CN100505525C - Filter circuit - Google Patents
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- CN100505525C CN100505525C CNB2003801005515A CN200380100551A CN100505525C CN 100505525 C CN100505525 C CN 100505525C CN B2003801005515 A CNB2003801005515 A CN B2003801005515A CN 200380100551 A CN200380100551 A CN 200380100551A CN 100505525 C CN100505525 C CN 100505525C
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Abstract
A distributor 103 distributes an input signal into two lines of distributed signals with equal amplitudes andequalphases. Buffers 104,105 suppress interference between distributed signals distributed into the two lines. A filter 106 performs a frequency selection which allows only a distributed signal in a predetermined band to pass. A differential amplifier 107 outputs a difference in amplitude components between a distributed signal frequency-selected by the filter 106 and the distributed signal which is not frequency-selected. This allows an attenuation characteristic or passage characteristic in a high-frequency band to be maintained.
Description
Technical field
The present invention relates to a kind of filter circuit and radio device, especially for example be used for the filter circuit and the radio device of the high frequency band of digit wireless communication system.
Background technology
The filter circuit of the use amplifier that some is traditional utilizes the electricity of amplifier to lead with electric capacity and realizes filtering characteristic.According to this filter circuit, the normal phase input end of the conductance amplifier of the leading portion of composition active filter is connected to the 1st input by the 1st resistor, and is connected to earth point by the 2nd resistor.In addition, the negative-phase input of the 1st conductance amplifier is connected to the 2nd input by the 3rd resistor, and is connected to outside output by the 4th resistor.Then, make between the 1st resistor and the 2nd resistor resistance value than with the 3rd resistor and the 4th resistor between resistance value than equating, and the signal that contains the in-phase signal component is added to the 1st input, another signal is added to the 2nd input.By this method, traditional filter circuit adopts every section multi-segment structure that is made of electric capacity and conductance amplifier, thereby can access rapid attenuation characteristic.
Yet, tradition filter circuit and radio device have just been realized the filter of low pass type structure, for realizing that at high frequency band the logical type structure of band need make up low pass type structure and high-pass type structure, in addition, therefore obtaining rapid attenuation characteristic needs the structure of multistage, exists the maximization of the circuit that the increase of electric capacity and conductance amplifier quantity brings to cause the problem of circuit integration difficulty.On the other hand, when reducing the attenuation of expected frequency component, bring again in high frequency band, to be difficult to realize rapid attenuation characteristic or the problem by characteristic for the maximization of avoiding circuit and the hop count that reduces filter circuit.
Summary of the invention
The purpose of this invention is to provide a kind of filter circuit and radio device, be used for solving at least above-mentioned all or part of problem of the prior art.
This purpose can realize that this filter circuit comprises by filter circuit: reference signal source produces the reference signal that is used to adjust the amount of phase rotation or amplitude fading amount; Distributor is assigned as described reference signal or input signal the distributing signal of two systems; Filter carries out frequency to first distributing signal that is distributed by described distributor and selects to pass through predetermined frequency band; Correcting circuit provides the amount of phase rotation or the amplitude fading amount that equates by rotation of the phase place in the frequency band of described filter or amplitude fading with described first distributing signal to second distributing signal that is distributed by described distributor; Differential amplifier, output is poor by the amplitude component between described correcting circuit described second distributing signal that the amount of phase rotation or amplitude fading amount be provided and described first distributing signal that is carried out the frequency selection by described filter; Switch, carry out and switch, so that when adjusting the amount of phase rotation that described correcting circuit will provide or amplitude fading amount, described reference signal is input to described distributor, and when described correcting circuit provides the amount of phase rotation or amplitude fading amount to described second distributing signal, described input signal is input to described distributor; And comparator, detect the poor of first distributing signal be input to described differential amplifier and the voltage between second distributing signal, and carry out described adjustment, so that the difference of described voltage is lower than predetermined value.
This filter circuit and radio device are eliminated effect by the homophase that utilizes differential amplifier and can be kept attenuation characteristic and pass through characteristic in high frequency band.
The present invention also provides a kind of filter circuit, comprising: reference signal source produces the reference signal that is used to adjust the amount of phase rotation; Distributor is assigned as described reference signal or input signal the distributing signal of two systems; Filter carries out frequency to first distributing signal that is distributed by described distributor and selects to pass through predetermined frequency band; Adjust circuit, provide predetermined the amount of phase rotation to described second distributing signal that distributes by described distributor, and make the described the amount of phase rotation that provides to described second distributing signal variable; Differential amplifier, output is poor by the amplitude component between described adjustment circuit described second distributing signal that described the amount of phase rotation is provided and described first distributing signal that has been carried out the frequency selection by described filter; Switch, carry out and switch, so that when adjusting the amount of phase rotation that described adjustment circuit will provide, described reference signal is input to described distributor, and when described adjustment circuit provides described the amount of phase rotation to described second distributing signal, described input signal is input to described distributor; Comparator detects the poor of described first distributing signal be input to described differential amplifier and the voltage between described second distributing signal, and carries out described adjustment, so that the difference of described voltage is lower than predetermined value.
The present invention also provides a kind of filter circuit, comprising: distributor is assigned as input signal the distributing signal of two systems; Filter carries out frequency to first distributing signal that is distributed by described distributor and selects to pass through predetermined frequency band; Differential amplifier, the described input signal of former state ground output when the described input signal of input, and when second distributing signal that distributes by described distributor during with described first distributing signal input of having been undertaken by described filter that frequency selects, export described second distributing signal with described first distributing signal that carried out the frequency selection between amplitude component poor; Detecting circuit detects expectation frequency component frequency component in addition; Switch, carry out and switch, so that when described detecting circuit detects frequency component beyond the expected frequency component, described input signal is input to described distributor, when described detecting circuit only detects the expected frequency component, described input signal is input to described differential amplifier.
Description of drawings
Fig. 1 is the block diagram of expression according to the structure of the filter circuit of the embodiment of the invention 1;
Fig. 2 is expression according to the schematic diagram that concerns of the power of the signal of the embodiment of the invention 1 and frequency;
Fig. 3 is expression according to the schematic diagram that concerns of the power of the signal of the embodiment of the invention 1 and frequency;
Fig. 4 A is expression according to the schematic diagram that concerns of the power of the signal of the embodiment of the invention 1 and frequency;
Fig. 4 B is expression according to the schematic diagram that concerns of the power of the signal of the embodiment of the invention 1 and frequency;
Fig. 4 C is expression according to the schematic diagram that concerns of the power of the signal of the embodiment of the invention 1 and frequency;
Fig. 5 A is expression according to the schematic diagram that concerns of the power of the signal of the embodiment of the invention 1 and frequency;
Fig. 5 B is expression according to the schematic diagram that concerns of the power of the signal of the embodiment of the invention 1 and frequency;
Fig. 5 C is expression according to the schematic diagram that concerns of the power of the signal of the embodiment of the invention 1 and frequency;
Fig. 6 is expression according to the schematic diagram that concerns of the power of the signal of the embodiment of the invention 1 and frequency;
Fig. 7 is expression according to the schematic diagram that concerns of the power of the signal of the embodiment of the invention 1 and frequency;
Fig. 8 is the block diagram of expression according to the filter circuit construction of the embodiment of the invention 2;
Fig. 9 is the block diagram of expression according to the filter circuit construction of the embodiment of the invention 3;
Figure 10 is the block diagram of expression according to the filter circuit construction of the embodiment of the invention 4;
Figure 11 is the block diagram of expression according to the radio device structure of the embodiment of the invention 5;
Figure 12 is the block diagram of expression according to the radio device structure of the embodiment of the invention 6;
Figure 13 is the block diagram of expression according to the radio device structure of the embodiment of the invention 7; And
Figure 14 is the block diagram of expression according to the radio device structure of the embodiment of the invention 8.
Embodiment
With reference to the accompanying drawings embodiments of the invention are described below.
Embodiment 1
Fig. 1 is the block diagram of expression according to the structure of the filter circuit 108 of the embodiment of the invention 1.
Below the operation of the filter circuit 108 in the said structure will be described according to Fig. 2 to Fig. 6.
At first, will be that the situation of low pass type, high-pass type or the logical type of band describes to the attenuation characteristic of filter 106.
At the beginning, as shown in Figure 2, be the f1 of P1 by input power from signal input part 101, f2, the signal that the f3 frequency component is constituted.Then, by distributor 103 with this signal allocation be wait amplitude, power is a plurality of parts that P2 (P1〉P2) and amplitude reduce by half, and carries out frequency to one in these signals outputs as shown in Figure 3 and select in filter 106.As a result, when filter 106 is the low pass type, just obtain power shown in Fig. 4 A by f1, f2, the output signal that the order of f3 is successively decreased.On the other hand, when filter 106 is high-pass type, just obtain power shown in Fig. 4 B according to f3, f2, the output signal that the order of f1 is successively decreased.In addition, when filter 106 is the logical type of band, just obtain the signal of the power of f2 power shown in Fig. 4 C the highest and f1 and f3 less than f2 power.On the other hand, another of distributor 103 output do not carry out any frequency to be selected, so the signal among Fig. 3 is imported into the non-inverting input of differential amplifier 107, and the signal among Fig. 4 is input to inverting input with same phase.Because the in-phase signal elimination effect of differential amplifier 107, obtain as shown in Figure 5 the output signal of distributing and being input to the difference of the amplitude component between the distributing signal of differential amplifier 107 by distributor 103 at signal output part 102.That is to say, when filter 106 adopts the low pass mode filters, just obtain that low territory amplitude component shown in Fig. 5 A is eliminated and power according to f3, f2, the output signal that the order of f1 is successively decreased.On the other hand, when filter 106 adopts the high-pass type filters, just obtain that high territory amplitude component shown in Fig. 5 B is eliminated and amplitude component power according to f1, f2, the output signal that the order of f3 is successively decreased.In addition, when filter 106 adopts the logical mode filter of band, the high-power output signal of the power ratio f2 of f1 and f3 just obtain f2 power minimum shown in Fig. 5 C.As shown in Figure 5, the power that the output signal power of every kind of frequency of differential amplifier 107 becomes the received signal of each peak frequency multiply by the P3 that the differential amplifier gain obtains (if gain is less than 0[dB] then P2 P3, if gain is equal to or greater than 0[dB] then P2 ≦ P3).
Next the situation in the time of will to the attenuation characteristic of filter 106 being the band resistance type describes.
As shown in Figure 2, be the frequency component f1 of P1 by power, f2, the signal that f3 constitutes is from signal input part 101 inputs.Then, by distributor 103 with this signal allocation be wait amplitude, power is a plurality of parts that P2 (P1〉P2) and amplitude reduce by half, and carries out frequency to one in these signals outputs as shown in Figure 3 and select in filter 106.As a result, just obtain the minimum and high output signal of power ratio f2 power of f1 and f3 of as shown in Figure 6 f2 power.On the other hand, other signals of distributor 103 output is not carried out any frequency and is selected, so the signal among Fig. 3 is imported into the non-inverting input of differential amplifier 107, and the signal among Fig. 6 is input to inverting input with same phase.Because the in-phase signal elimination effect of differential amplifier 107, obtain as shown in Figure 7 the output signal of distributing and being input to the difference of the amplitude component between the distributing signal of differential amplifier 107 by distributor 103 at signal output part 102.That is to say, obtain as shown in Figure 7 f2 power maximum and the power of f1 and f3 less than the output signal of f2 power.Here, the power that the output signal power of the differential amplifier 107 shown in Fig. 7 becomes the received signal of f2 multiply by the P3 that the differential amplifier gain obtains (if gain is less than 0[dB] then P2 P3, if gain is equal to or greater than 0[dB] then P2 ≦ P3).
Therefore, when the stopband of filter 106 is set at desired frequency band and receiving unit adopted filter circuit 108, the passband of filter 106 is set at the disturbing wave frequency band; And when filter circuit 108 is used for sending part and local oscillations part, the passband of filter 106 is set at unnecessary frequency component frequency band, thereby can only the expected frequency component extraction be come out.
Be present in the stopband of filter 106 from the output signal of signal output part 102, even produce some losses when the received signal of stopband is prevented from, this loss has only slight influence to the received signal of passband.
Therefore, according to present embodiment 1, input signal is assigned to two systems, differential amplifier output is carried out amplitude component poor between frequency a distributing signal of selecting and another distributing signal that does not carry out the frequency selection by filter, thereby can keep the attenuation characteristic of high frequency band or pass through characteristic.In addition, according to present embodiment 1, when filter 106 adopts the band resistance type filter that stops predetermined frequency band, can realize in high frequency band that the band with rapid attenuation characteristic leads to the integrated of type structure.In addition, present embodiment 1 has buffer 104 and 105 between the circuit of two outputs of distributor 103 and back, and suppresses from the interference between two output signals of distributor 103, thereby improves the stability of attenuation characteristic.
According to embodiment 1, be not imported into the inverting input of differential amplifier 107 by the distributing signal of filter, and be imported into non-inverting input by the distributing signal of filter, but present embodiment is not limited to this, also go for following mode: with the pole reversal of the input of differential amplifier 107, and will be not distributing signal by filter be input to non-inverting input, and will be input to inverting input by the distributing signal of filter.
Embodiment 2
Fig. 8 is the block diagram of expression according to filter circuit 800 structures of the embodiment of the invention 2.
In Fig. 8, when adjustment circuit 801 operates as correcting circuit, it carries out the amount of phase rotation that the signal with 106 pairs of passbands of filter carries out or the phase place rotation or the amplitude fading of amplitude fading amount equivalent to the distributing signal from buffer 104 input, and consequential signal is outputed to comparator 802 and differential amplifier 107.In addition, when adjusting circuit 801 and operate as correcting circuit, it carries out the phase place rotation of scheduled volume to the distributing signal from buffer 104 inputs, thereby makes that the frequency band of the output signal exported from differential amplifier 107 is variable.That is to say, adjust the amount that circuit 801 will carry out the phase place rotation to the distributing signal of buffer 104 inputs and be set at predetermined value, thereby make from the frequency band of the output signal of differential amplifier 107 outputs variable.
When adjusting under the situation of circuit 801 as the correcting circuit running, detect phase difference or difference of vibration between the in-phase input signals for 1 of differential amplifier 107 at timing comparator 802, first control signal of indication being adjusted circuit 801 correcting values outputs to adjustment circuit 801, thereby adjusts the correcting value of circuit 801 and preserve correction data after correction is finished.On the other hand, under the situation that adjustment circuit 801 does not move as correcting circuit, comparator 802 detects the phase difference between the in-phase input signals for 1 of differential amplifier 107 when the amount of phase rotation is adjusted, and will be used to set the amount of phase rotation and first control signal that makes the output signal frequency band of differential amplifier 107 output become predetermined frequency band outputs to and adjusts circuit 801, thereby adjust by adjusting the amount of phase rotation that circuit 801 is set, and be kept at the amount of phase rotation that the amount of phase rotation adjustment is set after finishing.
More particularly, adjusting under two kinds of situations that circuit 801 operates as correcting circuit and the adjustment circuit does not operate as correcting circuit, comparator 802 all can compare the voltage (the 1st voltage) that connects the transmission path mid point (being connected mid point) of adjusting the circuit 801 and the non-inverting input of differential amplifier 107 with the voltage (the 2nd voltage) of the transmission path mid point (being connected mid point) that is connected the filter 106 and the inverting input of differential amplifier 107, and correcting value or the amount of phase rotation of adjusting circuit 801 adjusted, thereby make voltage difference be lower than predetermined value.In addition, do not operate under the both of these case as correcting circuit as correcting circuit running and adjustment circuit 801 at adjustment circuit 801, comparator 802 is the switching of control switch 804 all.Higher and when surpassing the permission compare operation scope of comparator 802 when the frequency input signal of distributor 103, comparator 802 inside provide frequency dividing circuit to reduce comparison frequency.
Here, " timing " is meant phase place rotation or amplitude fading is set at the adjusting stage that the phase place that provides for the signal of passband with filter 106 is rotated or the amount of amplitude fading equates, " when correction is finished " is meant and finished the stage of setting phase place rotation or amplitude fading, " when the amount of phase rotation is adjusted " is meant and sets the amount of phase rotation to obtain the adjusting stage of the output signal of desired frequency band from differential amplifier 107, and " when the amount of phase rotation adjustment is finished " is meant and finished the stage of setting the amount of phase rotation.When adjustment circuit 801 operates as correcting circuit, at timing, all detected phase difference or difference of vibration repeatedly of comparator 802 when adjusting circuit 801 and filter 106 input distributing signals at every turn, and adjust correcting value so that detected phase difference or difference of vibration reduce to predetermined value.
On the other hand, under the situation that adjustment circuit 801 does not operate as correcting circuit, when the amount of phase rotation is adjusted, all detected phase is poor repeatedly for comparator 802 during at every turn from adjustment circuit 801 and filter 106 input distributing signals, and adjust the amount of phase rotation till phase difference reaches predetermined value, thereby can access the output signal of predetermined frequency band.When the timing of adjusting circuit 801 and the amount of phase rotation adjustment, reference signal source 803 carries out frequency sweep with certain output level, and outputs to distributor 103.The control of device 802 based on the comparison, when correction is finished and the amount of phase rotation adjustment when finishing, switch 804 short circuit between signal input part 101 and distributor 103; When timing and the amount of phase rotation adjustment, switch 804 short circuit between reference signal source 803 and distributor 103.
In addition, the amplitude component from differential amplifier 107 outputs when timing and the amount of phase rotation are adjusted is dropped, and when correction is finished and the amount of phase rotation adjustment when finishing comparator 802 place dormant state and do not export any signal to comparator.
Learn based on the research that arrives in the process of the present invention, when the phase error of the in-phase input signals for 1 of two inputs of difference amplifier 107 or amplitude error are equal to or higher than predetermined value, in-phase signal is eliminated effect and can be reduced, and we can say to reduce above-mentioned phase error and amplitude error is very important in the rapid attenuation characteristic that realizes filter circuit 800.
Therefore, will describe a kind of method and the process that can proofread and correct above-mentioned phase error and amplitude error accurately below.
Under ecotopia and when not having difference between the building block of filter circuit 800, adjustment circuit 801 is set at the amount of phase rotation that equates and the amplitude fading amount that is produced with filter 106 can be provided.
When filter circuit 800 is made of discrete parts, adjusting circuit 801 can adjust at each parts that is used for filter 106, yet when the building block of filter circuit 800 is formed at semi-conductive substrate, can not adjust individually according to the property difference of each building block, therefore the present embodiment 2 input path of at first using switch 804 will arrive the signal of distributor 103 when the power supply opening of filter circuit 800 switches to reference signal source 803 these sides, and the phase error and the amplitude error that use 802 pairs of comparators to be input between two signals of differential amplifier 107 monitor that control is adjusted circuit 801 so that phase error and amplitude error converge to predetermined error range.In addition, after next time during opening power, can adopt the method for carrying out correct operation once more, perhaps adopt and to be kept in the comparator 802 in first control signal that current timing outputs to correcting circuit and the fixing method of adjusting the state of circuit 801, and be that purpose is formed and adjusted circuit 801 can handle above-mentioned two kinds of situations.
Then, under situation as environmental changes such as variations in temperature, value when the amount of phase rotation that produces at filter 106 and amplitude fading amount may be from power supply openings changes, thereby the correction can be similar to when power supply opening by execution in the moment that filter circuit 800 is set to dormant state the time improves correction accuracy.Identical among remaining operation and the embodiment 1, so omit its related description.In addition, therefore identical among each output signal and Fig. 2～Fig. 7 omit its related description.
Next will circuit 801 provides the amplitude fading amount that equates in the passband with filter 106 and the situation of adjusting the amount of phase rotation describes to adjusting.
As mentioned above, when by equating in the passband of adjusting the amount of phase rotation that circuit 801 provides and filter 106, the frequency characteristic of filter 106 and filter circuit 800 is reversed.In addition, the cut-off frequency of filter 106 (3dB attenuation points) is identical with filter circuit 800.
When adjusting the amount of phase rotation of same frequency in the passband that the amount of phase rotation that circuit 801 provides is different from filter 106, the homophase that can't obtain differential amplifier 107 is eliminated effect, even the zone in the passband of filter 106 also no longer is the stopband of filter circuit 800.Therefore, can make the cut-off frequency varying of filter circuit 800.
As mentioned above, except the effect of the foregoing description 1, present embodiment 2 is by having adopted reference signal source 803, adjustment circuit 801 and the comparator 802 that is used to proofread and correct, the phase error or the amplitude error of the in-phase input signals for 1 of two inputs of differential amplifier 107 are suppressed to the value that is lower than predetermined value, thereby realize very rapid attenuation characteristic.In addition, embodiment 2 is adjusting timing short circuit between reference signal source and distributor of circuit 801, and the output frequency of reference signal source is carried out frequency sweep, thereby can realize more high-precision correction.
When adjustment circuit 801 does not operate as correcting circuit, present embodiment 2 is only adjusted the amount of phase rotation, but the present invention is not limited to this, also applicable to following mode: adjust circuit 801 and adjust the amplitude fading amount and adjust the amount of phase rotation, distributing signal from buffer 104 input is provided phase place rotation and the amplitude fading that the amount of phase rotation of providing with the signal of 106 pairs of passbands of filter and amplitude fading amount equate, and adjust the frequency band of the output signal of exporting from differential amplifier 107 simultaneously.In this case, the adjustment circuit of adjusting the output signal frequency band can be different from the correcting circuit that provides the amount of phase rotation and amplitude fading amount, perhaps also can be with these two circuit as a shared circuit.
Embodiment 3
Fig. 9 is the block diagram according to the filter circuit 900 of the embodiment of the invention 3.
As shown in Figure 9, corresponding to the filter circuit 800 shown in Fig. 8, increased selector 903, replaced filter 106, replaced adjustment circuit 801 with adjusting circuit 902 with filter 901 according to embodiment 2 according to the filter circuit 900 of present embodiment 3.In Fig. 9, the part identical with Fig. 1 and Fig. 8 is attached to be marked with same Reference numeral, will omit its related description.
In Fig. 9, filter 901 has the band resistance type structure that is made of inductor and electric capacity, thereby and by making the variable stopband that makes of inductance value or capacitance variable.That is to say that filter 901 stops passing through of the interior a part of frequency component of scheduled communication frequency band, and only allow predetermined frequency component to pass through.Then, filter 901 will be in the passband of the distributing signal of buffer 105 input, and the frequency component in the passband beyond the stopband outputs to differential amplifier 107.When adjusting under the situation of circuit 902 as the correcting circuit running, the output signal of adjusting 902 pairs of buffers 104 of circuit provides the phase place that the amount of phase rotation of providing with signal by 901 pairs of passbands of filter and amplitude fading amount equate and rotates and amplitude fading, and outputs to differential amplifier 107 and comparator 802.On the other hand,, adjust 902 pairs of distributing signals of circuit and provide predetermined the amount of phase rotation, thereby can make the frequency band of output signal of differential amplifier 107 outputs variable from buffer 104 inputs when adjusting circuit 902 not under the situation as the correcting circuit running.That is to say, the amount of phase rotation that adjustment circuit 902 will provide the distributing signal from buffer 104 inputs is set at predetermined the amount of phase rotation, thereby can make from the frequency band of the output signal of differential amplifier 107 output variable, just as the variable situation of frequency band that makes by the distributing signal of filter 106.Selector 903 is selected signal and the stopband of control filters 901 based on the frequency band from the frequency band of the selective filter 901 of detecting circuit (not shown) input, is used for variation that stopband according to filter 901 changes the amount of phase rotation that produces and amplitude fading amount and controls the amount of phase rotation of adjusting circuit 902 and the 2nd control signal of amplitude fading amount to adjusting circuit 902 outputs simultaneously.In addition, the amplitude component of exporting at timing differential amplifier 107 is dropped, and comparator 802 is set to dormant state when correction is finished, and does not export any signal to comparator.
To the operation of the filter circuit 900 of said structure be described below.
The user of the wireless device by using filter circuit 900 manually selects or based on the automatic selection of detected received electric field strength of described wireless device and base stations control channel information, frequency band selects signal to be imported into selector 903.The frequency band variable signal selects the selector 903 of signal to output to filter 901 from receiving frequency band, and the stopband of filter 901 is fixed.
When the frequency band that receives the frequency band of selecting to be different from last time was selected signal, because the change of stopband, the amount of phase rotation and amplitude fading amount in the passband also changed in filter 901.When 902 pairs of input signals of adjustment circuit provide fixing the amount of phase rotation and amplitude fading amount, filter circuit 900 can not be kept attenuation characteristic, therefore adjust circuit 902 and preserve the amount of phase rotation and the amplitude fading amount respective input signals correction data of the passband of the filter 901 that changes along with the variation of frequency band variable signal, individual circuits corresponding to every kind of the amount of phase rotation and amplitude fading amount perhaps is provided, based on the frequency band variable signal, selector 903 changes the state of adjusting circuit 902 according to second control signal.After above-mentioned change is finished, by with 2 kinds of identical processes of embodiment, the phase error of the in-phase input signals for 1 of 107 two inputs of differential amplifier or amplitude error be suppressed to be lower than predetermined value.In addition, when adjustment circuit 902 does not operate as correcting circuit, adjust the amount that 902 pairs of distributing signals from buffer 104 inputs of circuit provide predetermined phase place rotation, thereby can change from the frequency band of the output signal of differential amplifier 107 outputs by changing the same mode of stopband with filter 901.Identical among remaining operation and embodiment 1 and the embodiment 2, so omit its related description.In addition, therefore identical among each output signal and Fig. 2, Fig. 3, Fig. 6 and Fig. 7 omit its related description.
As implied above, except the effect of embodiment 1 and embodiment 2, the filter 901 of present embodiment 3 has adopted band resistance type structure, thereby can make the logical mode filter of the variable band of passband integrated.In addition, according to present embodiment 3, also adjust the amount of phase rotation and the amplitude fading amount of circuit 902 in the time of the stopband of control filters 901 according to the stopband control of filter 901, thus change that can the flexible processing desired frequency band, and realize rapider attenuation characteristic.In addition, present embodiment 3 can adopt filter 901 and adjust circuit 902 and change from the frequency band of the output signal of differential amplifier 107 outputs, thereby can obtain the output signal of desired frequency band at high speed.
According to present embodiment 3, frequency band selects signal to import into from the outside of filter circuit 900, but present embodiment is not limited to this, also go for following mode: generate frequency band and select the function of signal and the function of filter circuit 900 to be integrated, provide frequency band to select the signal generating portion, and frequency band select signal to select the signal generating portion to be input to selector 903 from the frequency band of filter circuit 900 inside.
Embodiment 4
Figure 10 is the block diagram of expression according to the filter circuit construction of the embodiment of the invention 4.
As shown in figure 10, filter circuit 1000 according to present embodiment 4 has increased detecting circuit 1001 in the filter circuit 108 according to embodiment shown in Figure 11, switch 1002, switch 1005 and switch 1006, and replaced original differential amplifier 107 with differential amplifier 1007.In addition, in Figure 10, mark with same Reference numeral with part identical among Fig. 1 is attached, and omit its related description.
In Figure 10, disturbing wave beyond the detecting circuit 1001 detection desired frequency band or unnecessary frequency component, and when detecting disturbing wave or unnecessary frequency component, detecting circuit 1001 changes switches 1002 makes signal input part 101 link to each other with distributor 103; And when not detecting disturbing wave or unnecessary frequency component, detecting circuit 1001 changes switches 1002 makes signal input part 101 link to each other with the non-inverting input of differential amplifier 1007.Switch 1002 comprises switch terminals 1003 and switch terminals 1004, based on testing result short circuit between signal input part 101 and switch terminals 1003 or switch terminals 1004 of detecting circuit 1001, thereby when signal input part 101 is connected to the non-inverting input of differential amplifier 1007 and signal input part 101 toggle path when being connected to distributor 103.Switch 1005 is connected under the situation of non-inverting input of differential amplifier 1007 and is free of attachment to toggle path under the situation of any circuit when buffer 104 when buffer 104 based on the testing result of detecting circuit 1001.Switch 1006 is based on the testing result of detecting circuit 1001, toggle path under the situation that the reverse inter-input-ing ending grounding and the inverting input of difference amplifier 1007 is connected to filter 106.Differential amplifier 1007 will be input to the distributing signal of non-inverting input and is input to the difference of the amplitude component between the distributing signal of inverting input from filter 106 or is input to the input signal of non-inverting input and the difference of the amplitude component between the ground connection inverting input outputs to signal output part 102 from signal input part 101 from buffer 104.In addition, differential amplifier 1007 changes gain based on the testing result of detecting circuit 1001.That is to say that differential amplifier 1007 provides the gain of the attenuated input signal that compensation produced when the distributor 103 distribution input signals for the distributing signal of input.
To the operation of the filter circuit of formation as implied above be described below.
When detecting circuit 1001 does not detect disturbing wave or unnecessary frequency component, switch 1002 short circuit between switch terminals 1003 and signal input part 101, switch 1005 disconnects input and output, switch 1006 short circuit between input and output, and with the reverse inter-input-ing ending grounding of differential amplifier 1007, the gain setting with differential amplifier 1007 is G1[dB simultaneously].On the other hand, when detecting circuit 1001 detects disturbing wave or unnecessary frequency component, switch 1002 short circuit between switch terminals 1004 and signal input part 101, switch 1005 short circuit between input and output, switch 1006 disconnects input and output, gain setting with differential amplifier 1007 is the decay that G2 (G2=G1+3) [dB] comes compensating filter 106 simultaneously, thereby the level of signal output part 102 changes when suppressing commutation circuit.Other the operation with embodiment 1 in identical, will omit its related description.In addition, therefore identical among each output end signal and Fig. 2～Fig. 7 omit its related description.
Therefore, the effect in embodiment 1, when not having disturbing wave and unnecessary frequency component to exist, present embodiment 4 diverter switches 1002 are so that signal input part 101 is directly connected to the non-inverting input of differential amplifier 1007, thereby between the operation/not operation of filter 106, switch, prevent the receiving signal attenuation of expected frequency, thereby suppress the gain of differential amplifier 1007 and reduce current drain.In addition, when detecting circuit 1001 detected frequency component outside the expected frequency, present embodiment 4 switched to the gain that compensating signal divides the timing decay with the setting of differential amplifier 1007, thereby can keep output level constant.
In present embodiment 4, be directly inputted to the non-inverting input of differential amplifier 1007 from the distributing signal of buffer 104 outputs, but the present invention is not limited to this, as the situation in embodiment 2, also can increase correcting circuit between the non-inverting input of buffer 104 and differential amplifier 1007 is suppressed to the phase error of the in-phase input signals for 1 of two inputs of differential amplifier 1007 or amplitude error and is lower than predetermined value, perhaps adopt the variable band resistance type filter of stopbands, increase correcting circuit simultaneously and the phase error of the in-phase input signals for 1 of two inputs of differential amplifier 1007 or amplitude error are suppressed to are lower than predetermined value or increase the selector that changes the frequency band of filter 106 in variable mode at filter 106.This just allows filter circuit to realize rapider attenuation characteristic.In addition, in embodiment 4, distributing signal frequency band by filter 106 is fixed, but the present invention is not limited to this, also go for following mode: filter 106 adopts band resistance type structure, and have selector the situation in embodiment 3, and the frequency band that the prevention of filter 106 is passed through is variable.In addition, when detecting circuit 1001 detected disturbing wave or unnecessary frequency component, present embodiment 4 increased 3[dB with the gain of differential amplifier 1007], but present embodiment is not limited to this, and gain also can be set at arbitrary value.
Embodiment 5
Figure 11 is the block diagram of expression according to the structure of the radio device 1100 of the embodiment of the invention 5.Low noise amplifier 1101, filter circuit 1102 and frequency mixer 1103 have constituted HFS 1104.
In Figure 11, low noise amplifier 1101 amplifies the received signal that antenna 1105 receives, and amplifying signal is outputed to filter circuit 1102.Filter circuit 1102 allows to pass through from the expected frequency component of the received signal of low noise amplifier 1101 inputs, and outputs to frequency mixer 1103.Here, for filter circuit 1102, any one among the filter circuit 800 among Fig. 1 among filter circuit 108, Fig. 8, the filter circuit 900 among Fig. 9 and the filter circuit 1000 among Figure 10 can suitably be used.Frequency mixer 1103 is changed from the frequency of the received signal of filter circuit 1102 inputs, and received signal is outputed to demodulator 1106.Demodulator 1106 will be from the receiving signal demodulation of frequency mixer 1103 input, and obtains receiving data.
To the operation of the radio device 1100 of formation as implied above be described below.
Be present in disturbing wave beyond the desired frequency band in the output of low noise amplifier 1101 or unnecessary filtered 1102 decay of frequency component to prevent the saturated of frequency mixer 1103.Identical among the operation of filter circuit 1102 and the embodiment 1～embodiment 4 described in any one will be omitted its related description.
Except the effect of embodiment 1～embodiment 4, present embodiment 5 adopts 1102 pairs of filter circuits to be present in disturbing wave beyond the desired frequency band among the low noise amplifier 1101 or unnecessary frequency component decays, prevent the saturated of frequency mixer 1103, thereby the susceptibility that can suppress demodulator 1106 worsens.In addition, by in filter circuit 1102, adopt with filter circuit 108,800,900,1000 among any one identical structure, present embodiment 5 forms HFS 1104 and is more prone on identical Semiconductor substrate, because all these filter circuits all have the integration and the compatibility (affinity) of height, thereby can realize the miniaturization of radio device 1100, and reduce number of components.
In present embodiment 5, filter circuit 1102 is disposed between low noise amplifier 1101 and the frequency mixer 1103, but present embodiment is not limited to this, also can be suitable for following mode: the position beyond filter circuit 1102 is disposed between low noise amplifier 1101 and the frequency mixer 1103 in HFS 1104, thereby strengthened the integrated of filter circuit in the high frequency band, and obtained rapid attenuation characteristic.In addition, in present embodiment 5, filter circuit 1102 is used for HFS 1104, but the present invention is not limited to this, and filter circuit 1102 also can use in the low frequency part except HFS 1104 etc.
Embodiment 6
Figure 12 is the block diagram of expression according to radio device 1200 structures of the embodiment of the invention 6.Modulator 1201, filter circuit 1202 and power amplifier 1203 constitute HFS 1204.
In Figure 12,1201 pairs of transmission signals from baseband portion 1206 inputs of modulator are modulated, and the signal after will modulating outputs to filter circuit 1202.Filter circuit 1202 allows to pass through from the expected frequency component of the transmission signals of modulator 1201 inputs, and this frequency component is outputed to power amplifier 1203.Here, the filter circuit 108 among Fig. 1, the filter circuit 800 among Fig. 8, filter circuit 900 among Fig. 9 and any one among the filter circuit 1000 among Figure 10 can be suitable is used for filter circuit 1202.Power amplifier 1203 will amplify from the transmitted power of the transmission signals of filter circuit 1202 input, and transmission signals is sent from antenna 1205.Baseband portion 1206 will send data processing to base band, generate transmission signals, and the transmission signals that generates is outputed to modulator 1201.
To the operation of the radio device 1200 of structure as implied above be described below.
The unnecessary frequency component that is present in beyond the desired frequency band in the output of modulator 1201 decays in filter circuit 1202.The operation of filter circuit 1202 is identical with embodiment 1～embodiment's 4, will omit its related description.
As mentioned above, except the effect of embodiment 1～embodiment 4, present embodiment 6 adopts the unnecessary frequency component beyond the desired frequency band that exists in the output of filter circuit 1202 with modulator 1201 to decay, thereby suppresses the unnecessary radiation from antenna 1205.In addition, by filter circuit 1202 being adopted and filter circuit 108,800,900,1000 any one identical structure wherein, present embodiment 6 is more prone to the formation of HFS 1204 on identical Semiconductor substrate, because all these filter circuits all have the integration and the compatibility of height, thereby can realize the miniaturization of radio device 1200 and reduce the quantity of parts.
In present embodiment 6, filter circuit 1202 is disposed between modulator 1201 and the power amplifier 1203, but the present invention is not limited to this, also applicable to following mode: filter circuit 1202 is the position beyond between modulator 1201 and power amplifier 1203 in HFS 1204, strengthening the integrated of filter circuit in the high frequency band, and obtain rapid attenuation characteristic.In addition, in present embodiment 6, filter circuit 1202 is used for HFS 1204, but the present invention is not limited to this, and filter circuit 1202 also can be used for the low frequency part except HFS 1204 etc.
Figure 13 is the block diagram of expression according to the structure of the radio device 1300 of the embodiment of the invention 7.
Corresponding to radio device 1100, local oscillator 1301 and filter circuit 1302 have been increased, as shown in figure 13 according to the radio device 1300 of present embodiment 7 according to the embodiment shown in Figure 11 5.In Figure 13, mark with same Reference numeral with part identical among Figure 11 is attached, and omit its related description.
In Figure 13, local oscillator 1301 generates the signal of the preset frequency that is used for frequency inverted, and this signal is outputed to filter circuit 1302.Filter circuit 1302 allows to pass through from the expected frequency component of the signal that is used for frequency inverted of local oscillator 1301 inputs, and the desired frequency component is outputed to frequency mixer 1103.Here, the filter circuit 108 among Fig. 1, the filter circuit 800 among Fig. 8, filter circuit 900 among Fig. 9 and any one among the filter circuit 1000 among Figure 10 can be suitable is used for filter circuit 1302.
In the radio device 1300 of structure as implied above, the unnecessary band component beyond the desired frequency band that exists in the output of local oscillator 1301 is decayed in filter circuit 1302.
Therefore, except the effect of embodiment 1～embodiment 4, unnecessary frequency component beyond the expected frequency component that exists in the output of present embodiment 7 with local oscillator 1301 decays, thereby can suppress the intermodulation distortion that frequency mixer 1103 produces, and suppress the deterioration of demodulator 1106 susceptibilitys.In addition, by filter circuit 1302 adopt with filter circuit 108,800,900,1000 among any one identical structure, present embodiment 7 is more prone to the formation of HFS 1303 on identical Semiconductor substrate, because all these filter circuits all have the integration and the compatibility of height, thereby can realize the miniaturization of radio device 1300, and reduce the quantity of parts.
In present embodiment 7, filter circuit 1102 is positioned in HFS 1303 between low noise amplifier 1101 and the frequency mixer 1103, and filter circuit 1302 is positioned in HFS 1303 between local oscillator 1301 and the frequency mixer 1103, but the present invention is not limited to this, also go for following mode: the position beyond filter circuit 1102 places between low noise amplifier 1101 and the frequency mixer 1103 in HFS 1303, position beyond perhaps filter circuit 1302 places between local oscillator 1301 and the frequency mixer 1103 in HFS 1303, strengthening the integrated of filter circuit in the high frequency band, and obtain rapid attenuation characteristic.In addition, in present embodiment 7, filter circuit 1102,1302 is used for HFS 1303, but the present invention is not limited to this, and filter circuit 1102,1302 also can be used for the low frequency part except HFS 1303 etc.
Embodiment 8
Figure 14 is the block diagram according to radio device 1400 structures of the embodiment of the invention 8.Distributor 1403,1/2 frequency dividers 1404, differential amplifier 1405, even harmonics frequency mixer 1406, even harmonics frequency mixer 1407, filter circuit 1408 and filter circuit 1409 constitute freq converting circuit 1410.In addition, quadrature demodulator 1411a and 1411b constitute receiver 1412.In addition, quadrature modulator 1414a and 1414b constitute receiver 1415.Here, it is the direct conversion receiver of 2.5 * f0 that receiver 1412 is to use wireless frequency, and receiver 1415 then is to use the direct conversion receiver of wireless frequency f0.
In Figure 14, local oscillator 1401 generated frequency f0 also output to distributor 1402 with it.Distributor 1402 will be that the signal of f0 distributes from the frequency of local oscillator 1401 inputs, and distributing signal is outputed to distributor 1403 and phase shifter 1413.Distributor 1403 will distribute from the signal of distributor 1402 inputs, and the signal that distributes is outputed to the non-inverting input of 1/2 frequency divider 1404 and differential amplifier 1405.1/2 frequency divider 1404 will be divided into 1/2 and it is outputed to even harmonics frequency mixer 1406 and even harmonics frequency mixer 1407 from the signal frequency of distributor 1403 input.The reverse inter-input-ing ending grounding of differential amplifier 1405, and differential amplifier 1405 will output to even harmonics frequency mixer 1406,1407 from the distributing signal of distributor 1403 inputs.Even harmonics frequency mixer 1406 mixes the twice (2 * f0) and the output frequency of 1/2 frequency divider 1404 (0.5 * f0), and mixed frequency outputed to filter circuit 1408 of the output frequency of differential amplifiers 1405.Even harmonics frequency mixer 1407 with the twice of the output frequency of differential amplifier 1405 (2 * f0) with the output frequency of 1/2 frequency divider 1404 (0.5 * f0) mixes mutually, and the frequency of mixing is outputed to filter circuit 1409.Filter circuit 1408 allows to pass through from the expected frequency component of the signal of even harmonics frequency mixer 1406 inputs, and the desired frequency component is outputed to quadrature demodulator 1411a.Here, the filter circuit 800 among the filter circuit among Fig. 1 108, Fig. 8, the filter circuit 900 among Fig. 9 and among the filter circuit 1000 among Figure 10 any one all can be suitable is used for filter circuit 1408.Filter circuit 1409 allows to pass through from the expected frequency component of the signal of even harmonics frequency mixer 1407 inputs, and the desired frequency component is outputed to quadrature demodulator 1411b.Here, the filter circuit 800 among the filter circuit among Fig. 1 108, Fig. 8, the filter circuit 900 among Fig. 9 and among the filter circuit 1000 among Figure 10 any one all can be suitable is used for filter circuit 1409.Quadrature demodulator 1411a carries out quadrature demodulation to the signal from filter circuit 1408 inputs, and obtains receiving data.Quadrature demodulator 1411b will carry out quadrature demodulation from the signal of filter circuit 1409 inputs, and obtain receiving data.Phase shifter 1413 generates two ripples with 90 degree phase differences according to the distributing signal from distributor 1402 inputs, and these two ripples are outputed to quadrature demodulator 1414a and quadrature demodulator 1414b.Quadrature demodulator 1414a will carry out quadrature demodulation from the signal of phase shifter 1413 inputs, and obtain receiving data.Quadrature demodulator 1414b carries out quadrature demodulation to the signal from phase shifter 1413 inputs, and obtains receiving data.
To the operation of the radio device 1400 of structure as implied above be described below.
At the output of even harmonics frequency mixer 1406,1407, with the amplitude that equates 2.5 * f0 of desired signal components and 1.5 * f0 of unnecessary frequency component appear.Adopt the low general character by the filter 106 that constitutes filter circuit 108,800 or 1000, can only extract the expected frequency component.
Situation about existing as unnecessary frequency when any frequency component except the said frequencies component can adopt the low pass type of filter 106 structures to transfer the filter 901 of being with resistance type to and handle.
Here, for example, suppose that f0 is the 2GHz frequency band, the output signal of 5GHz frequency band can extract from freq converting circuit 1410, therefore by the local oscillator of 2GHz frequency band is provided, can realize being applicable to the biobelt receiver of 2GHz frequency band/5GHz frequency band.Identical among the operation of filter circuit 1408,1409 and the embodiment 1～embodiment 4, and omit its related description.
Therefore, the effect in embodiment 1～embodiment 4, present embodiment 8 can provide a kind of radio device that is applicable to the biobelt system, has reduced because the unnecessary frequency that local oscillation frequency brings.
In present embodiment 8, the reverse inter-input-ing ending grounding of differential amplifier 1405, distributing signal is input to non-inverting input, but the present invention is not limited to this, also go for following mode: the input polarity inversion of differential amplifier 1405, non-inverting input ground connection, distributing signal is input to inverting input.In addition, present embodiment 8 uses differential amplifier 1405, but the present invention is not limited to this, and adopts distributor to replace differential amplifier 1405 also can obtain same effect.In addition, present embodiment 8 is applied to directly change receiver with freq converting circuit 1410, but the present invention is not limited to this, also can obtain same effect by freq converting circuit 1410 being applied to directly change transmitter.
As mentioned above, the present invention can use the homophase elimination effect of differential amplifier to keep the attenuation characteristic of high frequency band or pass through characteristic.
This specification is based on the Japanese patent application of Japanese patent application of submitting on November 1st, 2002 2002-319745 number and submission on May 29th, 2003 2003-152532 number, and its full content all is contained in this for reference.
Industrial applicibility
The present invention be more suitable for being applied to the high frequency band filter circuit that uses such as digital wireless communication system etc. and Radio device.
Claims (8)
1. filter circuit comprises:
Reference signal source produces the reference signal that is used to adjust the amount of phase rotation or amplitude fading amount;
Distributor is assigned as described reference signal or input signal the distributing signal of two systems;
Filter carries out frequency to first distributing signal that is distributed by described distributor and selects to pass through predetermined frequency band;
Correcting circuit provides the amount of phase rotation or the amplitude fading amount that equates by rotation of the phase place in the frequency band of described filter or amplitude fading with described first distributing signal to second distributing signal that is distributed by described distributor;
Differential amplifier, output is poor by the amplitude component between described correcting circuit described second distributing signal that the amount of phase rotation or amplitude fading amount be provided and described first distributing signal that is carried out the frequency selection by described filter;
Switch, carry out and switch, so that when adjusting the amount of phase rotation that described correcting circuit will provide or amplitude fading amount, described reference signal is input to described distributor, and when described correcting circuit provides the amount of phase rotation or amplitude fading amount to described second distributing signal, described input signal is input to described distributor; And
Comparator detects the poor of first distributing signal be input to described differential amplifier and the voltage between second distributing signal, and carries out described adjustment, so that the difference of described voltage is lower than predetermined value.
2. filter circuit as claimed in claim 1 also comprises:
First buffer to described first distributing signal, is suppressed at the interference that produces between described first distributing signal and described second distributing signal; And
Second buffer to described second distributing signal, suppresses described interference,
Wherein said filter carries out frequency to described first distributing signal that has been suppressed described interference by described first buffer and selects; And
The output of described differential amplifier has been suppressed amplitude component poor between described second distributing signal of described interference and described first distributing signal that is carried out the frequency selection by described filter by described second buffer.
3. filter circuit as claimed in claim 1, wherein, described comparator, the 1st voltage and the 2nd voltage are compared, here the 1st voltage is the voltage that connects the mid point on the transmission path of described correcting circuit and described differential amplifier, the 2nd voltage is the voltage that connects the mid point on the transmission path of described filter and described differential amplifier
Described correcting circuit provides described the amount of phase rotation or described amplitude fading amount to described second distributing signal, is that the difference of described the 1st voltage and described the 2nd voltage is lower than predetermined value up to the comparative result that obtains described comparator.
4. filter circuit as claimed in claim 1, wherein, described filter in stoping the stopband pass through, stop described first distributing signal pass through to come that described first distributing signal is carried out frequency and select, and
Described first distributing signal of the described filter of described differential amplifier output having passed through and the amplitude component between described second distributing signal poor.
5. filter circuit as claimed in claim 1, wherein, described filter stops passing through of described first distributing signal in the stopband that prevention is passed through, thereby described first distributing signal is carried out the frequency selection and makes described stopband variable, and
When described stopband changed, described correcting circuit provided the amount of phase rotation and the amplitude fading amount that equates by phase place rotation in the frequency band of the described filter of described stopband variation and amplitude fading with described first distributing signal to described second distributing signal at every turn.
6. filter circuit comprises:
Reference signal source produces the reference signal that is used to adjust the amount of phase rotation;
Distributor is assigned as described reference signal or input signal the distributing signal of two systems;
Filter carries out frequency to first distributing signal that is distributed by described distributor and selects to pass through predetermined frequency band;
Adjust circuit, provide predetermined the amount of phase rotation to described second distributing signal that distributes by described distributor, and make the described the amount of phase rotation that provides to described second distributing signal variable;
Differential amplifier, output is poor by the amplitude component between described adjustment circuit described second distributing signal that described the amount of phase rotation is provided and described first distributing signal that has been carried out the frequency selection by described filter;
Switch, carry out and switch, so that when adjusting the amount of phase rotation that described adjustment circuit will provide, described reference signal is input to described distributor, and when described adjustment circuit provides described the amount of phase rotation to described second distributing signal, described input signal is input to described distributor; And
Comparator detects the poor of described first distributing signal be input to described differential amplifier and the voltage between described second distributing signal, and carries out described adjustment, so that the difference of described voltage is lower than predetermined value.
7. filter circuit comprises:
Distributor is assigned as input signal the distributing signal of two systems;
Filter carries out frequency to first distributing signal that is distributed by described distributor and selects to pass through predetermined frequency band;
Differential amplifier, the described input signal of former state ground output when the described input signal of input, and when second distributing signal that distributes by described distributor during with described first distributing signal input of having been undertaken by described filter that frequency selects, export described second distributing signal with described first distributing signal that carried out the frequency selection between amplitude component poor;
Detecting circuit detects expectation frequency component frequency component in addition; And
Switch, carry out and switch, so that when described detecting circuit detects frequency component beyond the expected frequency component, described input signal is input to described distributor, when described detecting circuit only detects the expected frequency component, described input signal is input to described differential amplifier.
8. filter circuit as claimed in claim 7, wherein, when described detecting circuit detected frequency component beyond the expected frequency, the difference that described differential amplifier is exported described amplitude component adds to be used to compensate by described distributor distributed input signal and the gain of the attenuated input signal that produces.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2002319745 | 2002-11-01 | ||
| JP319745/2002 | 2002-11-01 | ||
| JP152532/2003 | 2003-05-29 |
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| CN1692550A CN1692550A (en) | 2005-11-02 |
| CN100505525C true CN100505525C (en) | 2009-06-24 |
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| CNB2003801005515A Expired - Fee Related CN100505525C (en) | 2002-11-01 | 2003-11-04 | Filter circuit |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102006052873B4 (en) * | 2006-11-09 | 2013-07-11 | Siemens Aktiengesellschaft | Filter circuitry |
| CN101521640B (en) * | 2008-02-29 | 2011-12-07 | 瑞昱半导体股份有限公司 | Filter |
| CN101997515B (en) * | 2009-08-31 | 2012-11-21 | 深圳市理邦精密仪器股份有限公司 | Full-differential same-phase parallel amplifying device for acquiring bioelectric signal |
| CN107579786B (en) * | 2017-07-14 | 2023-11-21 | 深圳市唐诚兴业科技有限公司 | HF VHF and UHF frequency band signal scanning detection system based on DDS |
| CN108649903A (en) * | 2018-07-13 | 2018-10-12 | 成都四威功率电子科技有限公司 | A kind of circuit inhibiting octave power amplifier second harmonic |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5654550A (en) * | 1994-09-28 | 1997-08-05 | Murata Manufacturing Co., Ltd. | Signal processor for pyroelectric infrared sensor |
| JP2001045336A (en) * | 1999-07-29 | 2001-02-16 | Matsushita Electric Ind Co Ltd | Noise detecting device and noise detecting method and signal processor and signal processing method |
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2003
- 2003-11-04 CN CNB2003801005515A patent/CN100505525C/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5654550A (en) * | 1994-09-28 | 1997-08-05 | Murata Manufacturing Co., Ltd. | Signal processor for pyroelectric infrared sensor |
| JP2001045336A (en) * | 1999-07-29 | 2001-02-16 | Matsushita Electric Ind Co Ltd | Noise detecting device and noise detecting method and signal processor and signal processing method |
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