when the non-calibrating state period elapses. After the restart timing, the non-calibration state period is sandwiched,
The calibration is configured to be repeatedly executed (2
) To (4).

In the wireless communication device of (5) above, particularly in the wireless communication device of any one of (2) to (4), the system controller maintains the switch circuit in a state for transmitting a feedback signal for a certain period of time. After calibrating the band amplifier, the switch circuit is turned off to transmit the feedback signal, and the bias switching circuit is switched on and off while maintaining the non-calibration state for a predetermined period. Since the calibration is repeated at the timing when the period of the non-calibration state has elapsed, and the calibration is repeatedly performed after the timing of the restart, with the period of the non-calibration state as described above being sandwiched. Even if the feedback voltage maintained by the low-pass filter gradually decreases, Deployment takes place, the removal of the DC offset operation done properly stabilized.

(6) The baseband amplifier includes a plurality of cascaded amplifiers,
The feedback circuit is
The wireless communication device according to any one of (1) to (5), wherein an output of a last-stage amplifier among the plurality of stages of amplifiers is provided so as to be fed back to an input of the first-stage amplifier.
In the wireless communication device of (6) above, in the wireless communication device of any one of (1) to (5), a high amplification factor is realized by a plurality of cascaded amplifiers. By the switch circuit inserted in the feedback circuit, it is possible to obtain a good characteristic in which the DC offset is appropriately removed.

(7) The baseband amplifier includes a plurality of cascaded amplifiers,
Any one of (1) to (5), wherein the feedback circuit is provided so as to feed back an output of each of the plurality of amplifiers to an input of each of the amplifiers. A wireless communication device.
In the wireless communication device of the above (7), in particular, in any one of the wireless communication devices of (1) to (5), a plurality of stages of amplifiers connected in cascade with a feedback circuit in which a switch circuit is inserted in each unit Thus, a high gain can be realized, and a good characteristic in which the DC offset is appropriately removed can be obtained by the feedback circuit and the switch circuit inserted in the feedback circuit.

(8) An amplifier having an amplifying circuit section and a feedback circuit section, wherein the amplifying circuit section is controlled to switch between an operating state in which operating power is supplied and a non-operating state in which the operating power supply is cut off. The feedback circuit unit includes a capacitive element that holds an output of the amplifier circuit unit in a feedback path, and a switch provided in a preceding stage of the capacitive element, and the switch includes the switching control. An amplifier configured to be controlled to open and close at a timing related to the above.

In the amplifier of the above (8), since the transmission of the feedback signal can be controlled to be cut off during the period when the amplifier is in the non-operating state by the switch circuit inserted in the feedback circuit of the amplifier, it is stored in the capacitive element. The signal level corresponding to the held feedback signal is maintained, and when the operation of the amplifier is resumed, the settling time of the feedback is greatly shortened, and the responsiveness to the switching of the operation of the amplifier is improved.

(9) The amplifying circuit unit is configured to be adapted to a receiving unit of a direct conversion wireless communication device including a transmitting unit and a receiving unit, and switching between an operating state and a non-operating state in the receiving unit. (8) The amplifier according to (8), wherein the switching control is performed in accordance with the control.
In the amplifier of (9), the amplifier of (8) is configured so as to be suitable for the receiving unit of the direct-conversion-type radio communication apparatus including the transmitting unit and the receiving unit, and the receiver is operated. Since operation / non-operation switching control is performed by intermittent supply of operating power in accordance with switching between the state and the non-operation state, power saving can be achieved.

(10) The amplifier circuit section is configured to be controlled to be switched between the operating state and the non-operating state by opening and closing a switching element provided in its own bias circuit. The amplifier according to any one of (9).
In the amplifier of the above (10), in particular, in the amplifier of any one of (8) to (9), the operation state and the non-operation state are switched and controlled by opening and closing a switching element provided in its own bias circuit. Therefore, a simple configuration that does not require other separate opening / closing means related to the intermittent supply of the operating power supply is realized.

(11) The amplifier according to any one of (8) to (10), wherein the capacitive element of the feedback circuit section is a capacitor constituting a low-pass filter.
In the amplifier of (11) above, particularly in the amplifier of any one of (8) to (10), the capacitive element of the feedback circuit unit is configured by a capacitor constituting a low-pass filter, and therefore maintains the feedback level. Therefore, a simple configuration that does not require other separate storage means is realized.

(12) When an amplifier having a feedback circuit is intermittently operated, the output of the amplifier is held in a capacitive element connected to the feedback circuit, and the amplifier is changed from an operating state to a non-operating state. An amplifier for a radio communication apparatus, wherein feedback by the feedback circuit is cut off at an earlier timing than before, the amplifier is switched from a non-operating state to an operating state, and feedback by the feedback circuit is started at a later timing Control method.

In the method for controlling an amplifier for a wireless communication device according to (12) above, when an amplifier having a feedback circuit is intermittently operated, the output of the amplifier is held in a capacitive element connected to the feedback circuit, and The feedback circuit cuts off the feedback at a timing earlier than when the amplifier is switched from the operating state to the non-operating state, and the amplifier is switched from the non-operating state to the operating state at a later timing. In order to restart, when the amplifier having the feedback circuit is temporarily stopped and then restarted, a quick response characteristic with a short settling time can be obtained.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings to be referred to below, for the sake of convenience, the main part that is the subject of the description is exaggerated as appropriate, and other than the main part is appropriately simplified or omitted.
FIG. 1 is a diagram showing a wireless communication apparatus as an embodiment of the present invention. The wireless communication apparatus of FIG. 1 is a direct conversion QPSK transceiver, and is configured such that a transmission unit 110 and a reception unit 120 are paired, for example, in one structural unit.

The local signal generated by the local oscillator 102 synchronized with the output of the PLL 101 is 2 × 2 whose phase is shifted to 0, −180 degrees, 90 degrees, and −90 degrees in the phase shifter 103. After being converted to a system signal, the corresponding mixer 1 for each of the I and Q signals
11 and 112, the baseband signal is mixed with the output of the local oscillator, and these I and Q signals are further mixed by the adder circuit 113.

The signal mixed by the adding circuit 113 is amplified by the power amplifier 114 and supplied to the antenna 151 through the transmission / reception switching circuit 140.
On the other hand, the signal wave received by the antenna 151 is supplied to the low noise amplifier 121 through the transmission / reception switching circuit 140 and amplified, and mixed with 2 × 2 local signals by the mixers 122 and 123 of the I and Q systems. Q is converted into each baseband signal of each system, I, Q
IF amplifier 124a as a baseband amplifier for amplifying a baseband signal of each system,
After being amplified by 125a, it is compared with each predetermined threshold value by comparators 126 and 127 provided corresponding to the outputs of the IF amplifiers 124a and 125a and reproduced as a digital signal.

In the wireless communication device of FIG. 1, in particular, during the period in which one of the transmission unit 110 and the reception unit 120 is in an operating state, the power feeding state is switched and controlled so that the other is in a non-operating state. And a system controller 130 for overall control.
FIG. 2 is a block diagram showing a configuration of IF amplifier 124a (125a) in the QPSK transceiver as the direct conversion wireless communication apparatus of FIG. Amplifier circuit 2
A feedback circuit 203 that feeds back (negative feedback) the output of 01 to the input side through a low-pass filter (hereinafter referred to as “LPF” as appropriate) 202 is provided. LPF 202 has a cutoff frequency f
_{In the} case of having an _LPF characteristic, only a signal that has passed through a band below this frequency f _{LPF is fed} back.
The feedback signal is subtracted from the input, so that the DC component is suppressed.

In particular, in the IF amplifier 124 (125) of FIG. 2, a switch circuit 204 is inserted in a path through which the output of the amplifier circuit 201 is supplied to the LPF 202 in the feedback circuit 203. The switch circuit 204 responds to a control signal from the system controller 130 of FIG.
In the feedback stop period that occupies at least a part of the period in which 20 is not operating, the feedback circuit 2
It operates to cut off the transmission of the 03 feedback signal.

In the QPSK transceiver described with reference to FIGS. 1 and 2, the direct conversion method is used to greatly simplify the configuration as compared to the heterodyne method, and the system controller 130 transmits the transmission unit 110 and the reception unit 120. Since either one of them is in the operating state, the other is controlled so as to turn into the non-operating state, so that power saving is achieved.

In addition, the feedback circuit during the feedback stop period occupying at least a part of the period in which the receiving unit 120 is not in operation by the switch circuit 204 inserted in the feedback circuit 203 of the baseband amplifier (IF amplifier) 124a (125a). Since the transmission of the feedback signal is interrupted, the LPF
The signal level corresponding to the feedback signal accumulated and held in the capacitive element (capacitor) 202 is maintained, and when the operation of the receiving circuit 120 is resumed, the settling time of the feedback circuit 203 is greatly shortened, and frequent switching between transmission and reception is performed. It is possible to respond appropriately.

FIG. 3 is a circuit diagram of the baseband amplifier (IF amplifier) 124a (125a) of FIG. Transistors M11, M12, M31, M32, M30, resistors R31, R32, and transistors M1, M2 that are complementary connected to form switches 304a, 304b, and resistors R, 302b, 302b A capacitor C is connected as shown in the figure.

In the drawing, one output OUT_N of the amplifier circuit 301 surrounded by a broken line is a switch circuit 304a.
And an input IN_P side (transistor M3 connected in parallel to the transistor M11 having its own gate as the input terminal IN_P) through a feedback circuit 303a in which the LPF 302a is inserted.
3).
Similarly, the other output OUT_P of the amplifier circuit 301 is connected to the switch circuit 304b and the LPF 30.
The other input IN_N side through the feedback circuit 303b in which 2b is inserted (the gate of the transistor M34 connected in parallel to the transistor M12 whose own gate is the input terminal IN_N)
It is comprised so that it may return to.

The switch circuit 304a described above includes an NMOS transistor M1 and a PMOS transistor M2.
The LPF 302a is composed of a resistor R and a capacitive element (capacitor) C connected to the subsequent stage.
Similarly, the switch circuit 304b described above is configured by a complementary connection of an NMOS transistor M1 and a PMOS transistor M2, and the LPF 302b is configured by a resistor R and a capacitive element (capacitor) C connected to the subsequent stage. .

The amplifying circuit 301 further includes a transistor M30 as a bias switching circuit that switches between an operating state and a non-operating state of the amplifying function by controlling on / off of supply of a bias voltage in response to a signal from the system controller 130 of FIG. Have.
In response to the signal (VB) from the system controller 130, the switch 304a (304b) is turned off at a timing earlier than the timing at which the transistor M30 is turned off and the amplification function is turned off (ie, the feedback signal). And the transistor M30 is turned on and turned on (that is, the state where the feedback signal is transmitted) at a timing delayed by a predetermined time from the time when the amplification function is turned on. Has been.

In other words, the transistor M30 also functions as a switching element related to the intermittent supply of operating power to the amplifier circuit 301, and is configured to be controlled to be switched between the operating state and the non-operating state of the amplifier circuit 301 by opening and closing the transistor M30. For this reason, the simple structure which does not require the other separate opening / closing means regarding the intermittent supply of an operating power supply is implement | achieved.
In the configuration example of FIG. 3, each of the switch circuits 304a and 304b is an NMO.
Although the complementary connection circuit of the S transistor and the PMOS transistor is applied, it is also possible to apply a single NMOS transistor or PMOS transistor instead.
The operation of the baseband amplifier (IF amplifier) 124a (125a) of FIGS. 2 and 3 will be described in further detail.

First, when there is a DC offset and there is no signal input, the system controller 130
It is assumed that the switch circuit 304a is kept on by the signal from (FIG. 1). In this state, it is assumed that a positive DC offset is applied to IN_P and a negative DC offset is applied to IN_N of the two inputs.
When a positive DC offset is applied to IN_P, the overdrive voltage of the transistor M11 increases, and the current flowing through the transistor M11 increases. As this current increases, the voltage drop in the transistor (so-called PMOS load voltage drop) increases and the voltage value of the output OUT_N decreases.

This output voltage is applied to the gate of the transistor M33 via the switch circuit 304a and the LPF 302a of the feedback circuit 303a. At this time, the output voltage OUT_N is lowered due to the influence of the DC offset.
For this reason, the overdrive voltage of the transistor M33 decreases, and the transistor M33
The current that flows through is reduced. As described above, the feedback is balanced under the condition that the current increased in the transistor M11 and the current decreased in the transistor M33 are balanced, and the DC offset is cancelled.

On the other hand, when a negative DC offset is applied to the input IN_N, the overdrive voltage of the transistor M12 decreases and the current flowing through the transistor M12 decreases.
When the current flowing through the transistor M12 decreases, the voltage drop in the transistor (so-called PMOS)
The voltage drop of the load) becomes smaller and the output voltage OUT_P rises.
The output voltage OUT_P is a feedback circuit 3 in which a switch circuit 304a and an LPF 302a are inserted.
The signal is fed back to the gate of the transistor M34 connected in parallel to the transistor M12 through 03a. Since the voltage value of the output OUT_P at this time increases due to the DC offset,
The overdrive voltage of M34 increases and the current flowing through M34 increases. The feedback is balanced under the condition that the current decreased by M12 and the current increased by M34 are balanced, and DC
The offset is cancelled.

FIG. 4 is a timing chart showing the operation of the circuit of FIG. When the power is turned on, a normal operation is performed after a calibration time for the feedback loop to converge.
The switch 304a of the feedback circuit 303a (303b) is slightly before the timing when the transistor M30 is turned off by the signal VB and the amplifier circuit 301 is turned off.
(304b) is cut off, and the feedback voltage at that timing is held in the form stored in the capacitor C. Next, the transistor M30 is turned off, the supply of current to the amplifier circuit 301 is cut off, and the state is shifted to a non-operating state.

The switch 304a (304b) is turned on after the operating point voltage of the amplifier circuit 301 is stabilized at a timing delayed by a predetermined time from the timing at which the transistor M30 is turned on by the signal VB and the amplifier circuit 301 is turned on. The transmission of the feedback signal by 303a (303b) is resumed.
As described above, by opening / closing the switch 304a (304b) and turning on / off the transistor M30, the potential difference between both ends of the switch can be reduced and the rise time (settling time) can be further shortened.

FIG. 5 shows how the voltage value held in the capacitive element (capacitor) C of the low-pass filter 302a (302b) changes according to the transition timing of the operation (amplification circuit 301) of the amplifier (amplifier circuit 301). FIG.
As shown in FIG. 5A, the switches 304a (304b) for a sufficiently long time.
Is maintained in the ON state, in other words, in a situation where the frequency of switching between the operation state and the non-operation state between the transmission unit 110 and the reception unit 120 in the transmission / reception apparatus of FIG. Accumulated errors are unlikely to remain in the voltage value held in the capacitor C), and the apparatus operates in a normal state in which the DC offset is canceled.

On the other hand, as shown in FIG. 5B, the switches 304a (304
When ON / OFF of b) is repeated, in other words, the transmission unit 11 in the transmission / reception apparatus of FIG.
In a situation where the frequency of switching between the operating state and the non-operating state between 0 and the receiving unit 120 is high, a capacitive element (
Errors gradually accumulate in the voltage value held in the capacitor (C), and the DC offset cannot be sufficiently canceled, making it difficult to operate in a normal state.

FIG. 6 is a timing chart showing a control mode for dealing with the situation of FIG. That is, the voltage value held in the capacitive element (capacitor) C gradually shifts as described above with reference to FIG. 5B, and therefore recalibration is performed as necessary.
The calibration in FIG. 6 is a non-calibration in which the switch state is maintained by turning off the switch circuit after performing calibration of the baseband amplifier by maintaining the switch circuit on state for a certain period by the system controller. The bias switching circuit is switched on and off while maintaining the calibration state for a predetermined period to switch between the operating state and the non-operating state of the receiving unit, and the calibration is restarted at the timing when the period of the non-calibration state has elapsed. After this timing, the calibration is repeatedly performed with the period of the non-calibration state as described above interposed therebetween. For this reason, even if the feedback voltage maintained by the low-pass filter gradually decreases with time, the calibration is performed again, and the DC offset is appropriately removed to stabilize the operation.

In the example of FIG. 6, calibration → receiving unit on (operation) → receiving unit off (non-operation) →.
→ Receiver on → Receiver off → Calibration → Receiver on ... The order before and after calibration may be on or off.
As understood from the above, in the present embodiment, the capacitor C constituting the low-pass filter is configured to function also as the capacitive element C for holding the feedback level in the feedback circuit. For this reason, a simple configuration is realized that does not require other separate storage means for maintaining the feedback level.

FIG. 7 is a diagram illustrating another configuration example of the IF amplifier 124a (125a) as a baseband amplifier applied to the reception unit 120 in the transmission / reception apparatus of FIG.
In the example of FIG. 7, a plurality of cascaded amplifiers 701a and 701 (two stages in the illustrated example) are connected.
b, and the final-stage amplifier 70 of the plurality of stages of amplifiers 701a and 701b.
A feedback circuit 703 is provided to feed back the output of 1b to the input of the first stage amplifier 701a.
A low-pass filter 702 and a switch 704 are inserted in the feedback circuit 703.

In the aspect of FIG. 7, a high amplification factor is realized by a plurality of cascaded amplifiers 701 a and 701 b, and a DC offset is achieved by the feedback circuit 703 and the switch 704 of the transistor circuit 710 inserted in the feedback circuit 703. It is possible to obtain good characteristics in which is appropriately removed.
FIG. 8 is a diagram illustrating still another configuration example of the IF amplifier 124a (125a) as a baseband amplifier applied to the reception unit 120 in the transmission / reception apparatus of FIG.

In the example of FIG. 8, an amplifier 801a provided with a feedback circuit 803a in which a low-pass filter 802a and a switch 804a are provided, and similarly, a feedback circuit 803b in which a low-pass filter 802b and a switch 804b are interposed. Is provided with an amplifier 801b
And a plurality of stages of amplifiers (two stages in the illustrated example).
In the embodiment of FIG. 8, a high amplification factor is realized by a plurality of stages of amplifiers 801a and 801b, each of which has feedback circuits 803a and 803b, and the feedback circuits 803a and 803 are connected in cascade.
With the switches 3804b and 804a and 804b inserted in the feedback circuit, it is possible to obtain a good characteristic in which the DC offset is appropriately removed.

It is a figure showing the radio | wireless communication apparatus as embodiment of this invention. FIG. 2 is a block diagram illustrating a configuration of a baseband amplifier in the wireless communication apparatus of FIG. 1. FIG. 3 is a circuit diagram of the baseband amplifier of FIG. 2. 4 is a timing chart illustrating the operation of the circuit of FIG. 3. It is a figure showing a mode that the voltage value hold | maintained at a capacitive element changes according to the timing of a transition of operation | movement of the amplifier of FIG. 3, and non-operation. It is a timing chart showing the control mode for coping with the situation of FIG. It is a figure showing the other structural example of the baseband amplifier applied to the receiving part in the transmission / reception apparatus of FIG. FIG. 10 is a diagram illustrating still another configuration example of a baseband amplifier applied to a reception unit in the transmission / reception apparatus of FIG. It is a block diagram showing the radio | wireless communication apparatus of the conventional direct conversion system. FIG. 10 is a block diagram illustrating a configuration of a baseband amplifier in the wireless communication apparatus of FIG. 9. It is a figure showing the characteristic of the baseband amplifier of FIG.

Explanation of symbols

101 ... PLL 102 ... Local transmitter 103 ... Phase shifter 110 ... Transmitter 111
, 112 ... Mixer 113 ... Adder circuit 114 ... Power amplifier 120 ... Receiver 121 ...
Low noise amplifier 122, 123 ... mixer 124, 124a ... IF amplifier 125,
125a ... IF amplifier 126, 127 ... comparator 130 ... system controller 140 ... transmission / reception switching circuit 151 ... antenna 201 ... amplifier circuit 202 ... low pass filter 203 ... feedback circuit 204 ... switch circuit 301 ... amplifier circuits 302a, 3
02b: Low-pass filter 303a, 303b ... Feedback circuit 304a, 304b ... Switch 310a, 310b ... MOS transistor circuit 701a, 701b ... Amplifier 7
02 ... Low-pass filter 703 ... Feedback circuit 704 ... Switch 710 ... Transistor circuit 801a, 801b ... Amplifier 802a, 802b ... Low-pass filter 803a
, 803b ... feedback circuit 804a, 804b ... switch 810a, 810b ... transistor circuit 1001 ... amplification circuit 1002 ... low-pass filter 1003 ... feedback circuit C
... capacitive element (capacitor) M1 ... NMOS transistor M2 ... PMOS transistor M11 ... transistor M12 ... transistor M30 ... transistor M31 ... transistor M32 ... transistor R31 ... resistor R32 ... resistor

Claims (12)

A direct conversion wireless communication device configured to include a transmission unit and a reception unit,
A system controller that outputs a control signal for switching control so that either one of the transmission unit and the reception unit is in an operating state and the other is in a non-operating state;
The receiver is
A mixer that mixes the received signal and the local transmission signal to obtain a baseband signal;
A baseband amplifier disposed after the mixer and amplifying the baseband signal;
With
The baseband amplifier is
A feedback circuit having a low-pass filter for removing a DC offset;
The feedback circuit is
A wireless communication comprising: a switch circuit that cuts off transmission of a feedback signal of the feedback circuit during a predetermined period of a period in which the receiving unit is in a non-operating state according to the control signal output from the system controller apparatus. The baseband amplifier further includes a bias switching circuit that switches between an operating state and a non-operating state of the amplification function by controlling supply of a bias voltage;
The switch circuit cuts off the transmission of the feedback signal of the feedback circuit at a timing earlier than the timing at which the bias switching circuit switches the amplification function to the non-operating state, and the bias switching circuit operates the amplification function 2. The wireless communication apparatus according to claim 1, wherein transmission of a feedback signal of the feedback circuit is started at a timing after a predetermined period from the timing of switching to. The wireless communication apparatus according to claim 1, wherein the switch circuit includes a complementary connection of a PMOS transistor, an NMOS, and a transistor. The system controller holds a state in which the switch circuit cuts off a feedback signal of the feedback circuit for a predetermined period after the bias switching circuit switches the amplification function to an operating state,
The wireless communication apparatus according to claim 2, wherein the baseband amplifier is controlled to perform calibration. The system controller performs calibration of the baseband amplifier while maintaining the switch circuit in a state for transmitting a feedback signal for a certain period of time, and then uncalibrating the switch circuit in a state in which the transmission of the feedback signal is cut off. The bias switching circuit is controlled to switch between the operating state and the non-operating state of the receiving unit while maintaining the state for a predetermined period, and the calibration is restarted at the timing when the period of the non-calibration state has elapsed, and the restarting is performed. The calibration is repeatedly performed after the non-calibration state period after the above-described timing.
5. The wireless communication device according to any one of 4. The baseband amplifier includes a plurality of cascaded amplifiers,
The feedback circuit is
6. The wireless communication apparatus according to claim 1, wherein an output of a last-stage amplifier among the plurality of stages of amplifiers is provided to be fed back to an input of a first-stage amplifier. . The baseband amplifier includes a plurality of cascaded amplifiers,
6. The feedback circuit according to claim 1, wherein the feedback circuit is provided so as to feed back an output of each of the plurality of amplifiers to an input of each of the amplifiers. 7. A wireless communication device according to 1. An amplifier having an amplifying circuit section and a feedback circuit section, wherein the amplifying circuit section is controlled to switch between an operating state in which operating power is supplied and a non-operating state in which the operating power supply is cut off. The feedback circuit unit includes a capacitive element that retains the output of the amplifier circuit unit in a feedback path, and a switch provided in a previous stage of the capacitive element, and the switch is related to the switching control. An amplifier configured to be opened and closed at timing. The amplifying circuit unit is configured to be adapted to a receiving unit of a direct conversion wireless communication device including a transmitting unit and a receiving unit, and according to switching between an operating state and a non-operating state in the receiving unit. The amplifier according to claim 8, wherein the switching control is performed. The amplification circuit section is configured to be controlled to be switched between the operating state and the non-operating state by opening and closing a switching element provided in its own bias circuit. An amplifier according to claim 1. The amplifier according to claim 8, wherein the capacitive element of the feedback circuit unit is a capacitor constituting a low-pass filter. When intermittently operating an amplifier having a feedback circuit, the output of the amplifier is held in a capacitive element connected to the feedback circuit, and the amplifier is switched from an operating state to a non-operating state. A method of controlling an amplifier for a radio communication device, wherein feedback by the feedback circuit is cut at a previous timing, the amplifier is changed from a non-operating state to an operating state, and feedback by the feedback circuit is started at a subsequent timing .

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