JPS6059870A - Frequency converting and amplifying device - Google Patents

Abstract

PURPOSE:To simplify an amplifier section and an AGC section by amplifying signals having different frequency band in common in a frequency converting amplifier for IF band VA ratio adjastment or the like. CONSTITUTION:An RF signal applied to an input terminal 1 is amplified by an amplifier 12, the amplifier signal is frequency-converted by a frequency converter 4 through an RF band pass filter 14 and an IF signal is amplified by the amplifier 12 through an IF band pass filter 15. The amplified IF signal is given to an output terminal 9 through an IF band pass filter 13. Furthermore, an AGC control voltage is formed by inputting the IF signal outputted through the IF band pass filter 13 to the amplifier 12, and an automatic gain is controlled for RF amplification and IF amplification so that the IF signal level is made constant.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a frequency conversion amplification device having both frequency conversion and amplification functions for adjusting the IF band VA ratio (video/audio signal ratio) in a CΔTV system or the like.

Conventionally, as this type of frequency conversion amplification device, one shown in FIG. 1, for example, is known.

In Figure 1, 1 is an RF signal such as a television signal (8@
2 is an RF bandpass filter that shifts the pass band of the RF signal to the right; 4 is a frequency converter equipped with a mixer 5 and a local oscillator 6 that converts the frequency of the RF multiplied signal and the IF multiplied signal; 7 kl main An amplifier, 8 is an IF bandpass filter having an IF multiplied signal passband, and 9 is an output terminal. This required a large number of amplifiers.

On the other hand, 10 is an AGC circuit, and when applying AGC,
If AGC is applied only by the preamplifier 3, it is disadvantageous in terms of C/N ratio, and if AGC is applied only by main amplifier 7, it is disadvantageous in terms of distortion. Therefore, the AGC circuit shown in the figure is 10, AGC is applied in common to both the preamplifier 3 and the main amplifier 7, and the AGC is applied in common to both the preamplifier 3 and the main amplifier 7.
There is also a problem that the configuration of the GC circuit becomes complicated.

The present invention has been made in view of such conventional problems, and is intended to be used in a frequency conversion amplifier device that has both frequency conversion and amplification functions for FlVA ratio adjustment, etc. For common amplification, J:ri amplification section and A
The purpose is to simplify the GC circuit section.

To achieve this objective, the present invention comprises a single amplifier having band characteristics including the frequency bands of each of the input signal and the frequency-converted output signal, and between the input terminal and the input terminal of the amplifier. the first frequency band (RF signal frequency band)
A first filter that passes the second frequency band and blocks the second frequency band (IF signal frequency band) is connected between the amplifier and the output terminal, and a first filter that passes the second frequency band and blocks the first frequency band is connected between the amplifier and the output terminal. 2 filters are connected between the output end and the input end of the amplifier, an M3 filter that passes the first frequency band and blocks the second frequency band, and an M3 filter that passes the first frequency band and blocks the second frequency band. A series circuit consisting of a frequency converter that performs frequency conversion on signals in a frequency band and a fourth filter that passes a second frequency band and blocks the first frequency band is connected to amplify signals of different frequencies. By using a single amplifier, the circuit configuration of the amplifier section and the AGC circuit section are simplified.

Embodiments of the present invention will be described below based on the drawings.

FIG. 2 is a circuit block diagram showing one embodiment of the present invention. First, to explain the configuration, 1 is an input terminal into which an RF multiplied signal such as a television signal is input.Following input terminal 1, the RF multiplied signal frequency band (first frequency band) is passed through, An RF filter 11 is provided as a first filter that blocks a frequency band (second frequency band), and the output of the RF filter 11 is connected to the input end of an amplifier 12. As the amplifier 12, a wideband amplifier having low distortion amplification characteristics in the RF multiplied signal and the 1F signal, ie, the first and second frequency bands, is used. Amplifier 12
Subsequently, an IF bandpass filter 13 is provided, and this IF bandpass filter 13 constitutes a second filter that blocks the RF multiplied signal frequency band and passes the IF multiplied signal frequency band. The output of bandpass filter 13 is connected to output terminal 9.

On the other hand, an RF band-pass filter 14, a mixer 5, and a local oscillator 6 are connected between the connection point of the amplifier 12 and the band-pass filter 13 and the connection point of the amplifier 12 and the RF band-pass filter 11. Converter 4 and ■F
A series circuit with the bandpass filter 15 is connected, and the RF
The band pass filter 14 constitutes a third filter that passes the RF multiplied signal frequency band and blocks the IF multiplied signal frequency band, and the IF band pass filter 15 passes the IF multiplied signal frequency band and constitutes a third filter that blocks the IF multiplied signal frequency band. A fourth filter is configured to block unnecessary spurious signals caused by signal frequency band and frequency conversion.

Furthermore, the output of the IF bandpass filter 13 is connected as an input to the AGC circuit 10, and the AGC control voltage of the AGC circuit 10 is applied to the amplifier 12.

Next, to explain the operation of the embodiment shown in FIG. 2, the input terminal 1
The RF multiplied signal such as a television signal added to the
F-fold signal preamplification is performed. R F amplified by the amplifier 12, the t= signal is R "band pass filter 1
4 is also input to the mixer 5 of the wave number converter 4, frequency-converted by the local oscillation frequency from the local oscillator 6, and output as an IF multiplied signal t. IF multiplied signal IF bandpass filter 1 frequency-converted by frequency converter 4
The IF multiplied signal is frequency-converted by the same amplifier 12 that is amplifying the RF multiplied signal, and the IF multiplied signal amplified by the amplifier 12 is input to the amplifier 12.
M@ passes through the IF bandpass filter 13 and is applied to the output terminal 9.

In addition, the 800 for the amplifier 12 passes through the 1F bandpass filter 13 and is output by the GC circuit 10 to create the AGO control voltage for the amplifier 12. Automatic gain control of the RF amplification and IF amplification in the amplifier 12 is performed so as to keep the double signal signal 8 level constant.

In the embodiment shown in FIG. 2, since the output of the amplifier 12 is fed back to the input, there may be problems such as oscillation due to positive feedback. :RF
The signal is frequency-converted by IF times by the frequency converter 4 and inputted to the amplifier 12, and since the output and input frequency bands are different, the RF bandpass filter 14 and I
``By keeping the out-of-band reduction in the Pandopa Suit Fruta 15 sufficiently large, problems such as oscillation will not occur.

In this way, in the embodiment of FIG. 2, the input R
Since the F-fold signal amplification and the IF-fold signal amplification which is frequency-converted and outputted are performed by the same amplifier 12, only one amplifier is required, and regarding AGC,
When applied to an RF amplifier, it has a good advantage in terms of distortion, but is disadvantageous in terms of a poor C/N ratio.On the other hand, when applied to an IF amplifier, it has an advantage in terms of a C/N ratio. However, it is disadvantageous in terms of distortion, so the RF
, AGC is applied to both widths of the IF.

Therefore, according to the present invention, since both RF and IF (M) AGO can be performed in a single circuit, C
/N ratio and distortion can be easily satisfied.

, Furthermore, the AGC range by the 〇〇 circuit 10 can also be reduced.

In the above embodiment, an RF multiplied signal such as a television signal is input, and the frequency is changed to the IF signal (11)' to produce a one-segment width output (1-).
The frequency band of the input signal and the frequency-converted and amplified signal are not limited to this, and the frequency conversion and amplification effect can be applied to any frequency band. It can also be used as a frequency conversion amplifier line.

Next, to explain the present invention in detail, the input signal is amplified by an amplifier, then frequency-converted, and the frequency-converted signal is amplified again by the same amplifier and output. Furthermore, since the frequency-converted signal can be amplified by a single amplifier, the configuration of the amplification circuit section can be greatly simplified. In addition, by applying AGC to a single amplifier, both the input signal and the frequency-converted signal can be commonly multiplied by 800, which simplifies the GC circuit and improves the C/N ratio and distortion. It is possible to perform ΔGC control that satisfies both characteristics.

[Brief explanation of drawings]

FIG. 1 is a circuit block diagram showing a conventional example, and FIG. 2 is a circuit block diagram showing an embodiment of the present invention. 1: Input terminal 4: Frequency converter 5: Local oscillator 10: ΔGC circuit 11: RF bandpass filter (first filter) 12
: Amplifier 13 : IF bandpass filter (second filter) 14
:RF bandpass filter (third filter) 15:I
'F bandpass filter (4th filter) Patent applicant: Susumu Takeuchi, agent of Bodgki Co., Ltd., patent attorney

Claims (1)

[Scope of Claims] A frequency conversion amplifier device for amplifying a signal at an input terminal with an amplifier, converting the frequency, and outputting the signal to an output terminal, comprising: a first frequency band between the input terminal and the amplifier; A first filter that passes through the amplifier and blocks a second frequency band is connected, and a second filter that blocks the first frequency band and passes a second frequency band is connected between the amplifier and the output terminal of the amplifier. , from the connection point between the second filter and the amplifier to the first
between the filter and the amplifier connection point, the first frequency band is passed and the second frequency band is passed through l! a third filter that blocks Jl, a frequency converter that converts a signal in the first frequency band to a signal in a second frequency band, and a fourth filter that blocks the first frequency band and passes the second frequency band. A frequency conversion amplification device characterized by connecting a series circuit with a filter.