JPH11177371A - Resistance ladder type electronic volume - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain this resistance laddertype electronic volume which has a relatively small number of switches and also has small click noise. SOLUTION: The resistance laddertype electronic volume which are provided with a 1st switch group 11 that comprises plural switches which bridge resistances 1 that are serially connected to a controlled circuit IC and adjust attenuation quantity with relatively small step width and a 2nd switch group 12 that comprises plural switches which bridge resistances 2 that are parallelly connected to the circuit IC and adjust attenuation quantity with relatively large step width. In such a case, a 3rd switch group 13 which bridges resistances 3 that are serially connected to the resistances 2 and adjusts the attenuation quantity with relatively small step width so that attenuation quantity may reduce volume switch noise around 0 dB.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mini component, T
The present invention relates to a resistance ladder type electronic volume applied to an electronic volume IC used for AV products such as V.

[0002]

2. Description of the Related Art A conventional resistance ladder type electronic volume is roughly classified as follows. [1] All volume steps are configured by independent switches ... FIG. [2] Among the volume steps, those in which small steps are shared by the same switch (block A)... FIG.

In FIG. 3, a resistor 3 connected in parallel with a controlled circuit IC is provided with a switch group 13 which bridges the resistor 3 and adjusts the attenuation with a relatively small step width of 1 dB.

In FIG. 4, in block A, a resistor 1 connected in series with a controlled circuit IC is connected to
A switch group 11 for adjusting the attenuation with a relatively small step width of B is provided, and a relatively large step width of 4 dB is bridged to the resistor 2 connected in parallel with the controlled circuit IC in the block B. A switch group 12 for adjusting the amount of attenuation is provided, and the block A having a small amount of adjustment of the amount of attenuation and the block B having a large amount of adjustment of the amount of attenuation can cooperate with each other to adjust the amount of attenuation to a desired amount.

A disadvantage of the configuration [1] shown in FIG. 3 is that the number of switches is large. For example, if the step width is 1 dB in a variable range of 0 to -80 dB, 81 switches are required. However, since all the switches are connected in series to the input of the buffer amplifier (= high input impedance), the on-resistance of the switch is the input impedance of this buffer amplifier (more than several MΩ)
(For example, about several kΩ), the switch itself can be made smaller because the gain and distortion between input and output do not deteriorate.

In the case of the configuration [2] shown in FIG. 4, the number of switches can be reduced (24 in FIG. 4). On the other hand, the on resistance of the switches in the block A is used to prevent a decrease in gain and a deterioration in distortion. Therefore, it is necessary to lower the switch size, and the switch size increases. This will be described with reference to FIG.

In FIG. 5, a resistance r of the block A indicates an on resistance when the 0 dB switch of the block A in FIG. 4 is turned on. Now, assuming that the total resistance of the block B is 20 kΩ, the gain is (20 k) / (20 k + r)
It can be seen that the gain attenuates from 0 dB unless r is made sufficiently smaller than 20 kΩ. Also, since r is a non-linear resistance, a large r results in a deterioration of the distortion factor. For these reasons, r needs to be usually about several tens Ω, and the switch size becomes large.

If r is the on-resistance, the gate width of the transistor is W, and the gate length is L, then r∝W / L, and the on-resistance r is proportional to the gate width of the transistor. Inversely proportional to length. In order to reduce the on-resistance, it is necessary to increase W → large, and as a result, the switch size becomes large.

Also, as the switch size increases,
The parasitic capacitance of the switch increases. This parasitic capacitance generates noise (click noise) at the time of volume switching.
This will be described with reference to FIG. Resistance R in block A
Switches that bridge 1, R2 and R3 0 dB, -1 dB,
The parasitic capacitance of -2 dB is denoted by C0, C1, and C2.

Now, it is assumed that C0, C1, and C2 store electric charges Q0, Q1, and Q2, respectively, with the -1 dB switch in the block A turned on. Switch condition in block A changes (-1dB switch; ON → OFF)
/ 0dB switch; OFF → ON), C0, C
1, C2 have charge amounts of Q0 → Q0 ′, Q1 → Q1 ′, Q2
→ If it changes to Q2 ′, the flow of electric charges becomes R1, R
2, R3, which appears as click noise in the output.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to realize a resistance ladder type electronic volume having a relatively small number of switches and a small click noise.

[0012]

In the resistor ladder type electronic volume according to the first invention, a plurality of switches for bridging resistors connected in series to the controlled circuit to adjust the attenuation with a relatively small step width. A first switch group consisting of
A second switch group including a plurality of switches for bridging resistors connected in parallel to the controlled circuit and adjusting the attenuation with a relatively large step width; A third switch group that adjusts the amount of attenuation with a relatively small step width by bridging a resistor connected in series with the resistance adjusted by the group of switches to reduce the volume switching noise when the amount of attenuation is around 0 dB It is.

In the resistor ladder type electronic volume according to the second invention, a first switch comprising a plurality of switches for bridging resistors connected in series to the controlled circuit and adjusting the attenuation with a relatively small step width. A resistor-ladder-type electronic volume comprising a group and a second switch group consisting of a plurality of switches for adjusting attenuation with a relatively large step width by bridging resistors connected in parallel to the controlled circuit. A third switch group for bridging a resistor connected in series with the resistor adjusted by the second switch group and adjusting the attenuation with a relatively small step width similar to that of the first switch group; When the amount is near 0 dB, the amount of attenuation is adjusted by the third switch group. When the amount of attenuation is not near 0 dB, the coordination between the first switch group and the second switch group is performed. So as to adjust the more attenuation,
This is to reduce the volume switching noise when the amount of attenuation is around 0 dB.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 shows the configuration of an embodiment of the present invention. In FIG. 1, IC is a controlled circuit, 1 is a resistor connected in series to the controlled circuit IC, 11 is an analog switch 0 dB that bridges the resistor 1 and adjusts the attenuation with a relatively small step width of 1 dB.
Analog switch-1dB, Analog switch-2dB
1 is a first switch group, and 2 is a resistor connected in parallel to the controlled circuit IC. 12 is an analog switch for bridging the resistor 2 and adjusting the attenuation with a relatively large step width of 4 dB -8 dB to -80 dB , A reference numeral 3 denotes a resistor connected in series to the resistor 12, and 13 denotes a bridge which bridges the resistor 3 and adjusts the attenuation with a relatively small step width of 1 dB.
It is a third switch group consisting of B to -4 dB. Resistance 1
And switch group 11 constitute block A, and include resistor 2 and switch group 12 and resistor 3 and switch group 1
3 constitutes a block B.

The volume operation will be described with reference to FIG. Now, the volume level is changed from -80 dB to 1 dB /
If you want to increase by the step width of step, block A
Of the first switch group 11 and the second switch of the block B
1 dB / step is realized by the cooperation of these switches, but the switch group 1 of the block A for the attenuation amount of -4 to 0 dB is realized.
1 is not used, and 0dB, -1dB, -2d of block B
Switch group 1 composed of B, -3 dB, and -4 dB switches
Use 3.

In the case of FIG. 3 showing the prior art, the amount of attenuation is 0 to 3
In the dB range (block B is set to 0 dB), the clock noise generated in block A is output without being attenuated in block B.
Since the switch group 11 in the block A which causes the click noise is not used in the range of -3 dB, the click noise can be greatly improved.

The range of -80 dB to -4 dB (block B
Is set to any of -80 dB to -4 dB), the switch of block A operates and click noise occurs, but the noise is attenuated at block B (-80 dB to -4 dB).
Range), which is a level that does not cause any problem in practical use.

According to the present invention, the number of switches is slightly increased (in FIG. 1, three switches of -1 dB, -2 dB and -3 dB,
With a total of 27 (<81 in FIG. 2), click noise can be significantly improved.

Embodiment 2 In order to further improve the click noise, as shown in FIG. 2, the attenuation amount is -8 dB to 0 dB.
A switch for adjusting the amount of attenuation with a step width of 1 dB / step on the block B side between 0 dB to -8 dB
By providing the switch group 13 composed of
Click noise in the range of 0 dB can be improved.

In FIG. 2, IC is a controlled circuit, 1 is a resistor connected in series with the controlled circuit IC, 11 is an analog switch for bridging the resistor 1 and adjusting the attenuation with a relatively small step width of 1 dB. 0dB, analog switch-
1 dB, a first switch group consisting of an analog switch-2, 2 is a resistor connected in parallel with the controlled circuit IC, 12
Are analog switches that bridge the resistor 2 and adjust the attenuation with a relatively large step width of 4 dB.
A second switch group of 0 dB, 3 is a resistor connected in series with the resistor 12, and 13 is an analog switch that bridges the resistor 3 and adjusts attenuation with a relatively small step width of 1 dB, and an analog switch 0dB and an analog switch -1dB. This is a third switch group consisting of up to -8 dB. The resistor 1 and the switch group 11 constitute a block A, and the resistor 2 and the switch group 12 and the resistor 3 and the switch group 13 constitute a block B.
Is configured.

Also in this case (30 switches <81 switches in FIG. 3), the number of switches can be reduced more effectively than in the case of FIG.

[0022]

According to the first aspect of the present invention, a first switch group including a plurality of switches for adjusting the attenuation with a relatively small step width by bridging resistors connected in series to a controlled circuit; A second switch group including a plurality of switches for bridging resistors connected in parallel to the controlled circuit and adjusting the attenuation with a relatively large step width; By providing a third switch group for adjusting the attenuation with a relatively small step width by bridging the resistance connected in series with the resistance adjusted by the switch group, the volume switching noise in which the attenuation is near 0 dB is reduced. can do.

According to the second invention, the first switch group consisting of a plurality of switches for adjusting the amount of attenuation with a relatively small step width by bridging resistors connected in series to the controlled circuit; A second switch group comprising a plurality of switches for bridging resistors connected in parallel to the circuit and adjusting the attenuation with a relatively large step width. A third switch group for bridging the resistance connected in series with the resistance adjusted by the above and adjusting the attenuation with a relatively small step width similar to that of the first switch group is provided. In this case, the attenuation is adjusted by the third switch group, and when the attenuation is not near 0 dB, the attenuation is adjusted by the cooperation of the first switch group and the second switch group. By doing Te can attenuation to reduce the volume switching noise around 0 dB.

[Brief description of the drawings]

FIG. 1 is a diagram showing a resistance ladder type electronic volume according to an embodiment of the present invention.

FIG. 2 is a view showing a resistance ladder type electronic volume showing another embodiment of the present invention.

FIG. 3 is a view showing a conventional resistance ladder type electronic volume.

FIG. 4 is a diagram showing a conventional resistance ladder type electronic volume.

FIG. 5 is a diagram illustrating a problem of a conventional resistance ladder type electronic volume.

FIG. 6 is a diagram illustrating a problem of a conventional resistance ladder type electronic volume.

[Explanation of symbols]

IC controlled circuit, 1 resistor, 11 first switch group, 2 resistor, 12 second switch group, 3 resistor, 1 resistor
3 Third switch group.

Claims (2)

[Claims] 1. A first switch group consisting of a plurality of switches for adjusting attenuation with a relatively small step width by bridging resistors connected in series to a controlled circuit, and connected in parallel to the controlled circuit. A second switch group consisting of a plurality of switches for bridging the resistance and adjusting the attenuation with a relatively large step width.
A third switch group is provided for adjusting the amount of attenuation with a relatively small step width by bridging a resistor connected in series with the resistance adjusted by the second switch group, and a volume switching noise in which the amount of attenuation is near 0 dB. Resistance ladder type electronic volume, characterized in that the volume is reduced. 2. A first switch group consisting of a plurality of switches for adjusting attenuation with a relatively small step width by bridging resistors connected in series to a controlled circuit, and connected in parallel to the controlled circuit. A second switch group consisting of a plurality of switches for bridging the resistance and adjusting the attenuation with a relatively large step width.
A third switch group for bridging a resistor connected in series with the resistor adjusted by the second switch group and adjusting the attenuation with a relatively small step width similar to that of the first switch group; When the amount of attenuation is near 0 dB, the third
When the attenuation is other than about 0 dB, the attenuation is adjusted by the cooperation of the first switch group and the second switch group. Characterized in that a volume switching noise near 0 dB is reduced.