JP2003169265A - Television signal receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a television signal receiver that can eliminate the effect of reduction in a dynamic range of an intermediate frequency amplifier circuit and mutual interference between circuits or the like. <P>SOLUTION: The television signal receiver is configured with an IC integrating a tuner circuit 10, a VIF amplifier 30, a video wave circuit 31 and an audio circuit 40 into a single chip. A pair of balanced outputs are adopted for the outputs of the tuner circuit 10. This pair of balanced outputs are outputted to IF output terminals 25, 26 and also fed to a pair of input terminals of the VIF amplifier 30 through a SAW filter 27 and IF input terminals 28, 29. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television signal receiver, and more particularly to a tuner circuit, an intermediate frequency amplifier circuit, a video detection circuit and an audio circuit which are integrated on one semiconductor chip or a plurality of semiconductor chips. The present invention relates to a television signal receiving device formed by sealing these chips with resin.

[0002]

2. Description of the Related Art FIG. 3 shows a circuit diagram of a conventional television signal receiving apparatus. High frequency television signal RF
Is input to the tuner 51 from the input terminal 50. An intermediate frequency signal (hereinafter referred to as an IF signal) is output from the tuner 51 to the output terminal 52. This IF signal is the SAW filter 5 externally attached to the semiconductor integrated circuit (IC).
3 is supplied to an intermediate frequency amplifier (hereinafter referred to as VIF amplifier) 54.

The output of the tuner 51 is a so-called single output, and is supplied to one input terminal of the SAW filter 53 via the output terminal 52. The other input terminal of the SAW filter 53 is grounded. And SA
A pair of balanced output signals (balanced output signals) are extracted from the W filter 53 and input to a pair of balanced input terminals of the VIF amplifier 54. The output signal from the VIF amplifier 54 is AM-detected by the video detection circuit 57 and taken out to the video output terminal (video output terminal) 58.

On the other hand, the output signal of the video detection circuit 57 is the SIF band pass filter 60 (hereinafter referred to as S
IF BPF) and an audio intermediate frequency signal (hereinafter referred to as SIF signal) is extracted. SIF B
The output signal of the PF 60 is FM-detected by the audio detection circuit 62 through the limiter circuit, and taken out from the audio output terminal (audio output terminal) 63.

In the television signal receiving apparatus having the above-mentioned structure, the circuit surrounded by the broken line is made into one chip, and the chip is packaged by resin sealing.
Alternatively, the SIF BPF 60 is provided as an external component.

[0006]

However, the above-mentioned one-chip television signal receiving apparatus has the following problems. First, the input dynamic range of the VIF amplifier 54 has narrowed because the standard of the power supply voltage of the IC has fallen today.

Secondly, the mixing circuit (mixer circuit) of the tuner 51, the VIF circuit (VIF amplifier 54 video detection circuit 57 and the like), and the SIF circuit (audio circuit 59 and the like) form one I.
Since they are incorporated in C, mutual interference between them occurs, and unnecessary components are likely to appear in the output signal of the tuner 51. Therefore, the image quality of the television screen is deteriorated.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and a tuner circuit for frequency-converting a television signal into an intermediate frequency signal, and an output from the tuner circuit. Intermediate frequency amplification circuit for amplifying the intermediate frequency signal, a video detection circuit for AM detection of the output signal of the intermediate frequency amplification circuit, an audio intermediate frequency signal extracted from the output signal of the video detection circuit, and FM detection. A television signal receiving device in which an audio circuit to be performed is integrated into a single chip or a plurality of chips, and the chips are resin-sealed, wherein the tuner circuit outputs a pair of balanced outputs. The balanced output of 1 is supplied to a pair of input terminals of the intermediate frequency amplifier circuit.

According to this structure, the output of the tuner circuit is a pair of balanced outputs, so that the input dynamic of the intermediate frequency amplifier circuit (VIF amplifier) is greater than that when the output of the tuner circuit is a single output. The range can be equivalently doubled.

In addition, the tuner circuit mixed circuit and VIF
Even if unnecessary harmonic components are superposed on the output of the mixing circuit due to mutual interference with the circuit and SIF circuit, these unnecessary components are in phase, so the balanced output of the mixing circuit is composed of a differential amplifier. By inputting the input signal to the VIF amplifier, the common mode is removed and unnecessary components are reduced.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a circuit diagram of a television signal receiving apparatus according to an embodiment of the present invention. In the figure, it is assumed that the circuit portion surrounded by the alternate long and short dash line is integrated in one IC chip or divided into a plurality of chips and resin-sealed in one package.

First, the configuration of the tuner circuit 10 will be described. The high frequency television signal RF passes through a tuning circuit (not shown) and is then amplified by the RF amplifier 11 via the input terminal 1. The amplified high frequency television signal RF and the local oscillation signal from the voltage controlled oscillator (local oscillator) 12 are mixed by the mixing circuit 13 (mixer circuit) to generate a signal (f1 + f2) and a signal (f1-f2). To be done. f1 is the frequency of the high frequency television signal RF, and f2 is the frequency of the voltage controlled oscillator 12.

The local oscillation signal from the voltage controlled oscillator 12 is frequency-divided by the frequency divider 14. The frequency division output and the reference oscillation signal from the oscillator (OSC) 15 are compared by the phase comparator 16, and the comparison output is supplied to the voltage controlled oscillator 12 to form a closed lock loop (PLL loop). There is.

As described above, from the mixing circuit 13, (f
1 + f2) signal and (f1-f2) signal are generated,
The necessary (f1−f2) IF signal is extracted by the bandpass filter 20 and supplied to the differential amplifier 17. The bandpass filter 20 may be externally attached to the terminals 21 and 22, or may be built in the IC.

The specific configuration of the differential amplifier 17 is shown in FIG. Reference numerals 18 and 19 are input terminals to which the balanced IF signals from the mixing circuit 13 are input, and TR1 and TR2 are differential transistors forming a differential amplifier in which the signals from the input terminals 18 and 19 are applied to the bases. is there. The balanced IF signal from the differential amplifier is the transistors TR3, T
It is output to the IF output terminals 25 and 26 via R4.

The balanced IF signal is SAW.
It is input to the pair of balanced input terminals of the VIF amplifier 30 through the filter 27 and the IF input terminals 28 and 29. The output signal from the VIF amplifier 30 is AM-detected by the video detection circuit 31, and then the amplifier 32 and the trap 33.
Through the video output terminal (video output terminal) 34.

On the other hand, the output signal of the video detection circuit 31 is input to the SIF BPF 41 of the audio circuit 40 through the amplifier 32, and the SIF signal is extracted. SIF BPF4
The output signal of No. 1 is FM-detected by the audio detection circuit 43 through the limiter circuit 42, and is taken out from the audio output terminal (audio output terminal) 44. In addition, SIF BPF41
The trap 33 may be externally attached to the IC.

According to the television signal receiving device having the above-described structure, the balanced I signal from the tuner circuit 10 is transmitted.
Since the F signal is input to the pair of balanced input terminals of the VIF amplifier 30, the dynamic range becomes twice as large as that of the conventional single input under the same conditions of the gain and output of the VIF amplifier 30. Further, the total gain of the VIF amplifier 30 is improved by 6 dB, the insertion loss of the SAW filter 27 can be reduced, and the S / N ratio can be improved.

Further, the mixing circuit 1 of the tuner circuit 10
3 and the influence of mutual interference between the differential amplifier 17 and the VIF circuit can be eliminated. Specifically, there is a jump from the oscillator 70 of the VIF circuit to the mixing circuit 13 and the differential amplifier 17.

Further, a high frequency component close to the VIF frequency generated in the limiter circuit 42 of the SIF circuit and a high frequency component close to the VIF frequency generated in the frequency divider 14 of the PLL circuit are superimposed on the output signal of the mixing circuit 13.

However, since these unnecessary components are in-phase, when the balanced mixing circuit 13 is balanced-input to the differential amplifier of the VIF amplifier 30, the unnecessary components are removed in-phase.

In the above embodiment, the tuner circuit 1
The balanced IF signal from 0 is the SAW filter 27.
Is input to the pair of balanced input terminals of the VIF amplifier 30 through the SAW filter 2.
Depending on the system having a circuit equivalent to 7, the balanced IF signal from the tuner circuit 10 may be directly input to the pair of balanced input terminals of the VIF amplifier 30 without passing through the SAW filter 27.

[0023]

According to the present invention, a tuner circuit, an intermediate frequency amplifier circuit, a video detection circuit and an audio circuit are integrated into one semiconductor integrated circuit (IC), or a plurality of ICs are integrated.
In a television signal receiving device that is divided and integrated into a single package and is resin-sealed in a single package, the output of the tuner circuit is made into a pair of balanced outputs, and the pair of balanced outputs is input to a pair of intermediate frequency amplifier circuits. Since it is supplied to the terminal, the input dynamic range of the intermediate frequency amplifier circuit can be equivalently doubled as compared with the case where the output of the tuner circuit is a single output.

Even if unnecessary harmonic components are superimposed on the output of the tuner circuit mixing circuit due to mutual interference between the tuner circuit mixing circuit and the intermediate frequency amplifier circuit or the audio circuit, the tuner circuit output is balanced. Therefore, in-phase removal is performed and unnecessary components are reduced.

Furthermore, there is an advantage that the insertion loss of the SAW filter inserted between the output of the tuner circuit and the intermediate frequency amplifier circuit can be compensated, and the S / N ratio is improved.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a television signal receiving device according to an embodiment of the present invention.

FIG. 2 is a circuit diagram of a differential amplifier 17 in the television signal receiving device according to the embodiment of the present invention.

FIG. 3 is a circuit diagram of a television signal receiving device according to a conventional example.

[Explanation of symbols]

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5C025 AA14 AA17 AA25 AA27                 5K020 AA02 DD01 FF15 GG01 HH13                       MM05

Claims (5)

[Claims] 1. A tuner circuit for frequency-converting a high-frequency television signal into an intermediate frequency signal, an intermediate frequency amplifier circuit for amplifying an intermediate frequency signal output from the tuner circuit, and an output signal of the intermediate frequency amplifier circuit for AM. A video detection circuit for detection and an audio circuit for performing FM detection while extracting an audio intermediate frequency signal from an output signal of the video detection circuit are integrated on a single chip or a plurality of chips, and the chip is sealed with a resin. A television signal receiving device that is configured to stop, wherein the output of the tuner circuit is a pair of balanced outputs, and the pair of balanced outputs is supplied to a pair of input terminals of the intermediate frequency amplifier circuit. Television signal receiving device. 2. The television signal receiving apparatus according to claim 1, wherein a pair of balanced outputs of the tuner circuit are supplied to a pair of input terminals of the intermediate frequency amplifier circuit via a SAW filter. 3. The tuner circuit includes a mixing circuit that mixes a high frequency television signal and an output of a local oscillator to generate an intermediate frequency signal, and a differential amplifier circuit that amplifies the output of the mixing circuit. 3. The television signal receiving apparatus according to claim 1, wherein a pair of differential outputs of the differential amplifier circuit are the pair of balanced outputs. 4. A PL for controlling the frequency of the local oscillator.
4. The television signal receiving apparatus according to claim 3, further comprising an L circuit. 5. The audio circuit includes a bandpass filter for extracting an audio intermediate frequency signal from the output signal of the video detection circuit, a limiter circuit for limiting the output of the bandpass filter, and an FM output for the limiter circuit. The television signal receiving apparatus according to claim 1, further comprising an audio detection circuit for detecting.