JPH0534736U - Integrated circuit for China - Google Patents

Abstract

(57) [Summary] [Configuration] An oscillation signal amplifier circuit 22 is inserted between a branch point provided on a transmission path of a VHF oscillation signal (or a UHF oscillation signal) and the frequency conversion circuit 10. [Effect] While the input level of the VHF oscillation signal (or UHF oscillation signal) to the PLL amplifier circuit 14 does not drop significantly in the high frequency band, a high level VHF RF signal (or UHF RF signal) is input. Even if it does, the malfunction of the PLL is eliminated.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a tuner integrated circuit which receives a VHF band or UHF band high frequency signal, converts the high frequency signal into an intermediate frequency signal, and outputs the intermediate frequency signal.

[0002]

[Prior Art]

 FIG. 3 is a block diagram showing a tuner circuit according to the applicant's utility model registration application dated September 13, 1991, and a dotted line frame indicates an integrated circuit for a tuner (hereinafter, the integrated circuit will be referred to as “IC”). Is abbreviated as “.”, And the area outside the dotted line frame indicates the IC peripheral circuit. The configuration and operation of the tuner circuit of FIG. 3 will be described below. Reference numeral 1 denotes an input terminal for a VHF / UHF switching signal. For example, when receiving a VHF high frequency signal (hereinafter, the high frequency signal is abbreviated as "RF signal"), a low level switching signal is input and UHF RF signal is input. A high-level switching signal is input during signal reception. Reference numeral 2 is a VHF RF signal input terminal, and reference numeral 3 is a UHF RF signal input terminal. Reference numeral 4 denotes a VHF / UHF switching circuit, which receives a VHF / UHF switching signal from the terminal 1 and activates the VHF RF amplification circuit 8, the VHF oscillation circuit 6, and the VHF amplification circuit 7 when receiving the VHF RF signal. , UHF RF amplifier circuit 9, UHF oscillation circuit 13, and UHF amplifier circuit 11 are deactivated. When receiving the UHF RF signal, the VHF RF amplification circuit 8, the VHF oscillation circuit 6, and the VHF amplification circuit 7 are deactivated, and the UHF RF amplification circuit 9, the UHF oscillation circuit 13, and the UHF amplification circuit 11 are operated. State.

Reference numeral 5 is a connection terminal between the VHF resonance circuit 18 and the VHF oscillation circuit 6. Reference numeral 6 is a VHF oscillation circuit for generating a VHF oscillation signal for converting the VHF RF signal into an intermediate frequency signal (hereinafter, the intermediate frequency is abbreviated as "IF"). A VHF amplifier circuit 7 amplifies the VHF oscillation signal generated by the VHF oscillation circuit. A VHF amplifier circuit 8 amplifies the VHF RF signal input from the terminal 2. Reference numeral 9 is a UHF amplifier circuit that amplifies the UHF RF signal input from the terminal 3.

Reference numeral 10 denotes a VHF oscillation signal (or a UHF oscillation signal) output from the VHF amplification circuit 7 (or a UHF amplification circuit 11) and a VHF RF amplification circuit 8 (or a UHF RF amplification circuit 9). The VHF RF signal (or UHF RF signal) output from is input, and the VHF RF signal (or UHF RF signal) is converted to an IF signal and output by the VHF oscillation signal (or UHF oscillation signal) Frequency conversion circuit. A UHF amplifier circuit 11 amplifies the UHF oscillation signal generated by the UHF oscillation circuit 13. Reference numeral 12 is a connection terminal between the UHF resonance circuit 19 and the UHF oscillation circuit 13. A UHF oscillation circuit 13 generates a UHF oscillation signal for converting the UHF RF signal into an IF signal. Reference numeral 14 is a PLL amplifier circuit that receives a part of the VHF oscillation signal (or UHF oscillation signal), amplifies these, and outputs them as a PLL sampling signal. Reference numeral 15 is a PLL sampling signal output terminal.

Reference numeral 16 is an IF amplifier circuit that amplifies the IF signal output from the frequency conversion circuit 10, and 17 is an IF signal output terminal. Reference numeral 18 is a VHF resonance circuit for setting the VHF oscillation signal frequency, and 19 is a UHF resonance circuit for setting the UHF oscillation signal frequency. The PLL sampling signals from the balanced / unbalanced conversion circuit 21 are input to the circuit 20, which generates an oscillation frequency control signal based on these signals and outputs the oscillation frequency control signal to the VHF resonance circuit 18 or the UHF resonance circuit 19. It is a PLL circuit that outputs a signal. Reference numeral 21 denotes a balanced / unbalanced conversion circuit for converting the balanced PLL sampling signal output from the terminal 15 into an unbalanced PLL sampling signal.

[0006]

[Problems to be solved by the device]

 In the tuner integrated circuit described above, the input impedance at the VHF oscillation signal (or UHF oscillation signal) input terminal in the frequency conversion circuit is greatly reduced in the high frequency band due to the influence of the distributed capacitance inside the frequency conversion circuit. Therefore, there is a drawback in that the input level of the VHF oscillation signal (or UHF oscillation signal) to the PLL amplifier circuit also drops significantly in the high frequency band. In addition, when a high level VHF RF signal (or UHF RF signal) is input, those signals pass through the VHF RF amplifier circuit (or UHF RF amplifier circuit) and then the VHF oscillation signal of the frequency conversion circuit. (Or, the UHF oscillation signal) is output from the input terminal and input to the PLL amplifier circuit, which may cause a PLL malfunction. Therefore, an object of the present invention is that the input level of a VHF oscillation signal (or UHF oscillation signal) to a PLL amplifier circuit does not drop significantly even in a high frequency band, and a large level VHF RF signal (or UHF RF signal). It is an object of the present invention to provide an integrated circuit for a tuner that eliminates the malfunction of PLL even when a signal) is input.

[0007]

[Means for solving the problem]

 In order to solve the above problems, the present invention is directed to a VHF oscillation signal generated by a VHF oscillation circuit, which amplifies and outputs the VHF oscillation signal, and a UHF oscillation generated by the UHF oscillation circuit. A UHF amplifier circuit that receives a signal, amplifies and outputs the UHF oscillation signal, a high-frequency signal in the VHF band or the UHF band, the VHF amplifier circuit, or the VHF oscillation signal output from the UHF amplifier circuit or the A UHF oscillation signal is input, and a frequency conversion circuit that converts the VHF band or UHF band high frequency signal into an intermediate frequency signal and outputs it, and the VHF amplification circuit or the UHF amplification circuit and the frequency conversion circuit. A branch point provided on the transmission path of the VHF oscillation signal or the UHF oscillation signal to be coupled, and the VHF oscillation signal or the branch point extracted from the branch point. In the tuner integrated circuit having a PLL amplifier circuit to which the UHF oscillation signal is input and which amplifies the VHF oscillation signal or the UHF oscillation signal and outputs it as a PLL sampling signal, the branch point and the frequency conversion circuit The VHF oscillation signal or the UHF oscillation signal is input in between, and an oscillation signal amplification circuit for amplifying the VHF oscillation signal or the UHF oscillation signal and outputting the amplified signal to the frequency conversion circuit is inserted. .

[0008]

[Operation] The above technical means operates as follows. The VHF oscillation signal (or UHF oscillation signal) output from the VHF amplification circuit (or UHF amplification circuit) is input to the frequency conversion circuit through the oscillation signal amplification circuit, and at the same time the VHF amplification circuit (or UHF) is input. (Amplification circuit) and the oscillation signal amplification circuit, the VHF oscillation signal (or UHF oscillation signal) is also input to the PLL amplification circuit from a branch point provided on the transmission path.

[0009]

【Example】

 Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an embodiment shown in a block diagram, in which an IC is shown inside a dotted line frame and an IC peripheral circuit is shown outside the dotted line frame. FIG. 2 is a detailed circuit diagram showing a configuration example of the oscillation signal amplifier circuit 22 in FIG. First, the configuration and operation will be described with reference to FIG. The same blocks as those in FIG. 3 are denoted by the same reference numerals and the description thereof will be omitted. Reference numeral 22 is an oscillation signal amplifier circuit to which the VHF oscillation signal (or UHF oscillation signal) is input and which amplifies these signals and outputs them to the frequency conversion circuit 10. This embodiment is different from the conventional example shown in FIG. 3 in that an oscillating signal amplifier circuit 22 is provided between a branch point provided on a VHF oscillation signal (or UHF oscillation signal) transmission path and the frequency conversion circuit 10. It is inserted.

As described above, since the input impedance of the oscillation signal amplifier circuit 22 is extremely high from the low frequency band to the high frequency band, the input level of the VHF oscillation signal (or UHF oscillation signal) to the PLL amplifier circuit 14 is high. The problem of a significant drop in bandwidth is gone. In addition, when a large level VHF RF signal (or UHF RF signal) is input, those signals pass through the VHF RF amplifier circuit 8 (or UHF RF amplifier circuit 9) and are fed to the frequency conversion circuit 10. Even if the VHF oscillation signal (or the UHF oscillation signal) is output from the input terminal, the oscillation signal amplification circuit 22 has a large reverse direction iris, so that it is not input to the PLL amplification circuit 14 and causes a PLL malfunction. Is gone.

Next, FIG. 2 will be described. The transistors 32 and 33 perform signal amplification, and the constant voltage power supply 38 supplies collector currents to the transistors 32 and 33. The resistors 34 to 37 are resistors for supplying a base bias voltage to the transistors 32 and 33. Transistors 39 and 40 are transistors for a constant current circuit, and flow a constant current set by a constant voltage power source 43 and resistors 41 and 42. The VHF oscillation signal (or UHF oscillation signal) input from the input terminal 31 is amplified by the transistors 32 and 33 and output from the output terminal 44.

[0012]

[Effect of the device]

 As described above, according to the present invention, the oscillation signal amplification circuit is inserted between the branch point provided on the transmission path of the VHF oscillation signal (or the UHF oscillation signal) and the frequency conversion circuit. As a result, the input level of the VHF oscillation signal (or UHF oscillation signal) to the PLL amplifier circuit does not drop significantly in the high frequency band, and a large level VHF RF signal (or UHF RF signal) is input. Even in this case, the remarkable effect that the malfunction of the PLL is eliminated can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram of a tuner IC and its peripheral circuit according to an embodiment of the present invention.

FIG. 2 is a detailed electric circuit diagram of an oscillation signal amplifier circuit in FIG.

FIG. 3 is a block diagram of a conventional tuner IC and its peripheral circuit.

[Explanation of symbols]

 7 VHF amplification circuit 10 Frequency conversion circuit 11 UHF amplification circuit 14 PLL amplification circuit 22 Oscillation signal amplification circuit

Claims (1)

[Scope of utility model registration request] 1. A VHF amplifier circuit which receives a VHF oscillation signal generated by a VHF oscillation circuit, amplifies and outputs the VHF oscillation signal, and a UHF generated by the UHF oscillation circuit.
A UHF amplifier circuit that receives an oscillation signal and amplifies and outputs the UHF oscillation signal, a high-frequency signal in the VHF band or the UHF band, the VHF amplifier circuit, or the VHF oscillation signal output from the UHF amplifier circuit or A frequency conversion circuit that receives the UHF oscillation signal and converts the high-frequency signal of the VHF band or the UHF band into an intermediate frequency signal and outputs the intermediate frequency signal, and the VHF amplification circuit or the UHF amplification circuit and the frequency conversion circuit A branch point provided on the transmission path of the VHF oscillation signal or the UHF oscillation signal, and the VHF oscillation signal or the U extracted from the branch point.
A tuner integrated circuit having a PLL amplifier circuit that receives an HF oscillation signal, amplifies the VHF oscillation signal or the UHF oscillation signal, and outputs the amplified signal as a PLL sampling signal, wherein the branch point and the frequency conversion circuit are included. During the VH
F oscillation signal or the UHF oscillation signal is input,
An integrated circuit for a tuner, wherein an oscillating signal amplifying circuit for amplifying an HF oscillating signal or the UHF oscillating signal and outputting the amplified signal to the frequency converting circuit is inserted.