JPH03218106A - RF amplifier - Google Patents

Abstract

PURPOSE:To reduce the cost and to make the size small for a TV, VTR tuner and to improve the power amplification factor and noise figure over the entire reception band by incorporating plural RF amplifier active elements and their bias circuits in a same package and forming a single common terminal for an AGC element controlling the gain. CONSTITUTION:The share of RF amplifier active elements 11-14 is allocated so as to obtain optimum power amplification factor and noise figure characteristic depending on the operating frequency band. An RF signal inputted to input terminals 2-5 is amplified by the RF amplifier active elements 11-14, outputted from output terminals 6-9 and used for each band. The power amplification factor of each band is controlled through only one terminal over the entire reception band properly by a gain control voltage applied to an AGC terminal 10. Thus, a TV/VTR tuner having flat and excellent power amplification factor and noise figure characteristic over the reception band is obtained inexpensively with simple circuit constitution.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an RF amplifier used in tuners for TVs and VTRs.

BACKGROUND OF THE INVENTION Conventional RF amplifiers used in TV/VTR tuners have used discrete MOSFETs, MESFETs, and high-vola transistors.

The following will explain based on the drawings.

FIG. 3 shows a circuit diagram of a conventional TV/VTR tuner having a UHFI hand and a plurality of receiving hands for three VHF bands.

19 is a UHFRF signal input terminal, 20 is a VHFRF signal, 21. 22, 23. 24 is a band pass filter that is tuned and variable in frequency of each RF signal within the frequency band of each receiving band, and 29 is a UHF discrete R.
F Amb device, 30 is discrete RF for VHF
Amb device, 31 is the AGC terminal, 32.33 is part of the bias circuit, 25 is the mixer, 26 is the local oscillator,
27 is an IF amplifier, and 28 is an IF output terminal.

In this conventional example, each of the LIHF band and the VHF band is configured with one discrete RF amplifier device, and especially in the VHF band, the band divided into three is also used with one discrete RF amplifier device.

The UHF RF signal [. J is sent to a UHF band band pass filter 21, selected in tune with its input frequency, and amplified by a UHF discrete RF amplifier dehyde 29. Next, the signal f, is mixed with the signal flo of the local oscillator 26 in the mixer 25, and a frequency difference component r, of the two signals is obtained. 1rLl
is amplified by the IF amplifier 27, and the I
Output as F frequency.

The VHF RF signal input to the VHF RF signal input terminal 20 is inputted into VH, V, VH, VH, V, VH, VH, V, V, etc.
, and a band pass filter for each band 22, 23 . After being selected in tune with its input frequency at 24, each band is sent to the same VHF discrete RF amplifier device for amplification.

Next, the RF signal f. is amplified in each VHF band. ．． f.
．． f. is transmitted as an IP frequency via the mixer 25 and IP amplifier 27 in the same way as when receiving a UHFRF signal.
It is output from the output terminal 28.

Problems to be Solved by the Invention In such a conventional system, especially in the case of VHF hand reception, a wide reception band must be covered by one discrete RF receiver. However, in a single discrete RF amplification device, there is always a change in frequency characteristics in terms of power amplification and noise figure characteristics, and within the receiving band assigned to the discrete RF amplification factor, there is a flatness in terms of power amplification and noise figure characteristics. The problem was that it was difficult to obtain accurate frequency characteristics.

The present invention is intended to solve the above problems, and aims to provide uniform and good power amplification and noise figure characteristics over the entire RF frequency band input to the RF input terminal.

Means for Solving the Problem In order to solve this problem, the RF amplifier of the present invention houses a plurality of RF amplifier active elements and at least part of their bias circuits in the same path cage, and
This device is characterized in that the AGC terminal for controlling the gain of the amplifier active element is configured as a common single terminal.

Effect? The invention provides a TV/VTR tuner with a simple circuit configuration, low cost, small size, flatness over the entire reception band, good power amplification and noise figure characteristics, and high image quality. TV images will be provided.

EXAMPLE Hereinafter, an example of the present invention will be described based on the accompanying drawings.

FIG. 1 shows a block diagram of an RF amplifier device that is an embodiment of the present invention.

In FIG. 1, 1 is an RF amplifier dehyss bass cage;
2, 3 ■ 4, 5 are each RF signal input terminal, 6 7 8
9 is each output terminal, 10 is AGC terminal, 11 12,
13. 14 is each RF amplifier active element, 15, 161
7 and 18 indicate parts of each bias circuit.

Each RF amplifier active element 11, 12, 13. 14 are assigned duties depending on the operating frequency band so as to provide optimum power amplification and noise figure characteristics, respectively.

The RF signal input to the input terminal 2 is amplified by the RF amplifier active element 11 and output from the output terminal 6. Similarly, in the case of input terminals 3, 4, and 5, each RF amplifier active element 1
2. 13. 14, operates for each hunt through output terminal 7.89.

The power amplification degree in each hand can be appropriately controlled by the gain control voltage applied to the AGC terminal 10 over the entire reception band using only the l terminal.

FIG. 2 shows an RF
It is a circuit diagram of a TV/VTR tuner using an amplifier.

Each number shown in FIG. 2 represents the same content as in FIG. 3 and FIG. 1 described above.

The UHF RF signal f, input to the UHF RF signal input terminal 19, is selected by a bandpass filter 21 in tune with fU, and is made of semiconductor material and a semiconductor material set to have the optimal power amplification degree and noise figure for the UHF RF signal band. Bias value R
The signal is amplified by the F amplifier active element 15 and sent to the mixer 25. Furthermore, the signal fU sent to the mixer 25 is mixed with the signal flo from the local oscillator 26, and the difference component (rt) between the two signal frequencies.

ru) is amplified by the 1F amplifier 27 and sent to the IF output terminal 28.
is output as an IF frequency.

The VHF RF signal input to the VHF RF signal input terminal 20 is inputted into V, V, V, in descending order of frequency.
, and band pass filters 22, 23 . for each band. 24, each input frequency fH. After being selected in synchronization with fM and ft, they are individually input to input terminals 3 and 4.5 of the RF amplifier device, respectively. The input VHF RF signals fM, fs. ft.
are the RF values of semiconductor materials and bias values that are individually set to have suitable power amplification and noise figure characteristics.
Amplifier active elements 12, 13. 14 and sent to the mixer 25 at the subsequent stage. In this case, the power amplification degree in each band can be appropriately controlled by the gain control voltage applied to the AGC terminal 10 over the entire reception band using only the l terminal. Thereafter, as in the case of UHF reception, the frequency is converted by the mixer 25, amplified by the IF amplifier 27, and the IF output terminal 2
8 is output as an IF frequency.

As described above, according to this embodiment, the conventional TV. VTR tuners allocate a wide receiving band to one RF amplifier, and due to power amplification and noise figure characteristics, there are frequency bands where flat frequency characteristics cannot be obtained and become characteristic. Good characteristics can now be obtained over the entire receiving band.

Additionally, compared to the case of conventional discrete RF amplifier devices, it is possible to combine part or all of the RF amplifier device and bias circuit in the same package, reducing the overall space required to mount the RF amplifier device. There are also benefits.

Furthermore, each RF amplifier active element 11, 12. 13.
14, depending on the characteristics required, different combinations of semiconductor materials, for example MESFET and MO. It is also possible to set SFET, etc., and it is possible to uniformize the characteristics with optimum characteristics for the operating frequency band.

Note that each RF amplifier active element 11, 12, 13. 1
4 can be made monolithic and used as an ultra-miniaturized RF amplifier device, which also has the effect of miniaturizing TV/VTR tuners.

On the other hand, it is also possible to connect a mixer connected after the RF amplifier device to each hand individually, and furthermore, the characteristics of each frequency band can be uniformly flattened with high performance.

In this embodiment, the case of four RF amplifier active elements has been described, but it is clear that the same effect can be obtained by increasing or decreasing the number of RF amplifier active elements as necessary.

Effects of the Invention As described above, according to the present invention, it is possible to make a TV/VTR tuner inexpensive and small, and to maintain good power amplification and noise figure over the entire reception band, thereby improving the high picture quality of TV receivers. This has the effect of making it possible to improve the

[Brief explanation of drawings]

FIG. 1 is a Bronnock diagram of an RF amplifier that is an embodiment of the present invention, and FIG. 2 is a Bronnock diagram of an RF amplifier that is an embodiment of the present invention shown in FIG.
Circuit block diagram of TV/VTR tuner using F amplifier FIG. 3 shows a circuit block diagram of a TV/VTR tuner having a plurality of reception bands of the conventional UHFl hand and three VHF bands.

Claims (2)

[Claims] (1) A plurality of RF amplifier active elements and at least part of their bias circuits are built into the same package, and each RF amplifier active element has independent input/output terminals, and each RF amplifier active element has independent input/output terminals; An RF amplifier characterized in that an AGC terminal for controlling the gain of the elements is provided as a common single terminal. (2) The RF amplifier according to claim 1, wherein the RF amplifier active elements are made of different semiconductor materials.