JPH104564A - Reproduced chroma signal processing unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To integrate the circuits for the processing unit onto one and same semiconductor substrate and to improve the C/N of a conversion frequency use signal. SOLUTION: An input signal 71 is multiplied with a separation frequency conversion signal 72A by a 1st separation frequency multiplier 13 on one hand, the input signal 71 is multiplied with a 3rd conversion signal 72B having a phase difference of 90 deg. to the signal 72A at a 2nd separation frequency multiplier 18 on the other hand, resulting that the input signal 71 is decomposed as color difference signals. The color difference signals are given to 1st or 2nd low pass filters 14, 19 passing low frequencies, where undesired high frequency components are eliminated, the resulting signal passes respectively through 1st or 2nd comb-line filters 15, 20. The output of the filter 15 is multiplied with a decoding frequency conversion signal 73A at a 1st decoding frequency multiplier 16, and the output of the filter 20 is multiplied with a decoding frequency conversion signal 73B with a phase difference of 90 deg. with respect to the signal 73A at a 2nd decoding frequency multiplier 22 and they are respectively decoded into a chroma carrier frequency band.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reproduced chroma signal processing device for stabilizing a normal chroma (color) signal among reproduced video signals of a video tape recorder (VTR).

[0002]

2. Description of the Related Art Conventionally, an example in which a band-pass filter (BPF) is configured by using a low-pass filter (LPF) and a frequency multiplier is applied to an IEEE AUGUST 1 system.
995, VOL41, NO. P.3 796.

[0003] The reproduction chroma signal processing used for a VTR is disclosed in JP-A-5-38517 and JP-A-5-480.
No. 37 is disclosed in each gazette.

A conventional band-pass filter using a low-pass filter and a frequency multiplier will be described below with reference to the drawings.

FIG. 4 is a block diagram of a conventional band-pass filter using a low-pass filter and a frequency multiplier. As shown in FIG. 4, a modulation center frequency signal 202A and an input signal 201 modulated by the modulation center frequency of the modulation center frequency signal 202A are connected to a first frequency multiplier 10A.
The output signal of the first frequency multiplier 101 is removed by a first low-pass filter 102 to remove unnecessary high-frequency components, thereby obtaining an original signal 203A before modulation. The center frequency signal 204A is multiplied by the second frequency multiplier 103.

A third frequency multiplier 105 multiplies the modulation center frequency signal 202B having a phase difference of 90 degrees with respect to the modulation center frequency signal 202A through the first phase shifter 104 and the input signal 201. The output signal of the third frequency multiplier 105 has an unnecessary high-frequency component removed by a second low-pass filter 106, and an original signal 203B having a phase difference of 90 degrees from the original signal 203A before modulation. Then, through the second phase shifter 107, the demodulated center frequency signal 204
A demodulation center frequency signal 204B having a phase difference of 90 degrees with respect to A, and original signal 203B having a phase difference of 90 degrees
Is multiplied by a fourth frequency multiplier 108.

Further, a signal output from the second frequency multiplier 103 and a signal output from the fourth frequency multiplier 108 are added by the adder 109 to obtain an output signal demodulated and converted. .

As described above, the operation can be performed even if the band pass filter required between the modulation and the demodulation is omitted.

Hereinafter, a conventional reproduction chroma signal processing apparatus will be described with reference to the drawings.

FIG. 5 is a block diagram of a conventional reproduced chroma signal processing device. In FIG. 5, reference numeral 111 denotes an input terminal to which a reproduced low-band chroma signal 205 as an input signal is input; 112, a first multiplier for multiplying the reproduced low-band chroma signal 205 by a frequency conversion signal 206; 1 is a first band-pass filter that passes only a predetermined frequency of the signal output from the frequency multiplier 112,
A CD delay 114a and an adder 114b,
A comb filter 115 that adds a signal output from the band-pass filter 113 and a signal output from the CCD delay unit 114a by an adder 114b to obtain a comb-shaped frequency characteristic.
Is an output terminal for outputting a chroma signal of a normal band, and 116 is a crystal oscillator (X ′) for generating a chroma carrier frequency signal.
tal OSC), 117 is a phase comparator for comparing the phase of the signal output from the comb filter 114 with the signal output from the crystal oscillator 116, and 118 is the phase comparator 11
7 is a low-pass filter that removes unnecessary high-frequency components output from 7, 119 is a voltage-controlled oscillator (VCO) whose output signal frequency is controlled by the signal voltage output from the low-pass filter 118, 120 is voltage control Oscillator 119
A frequency divider for dividing the frequency of the signal output from the frequency divider to a predetermined frequency; a second frequency multiplier 121 for multiplying the signal output from the crystal oscillator 116 by the signal output from the frequency divider 120 , 122 are second band-pass filters that pass only a predetermined frequency of a signal output from the second frequency multiplier 121 to generate a frequency conversion signal 206.

The operation of the reproduced chroma signal processing apparatus thus constructed will be described.
Is a frequency conversion signal 206 generated by the first frequency multiplier 112 by the second band-pass filter 122.
Is multiplied and converted into a chroma signal 207 in the normal band. The chroma signal 207 in the normal band passes through the first band-pass filter 113 and the comb filter 114 to remove unnecessary components. Then, the phase difference between the chroma signal 207 and the output signal of the crystal oscillator 116 is And a low frequency voltage signal. Next, the converted signal is
Only the DC and low frequency voltage components are extracted by the low-pass filter 118, and the oscillation frequency of the voltage controlled oscillator 119 is controlled. Next, the signal output from the voltage controlled oscillator 119 is frequency-divided by the frequency divider 120 to 1 / N, and then multiplied by the frequency of the crystal oscillator 116 and passes through the second band-pass filter 122. Thus, a signal 206 for frequency conversion is obtained. The frequency of the chroma signal 207 in the normal band is stabilized by the loop in which the output signal of the comb filter 14 is input to the first multiplier 112.

A VTR reproduced low-band chroma signal 205
The jitter of the time axis (hereinafter referred to as a jitter signal) of the signal is detected by a phase comparator 117, and the jitter signal is synchronized with a voltage-controlled oscillator 119 that generates a signal 206 for frequency conversion, whereby a chroma signal of a normal band is obtained. 207 removes the jitter signal.

FIG. 6 is a block diagram of a conventional reproduced chroma signal processing device. The same components as those in the reproduced chroma signal processing device shown in FIG. 5 are denoted by the same reference numerals, and description thereof is omitted. The difference from the configuration of the reproduction chroma signal processing apparatus shown in FIG. 5 is that the voltage controlled oscillator 119A shown in FIG.
Directly produces N times the frequency conversion signal 206, thereby eliminating the need for the second frequency multiplier 121 and the second bandpass filter 122. The reproduced chroma signal processing apparatus shown in FIG. Performs the same operation as the device shown in FIG.

[0014]

However, in the conventional reproduction chroma signal processing device, a delay device in a VTR device as shown in FIG. 5 or 6 is generally a CCD delay device, and the CCD is driven. The required clock frequency is three or four times the chroma carrier frequency. In addition, as the clock frequency increases, the number of stages of the delay circuit increases in order to obtain the same delay time, so that the circuit scale and chip size increase, so that it is impossible to incorporate the delay circuit in a signal processing IC chip. There is a problem that.

Further, the reproduction chroma signal processing apparatus shown in FIG. 5 requires the second band-pass filter 122 having high frequency selectivity to obtain the converted frequency signal 206.
Higher order filters are required. At present, the second bandpass filter 122 is integrated into an IC chip, but the circuit scale is large and complicated, so that noise is easily added to the frequency conversion signal 206, and the chip area and consumption are reduced. There is a problem that the current increases.

In the reproduction chroma signal processing apparatus shown in FIG. 6, the band-pass filter for obtaining the converted frequency signal 206 is omitted, but the frequency of the signal output from the voltage controlled oscillator 119A is changed to the converted frequency signal. Since it is possible to select only an integral multiple of 206, taking into account the fact that it is built into an IC chip, the limit is 4 or 5 times the conversion frequency signal 206, so that the frequency division ratio of the frequency divider 120 is also a voltage controlled oscillator. 1
It will be limited to the order of 19A.

Generally, the noise of the reproduced chroma signal processing device can be divided into phase modulation (PM) noise and amplitude modulation (AM) noise. In particular, to reduce PM noise, the conversion frequency of the chroma signal processing loop is reduced. Signal 206
Of the voltage-controlled oscillator 1
It is said that it is necessary to increase the C / N ratio of the frequency divider 19 and 119A and to increase the frequency division ratio of the frequency divider 120.

C / N of voltage controlled oscillators 119 and 119A
The ratio deteriorates with increasing frequency. As a result, when the converted frequency signal 206 is generated by the reproduced chroma signal processing device shown in FIG.
The / N ratio and the frequency division ratio are important factors for reducing PM noise. However, since the frequency output by the voltage controlled oscillator 119 and the order of the frequency divider 120 are limited, the voltage controlled oscillator 119 is limited. However, there is a problem that the output frequency cannot be set low.

An object of the present invention is to solve the above-mentioned conventional problems at once, and to improve the C / N ratio of a signal for a conversion frequency while being able to be integrated on the same semiconductor substrate. .

[0020]

In order to achieve the above object, the present invention comprises a low pass filter instead of a band pass filter for generating a signal for a converted frequency, and a comb filter having a delay unit. Configuration.

[0021] Specifically, the first aspect of the present invention is directed to a reproduced chroma signal processing device for stabilizing a chroma signal in a normal band of a video signal, and an input signal which is a reproduced low-band chroma signal. A first frequency at which a first converted signal having the same specific center frequency is input to the input signal and a first multiplied signal obtained by multiplying the input signal by the first converted signal is output; A multiplier; a first low-pass filter that removes a high-frequency component of the first multiplied signal output from the first frequency multiplier; and a output from the first low-pass frequency filter A first comb filter for removing unnecessary components of the signal, a first filter-passed signal output from the first comb filter and a second converted signal having a predetermined specific center frequency are input; 1 filter A second frequency multiplier passing signal and the second converted signal and outputs a second multiplication signal multiplied, 90 with respect to the input signal and the first converted signal
A third frequency multiplier that receives a third conversion signal having a phase difference of degrees and outputs a third multiplication signal obtained by multiplying the input signal by the third conversion signal; A second low-pass filter that removes a high-frequency component of a third multiplied signal output from the frequency multiplier, and an unnecessary component of a signal that is output from the second low-pass filter. A second comb filter, a second conversion signal having a phase difference of 90 degrees with respect to the second conversion signal, and a second filter passing signal output from the second comb filter; A fourth frequency multiplier that outputs a fourth multiplication signal obtained by multiplying the second filter-passed signal and the fourth conversion signal, and a second multiplication output from the second frequency multiplier Signal and output from the fourth frequency multiplier 4 is multiplied signal and the input is for the configuration and a these second multiplication signal and the fourth multiplied signal and an adder for outputting the added output signal.

According to the first aspect of the present invention, the first and third frequency multipliers are used to temporarily convert an input signal composed of a reproduced low band chroma signal into a color difference signal as a first and third multiplied signal, respectively. Further, by passing through the first and second low-pass filters, the conventional band-pass filter is not required, and since the signal passes through the first and second low-pass filters, the signal frequency passing through the comb filter is reduced by 50%.
Since the frequency can be reduced to 0 kHz or less, the clock frequency for driving the comb filter can be set to 2 MHz or less.

According to a second aspect of the present invention, in the configuration of the first aspect, a crystal oscillator serving as a supply source of the second and fourth converted signals and outputting a reference signal, and an output signal output from the adder A phase comparator that compares a phase of the reference signal output from the crystal oscillator with a phase of a reference signal output from the crystal oscillator; a third low-pass filter that removes a high-frequency component of the signal output from the phase comparator; A voltage-controlled oscillator whose oscillation frequency is controlled by a signal output from a third low-pass filter; and a frequency divider that divides a frequency of the signal output from the voltage-controlled oscillator. The frequency divider adds a configuration serving as a supply source of the first and third converted signals.

According to the second aspect of the present invention, the first and third frequency multipliers are used to temporarily convert an input signal composed of a reproduced low-band chroma signal into color difference signals as first and third multiplied signals, respectively. Further, by passing through the first and second low-pass filters, the conventional band-pass filter becomes unnecessary, and since the signal passes through the first and second low-pass filters, the first and third frequencies are returned at the time of feedback. The frequencies of the first and third converted signals respectively input to the multiplier can be reduced as compared with the conventional case.

According to a third aspect of the present invention, in the first or second aspect, at least one of the first comb filter and the second comb filter delays an input signal by a predetermined amount. , And an adder for adding an input signal and a signal output from the delay filter.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a reproduced chroma signal processing apparatus according to a first embodiment of the present invention. As shown in FIG. 1, an input signal 71 which is a reproduced low-band chroma signal input from an input terminal 11 is input via a gain control amplifier (GCA) 12 for adjusting the voltage of the input signal 71 to a predetermined range. , The input signal 71 and the separation frequency conversion signal 72A as the first conversion signal having the same specific center frequency are input, and the input signal 71 and the separation frequency conversion signal 72A are multiplied to form a color difference signal. A first separation frequency multiplier 13 serving as a first frequency multiplier that outputs a decomposed signal; and a signal connected to the first separation frequency multiplier 13 and output from the first separation frequency multiplier 13 A first low-pass filter 14 for removing unnecessary components, a first CCD delay unit 15a as a delay filter, which is connected to the first low-pass filter 14, and a first low-pass filter. It comprises a first adder 15b for adding the signals output from the wave number pass filter 14 and first CCD delay device 15a, a first low-frequency pass filter 14
A first comb filter 15 for removing unnecessary components of a signal output from the first comb filter, the first comb filter 15 being connected to the first comb filter 15, and having a predetermined specific center frequency with the signal output from the first comb filter 15 A reproduction / recording carrier frequency signal 73A as a second converted signal is input, and a signal output from the first comb filter 15 is multiplied by the reproduction / recording carrier frequency signal 73A to restore a signal suitable for reproduction / recording. And a first restored frequency multiplier 16 as a second frequency multiplier.

A third conversion signal 72B having a phase difference of 90 degrees with respect to the separation frequency conversion signal 72A via the input signal 71 and the first phase shifter 17 is input. A second separation frequency multiplier 18 as a third frequency multiplier that outputs a signal multiplied by the third conversion signal 72B and decomposed into a color difference signal; and a second separation frequency multiplier 18, And a second low-pass filter 19 connected to the second low-pass filter 19 for removing unnecessary components of the signal output from the second separation frequency multiplier 18 and a second C as a delay filter.
CD delay unit 20a and second low-pass filter 19
And a second adder 20b for adding a signal output from the second CCD delay unit 20a, and a second comb-shaped filter for removing unnecessary components of the signal output from the second low-pass filter 19. The filter 20 is connected to the filter 20 and the second comb filter 20. The signal output from the second comb filter 20 and the reproduced / recorded carrier frequency signal 73 A via the second phase shifter 21 are separated by 90 degrees. A fourth converted signal 73B having a phase difference is input, and a signal output from the second comb filter 20 and the fourth converted signal 73B
And a second restored frequency multiplier 22 as a fourth frequency multiplier for restoring a signal suitable for reproduction / recording.

Further, the signal outputted from the first restoration frequency multiplier 16 and the second restoration frequency multiplier are connected to the first restoration frequency multiplier 16 and the second restoration frequency multiplier 22. 3 which adds the signal output from
And an output terminal 24 connected to the third adder 23 for outputting an output signal which is a chroma signal of a normal band.
And a detector 25 connected between the third adder 23 and the output terminal 24 for detecting the voltage of the output signal of the third adder 23 into a first sub-configuration and a second sub-configuration. This is a configuration of adding.

Hereinafter, the operation of the reproduced chroma signal processing apparatus having the above-described configuration will be described with reference to FIGS.

FIGS. 2A and 2B are frequency characteristic diagrams of the reproduced chroma signal processing apparatus according to the first embodiment of the present invention, wherein FIG. 2A shows an input signal frequency band, FIG. 2B shows a frequency conversion signal for separation, and FIG. c) is the output frequency band of the separation frequency multiplier,
(D) is the output frequency band of the low-pass filter, (e) is the output signal frequency band of the comb filter, and (f) is the third frequency band.
Respectively represent output frequency bands of the adders.

First, an input signal having a frequency band as shown in FIG. 2 (a) is generally expressed as: A cos {(ω _L + p) t + θ ₁ } (1) (where A is a non-zero constant, | p | <500kHz, ω _L
Represents a low-band chroma carrier frequency. ), The first separation frequency multiplier 1
3 by the equation (1) 2 to the input signal shown in Bcos representing the separation frequency conversion signal shown in _{(b) (ω L t +} θ 2) ... (2) ( where, B is non-zero constants) Multiplying as shown in FIG. 2 (c), the output of the first separation frequency multiplier 13, AB / 2 · {cos ( pt + θ) + cos (2ω L t + pt + θ)} ... (3) ( where, theta = theta ₁ + Θ ₂ ).

Next, as shown in FIG.
The output signal shown in FIG.
The frequency band of 00 kHz or more is removed, and AB / 2 · cos (pt + θ) (4)

Next, as shown in FIG.
When the output signal shown in (1) passes through the first comb filter 15, AB / 2 · {cos (pt + θ) + cos (p (t + T) + θ)} (5), and the well-known frequency characteristics of the comb shape obtain.

Next, the first restoration frequency multiplier 16 uses the output signal shown in equation (5) to represent the restoration frequency conversion signal Ccos (ft + θ ₃ ) (6) (where C is a non-zero constant, f represents the chroma carrier frequency.) When multiplied by: ABC / 4 · {cos (ft + pt + θ ₃ + θ) + cos (ft−pt + θ ₃ + θ) + cos (ft + pt + PT + θ ₃ + θ) + cos (ft−pt−PT + PT + θ ₃ + θ)} (7) is obtained.

Further, the second separation frequency multiplier 18 by Bcos shifted phase of 90 degrees with respect to the separation frequency converted signal to an input signal shown in Equation _{(1) (ω L t +} θ 2 + π / 2) ... multiplying (8), as shown in FIG. 2 (c), the output of the second separation frequency multiplier 18, AB / 2 · {cos ( pt + θ-π / 2) + cos (2ω L t + pt + θ-π / 2)… (9) (where θ = θ ₁ + θ ₂ ).

Next, as shown in FIG.
The output signal shown in FIG.
The frequency band of 00 KHz or more is removed, and AB / 2 · cos (pt + θ−π / 2) (10) is obtained.

Next, as shown in FIG.
When the output signal shown in (0) passes through the second comb filter 20, AB / 2 · {cos (pt + θ−π / 2) + cos (p (t + T) + θ−π / 2)} (11) Obtain the frequency characteristics of the shape.

Then, the second restoration frequency multiplier 22 shifts the phase of the output signal shown in equation (11) by 90 degrees with respect to the restoration frequency conversion signal. Ccos (ft + θ ₃ + π / 2) (12) ) (However, if f multiplies represent.) chroma carrier frequency, ABC / 4 · {cos ( ft + pt + θ 3 + θ) -cos (ft-pt + θ 3 + θ) + cos (ft + pt + PT + θ 3 + θ) -cos (ft-pt- PT + θ ₃ + θ)｝ (13)

Next, as shown in FIG.
The output signal of the first restoration frequency multiplier 16 shown in FIG.
When the output signal of the second restoration frequency multiplier 22 shown in 3) and the output signal of the second restoration frequency multiplier 22 are added by the third adder 23, ABC / 2 · {cos (ft + pt + θ ₀ ) + cos (ft + pt + PT + θ ₀ )} (14) θ ₀ = θ ₃ + θ), and the band is restored to the normal band.

As described above, according to the first embodiment, the function of the band-pass filter can be realized by using the first and second two low-pass filters. Since the frequency of the signal passing through the device is 1/4 or less (500 kHz at the maximum) of the related art, the clock frequency for driving the CCD can be reduced to 2 MHz or less.
Can be fully integrated on one chip.

Since a band-pass filter occupying a large area on the substrate and consuming a large amount of current is not required, the signal processing LS
I can achieve high integration and low power consumption.

Hereinafter, a second embodiment of the present invention will be described with reference to the drawings.

FIG. 3 is a block diagram of a reproduced chroma signal processing device according to a second embodiment of the present invention. In FIG. 3, the same components as those in the reproduced chroma signal processing device according to the first embodiment are denoted by the same reference numerals, and description thereof is omitted. As shown in FIG. 3, the reproduced chroma signal processing device according to the present embodiment is different from the reproduced chroma signal processing device according to the aforementioned embodiment in that the first restored frequency multiplier 16 and the second phase shifter 21 The third adder 23 is connected to the crystal oscillator 26 serving as a supply source of a chroma carrier frequency signal as a reference signal serving as the restoration frequency conversion signal 73A, the third adder 23, and the crystal oscillator 26.
3 and a phase comparator 27 for comparing the phase of the output signal of the crystal oscillator 26 with the phase of the output signal of the crystal oscillator 26.
A third low-pass filter 28 for removing unnecessary high-frequency components of the signal output from the phase comparator 27, and a third low-pass filter 28 connected to the third low-pass filter 28, An oscillation frequency is controlled by a signal to be output, and a voltage-controlled oscillator 29 that outputs a signal having a frequency that is an integral multiple of the low-band chroma carrier frequency is connected to the voltage-controlled oscillator 29 and output from the voltage-controlled oscillator 29. A frequency divider 30 for reducing the frequency of the signal, and a fourth low-pass filter 31 connected to the frequency divider 30 and generating a separation frequency conversion signal 72A from the signal output from the frequency divider 30 are provided. .

Hereinafter, the operation of the reproduced chroma signal processing device having the above-described configuration will be described.

As described in the first embodiment, the input signal 71 is multiplied on the one hand by the first separation frequency multiplier 13 together with the separation frequency conversion signal 72A, and on the other hand the second separation frequency multiplier The signal 18 is multiplied by 18 with a third conversion signal 72B having a phase difference of 90 degrees with respect to the separation frequency conversion signal 72A, and is once converted and decomposed as a color difference signal.

Next, each of the color difference signals is supplied to a first or second low-pass filter 1 that passes a frequency of 500 kHz or less.
After unnecessary high frequency components are removed by the filters 4 and 19, the filters pass through the first and second comb filters 15 and 20, respectively. Thereafter, the color difference signal is multiplied by the first restoration frequency multiplier 16 together with the restoration frequency conversion signal 73A output from the crystal oscillator 26 on the one hand, and on the other hand, the restoration frequency conversion signal 7 by the second frequency multiplier 22.
Fourth converted signal 7 having a phase difference of 90 degrees with respect to 3A
It is multiplied with 3B and restored to the chroma carrier frequency band.

Next, each color difference signal is added by the third adder 23 to become a normal chroma signal. The phase difference between the normal chroma signal and the output signal of the crystal oscillator 26 is detected by the phase comparator 27, and the phase comparator 27 outputs a direct current or a low-frequency alternating current proportional to the detected phase difference.

Next, an unnecessary high-frequency component is removed from the signal output from the phase comparator 27 by a third low-pass filter 28, and the signal N1 is an integer multiple of the low-band chroma carrier frequency.
The oscillation frequency of the voltage controlled oscillator 29 oscillating at (N1 ≧ 16) is controlled.

Next, the signal output from the voltage-controlled oscillator 29 is divided by the frequency divider 30 into 1 / N1 and then to the low-band chroma carrier frequency output from the frequency divider 30. A separation frequency conversion signal 72A is generated by a fourth low-pass filter 31 that passes only a signal of a corresponding frequency, and supplied to the first separation frequency multiplier 13 and the second separation frequency multiplier 18, respectively. Is formed. This loop stabilizes the output signal of the third adder 23, that is, the frequency of the normal chroma signal.

As described above, according to the second embodiment, the oscillation frequency oscillated by the voltage controlled oscillator 29 can be freely set to an even multiple of N1 (N1 ≧ 16) of the low-band chroma carrier frequency, and the frequency divider can be set. 30 can be increased to the same value as N1.
Since the N ratio can be made sufficiently large,
PM of chroma signal by APC (automatic phase control) loop
Noise degradation can be minimized.

[0052]

According to the reproduction chroma signal processing apparatus of the first aspect, the signal frequency passing through the comb filter is set to 500 kHz.
Since the frequency can be reduced to z or less, the clock frequency for driving the comb filter can be set to 2 MHz or less, so that the signal processing LSI can be integrated on one semiconductor substrate.

Further, since a band-pass filter occupying a large area on the substrate and consuming a large amount of current is not required, the signal processing LS
I can achieve high integration and low power consumption.

According to the reproduction chroma signal processing device of the second aspect, the effect of the reproduction chroma signal processing device of the first aspect can be obtained, and the first and third frequency multipliers input to the first and third frequency multipliers, respectively. 3, since the frequency of the converted signal can be made lower than before, the frequency division ratio of the frequency divider can be increased, so that the C / N ratios of the first and third converted signals are increased, and as a result, the chroma signal Degradation due to PM noise can be suppressed.

According to the reproduction chroma signal processing device of the third aspect, the first or second comb filter has a delay filter having a predetermined delay amount, a signal input to the delay filter, and an output from the delay filter. Since it is composed of an adder for adding the signal and the signal, the reproduced low-band chroma signal, which is the input force signal, can be reliably demodulated into a normal-band chroma signal.

[Brief description of the drawings]

FIG. 1 is a block diagram of a reproduced chroma signal processing device according to a first embodiment of the present invention.

FIGS. 2A and 2B are frequency characteristic diagrams of the reproduced chroma signal processing device according to the first embodiment of the present invention, wherein FIG. 2A shows an input signal frequency band, FIG. 2B shows a frequency conversion signal for separation, and FIG. Is the output frequency band of the separation frequency multiplier, (d) is the output frequency band of the low-pass filter, (e) is the output signal frequency band of the comb filter, and (f) is the output frequency band of the third adder. It is a figure showing each.

FIG. 3 is a block diagram of a reproduced chroma signal processing device according to a second embodiment of the present invention.

FIG. 4 is a block diagram of a band-pass filter using a conventional low-pass filter and a frequency multiplier.

FIG. 5 is a block diagram of a conventional reproduced chroma signal processing device.

FIG. 6 is a block diagram of a conventional reproduced chroma signal processing device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11 Input terminal 12 Gain control amplifier (AGC) 13 1st separation frequency multiplier 14 1st low frequency pass filter (LPF) 15 1st comb filter 15a 1st CCD delay 15b 1st adder 16 1st restoration frequency multiplier 17 1st phase shifter 18 2nd separation frequency multiplier 19 2nd low frequency pass filter 20 2nd comb filter 20a 2nd CCD delay unit 20b 2nd adder 21 Second phase shifter 22 Second restoration frequency multiplier 23 Third adder 24 Output terminal 25 Detector 26 Crystal oscillator 27 Phase comparator 28 Third low-pass filter 29 Voltage controlled oscillator 30 Divider 31 fourth low-pass filter 71 input signal 72A separation frequency conversion signal (first conversion signal) 72B third conversion signal 73A And recording the carrier frequency signal (a second conversion signal) 73B fourth conversion signal

Claims (3)

[Claims] 1. A reproduction chroma signal processing device for stabilizing a chroma signal in a normal band of a video signal, wherein the input signal is a reproduced low band chroma signal and has the same specific center frequency as the input signal. A first frequency multiplier that receives a first converted signal and outputs a first multiplied signal obtained by multiplying the input signal and the first converted signal; and an output from the first frequency multiplier. A first low-pass filter that removes a high-frequency component of the first multiplied signal, and a first comb filter that removes unnecessary components of a signal output from the first low-pass filter. A first filtered signal output from the first comb filter and a second converted signal having a predetermined specific center frequency are input, and the first filtered signal, the second converted signal, Is multiplied A second frequency multiplier that outputs a second multiplied signal, and a third converted signal having a phase difference of 90 degrees with respect to the input signal and the first converted signal, and the input signal A third frequency multiplier that outputs a third multiplied signal obtained by multiplying the third multiplied signal with the third converted signal; and removing a high-frequency component of the third multiplied signal output from the third frequency multiplier. A second low-pass filter, a second comb filter for removing unnecessary components of a signal output from the second low-pass filter, and a second comb filter output from the second comb filter. And the fourth converted signal having a phase difference of 90 degrees with respect to the second converted signal are input, and the second filtered signal and the fourth converted signal are multiplied. Fourth power to output a fourth multiplication signal And a second multiplied signal output from the second frequency multiplier and a fourth multiplied signal output from the fourth frequency multiplier are input. A reproduction chroma signal processing device, comprising: 2. A crystal oscillator serving as a supply source of the second and fourth converted signals and outputting a reference signal, a phase of an output signal output from the adder, and a reference signal output from the crystal oscillator A third low-pass filter that removes a high-frequency component of a signal output from the phase comparator, and a third low-pass filter that is output from the third low-pass filter. A voltage-controlled oscillator whose oscillation frequency is controlled by a signal; and a frequency divider that divides a signal output from the voltage-controlled oscillator, wherein the frequency divider includes the first and third conversion signals. The reproduction chroma signal processing apparatus according to claim 1, wherein the reproduction chroma signal processing apparatus serves as a supply source of the chroma signal. 3. At least one of the first comb filter and the second comb filter includes: a delay filter for delaying an input signal by a predetermined amount and outputting the signal; 3. The reproduced chroma signal processing device according to claim 1, further comprising an adder for adding a signal output from the filter.