CN102025346A - Tuner and pre-circuit thereof - Google Patents
Tuner and pre-circuit thereof Download PDFInfo
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- CN102025346A CN102025346A CN2009101750184A CN200910175018A CN102025346A CN 102025346 A CN102025346 A CN 102025346A CN 2009101750184 A CN2009101750184 A CN 2009101750184A CN 200910175018 A CN200910175018 A CN 200910175018A CN 102025346 A CN102025346 A CN 102025346A
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Abstract
The invention discloses a tuner and a pre-circuit thereof. The tuner comprises a plurality of channels, wherein at least one channel comprises a pre-filtering circuit, an amplifier and a tracking filter; the tracking filter comprises a variable capacitor and an inductor; and the variable capacitor and the inductor are coupled to an output end of the amplifier. In addition, in the tuner, at least the amplifier and the variable capacitor are arranged in a complementary metal oxide semiconductor chip. The tuner and the pre-circuit thereof have low manufacturing cost and higher filtering quality.
Description
Technical field
The relevant tuner (tuner) of the present invention refers to that especially a kind of general's part or whole element are made in the tuner and the front stage circuits thereof of a silicon.
Background technology
In television system, one of function of tuner is to be used for selecting needed channel signals from the TV signal in a received broadband (broadband), carries out follow-up signal processing at the selected channel signals that goes out again.Yet tuner commonly used at present is an iron-clad tuner (CAN tuner), and it has bigger volume.In addition, be to use the capacitor and inductor filter to come to make tracking filter to select needed frequency in fact in the tuner, and the electric capacity in the tracking filter is a variable capacitance (varactor), yet, because tuner signal to be processed be the TV signal (that is, have very big frequency range) of broadband (broadband), so this variable capacitance needs very big adjustable extent, that is, need very high supply voltage (approximately greater than 30 volts) to drive this variable capacitance.
In addition, there is a kind of silicon tuner to be developed at present with the shortcoming that overcomes above-mentioned iron-clad tuner (variable capacitance that volume is big, need high supply voltage).Yet, though present silicon tuner has the advantage of the little and low supply voltage (about 3 volts) of volume, but, need consider the transduction value (transconductance) and the noise factors such as (noise) of element because the tracking filter of silicon tuner need use active member (active device) to do in fact.Therefore, the silicon tuner need use two-carrier junction transistor (BipolarJunction Transistor, BJT) technology.Can make the silicon tuner have bigger chip area but be to use two-carrier junction transistor technology to come to make the silicon tuner in fact, and two-carrier junction transistor technology is also somewhat expensive, therefore can't reduces the cost of manufacture of tuner really.
In addition, general tuner can have three prime filter circuits, is respectively low-pass filter circuit, bandwidth-limited circuit and high-pass filtering circuit.Yet because considering on the cost, these three prime filter circuits only use single capacitor and inductor to do in fact usually, thus, though reduced cost, but do not have high filtering quality.
Summary of the invention
Therefore, one of purpose of the present invention be to provide a kind of will be partly or tuner that all element is made in a silicon, and this tuner has the prime filter circuit of low-cost high filtering quality, to solve the above problems.
According to an aspect of of the present present invention, a kind of front stage circuits of tuner includes a transformer and a plurality of passage.Wherein this transformer is used for converting single-ended signal to differential wave; And these a plurality of passages, include a filter circuit respectively, wherein this filter circuit of these a plurality of passages all directly is electrically connected on a node, and this node is an output that is coupled to this transformer.
According to another aspect of the present invention, a kind of tuner includes a plurality of passages, and wherein at least one passage includes a prime filter circuit, a differential amplifier and a tracking filter.This tracking filter includes a variable capacitance and an inductance, and wherein this variable capacitance and this inductance are two outputs that are coupled to this differential amplifier.In addition, this amplifier and this variable capacitance are to be arranged in the CMOS (Complementary Metal Oxide Semiconductor) chip (Complementary Metal-Oxide-Semiconductor chip, CMOS chip) at least in this tuner.
According to another aspect of the present invention, a kind of tuner includes a plurality of passages, and wherein at least one passage includes a prime filter circuit, a differential amplifier and a tracking filter.This tracking filter includes a variable capacitance and an inductance, and wherein this variable capacitance and this inductance are two outputs that are coupled to this differential amplifier.In addition, in this tuner at least this amplifier and this variable capacitance be to be arranged in the chip, and this inductance is to be external in this chip.
According to tuner of the present invention and front stage circuits thereof, its manufacturing cost can reduce, and has preferable filtering quality.
Description of drawings
Fig. 1 is the schematic diagram according to the TV tuner of one embodiment of the invention.
Figure 2 shows that the front stage circuits of tuner can equivalence be the schematic diagram of a low-pass filter circuit when the selected channel of user during for low frequency domain channel.
Fig. 3 is the comparison schematic diagram of the transfer function of low-pass filter circuit shown in Figure 2 and low-pass filter circuit shown in Figure 1.
Figure 4 shows that when the selected channel of user is high frequency domain channel the front stage circuits of tuner can equivalence be the schematic diagram of a high-pass filtering circuit.
Fig. 5 is the comparison schematic diagram of the transfer function of high-pass filtering circuit shown in Figure 4 and high-pass filtering circuit shown in Figure 1.
Figure 6 shows that when the selected channel of user is middle frequency domain channel the front stage circuits of tuner can equivalence be the schematic diagram of a bandwidth-limited circuit.
Fig. 7 is the comparison schematic diagram of the transfer function of bandwidth-limited circuit shown in Figure 6 and bandwidth-limited circuit shown in Figure 1.
Fig. 8 is used for detecting automatically the installation drawing that variable capacitance corresponds to the capacitance of each channel.
When Fig. 9 corresponds to the capacitance of each channel for beginning to detect variable capacitance when tuner, the curve chart of the intensity level signal that the capacitance of variable capacitance and signal strength detection unit are exported.
Embodiment
Please refer to Fig. 1, Fig. 1 is the schematic diagram according to the TV tuner 100 of a preferred embodiment of the present invention.As shown in Figure 1, TV tuner 100 includes a transformer 102, a first passage 110, a second channel 120, a third channel 130 and a back end signal treatment circuit 140, and wherein first passage 110 includes two low-pass filter circuit 111_1 and 111_2, two switch SW
1_1And SW
1_2, an attenuator 112, two low noise amplifiers 114 and 116 and one tracking filters 117; Second channel 120 includes two high-pass filtering circuit 121_1 and 121_2, two switch SW
2_1And SW
2_2, an attenuator 122, two low noise amplifiers 124 and 126 and one tracking filters 127; Third channel 130 includes two bandwidth-limited circuit 131_1 and 131_2, four switch SW 3_1, SW3_2, SW3_3, SW3_4, an attenuator 132, two low noise amplifiers 134 and 136 and one tracking filters 137.In addition, low-pass filter circuit 111_1 includes an inductance L
1_1An and capacitor C
1_1Low-pass filter circuit 111_2 includes an inductance L
1_2An and capacitor C
1_2High-pass filtering circuit 121_1 includes a capacitor C
2_1An and inductance L
2_1High-pass filtering circuit 121_2 includes a capacitor C
2_2An and inductance L
2_2Bandwidth-limited circuit 131_1 includes an inductance L
3_1And two capacitor C
3_1, C
3_3Bandwidth-limited circuit 131_2 includes an inductance L
3_2And two capacitor C
3_2, C
3_4Tracking filter 117 includes an inductance L
LBAn and variable capacitance 118; Tracking filter 127 includes an inductance L
HBAn and variable capacitance 128; Tracking filter 137 includes an inductance L
MBAn and variable capacitance 138.
In addition, TV tuner 100 shown in Figure 1 be made in a printed circuit board (PCB) (Printed Circuit Board, PCB) on, and switch SW
1_1, SW
1_2, SW
2_1, SW
2_2, SW
3_1, SW
3_2, SW
3_3, SW
3_4, capacitor C
3_1, C
3_3, C
3_2, C
3_4, attenuator 112,122,132, amplifier 114,116,124,126,134,136, variable capacitance 118,128,138 and back end signal treatment circuit 140 be to be made in the chip 150.At present embodiment, chip 150 is a CMOS (Complementary Metal Oxide Semiconductor) chip (Complementary Metal-Oxide-Semiconductor chip, CMOS chip).In addition, low-pass filter circuit 111_1,111_2, high-pass filtering circuit 121_1,121_2 and inductance L
3_1, L
3_2, L
LB, L
HB, L
MBBe to be made in outside the chip 150, and be ready-made (off-the-shelf) element.
One of function of TV tuner 100 is to be used for that (frequency range is about the 48MHz～850MHz) and selects needed channel signals, carries out follow-up signal processing at the selected channel signals that goes out again from the TV signal Vin in a received broadband (broadband).For instance, if using a teleswitch now, the user selects a channel, and the centre frequency of this channel is 200MHz, then TV tuner 100 can be carried out the filtering operation to TV signal Vin, so that only there is near the signal the 200MHz frequency can enter back end signal treatment circuit 140 among the TV signal Vin, to carry out follow-up signal processing.And the Filtering Processing of TV tuner 100 mainly is divided into two stages, phase I is the filtering operation of prime, that is low-pass filter circuit 111_1,111_2, high-pass filtering circuit 121_1,121_2 or bandwidth-limited circuit 131_1, the filtering operation that 131_2 carried out, the filtering operation of phase I mainly is that the TV signal Vin with broadband (broadband) carries out low pass, high pass or bandpass filtering operation are to produce TV signal after the low-pass filtering, TV signal behind a TV signal or the bandpass filtering after one high-pass filtering, TV signal has a plurality of different TV channel signal respectively after these three filtering; Second stage is the tracking filter operation, that is tracking filter 117,127, the 137 filtering operations of being carried out, the filtering operation of second stage mainly is that TV signal behind TV signal or the bandpass filtering after TV signal, the high-pass filtering after the low-pass filtering is carried out the tracking filter operation to produce the single television channel signal, for instance, tracking filter 137 can carry out TV signal behind the bandpass filtering tracking filter to obtain the TV channel signal that centre frequency is 200MHz.But in the ordinary course of things, second stage is followed the trail of the filtering operation SAW filter of can arranging in pairs or groups, be used for target signal filter with the target channel adjacent band get cleaner, to produce this single television channel signal.
Be noted that low-pass filter circuit 111_1, high-pass filtering circuit 121_1 and bandwidth-limited circuit 131_1 are output node N who directly is electrically connected on transformer 102
1, and low-pass filter circuit 111_2, high-pass filtering circuit 121_2 and bandwidth-limited circuit 131_2 are output node N who directly is electrically connected on transformer 102
2In other words, do not have other element (for example switch element or the like) between node N1 and low-pass filter circuit 111_1, high-pass filtering circuit 121_1 and the bandwidth-limited circuit 131_1, and node N
2And also do not have other element between low-pass filter circuit 111_2, high-pass filtering circuit 121_2 and the bandwidth-limited circuit 131_2.In addition, in the embodiment shown in fig. 1, node N
1, N
2Respectively as two output nodes of transformer 102, yet, in other embodiments of the invention, node N
1, N
2Be the output that is coupled to transformer 102, that is, node N shown in Figure 1
1, N
2And can there be other element to exist between the transformer 102.
In the operation of tuner 100, at first, tuner 100 can decide the opening of amplifier 114,116,124,126,134,136 earlier according to the selected channel of user, and determine switch SW
1_1, SW
1_2, SW
2_1, SW
2_2, SW
3_1, SW
3_2, SW
3_3, SW
3_4Whether conducting.For instance, suppose that its centre frequency of the selected channel of user is 80MHz, that is for tuner 100 be low-frequency channel (that is, need to use first passage 110 to come TV signal Vin ' after the transformation is carried out filtering to select this channel), then tuner 100 can cut out the amplifier 124,126 of second channel 120 and the amplifier 134,136 of third channel 130.That is for TV signal Vin ' after the transformation that inputs to first, second, third passage 110,120,130, the amplifier 124,126 of second channel 120 and the amplifier 134,136 of third channel 130 can have great impedance.Therefore, TV signal Vin ' can carry out low-pass filtering by low-pass filter circuit 111_1,111_2 in the first passage 110 after the transformation under the situation of attenuated signal intensity not, to obtain required signal.In addition, this moment, tuner 100 also can be with switch SW
2_1, SW
2_2, SW
3_1, SW
3_2, SW
3_3, SW
3_4Conducting, and actuating switch SW not
1_1, SW
1_2, because with switch SW
2_1, SW
2_2, SW
3_1, SW
3_2, SW
3_3, SW
3_4The conducting meeting makes the situation that second channel 120 and third channel 130 are signal ground in those switch places.Thus, the front stage circuits of tuner 100 can form two low-pass filter circuits as shown in Figure 2, and therefore the exponent number of two low-pass filter circuits shown in Figure 2, can increase the low-pass filtering quality of tuner 100 than the exponent number height of low-pass filter circuit 111_1,111_2.Please refer to Fig. 3, Fig. 3 is the comparison schematic diagram of the transfer function (frequency response) of low-pass filter circuit shown in Figure 2 and low-pass filter circuit 111_1 shown in Figure 1.As shown in Figure 3, solid line partly is the transfer function of low-pass filter circuit shown in Figure 2, and dotted line partly is the transfer function of low-pass filter circuit 111_1.Relatively both difference can know that its transfer function of low-pass filter circuit shown in Figure 2 has a recess (notch) in the part of intermediate frequency, and therefore, the signal of intermediate-frequency section has bigger decay, and then promotes the low-pass filtering quality.
In addition, with its centre frequency of the selected channel of user is that 750MHz is an example, this frequency for tuner 100 be high frequency channel (that is, need to use second channel 120 to come TV signal Vin ' after the transformation is carried out filtering to select this channel), then tuner 100 can cut out the amplifier 114,116 of first passage 110 and the amplifier 134,136 of third channel 130.That is for TV signal Vin ' after the transformation that inputs to first, second, third passage 110,120,130, the amplifier 114,116 of first passage 110 and the amplifier 134,136 of third channel 130 can have great impedance.Therefore, TV signal Vin ' can carry out high-pass filtering by high-pass filtering circuit 121_1,121_2 in the second channel 120 after the transformation under the situation of attenuated signal intensity not, to obtain required signal.In addition, tuner 100 also can be with switch SW
1_1, SW
1_2, SW
3_1, SW
3_2, SW
3_3, SW
3_4Conducting, and actuating switch SW not
2_1, SW
2_2, because with switch SW
1_1, SW
1_2, SW
3_1, SW
3_2, SW
3_3, SW
3_4The conducting meeting makes the situation that first passage 110 and third channel 130 are signal ground in these switch places.Thus, the front stage circuits of tuner 100 can form two high-pass filtering circuits as shown in Figure 4, and therefore the exponent number of two high-pass filtering circuits shown in Figure 4, can increase the high-pass filtering quality of tuner 100 than exponent number (order) height of high-pass filtering circuit 121_1,121_2.Please refer to Fig. 5, Fig. 5 is the comparison schematic diagram of the transfer function (frequency response) of high-pass filtering circuit shown in Figure 4 and high-pass filtering circuit 121_1 shown in Figure 1.As shown in Figure 5, solid line partly is the transfer function of high-pass filtering circuit shown in Figure 4, and dotted line partly is the transfer function of high-pass filtering circuit 121_1.The difference that compares both, can know that its transfer function of high-pass filtering circuit shown in Figure 4 has a recess (notch) (referring to Fig. 5) in the part of low frequency, that is the signal of low frequency part has bigger strength retrogression, therefore, therefore high-pass filtering quality also can improve.
In addition, with its centre frequency of the selected channel of user is that 300MHz is an example, this frequency for tuner 100 be intermediate frequency channel (that is, need to use third channel 130 to come TV signal Vin ' after the transformation is carried out filtering to select this channel), then tuner 100 can cut out the amplifier 114,116 of first passage 110 and the amplifier 124,126 of second channel 120.That is for TV signal Vin ' after the transformation that inputs to first, second, third passage 110,120,130, the amplifier 114,116 of first passage 110 and the amplifier 124,126 of second channel 120 can have great impedance.Therefore, TV signal Vin ' can carry out filtering by bandwidth-limited circuit 131_1,131_2 in the third channel 130 after the transformation under the situation of attenuated signal intensity not, to obtain required signal.In addition, tuner 100 also can be with switch SW
1_1, SW
1_2, SW
2_1, SW
2_2Conducting, and actuating switch SW not
3_1, SW
3_2, SW
3_3, SW
3_4, with switch SW
1_1, SW
1_2, SW
2_1, SW
2_2The conducting meeting makes the situation that first passage 110 and second channel 120 are signal ground in these switch places.Thus, the front stage circuits of tuner 100 can form two bandwidth-limited circuits as shown in Figure 6, and therefore the exponent number of two bandwidth-limited circuits shown in Figure 6, can increase the bandpass filtering quality of tuner 100 than the exponent number height of bandwidth-limited circuit 131_1,131_2.Please refer to Fig. 7, Fig. 7 is the comparison schematic diagram of the transfer function (frequency response) of bandwidth-limited circuit shown in Figure 6 and bandwidth-limited circuit 131_1 shown in Figure 1.As shown in Figure 7, solid line partly is the transfer function of bandwidth-limited circuit shown in Figure 6, and dotted line partly is the transfer function of bandwidth-limited circuit 131_1.Relatively both difference can know that bandwidth-limited circuit shown in Figure 6 has bigger frequency range (bandwidth) (referring to Fig. 7), and therefore, the signal of intermediate-frequency section has less strength retrogression, and then promotes the bandpass filtering quality.
Take a broad view of the narration of above relevant Fig. 2 to Fig. 7, can know, though in embodiments of the invention, low-pass filter circuit 111_1,111_2, bandwidth-limited circuit 121_1,121_2, high-pass filtering circuit 131_1,131_2 only use simple elements to do in fact, yet, in embodiment shown in Figure 1, by the opening and the control switch SW of control amplifier 114,116,124,126,134,136
1_1, SW
1_2, SW
2_1, SW
2_2, SW
3_1, SW
3_2, SW
3_3, SW
3_4Conducting state, can allow filter circuit originally utilize the filter circuit element of other passage to reach better filtering quality.At length illustrate: when the selected channel of user is the channel of low frequency, because switch SW with low-pass filter circuit 111_1, high-pass filtering circuit 121_1, bandwidth-limited circuit 131_1
2_1, SW
2_2, SW
3_1, SW
3_2, SW
3_3, SW
3_4Conducting state, therefore, the low-pass filter circuit 111_1 of first passage 110, the capacitor C of second channel 120
2_1And the inductance L of third channel 130
3_1, capacitor C
3_1Can form the low-pass filter circuit of high-order as shown in Figure 2; In addition, when the selected channel of user is the channel of high frequency, because switch SW
1_1, SW
1_2, SW
3_1, SW
3_2, SW
3_3, SW
3_4Conducting state.Therefore, the inductance L of the high-pass filtering circuit 121_1 of second channel 120, first passage 110
1_1And the inductance L of third channel 130
3_1, capacitor C
3_1Can form the high-pass filtering circuit of high-order as shown in Figure 4; In addition, when the selected channel of user is the channel of intermediate frequency, because switch SW
1_1, SW
1_2, SW
3_1, SW
3_2, SW
3_3, SW
3_4Conducting state.Therefore, the inductance L of the bandwidth-limited circuit 131_1 of third channel 130, first passage 110
1_1And the capacitor C of second channel 120
2_1Can form the bandwidth-limited circuit of high-order as shown in Figure 6.Therefore, in embodiments of the invention, can utilize lower-cost filter circuit to reach preferable filtering quality.
After carrying out the filtering operation, the prime filter circuit of tuner 110 (as Fig. 2, Fig. 4 or filter circuit shown in Figure 6) TV signal Vin ' after to transformation can produce signal after the filtering.Afterwards, signal can be selected needed channel by tracking filter 117,127 or 137 afterwards more earlier via amplifier 114,116,124,126,134 or 136 processing after the filtering.Specifically, suppose the selected channel of user for having the channel of low frequency centre frequency (for example 80MHz), then after the transformation TV signal Vin ' can generation one low-pass filtering after by low-pass filter circuit filtering shown in Figure 2 after signal.Then, if signal has excessive amplitude (intensity) after this low-pass filtering, tuner 100 shutdown amplifiers 114 then, and after making that signal reduces intensity by attenuator 112 earlier after this low-pass filtering, by amplifier 116 signal is amplified to avoid amplifier 116 saturated again; Otherwise if the intensity of signal is in permissible range after this low-pass filtering, then shutdown amplifier 116, and make that signal directly amplifies signal by amplifier 114 after this low-pass filtering.Then, amplifier 114 or 116 signals of being exported can carry out the tracking filter operation to select needed channel signals by tracking filter 117, and the signal exported of tracking filter 117 carries out back end signal by back-end processing circuit 140 again and handles to produce an output signal Vout afterwards.
As in the operation of tracking filter 117, tuner 100 can be according to the selected channel of user, decide the capacitance of variable capacitance 118 in the tracking filter 117, so that the signal that tracking filter 117 is exported has correct frequency (that is centre frequency of the selected channel of user).The capacitance (for example: when TV has just been started shooting) before system stability that variable capacitance 118 corresponds to each channel decides according to an automatic adjustment mode, for instance, suppose that first passage 110 can be used for exporting the signal of 50 channels to back end signal treatment circuit 140, then before system stability, tuner 100 can test out 50 capacitances of variable capacitance 118, and these 50 capacitances make tracking filter 117 can correctly export the signal of these 50 channels respectively.
In addition, corresponding to aspect the capacitance of each channel at decision variable capacitance 118, in embodiments of the invention, is to utilize following mode to detect the capacitance that corresponds to each channel automatically.Please refer to Fig. 8, Fig. 8 is used for detecting automatically the installation drawing that variable capacitance 118 corresponds to the capacitance of each channel.As shown in Figure 8, one frequency generator 810 is coupled to the input of tracking filter 117, one signal strength detection unit 820 is coupled to the output of tracking filter 117, and one adjustment unit 830 be coupled between signal strength detection unit 820 and the variable capacitance 118, wherein frequency generator 810, signal strength detection unit 820 and adjustment unit 830 all are made in the chip 150.
Please also refer to Fig. 8 and Fig. 9, when Fig. 9 corresponds to the capacitance of each channel for beginning to detect variable capacitance 118 when tuner 100, the curve chart of the intensity level signal that the capacitance of variable capacitance 118 and signal strength detection unit 820 are exported.Be noted that shown in Figure 9 only is to be used for explaining that tuner 100 detects the example explanation that variable capacitances 118 correspond to the capacitance of each channel, and is not to be used as restriction of the present invention.Detecting in the operation of capacitance that variable capacitance 118 corresponds to each channel, at first, tuner can cut out amplifier 114 and 116 earlier, and variable capacitance has a default capacitance (C as shown in Figure 9 118 this moments
Pre).Afterwards, frequency generator 810 can produce the adjustment signal V with a characteristic frequency
FreTo the input of tracking filter 117, wherein adjust signal V
FreThis characteristic frequency be from the selected taking-up of a plurality of characteristic frequency, and these a plurality of characteristic frequency are respectively a plurality of television channel in the television system and distinguish corresponding a plurality of centre frequencies.Simple example supposes that tuner 100 will detect variable capacitance 118 and correspond to centre frequency when being the capacitance of a channel of 50MHz, and frequency generator 810 can produce have the adjustment signal V that characteristic frequency is 50MHz
FreInput to tracking filter 117.
Can produce adjustment signal V at frequency generator 810 with characteristic frequency
FreTo the input of tracking filter 117, tracking filter 117 is exchanged entire signal V
FreCarry out the filtering operation and after producing a filtering, adjust signal V
FilAfterwards, adjust signal V after signal strength detection unit 820 detection filter
FilIntensity level and produce an intensity level signal V
AThen, adjustment unit 830 is according to intensity level signal V
A(capacitance of variable capacitance 118 is adjusted into C in the embodiment of Fig. 9 to adjust the capacitance of variable capacitance 118
1).
At adjustment unit 830 according to intensity level signal V
AAdjust after the capacitance of variable capacitance 118, tracking filter 117 continues to exchange entire signal V
FreCarry out the filtering operation and after producing filtering, adjust signal V
Fil, and signal strength detection unit 820 also continues to adjust signal V after the detection filter
FilIntensity level and produce intensity level signal V
AIn addition, the capacitance of also constantly adjusting variable capacitance 118 after the adjustment unit 830 is adjusted signal V after 820 filtering in signal strength detection unit
FilIntensity level (intensity level signal V
A) can be judged as till the maximum intensity value.Figure 9 shows that example, when variable capacitance 118 has capacitance C
NThe time, can judge intensity level signal V with maximum
ATherefore, suppose to adjust this moment signal V
FreFrequency be 50MHz, then to correspond to centre frequency be that the capacitance of the channel of 50MHz is C to variable capacitance 118
N(that is, when after its centre frequency of the selected channel of user when being 50MHz, the capacitance of variable capacitance 118 can switch to C
N).
Be noted that, find out variable capacitance 118 corresponding to maximum intensity value signal V
AThe method flow of capacitance many kinds are arranged, Figure 9 shows that an example of climbing the mountain search method (mountain-climbing search method).Yet, in other embodiments of the invention, also can utilize other search algorithm (for example binary search) to find out variable capacitance 118 corresponding to maximum intensity value signal V
ACapacitance, these the design on variation all should be under the jurisdiction of category of the present invention.
Signal is earlier by amplifier 114,116,124,126,134 or 136 processing after getting back to previous relevant filtering, select in the narration of needed channel by tracking filter 117,127 or 137 more afterwards, aspect second channel 120, in like manner, suppose that the selected channel of user is the channel with high frequency centre frequency, then TV signal Vin ' can produce signal after the high-pass filtering after by high-pass filtering circuit filtering shown in Figure 4 after the transformation.Then, if signal has excessive amplitude (intensity) after this high-pass filtering, tuner 100 shutdown amplifiers 124 then, and after making that signal reduces intensity by attenuator 122 earlier after this high-pass filtering, by amplifier 126 signal is amplified to avoid amplifier 126 saturated again; Otherwise if the intensity of signal is in permissible range after this high-pass filtering, then shutdown amplifier 126, and make that signal directly amplifies signal by amplifier 124 after this high-pass filtering.Then, amplifier 124 or 126 signals of being exported can carry out the tracking filter operation to select needed channel signals by tracking filter 127, and the signal exported of tracking filter 127 carries out back end signal by back-end processing circuit 140 again and handles to produce output signal Vout afterwards.
As at tracking filter 127 and wherein aspect the adjustment of the capacitance of variable capacitance 128, be very similar with the narrating content of above-mentioned relevant tracking filter 117 and variable capacitance 118, have in this area and know that usually the knowledgeable should be able to can recognize tracking filter 127 and the wherein operation of variable capacitance 128 in the narration of reading above-mentioned relevant tracking filter 117 and variable capacitance 118, therefore, details does not repeat them here.
In like manner, aspect third channel 130, suppose that the selected channel of user is the channel with intermediate frequency center frequency, then TV signal Vin ' can produce signal behind the bandpass filtering after by bandwidth-limited circuit filtering shown in Figure 6 after the transformation, then, if signal has excessive amplitude (intensity) behind this bandpass filtering, tuner 100 shutdown amplifiers 134 then, and after making that signal reduces intensity by attenuator 132 earlier behind this bandpass filtering, by amplifier 136 signal is amplified to avoid amplifier 136 saturated again; Otherwise if the intensity of signal is in permissible range behind this bandpass filtering, then shutdown amplifier 136, and make that signal directly amplifies signal by amplifier 134 behind this bandpass filtering.Then, amplifier 134 or 136 signals of being exported can carry out the tracking filter operation to select needed channel signals by tracking filter 137, and the signal exported of tracking filter 137 carries out back end signal by back-end processing circuit 140 again and handles to produce output signal Vout afterwards.
As at tracking filter 137 and wherein aspect the adjustment of the capacitance of variable capacitance 138, it is very similar with the narrating content of above-mentioned relevant tracking filter 117 and variable capacitance 118, have in this area and know that usually the knowledgeable should be able to can recognize tracking filter 137 and the wherein operation of variable capacitance 138 in the narration of reading above-mentioned relevant tracking filter 117 and variable capacitance 118, therefore, details does not repeat them here.
In addition, in another embodiment of the present invention, first passage 110, second channel 120, can only have an amplifier in the third channel 130, that is, amplifier 114, one of them can remove in first passage 110 (if remove amplifier 116 in 116, then attenuator 112 also can remove in the lump), amplifier 124, one of them can remove in second channel 120 (if remove amplifier 126 in 126, then attenuator 122 also can remove in the lump), and amplifier 134, one of them can remove in third channel 130 (if remove amplifier 136 in 136, then attenuator 132 also can remove in the lump), the variation in these designs all should be under the jurisdiction of category of the present invention.
In addition, tuner 100 shown in Figure 1 is full differential architecture (fully differential configuration), that is, transformer 102 is output one differential waves, and first passage 110, second channel 120 and third channel 130 have two filter circuits respectively so that this differential wave (that is, TV signal Vin ' after the transformation shown in Figure 1) is carried out filtering.It has been reduction noise jamming (noise coupling) and harmonic distortion (harmonic distortion) that tuner 100 uses the purpose of full differential architecture, yet, in another embodiment of the present invention, tuner 100 can also use single-ended framework to save cost, that is low-pass filter circuit 111_2, high-pass filtering circuit 121_2 and bandwidth-limited circuit 131_2 can remove in the self-tuner 100, have in this area and know that usually the knowledgeable should be able to be after reading the above-mentioned relevant operation of tuner 100, easily tuner 100 is designed to single-ended framework, therefore, details does not repeat them here.
Concise and to the point conclusion the present invention in the front stage circuits of tuner of the present invention, only needs to use simple elements promptly can reach higher filtering quality; In addition, tuner of the present invention is that most element is made in the silicon, therefore has smaller volume and lower manufacturing cost.
The above only is preferred embodiment of the present invention, and all equalizations of being done according to the present patent application claim change and modify, and all should belong to covering scope of the present invention.
Claims (20)
1. the front stage circuits of a tuner includes:
One transformer is used for converting a single-ended signal to a differential wave; And
A plurality of passages include a filter circuit respectively, and wherein the filter circuit of these a plurality of passages all directly is electrically connected on a node, and this node is coupled to an output of this transformer.
2. front stage circuits according to claim 1, it is characterized in that, these a plurality of passages include an at least one first passage and a second channel, this first, second passage comprises one first filter circuit and one second filter circuit respectively, and this first filter circuit and this second filter circuit have two filtering characteristics in a low-frequency filter characteristics, a high-pass filtering characteristic and the band-pass filtering property respectively.
3. front stage circuits according to claim 1, it is characterized in that, these a plurality of passages include a first passage, a second channel and a third channel, and this first, second and third channel comprise one first filter circuit, one second filter circuit and one the 3rd filter circuit respectively, this first filter circuit includes:
One first inductance, wherein one first end points of this first inductance is this output that directly is electrically connected on this transformer; And
One first electric capacity is coupled between one second end points and a reference voltage of this first inductance;
This second filter circuit includes:
One second electric capacity, wherein one first end points of this second electric capacity is this output that directly is electrically connected on this transformer; And
One second inductance is coupled between one second end points and this reference voltage of this second electric capacity;
The 3rd filter circuit includes:
One the 3rd inductance, wherein one first end points of the 3rd inductance is this output that directly is electrically connected on this transformer; And
One the 3rd electric capacity is coupled between the output of one second end points of the 3rd inductance and the 3rd filter circuit.
4. front stage circuits according to claim 3 is characterized in that, this first passage includes one first switch in addition, and this first switch is to be coupled between this second end points and this reference voltage of this first inductance; This second channel includes a second switch in addition, and this second switch is to be coupled between this second end points and this reference voltage of this second electric capacity; And this third channel includes one the 3rd switch in addition, and the 3rd switch is to be coupled between this second end points and this reference voltage of the 3rd inductance.
5. front stage circuits according to claim 4 is characterized in that, when this tuner carries out the channel selection operation, this first, second and the 3rd switch in only have a switch to be conducting state not, and two other switch is a conducting state.
6. front stage circuits according to claim 4 is characterized in that, this first switch, this second switch and the 3rd switch are to be arranged in the middle of the chip, and this first inductance, this second inductance and the 3rd inductance are to be arranged at outside this chip.
7. front stage circuits according to claim 6 is characterized in that, the 3rd electric capacity is to be arranged in the middle of this chip, and this first electric capacity and this second electric capacity are to be arranged at outside this chip.
8. tuner includes:
A plurality of passages, wherein at least one passage includes:
One prime filter circuit;
One differential amplifier is coupled to this prime filter circuit; And
One tracking filter includes:
One variable capacitance is coupled to two outputs of this differential amplifier; And
One inductance is parallel to this variable capacitance;
Wherein this amplifier and this variable capacitance are to be arranged in the CMOS (Complementary Metal Oxide Semiconductor) chip at least.
9. tuner according to claim 8 is characterized in that, this prime filter circuit includes:
One transformer is used for converting single-ended signal to differential wave; And
A plurality of passages include a filter circuit respectively, and wherein this filter circuit of these a plurality of passages all directly is electrically connected on a node, and this node is an output that is coupled to this transformer.
10. tuner according to claim 8 is characterized in that, also comprises an attenuator, and it is coupled between this prime filter circuit and the differential amplifier.
11. tuner according to claim 8 is characterized in that, this inductance is to be arranged in this CMOS (Complementary Metal Oxide Semiconductor) chip.
12. tuner according to claim 8 is characterized in that, this passage includes in addition:
One frequency generator, be coupled to an input of this tracking filter, be used for producing one and adjust signal this input to this tracking filter, wherein this adjustment signal has a characteristic frequency, and this tracking filter carries out the filtering operation to this adjustment signal adjust signal after producing a filtering;
One signal strength detection unit is coupled to this tracking filter, is used for detecting an intensity level of adjusting signal after this filtering; And
One adjustment unit is coupled to this signal strength detection unit, is used for adjusting according to this intensity level of adjusting signal after this filtering the capacitance of this variable capacitance.
13. tuner according to claim 12, it is characterized in that, this adjustment unit is constantly adjusted the capacitance of this variable capacitance, till the intensity level of adjustment signal can be judged as a maximum intensity value after this signal strength detection unit detects this filtering.
14. tuner according to claim 12, it is characterized in that, this frequency generator is chosen this characteristic frequency from a plurality of characteristic frequency and is produced this adjustment signal, and these a plurality of characteristic frequency are respectively a plurality of television channel in the television system and distinguish corresponding a plurality of centre frequencies.
15. a tuner includes:
A plurality of passages, wherein at least one passage includes:
One prime filter circuit;
One amplifier is coupled to this prime filter circuit; And
One tracking filter includes:
One variable capacitance is coupled to an output and an earth terminal of this amplifier; And
One inductance is parallel to this variable capacitance;
Wherein this amplifier and this variable capacitance are to be arranged in the chip at least, and this inductance is to be external in this chip.
16. tuner according to claim 15 is characterized in that, this prime filter circuit includes:
A plurality of passages include a filter circuit respectively, and wherein this filter circuit of these a plurality of passages all directly is electrically connected on a node.
17. tuner according to claim 15 is characterized in that, also comprises an attenuator, it is coupled between this prime filter circuit and the amplifier.
18. tuner according to claim 15 is characterized in that, this passage includes in addition:
One frequency generator, be coupled to an input of this tracking filter, be used for producing one and adjust signal this input to this tracking filter, wherein this adjustment signal has a characteristic frequency, and this tracking filter carries out the filtering operation to this adjustment signal adjust signal after producing a filtering;
One signal strength detection unit is coupled to this tracking filter, is used for detecting an intensity level of adjusting signal after this filtering; And
One adjustment unit is coupled to this signal strength detection unit, is used for adjusting according to this intensity level of adjusting signal after this filtering the capacitance of this variable capacitance.
19. tuner according to claim 18, it is characterized in that, this adjustment unit is constantly adjusted the capacitance of this variable capacitance, till the intensity level of adjustment signal can be judged as a maximum intensity value after this signal strength detection unit detects this filtering.
20. tuner according to claim 18, it is characterized in that, this frequency generator is chosen this characteristic frequency from a plurality of characteristic frequency and is produced this adjustment signal, and these a plurality of characteristic frequency are respectively a plurality of television channel in the television system and distinguish corresponding a plurality of centre frequencies.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200910175018.4A CN102025346B (en) | 2009-09-11 | 2009-09-11 | Tuner and pre-circuit thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200910175018.4A CN102025346B (en) | 2009-09-11 | 2009-09-11 | Tuner and pre-circuit thereof |
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| Publication Number | Publication Date |
|---|---|
| CN102025346A true CN102025346A (en) | 2011-04-20 |
| CN102025346B CN102025346B (en) | 2014-09-17 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN200910175018.4A Active CN102025346B (en) | 2009-09-11 | 2009-09-11 | Tuner and pre-circuit thereof |
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| Country | Link |
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| CN (1) | CN102025346B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104579408A (en) * | 2013-12-19 | 2015-04-29 | 深圳市金溢科技股份有限公司 | On-board unit (OBU) and awakening receiving circuit thereof |
| CN104853170A (en) * | 2014-02-14 | 2015-08-19 | 宏观微电子股份有限公司 | Integrated circuit chip for receiver collecting signals from satellites |
| CN114731170A (en) * | 2019-11-20 | 2022-07-08 | 株式会社村田制作所 | High-frequency module and communication device |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1190964C (en) * | 2000-02-14 | 2005-02-23 | 夏普公司 | Tuner of cable modem |
| US6940365B2 (en) * | 2003-07-18 | 2005-09-06 | Rfstream Corporation | Methods and apparatus for an improved discrete LC filter |
| KR100733981B1 (en) * | 2005-07-05 | 2007-07-02 | 삼성전자주식회사 | Tuner And Broadcast Processing Apparatus Comprising The Same |
| US7620381B2 (en) * | 2006-05-21 | 2009-11-17 | Realtek Semiconductor Corp. | Tri-state chopper for frequency conversion |
| TWI470928B (en) * | 2009-09-02 | 2015-01-21 | Mstar Semiconductor Inc | Tuner and its front-end circuit |
-
2009
- 2009-09-11 CN CN200910175018.4A patent/CN102025346B/en active Active
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104579408A (en) * | 2013-12-19 | 2015-04-29 | 深圳市金溢科技股份有限公司 | On-board unit (OBU) and awakening receiving circuit thereof |
| CN104579408B (en) * | 2013-12-19 | 2017-03-29 | 深圳市金溢科技股份有限公司 | Board units OBU and its wake-up receiving circuit |
| CN104853170A (en) * | 2014-02-14 | 2015-08-19 | 宏观微电子股份有限公司 | Integrated circuit chip for receiver collecting signals from satellites |
| CN104853170B (en) * | 2014-02-14 | 2017-12-05 | 宏观微电子股份有限公司 | A kind of IC chip for being used to collect the receiver of satellite-signal |
| CN114731170A (en) * | 2019-11-20 | 2022-07-08 | 株式会社村田制作所 | High-frequency module and communication device |
| CN114731170B (en) * | 2019-11-20 | 2023-12-22 | 株式会社村田制作所 | High-frequency module and communication device |
Also Published As
| Publication number | Publication date |
|---|---|
| CN102025346B (en) | 2014-09-17 |
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Effective date of registration: 20201022 Address after: No. 1, Xingzhu Road, Hsinchu Science Park, Taiwan, China Patentee after: MEDIATEK Inc. Address before: 405, 4th floor, 1st District, Shenzhen Bay science and technology ecological park, Aohai street, Nanshan District, Shenzhen City, Guangdong Province Patentee before: Mstar Semiconductor,Inc. Patentee before: MEDIATEK Inc. Effective date of registration: 20201022 Address after: 405, 4th floor, 1st District, Shenzhen Bay science and technology ecological park, Aohai street, Nanshan District, Shenzhen City, Guangdong Province Patentee after: Mstar Semiconductor,Inc. Patentee after: MEDIATEK Inc. Address before: 518057, Guangdong, Shenzhen hi tech Zone, South District, science and technology, South ten road, Shenzhen Institute of Aerospace Science and technology innovation, C block, building 4 Patentee before: Mstar Semiconductor,Inc. Patentee before: MSTAR SEMICONDUCTOR Inc. |