GB2324665A

GB2324665A - VTR tuner assembly with rejection of modulator harmonics in tuner channel

Info

Publication number: GB2324665A
Application number: GB9807410A
Authority: GB
Inventors: Masahiko Saito; Machinori Sasaki
Original assignee: Alps Electric Co Ltd
Current assignee: Alps Alpine Co Ltd
Priority date: 1997-04-25
Filing date: 1998-04-07
Publication date: 1998-10-28
Anticipated expiration: 2018-04-07
Also published as: MY120737A; GB9807410D0; GB2324665B; KR100247832B1; JPH10303766A; CN1090843C; JP3573591B2; CN1198617A; KR19980081684A

Abstract

Low pass filters 18 and 19 are inserted before the mixers 12,15 in the UHF and VHF receiver channels in a video tape recorder tuner. The filters reject harmonics emanating from the modulation carrier signal generator 9, which is enclosed in the same metal housing as the receiver circuits. The filters are added because the harmonics from the modulation carrier signal generator 9 can mix with local oscillator 13,16 harmonics to produce interfering modulation products in the desired signal frequency band.The filters may be of m-derived type or may be constant-k T,L or Pi sections.

Description

riIGH-FREQUENCY ELECTRONIC DEVICE This invention relates to a high-frequency electronic device wherein a modulation part and a tuner part are configured within a single metal housing.

A high-frequency electronic device having a modulation part and a tuner provided within a single metal housing has been used in a recent video tape recorder (hereinafter called "VTR").

Fig. 4 is a block diagram for describing this type of prior high-frequency electronic device. In Fig. 4, a high-frequency electronic device 41 comprises a modulation part 44 and a tuner part 45 mounted on a printed wiring board 43 held within a single metal housing 42. The modulation part 44 includes a distributor 46, a mixer 47, a modulator 48, a PLL circuit 49, etc. On the other hand, the tuner part 45 includes a VHF high-frequency unit 50, a VHF mixer 51, a VHF local oscillator 52, a UHF high-frequency unit 53, a UHF mixer 54, a UHF local oscillator 55, an intermediate frequency amplifier 56, etc.

Further, an input terminal 57 and an output terminal 58 are attached to the metal housing 42. Moreover, the modulation part 44 and the tuner part 45 are shielded from each other by a shielding plate 59 electrically connected to the metal housing 42.

A television signal inputted to the input terminal 57 is inputted to an unillustrated television receiver from the output terminal 58 through the distributor 46 and the mixer 47. On the other hand, the television signal distributed by the distributor 6 is ir,putted to the VHF high-frequency unit 50 and the UHF high-frequency unit 53 of the tuner part 45.

Further, the PLL circuit 49 of the modulation part 44 is provided with a voltage-controlled oscillator (hereinafter called "VCO") for outputting an unillustrated carrier signal.

The carrier signal outputted from the VCO is modulated by the modulator 48 based on a video signal or the ike reproduced by an unillustrated VTR. The modulated signal is inputted to the unillustrated television receiver through the mixer 47 and the output terminal 58 as a television signal. Thus, the frequency of the carrier signal outputted from the VCO is controlled by the PLL circuit 49 so as to coincide with the frequency of a predetermined video carrier signal receivable by the television receiver. However, the present frequency is normally set to the frequency of a channel unused for a broadcast in the area where the VTR is used.

On the other hand, the VHF high-frequency unit 50 of the tuner part 45 selects a television signal in a desired channel form television signals in a VHF band. Similarly, the UHF high-frequency unit 53 of the tuner part 45 selects a television signal in a desired channel from television signals in a UHF band. Although not shown in the drawing, each of the VHF high-frequency unit 50 and the UHF high-frequency unit 53 has an input tuning circuit comprised of a single-tuned circuit, a high-frequency amplifier, an interstage tuning circuit comprised of a double-tuned circuit, etc. The television signals in the selected channels are inputted from their interstage tuning circuits to the VHF mixer 51 and the UHF mixer 54 respectively. Thereafter, the television signals are mixed with local oscillation signals outputted from the VHF local oscillator 52 and the UHF local oscillator 55, so that the mixed signal is frequency-converted into an intermediate frequency signal, after which it is inputted to an unillustrated post-stage circuit through the intermediate frequency amplifier 56.

In the prior high-frequency electronic device, however, a supply voltage is always applied to the modulation part 44 and the tuner part 45 regardless of upon recording and reproduction of the VTR when the high-frequency electronic device is in a state of being built in the VTR. Therefore, a harmonic of an oscillation signal (carrier wave) outputted from the VCO of the PLL circuit 49 in the modulation part 44 easily leaps or jumps at the VHF high-frequency unit 50 or the UHF high-frequency unit 53 of the tuner part 45. The jumped harmonic is inputted to the VHF mixer 51 and the UHF mixer 54 through the VHF high-frequency unit 50 or the UHF high-frequency unit 53. The harmonic is mixed with a harmonic of a local oscillation signal outputted from the VHF local oscillator 52 or the UHF local oscillator 55 by the VHF mixer 51 or the UHF mixer 54. As a result, a problem arises in that an interference signal of a frequency extremely close to that of the intermediate frequency signal is produced.

The above-described one example confronting the problem will be explained for cases where the prior high-frequency electronic device is used in a VTR whose output channel is set to a channel 32 (that is to say, a carrier signal outputted from the VCO in the modulation part 44 is set to the frequency of the channel 32) and which is placed under European specificatIons such as German specifications, and a channel 26 is recorded by the VTR.

In this case, the channel 26 employed in the European television system corresponds to a UHF band. The UHF local oscillator 55 of the tuner part 5 in the high-frequency electronic device 41 outputs a local oscillation signal of 550.15MHz. On the other hand, since the output channel of the VTR is set to the channel 32, the VCO of the PLL circuit 49 in the modulation part 4 oscillates at 559.25MHz. Although the two oscillation signals are inputted to the UHF mixer 54, their harmonics are also inputted thereto.

Further, the frequency corresponding to the difference between a fourth harmonic (2237MHz) of an oscillation signal produced from the VCO and a fourth harmonic (2200.6MHz) of an oscillation signal produced from the UHF local oscillator 55 results in 36.4MHz. This frequency (36.4MHz) falls between a video intermediate frequency (38.9MHz) and a speech or voice intermediate frequency (33.4MHz) employed in a television system placed under European specifications, thus resulting in an interference signal against the normal receiving channel 26. As a result, the quality of an image for the recorded television signal is deteriorated.

The interference signals based on the above-described relations will occur according to many combinations such as where the output channel of the VTR is set to the channel 63 when the receiving channel corresponds to the channel 26, where the output channel of the VTR is set to a channel 44 or 54 when the receiving c-arrel corresponds to a channel 38, where the output channel of the VTR is set to a channel 22 or 52 when the receiving channel corresponds to a cnannel 46, etc.

With the foregoing problems in view, it is therefore an object of this Invention to provide a high-frequency electronic device wherein interference signals developed by an oscillation signal produced from a modulation part and an oscillation signal produced from a tuner part at the time that the modulation part and the tuner part are activated simultaneously, can be controlled low in level so as to improve the quality of an image.

According to one aspect of this invention, for achieving the above object, there is provided a high-frequency electronic device comprising: a metal housing; a printed wiring board held within the metal housing; a modulation part formed on the printed wiring board and having an oscillator; and a tuner part including a high-frequency portion formed on the printed wiring board, for selecting a television signal to be received from television signals and outputting the selected television signal, a mixer or effecting frequency conversion on the selected television signal outputted from the high-frequency portion and a local oscillator for supplying a local oscillation signal to the mixer, wherein the high-frequency portion has an interstage tuning circuit for inputting the selected television signal to the mixer, and wherein a low-pass filter is connected between the interstage tuning circuit and the mixer so that a cut-off frequency thereof is set so as to be higher than the maximum frequency of the television signal received by the high-frequency portion.

Preferably, in the high-frequency electronic device of the present invention, the high-fequency portion includes a UHF high-frequency unit for selecting a television signal in a UHF band to be received from television signals in the UHF band and outputting the selected television signal, the mixer includes a UHF mixer for effecting frequency conversion on the selected television outputted from the UHF high- frequency unit, the local oscillator includes a UHF local oscillator for supplying a local oscillation signal to the UHF mixer, the UHF high-frequency unit includes a UHF interstate tuning circuit for inputting the selected television signal in the UHF band to the UHF mixer, and the low-pass filter is electrically connected between at least the UHF interstage tuning circuit and the UHF mixer.

Preferably, in the high-frequency electronic device of the present invention, the low-pass filter comprises an Ltype low-pass filter comprised of an inductive element and a capacitive element electrically connected between one end of the inductive element and ground.

Preferably, in the high-frequency electronic device of the present invent ion, the low-pass filter comprises a derived M-type low-pass filter comprised of an inductive element and a capacitor electrically parallel-connected to one another and a capacitive element electrically connected between one ends of the mutually parallel-connected inductive element and capacitor and ground.

Preferably, in the high-frequency electronic device of the present invention, the capacitive element is made up of a stray capacitance formed between two conductive patterns provided on the printed wiring board.

While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention, it is believed that the invention, the objects and features of the invention and further objects, features and advantages thereof will be better understood from the following description taken in connection with the accompanying drawings in which: Fig. 1 is a block diagram showing a high-frequency electronic device of the present invention; Fig. 2 is a circuit diagram illustrating a low-pass filter employed in the high-frequency electronic device of the present invent ion; Fig. 3 is a diagram for describing a method of forming a capacitor of the low-pass filter employed in the highfrequency electronic device of the present invention; and Fig. 4 is a block diagram showing a conventional high-frequency electronic device.

An embodiment of the invention, by way of example only, will hereinafter bedescribedwith reference to Figs.

1 through 3. First, Fig. 1 is a block diagram showing a high-frequency electronic device of the present invention.

The high-frequency electronic device 1 comprises a modulation part g and a tuner part 5 mounted or installed on a printed wiring board 3 held within a single metal housing 2. Further, the modulation part 4 includes a distributor 5, a mixer 7, a modulator 8, a PLL circuit 9, etc. The PLL circuit 9 has a voltage-controlled oscillator (hereinafter called "VCO") 10 which serves as an oscillator for generating a carrier signal.

On the other hand, the tuner part 5 comprises a VHF high-frequency unit 11 which serves as ahigh-frequencysection for selecting and outputting a television signal lying within a VHF band to be received from television signals in the VHF band, a VHF mixer 12 which serves as a mixer for frequency-converting the television signal in the VHF band outputted from the VHF high-frequency unit 11 into an intermediate frequency signal and outputting the intermediate frequency signal, a VHF local oscillator 13 which serves as a local oscillator for supplying a local oscillation signal to the VHF mixer 12, a UHF high-frequency unit 14 which serves as a high-frequency section for selecting and outputting a television signal lying in a UHF band to be received from television signals in the UHF band, a UHF mixer 15 which serves as a mixer for frequency-converting the television signal in the UHF band outputted from the UHF high-frequency unit 14 into an intermediate frequency signal and outputting the intermediate frequency signal, a UHF local oscillator 16 which serves as a local oscillator for supplying a local oscillation signal to the UHF mixer 15, an intermediate frequency amplifier 17 for amplifying the intermediate frequency signal outputted from the VHF mixer 12 or the UHF mixer 15, etc.

Further, each of the VHF high-frequency unit 11 and the UHF high-frequency unit 14 has an input tuning circuit, a high-frequency amplifier, an interstage tuning circuit, etc.

Moreover, a first low-pass filter 18 and a second low-pass filter 19 are respectively provided between the VHF highfrequency unit 11 and the VHF mixer 12 and between the UHF high-frequency unit 14 and the UHF mixer 15.

Now, the VHF high-frequency unit 11 is configured in such amanner that aVHF input tuning circuit 20, aVHFhigh-frequency amplifier 21 and a VHF interstage tuning circuit 22 are successively electrically connected to one another. Further, the UHF high-frequency unit 14 is also constructed so that a UHF input tuning circuit 23, a UHF high-frequency amplifier 24 and a UHF interstage tuning circuit 25 are successively electrically connected to one another. The first low-pass filter 18 is electrically connected to the VHF interstage tuning circuit 22 of the VHF high-frequency unit 11 and the VHF mixer 12, whereas the second low-pass filter 19 is electrically connected to the UHF interstage tuning circuit 25 of the UHF high-frequency unit 14 and the UHF mixer 15.

The first low-pass filter 18 comprises a derived M-type filter and has a first Inductive element 26 and a first capacitor 27 electrically parallel-connected to one another, and a second capacitor 28 which serves as a capacitive element electrically connected between one ends of the parallel-connected first inductive element 26 and first capacitor 27 and ground.

Similarly, the second low-pass filter 19 also comprises a derived M-type filter and includes a second inductive element 29 and a third capacitor 30 electrically parallel-connected to one another, and a fourth capacitor 31 which serves as a capacitive element electrIcally connected between one ends of the parallel-connected second inductive element 29 and third capacitor 30 and ground.

The first low-pass filter 18 allows a television signal having the highest or maximum frequency (230MHz in the European television system), of the television signals in the VHF band received by the VHF high-frequency unit 11 to pass therethrough and thereby sets a cut-off frequency thereof between 1000MHz and 1500MHz, for example so as to attenuate a signal of a frequency higher than the maximum frequency. Further, the second low-pass filter 19 allows a television signal having the maximum frequency (corresponding to 862MHz in the European television system), of the television signals in the UHF band received by the UHF high-frequency unit 14 to pass therethrough and thereby sets a cut-off frequency thereof between 1500MHz and 2000MHz, for example so as to attenuate a signal having a frequency higher than the maximum frequency.

Therefore, the VHF mixer 12 is blocked from the input of signals of frequencies above about 1000MHz to 1500MHz each corresponding to the cut-off frequency. Alternatively, even if the signals are input to the VHF mixer 12, they are controlled low in level. Similarly, the UHF mixer 15 is blocked from the input of signals having frequencies above about 1500MHz to 2000MHz. Alternatively, even if the signals are input to the UHF mixer 15, they are controlled low in level.

Incidentally, an input terminal 32 and an output terminal 33 are attached to the metal housing 2 of the high-frequency electronic device 1 according to the present invention.

Further, the modulation part 4 and the tuner part 5 are shielded from each other by a shielding plate 34 electrically connected to the metal housing 2.

A television signal input to the input terminal 32 is inputted via the distributor 6 and the mixer 7 from the output terminal 33 to an unillustrated television receiver where the television signal can be viewed. On the other hand, the television signal distributed by the distributor 6 is to be inputted to the VHF high-frequency unit 11 and the UHF high-frequency unit 14 of the tuner part 5. Further, an oscillation signal outputted from the VCO 10 of the PLL circuit 9 in the modulation part 4 is set as a carrier signal. The carrier signal is modulated by the modulator 8 based on a video signal or the like reproduced by an unillustrated VTR with the high-frequency electronic device 1 incorporated therein.

Thereafter, the modulated signal is inputted to the unillustrated television receiver through the mixer 7 and the output terminal 33 as a television signal.

Thus, the frequency of the carrier signal outputted from the VCO 10 is matched with the frequency of a predetermined video carrier signal corresponding to a channel determined by a television system so that it can be received by the television receiver. Therefore1 the VCO 10 is PLL-controlled for its matching. The frequency of the carrier signal is generally set to the frequency of a channel unused for a broadcast in the area where the VTR is used. However, this frequency can be set to the frequency of an arbitrary channel by the PLL circuit 9.

On the other hand, the VHF high-frequency unit 11 of the tuner part 5 selects a television signal in a desired channel from the television signals in the VHF band. Similarly, the UHF high-frequency unit 14 selects a television signal in a desired channel from the television signals in the UHF band.

The selected television signal in the VHF band is outputted from the VHF interstage tuning circuit 22, after which it is inputted to the VHF mixer 12 through the first low-pass filter 18. Similarly, the television signal in the UHF band selected by the UHF high-frequency unit 14 is outputted from the UHF interstage tuning circuit 25, after which it is inputted to the UHF mixer 15 through the second low-pass filter 19.

As described above, the first low-pass filter 18 has the cut-off frequency set to the frequency (e.g., 1500MHz) higher than the maximum frequency of the television signal in the VHF band received by the VHF high-frequency unit 11. Therefore, the VHF mixer 12 is blocked from the input of the harmonic above 1500MHz from the VCO 10 of the PLL circuit 9 in the modulation part , or the level of the harmonic is controlled low even i- the harmonic is inputted to the VHF mixer 12. Similarly, the second low-pass filter 31 has the cut-off frequency set to the frequency (e.g., 2000MHz) higher than the maximum frequency of the television signal in the UHF band received by the UHF high-frequency unit 14. Therefore, the UHF mixer 15 is blocked from the input of the harmonic above 2000MHz from the VCO 10 of the PLL circuit 9 in the modulation part 4, or the level of the harmonic is controlled low even if it is inputted to the UHF mixer 15.

The television signal in the VHF band input ted to the VHF mixer 12 is mixed with a local oscillation signal outputted from the VHF local oscillator 13 by the VHF mixer 12 so that the television signal is frequency-converted into an intermediate frequency signal. Thus, the intermediate frequency output is inputted to an unillustrated circuit placed in the subsequent stage through the intermediate frequency amplifier 17. Similarly, the television signal in the UHF band inputted to the UHF mixer 15 is mixed with a local oscillation signal outputted from the UHF local oscillator 16 by the UHF mixer 15 so that the television signal is frequency-converted into an intermediate frequency signal. Thus, the converted intermediate frequency output is inputted to the unillustrated post-stage circuit through the intermediate frequency amplifier 17. An unillustrated video demodulator and the like are provided at the stage subsequent to the intermediate frequency amplifier 17. A video signal demodulated by the video demodulator is recorded.

Since the first low-pass filter 18 is provided between the VHF interstage tuning circuit 22 of the VHF high-frequency unit 11 and the VHF mixer 12 and the second low-pass filter 19 is provided between the UHF interstage tuning circuit 25 of the UHF high-frequency unit 14 and the UHF mixer 15 in the high-frequency electronic device of the present invention as described above, the harmonic of the oscillation signal outputted from the VCO 10 of the PLL circuit 9 in the modulation part 4 is hard to be input to the VHF mixer 12 and the UHF mixer 15, so that interference signals generated in the VHF mixer 12 and the UHF mixer 15 can be controlled very low in level.

If a comparison is made between the harmonic produced from the VHF local oscillator 13 and the harmonic produced from the UHF local oscillator 16, both of which are mixed with the harmonic of the oscillation signal outputted from the VCO 10 to thereby produce the interference signals, then the degree of the harmonic produced from the UHF local oscillator 16 is ow and hence the harmonic produced from the UHF local oscillator 16 becomes nigh in level (the level of each harmonic becomes high in general as the degree thereof decreases).

Therefore, the interference signal is pronouncedly outputted from the UHF mixer 15 rather than from the VHF mixer 12. Thus, the provision of the second low-pass filter 19 at least between the UHF interstage tuning circuit 25 of the UHF high-frequency unit 14 and the UHF mixer 15 permits effective prevention of the occurrence of the interference signals.

Circuit configurations of the first low-pass filter 18 and the second low-pass filter 19 are not limited to the circuit configuration of the derived M-type low-pass filter shown in Fig. 1. Theymayutilize constant K-type fIlters suchasT-type, type, etc. or an L-type low-pass filter 35 shown in Fig. 2, which is configured in a mid-section of the constant K-type filter. Since the low-pass filter 35 can be simply made up of two parts of an inductive element 36 and a capacitor 37 corresponding to a capacitive element connected to ground, it does not make up an extra space for the printed wiring board 3 held within the metal housing 2. The matching of the impedance of the VHF interstage tuning circuit 22 to that of the VHF mixer 12, and the matching of the impedance of the UHF interstage tuning circuit 25 to that of the UHF mixer 15 can be simply obtained.

If the first low-pass filter 18 and the second low-pass filter 19 are configured as the derived M-type low-pass filter shown in Fig. 1, then the harmonics produced from the VCO 10, which exist in a range up to the neighborhood of the cut-off frequency can be attenuated. Therefore, many interference signals produced in the VHF mixer 12 or the UHF mixer 15 can be suppressed.

Since any of the second capacitor 28 of the first low-pass filter 18 and the second capacitor 31 of the second low-pass filter 19 both shown in Fig. 1 and the capacitor 37 shown in Fig. 2 is used as the capacitive element connected to ground, these capacitors 28, 31 and 37 can be replaced with a stray capacitance 40 created between two conductive patterns 38 and 39 provided on a printed wiring board 3 as shown in Fig. 3.

Thecoil 36 of thelow-pass filter 35 showninFig. 2, forexample, is electrically connected to one conductive pattern 38 and the other conductive pattern 39 may be electrically connected to the metal housing 2. Thus, if the stray capacitance 40 using the printed wiring board 3 is used, then the capacitor 37 can be eliminated.

As described above, the high-frequency electronic device according to the present invention includes a modulation part having an oscillator, and a tuner part having a high-frequency unit, a mixer and a local oscillator. The high-frequency unit has an interstage tuning circuit. Further, a low-pass filter is electrically connected between the interstage tuning circuit and the mixer to set a cut-off frequency thereof to a frequency higher than the maximum frequency of a television signal received by the high-frequency unit. Therefore, a harmonic of an oscillation signal produced from the oscillator of the modulation part is hard to be input to the mixer, so that an interference signal produced in the mixer can be controlled extremely low in level.

According to the high-frequency electronic device of the present invention, since the low-pass filter is electrically connected between at least a UHF interstage tuning circuit and a UHF mixer, interference signals can be effectively prevented from occurring.

According to the high-frequency electronic device of the present invention as well, since the low-pass filter comprises an L-type low-pass filter comprised of an inductive element and a capacitive element, it can be simply made up of two parts and thereby does not make up an extra space for a printed wiring board. Further, the matching of the impedance between the interstage tuning circuit and the mixer can be simply obtained.

Further, according to the high-frequency electronic device of the present invention, since the low-pass filter is made up of a derived M-type low-pass filter, harmonics produced from the oscillator of the modulation part, which exist in a range up to the neighborhood of a cut-off frequency of the low-pass filter, can be attenuated so that many interference signals produced in the mixer can be suppressed.

Moreover, according to the high-frequency electronic device of the present invention, since a capacitive element of a grounded low-pass filter is made up of a stray capacitance formed between two conductive patterns provided on a printed wiring board, the capacitor becomes unnecessary so that parts can be reduced in number.

While the present invention has been described with reference to the illustrative embodiment, this description is not intended to be construed in a limiting sense. Various modifications of the illustrative embodiment will be apparent to those skilled in the art on reference to this description.

It is therefore contemplated that the appended claims will cover any such modifications or embodiments as fall within the true scope of the invention.

Claims

claimS

1. A high-frequency electronic device comprising: a metal housing; a printed wiring board held within said metal housing; a modulation part formed on said printed wiring board and having an oscillator; and a tuner part including, a high-frequency portion formed on said printed wiring board, for selecting a television signal to be received from television signals and outputting the selected television signal; a mixer for effecting frequency conversion on the selected television signal outputted from said high-frequency portion; and a local oscillator for supplying a local oscillation signal to said mixer, wherein said high-frequency portion has a tuning circuit for inputting the selected television signal to said mIxer, and wherein a low-pass filter Is connected between said tuning circuit and said mixer so that a cut-off frequency thereof is set so as to be higher than the maximum frequency of the television signal received by said high-frequency portion.

2. A high-frequency electronic device according to claim 1, wherein said high-frequency portion includes a UHF high-frequency unit for selecting a television signal to be received from television signals in the UHF band and outputting the selected television signal, said mixer includes a UHF mixer for effecting frequency conversion on the selected television signal outputted from said UHF high-frequency unit, said local oscillator includes a UHF local oscillator for supplying a local oscillation signal to said UHF mixer, said UHF high-frequency unit includes a UHF tuning circuit for inputting the selected television signal to said UHF mixer, and said low-pass filter is electrically connected between said UHF tuning circuit and said UHF mixer.

3. A high-frequency electronic device according to claim 2, wherein said low-pass filter comprises an L-type low-pass filter comprised of an inductive element and a capacitive element electrically connected between one end of said inductive element and ground.

4. A high-frequency electronic device according to claim 3, wherein said capacitive element is made up of a stray capacitance formed between two conductive patterns provided on said printed wiring board.

5. A high-frequency electronic device according to claim 2, wherein said low-pass filter comprises a derived M-type low-pass filter comprised of an inductive element and a capacitor electrically parallel-connected to one another and a capacitive element electrically connected between one ends of said mutually parallel-connected inductive element and capacitor and ground.

6. A high-frequency electronic device according to claim 5, wherein said capacitive element is made up of a stray capacitance formed between two conductive patterns provided on said printed wiring board.

7. A high-frequency electronic device according to claim 1, wherein said low-pass filter comprises an L-type low-pass filter comprised of an inductive element and a capacitive element electrically connected between one end of said inductive element and ground.

8. A high-frequency electronic device according to claim 7, wherein said capacitive element is made up of a stray capacitance formed between two conductive patterns provided on said printed wiring board.

9. A high-frequency electronic device according to claim 1, wherein said low-pass filter comprises a derived M-type low-pass filter comprised of an inductive element and a capacitor electrically parallel-connected to one another and a capacitive element electrically connected between one ends of said mutually parallel-connected Inductive element and capacitor and ground.

10. A high-frequency electronic device according to claim 9, wherein saia capacitive element is made up of a stray capacitance formed between two conductive patterns provided on said printed wiring board.

11. A high-frequency electronic device substantially as hereinbefore described with reference to, and as illustrated by, the accompanying drawings.

Amendments to the claims have been filed as follows CLAIMS

1. A high-frequency electronic device comprising: a modulation part having an oscillator for generating a carrier frequency of UHF television broadcast channel; and a tuner part including, a high-frequency portion for selecting a television signal to be received from television signals and outputting the selected television signal; a mixer for effecting frequency conversion on the selected television signal outputted from said high-frequency portion; and a local oscillator for supplying a local oscillation signal to said mixer, wherein said high-frequency portion has a tuning circuit for inputting the selected television signal to said mixer, and wherein a low-pass filter is connected between said tuning circuit and said mixer so that a cut-off frequency thereof is set so as to be higher than the maximum frequency of the television signal received by said high-frequency portion.

4. A high-frequency electronic device according to claim 3, wherein said capacitive element is made up of a stray capacitance formed between two conductive patterns provided on a printed wiring board.

6. A high-frequency electronic device according to claim 5, wherein said capacitive element is made up of a stray capacitance formed between two conductive patterns provided on a printed wiring board.

8. A high-frequency electronic device according to claim 7, wherein said capacitive element is made up of a stray capacitance formed between two conductive patterns provided on a printed wiring board.

10. A high-frequency electronic device according to claim 9, wherein said capacitive element is made up of a stray capacitance formed between two conductive patterns provided on a printed wiring board.