JPS6157178A - Ic circuit with limiter circuit - Google Patents

Abstract

PURPOSE:To realize an effective IC circuit including various signal processing features by coming a limiting circuit with other signal processing circuit. CONSTITUTION:An output select circuit 21 is installed at the output lines of the limiter circuit 7 and a shift register 3 to select either pulse SC or reverse SC for the output supplied to a terminal 18. In this case, the circuit 7, the register 3, and the circuit 21 are integrated in a chip. There are eight input pins and six output pins for data of the circuit 7. With the number of input pins of the register 3 being eight, it is enough for information data to be the number of pins required for the register 13, because eight input and output pins are required. If 2-bit data is used as a selection pulse, two pins are required and only a pin is required for the pulsed and reverse Scs because of a bit data.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is suitable for application to digital signal processing devices that require a limiter circuit for word length limitation, such as a contour correction circuit for a television receiver. This invention relates to an IC circuit with a limiter circuit.

[Prior Art] For example, a television receiver is provided with a contour correction circuit in order to emphasize the contours of an image and reproduce a clear image.

Fig. 3 shows a conventional example of this, in which the luminance signal (n-bit digital signal) Yi, which has been digitally processed and supplied to the second terminal (1), is filtered through a bypass filter ( 2) Ic is supplied to extract the high frequency signal Yh at the outline of the image.

The luminance signal Yi is further supplied to a shift register (3) and delayed by a time corresponding to the delay time of the bypass filter (2). Delayed luminance signal Yi and high frequency signal Yh
is supplied to the adder (4), and the output luminance signal Ya is sent to the limiter circuit (7) for word length limitation via the correspondingly provided rounding circuit (6). Then, the redundant word length caused by signal addition etc. is limited to the required word length. Therefore, the output terminal (8) receives the edge-enhanced luminance signal YO with word length restriction.

Since the limiter circuit (7) is for limiting the maximum length bit, it can be configured as shown in FIG. 4, for example.

The figure shows a case where the upper 2 bits of the input 8-bit luminance signal Ya are removed to obtain a 6-bit luminance signal Yo. It is input to the A terminal side of (8). Furthermore, the data of the MSB bit of the input luminance signal Ya is supplied to the MSB terminal of the B terminal, and the bit-inverted data of this is passed through the inverter (9).
-1) Commonly supplied from the terminal to the LSB terminal.

Therefore, if the brightness signal Ya is a digital signal expressed in two's complement format, the relationship between this brightness signal Ya and the brightness signal Yo obtained by limiting the word length is as shown in FIG. Therefore, if the input level is within the interval TA, the lower 6 bits of the input luminance signal Ya are output as is, and if the input level is within the interval TB exceeding the interval TA, the B end input bits (6 bits) with the word length limited are output. ), it is possible to obtain the limited brightness signal Yo of 1,55.

Therefore, a matching circuit αυ-1 is provided to detect whether the input luminance signal Ya exceeds the upper and lower output limits. When the input luminance signal Ya exceeds the upper and lower output limits, the upper three bits of the input at that time are switched from the terminal A side to the terminal B side with the matching output obtained at this time.

The shift register (3) used in the contour correction circuit α0 is a programmable shift register whose delay time can be arbitrarily selected in consideration of the versatility of the shift register.

As shown in Fig. 6, this type of shift register (3) is composed of a shift register (3) having a predetermined number of stages, and a selector α4 for switching the number of stages, that is, selecting a delay time, and is connected to a terminal αDK. The delay time is selected by the selection pulse (digital code signal) SP.Therefore, the digital signal supplied to the input terminal Q51 is obtained at the output terminal αω after being delayed by a predetermined time.

[Problem that the invention seeks to solve]

By the way, when the contour correction circuit αω is configured as a digital processing device in this way, j−j, digital filter (2), and shift register (3) are all I.
While a C IC is used, its peripheral circuits such as a limiter circuit (7) are not general KIC.

S, mi, ivy episode! If 78 (7) is implemented in hardware, the number of discrete components will increase, and the area occupied by the limiter circuit (7) itself will increase. It is preferable to

However, as shown in Figure 4, this limiter circuit (7) consists only of a selector (8) and a matching circuit (11) and is distorted, so when considered in terms of the number of circuit elements (number of gates), the current semiconductor As a technology, it is inevitable that it will be a fairly small-scale IC circuit.

On the other hand, when considering the number of pins when integrated into an IC, only the minimum number of bits for input and output is required, so it is quite large (because of this number of pins, it is necessary to use a large package, and a large package is required. This results in an IC circuit with a poor gate.

Therefore, rather than making the limiter circuit (7) into an IC alone,
After combining the limiter circuit (7) with other circuits,
In 2017, more efficient IC circuits could be realized.

In this case, even if the limiter circuit (7) and other signal processing circuits are combined, it may not be possible to select each processing function independently, or the number of bins may be significantly greater than when each is integrated into an IC. , or the price will increase significantly.
In this case, there is no advantage in combining the limiter circuit (7) into an IC.

This invention solves the above-mentioned problem, and by combining the limiter circuit (7) with other signal processing circuits, it maintains the respective signal processing functions and provides efficient I/O.
This is a realization of the C circuit.

[Means for solving problems]

In order to solve the above problems, in the present invention, a limiter circuit (7) and other signal processing circuits are combined and configured on an ICC circuit.

In this case, the signal processing circuit to be combined should have the same number of input/output bins as the limiter circuit for word length limitation, and the number of circuit elements is far greater than the number of circuit elements of the limiter circuit. used.

As a signal processing circuit satisfying such conditions, a shift register (3) having a programmable function as shown in FIG. 1 is used in the embodiment. This shift register (
3) requires approximately the same number of pins as the limiter circuit (7) when integrated into an IC, and the number of circuit elements is about 2000, so the limiter circuit (
This is because the number of circuit elements is about 10 times that of 7).

[Effect]

Since the shift register (3) has a large number of circuit elements, even if the KIJ transmitter circuit (7) is incorporated therein, the IC scale will hardly change. The number of pins used in the shift register (3)K is not much different from the number of pins when the limiter circuit (7) is made into an IC alone, so the package size is the same as when the shift register is made into an IC.

Since the output selection circuit Qυ is provided, each signal processing function can be arbitrarily selected from the outside. Therefore, this I
By simply connecting the C circuit (2Ql) to the conventional signal processing positions as shown in FIG. 2, it can function as a shift register and can also function as a limiter.

〔Example〕

FIG. 1 shows an embodiment of an IC circuit board with a limiter circuit according to the present invention, which includes a limiter circuit (7) and a programmable shift register (3).

The limiter circuit (7) shown in FIG. 4 is used, and the shift register (3) shown in FIG. 6 is used. An output selection circuit Qυ is provided at each output stage of the limiter circuit (7) and the shift register (3), and one of the outputs is selected by the pulses SC and SC supplied to the terminal (1B. In this example, the pulse It is assumed that the output of the limiter circuit (7) is selected by SC.

The limiter circuit (7), shift register (3) and output selection circuit (21) are integrated into one chip. If the circuit shown in Figure 4 is used as limiter 1 circuit (7), there will be 8 input bins for data and 6 output bins.
If the number of input bits for the shift register (3) is 8 bits, eight input and output bins are required, so the number of pins required for the shift register (3) is sufficient for information data. be.

Further, when 2-bit data is used as the selection pulse, the number of pins is two, and the pulses sc and sc can be 1-bit data, so the number of pins is one. Therefore, the number of pins on the IC circuit board increases by only one pin compared to the case where a single shift register including one for control data is integrated into an IC.

When applying the IC circuit with limiter circuit (to) to the above-mentioned contour correction circuit αQ, as shown in FIG. An IC circuit board with a limiter circuit is used in each case.

The IC circuit with limiter circuit (20) used at the shift register (3) is (20A), and the IC circuit (to) used at the limiter circuit (7) is (20A).
0B), the pulse SC is supplied to the IC circuit (2OA) from the terminal (c). This allows the IC circuit (2
Since the output selection circuit Qυ of 0A) is switched to the terminal R side, the IC circuit (20A) operates as a shift register.

Pulse SC is further inverter C! The phase of the phase-inverted pulse SC is inverted by the IC circuit (20B
) K is supplied. With this, the IC circuit (20B)
Since the output selection circuit υ inside is switched to the terminal side, the IC circuit (20B) operates as a limiter circuit.

In the above description, the present invention is applied to the limiter circuit of the contour correction circuit αi, but the limiter circuit and the programmable shift register are the same.

If the vision receiver is a digital signal processing system, it can also be used in parts other than the contour correction circuit α, such as a Y/C separation circuit.

In addition, the IB processing circuit to be integrated into an IC is not limited to shift registers, but has a large number of circuit elements as mentioned above. Therefore, even if a limiter circuit is incorporated, it will not significantly increase the cost (and the number of input/output pins may increase). is about the same as the limiter circuit 8
If you have a comfortable digital signal processing device (not limited to 4-channel television receiver), you can use it in combination with a limiter circuit.
When it is converted to C, it forms.

〔Effect of the invention〕

As explained above, the present invention uses a signal processing circuit which uses the same number of input/output bins as the limiter circuit for word length limitation, and which has far more circuit elements than the limiter circuit. Since the above limiter circuit is made into the same chip KIC, it has the following characteristics.

First, since the limiter circuit is integrated into an IC, the area it occupies when mounted is reduced.

Second, since the number of circuit elements in the signal processing circuit into which the limiter circuit is to be incorporated is far greater than that of the limiter circuit, incorporating the limiter circuit into an IC will not result in a significant increase in cost.

Third, since the number of bins is about the same as the number of bins for a single signal processing circuit, the package does not become so large.

Since the integration density is also high, highly efficient IC circuits can be realized.

Therefore, the present invention is applicable to a signal processing device that digitizes and processes a television signal.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing an example of an IC circuit with a limiter circuit according to the present invention, FIG. 2 is a system diagram showing an example of a contour correction circuit to which this is applied, and FIG. 3 is a system diagram of a conventional contour correction circuit. , FIG. 4 is a system diagram showing an example of a limiter circuit, FIG. 5 is a chart for explaining its operation, and FIG. 6 is a system diagram showing an example of a programmable shift register. αω is a contour correction circuit, (3) is a programmable shift register, (7) is a limiter circuit, 翺 is an IC circuit with a limiter circuit, and +21> is an output selection circuit.

Claims (1)

[Claims] A signal processing circuit that uses the same number of input/output pins as the limiter circuit for word length limitation, and has far more circuit elements than the limiter circuit, and the limiter circuit are integrated into the same chip. An IC circuit with a limiter circuit, the input and output pins of which are commonly used, and an output selection circuit that can select the outputs of at least the signal processing circuit and the limiter circuit.