JP2001036361A - Electronic volume - Google Patents

Abstract

PROBLEM TO BE SOLVED: To exactly prevent a noise at the time of volume switching. SOLUTION: This electronic volume is provided with a switching means, composed of an operational amplifier SA with switch for making effective setting of a resistance value due to switching elements A1 to An or B1 to Bn in one of first and second switch element groups A and B. At switching from one of first and second switch element groups A and B to the other group, this switching means makes effective setting of the resistance value in the other one of first and second switching element groups A and B, by changing a current through the switching elements in one of first or second switching element groups A and B, from high level to zero level with a prescribed time constant and changing a current through the switching elements in the other group of first and second switching element groups A and B from zero level to high level with a prescribed time constant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in the performance of a shock noise prevention circuit in an electronic volume as a signal attenuator mounted on an audio product.

[0002]

2. Description of the Related Art FIG.
As shown in (1), a resistor ladder circuit composed of CMOS transistors is combined with an output operational amplifier. In these general circuits, a transient output voltage appears at the output when the volume is switched due to several factors, and as a result, an abnormal sound (shock sound) is generated at the speaker output.

(Factor 1) A general operational amplifier has a unique input power supply determined by a bias current of a differential input stage, and is viewed from the input side of the operational amplifier when the switch of the resistance ladder circuit is switched as described above. A change in impedance appears as a change in input power. This is one of the factors of the shock sound at the time of switching.

(Factor 2) It is generally known that a switch element composed of a CMOS transistor, which is a component of a resistance ladder circuit, has equivalent parasitic capacitances CDG and CGS as shown in FIG. 6A is a configuration diagram of a switch formed of a CMOS transistor, FIG. 6B is an equivalent circuit diagram, and FIG. 6C is a waveform diagram. This parasitic capacitance CDG,
CGS is a gate for controlling ON / OFF of a CMOS transistor: G and a drain serving as a base constituting a switch:
D or lease: S, and a power supply voltage or a GND voltage is input to a gate for controlling this transistor. This voltage changes when the switch is switched. As can be seen from this equivalent circuit (FIG. 6), when the gate voltage VG changes, a transient signal is generated on the signal line of the volume via the parasitic capacitance. This is also one of the causes of the shock noise.

In audio equipment, the electronic volume for volume adjustment is switched while listening to music, and cannot be switched while muting the output. Therefore, the shock sound at the time of this switching is an important parameter that determines the performance of the electronic volume.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electronic volume that can accurately prevent noise at the time of volume switching.

[0007]

According to a first aspect of the invention, there is provided an electronic volume comprising a resistance element group including a plurality of resistance elements connected in series to each other, and a plurality of switch elements respectively connected to the resistance elements. A first switch element group for setting a resistance value of the resistor element group according to a switching operation of each switch element, and a plurality of switch elements connected in parallel to the plurality of switch elements in the first switch element group, respectively. A second switch element group for pairing with the first switch element group and setting a resistance value of the resistor element group in accordance with a switching operation of each switch element; and One of the first and second switch element groups is selected to derive a current passing through the switch element, and one of the first and second switch element groups is selected. Wherein a switching means to enable the setting of the resistance value, the switching means, when switching from one to the other of said first and second switching element group in,
The current passing through the switch element in one of the first and second switch element groups changes from a high level to a zero level with a predetermined time constant, and the switch element in the other of the first and second switch element groups is By changing the passing current from zero level to high level with a predetermined time constant, the setting of the resistance value in the other of the first and second switch element groups is made effective.

In the electronic volume according to the second aspect of the invention, the electronic volume includes a resistance element group composed of a plurality of resistance elements connected in series to each other, and a plurality of switch elements connected to the resistance elements, respectively. A first method for setting a resistance value of the resistance element group according to an operation.
And a plurality of switch elements connected in parallel to the plurality of switch elements in the first switch element group, respectively, and each of the switch elements is paired with the first switch element group. A second switch element group for setting the resistance value of the resistor element group in accordance with a switch operation, and either one of the first and second switch element groups are selected and a current passing through the switch element is selected. Switching means for deriving and setting the resistance value in one of the first and second switch element groups, and changing the resistance value of the resistance element group by the switching operation of the switching means to change the volume value. When changing, the other set resistance value of the first and second switch element groups not selected by the switching means is set to a value corresponding to the volume value to be changed. And the switching means changes a current passing through a switch element in one of the first and second switch element groups in response to switching from one of the first and second switch element groups to the other. By changing from a high level to a zero level with a predetermined time constant, and changing a current passing through a switch element in the other of the first and second switch element groups from a zero level to a high level with a predetermined time constant, The setting of the resistance value in the other of the first and second switch element groups is made effective.

In the electronic volume according to a third aspect of the present invention, the switching means comprises an operational amplifier with a switch to which a bias current is supplied by first and second bias current sources, and wherein the first and second bias current sources are provided. The current passing through the switch element in one or the other of the first and second switch element groups is changed from zero level to high level or from high level to zero level with a predetermined time constant by increasing or decreasing the bias current. It is.

In the electronic volume according to the fourth invention, a timing circuit for setting a switching timing from one of the first and second switch elements to the other or from the other in response to a volume switching command, and a volume switching command. And a bias switching circuit for changing the bias current in the first and second bias current sources of the switching means comprising the operational amplifier with a switch with a predetermined time constant.

In the electronic volume according to a fifth aspect of the present invention, the first and second switch element groups are switched at a rising edge of a volume switching command signal. At the falling edge of the command signal, a bias switching circuit is operated to switch the first and second switch element groups.

In an electronic volume according to a sixth aspect of the present invention, one of the first and second switching element groups is made operable and the other is made inoperative in response to a rising edge of a volume switching command signal. 1 and the first and second flip-flops and the bias switching circuit in response to the falling edge of the volume switching command signal.
And a second flip-flop for switching the group of switch elements.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a connection diagram showing a circuit configuration of a first embodiment according to the present invention. In the figure, RL is a resistance ladder section, SA is an operational amplifier section with a switch, and TC is a timing circuit section. Vin is an input terminal, R1, R2, R3, R4, R5,..., Rn are resistance elements constituting the resistance element group R, A1, A2, A3, A
, An are switch elements constituting the switch element group A, B1, B2, B3, B4, B5,..., Bn are switch elements constituting the switch element group B, Vout is an output terminal, and 11 is a timing. A bias switching circuit constituting the circuit section TC, and 13 is a timing circuit constituting the timing circuit section TC.

This circuit is composed of three main blocks: a resistance ladder section RL, an operational amplifier section with switch SA, and a timing circuit section TC. The resistance ladder unit RL is provided with two switch element groups A and B, and operates so that one of the switch elements corresponding to the set attenuation is turned on.

Each of the switch common contacts A to the operational amplifier with switch SA having two input stages corresponding to the switch element group A and the switch element group B, respectively.
The current flowing through c and Bc is input. The output of the operational amplifier with switch SA is a common output. In this example, a voltage follower configuration is used to output a voltage value of one of the selected input sides. The selection of the input stage of the operational amplifier SA is controlled by the bias currents IA and IB of the differential transistors constituting the operational amplifier SA.

The bias currents IA and IB are slowly changed by the soft switching circuit 11 with a time constant determined by CR, so that either one of the selected currents IA or IB flows, and the other non-selected side has zero current. (Operation by one volume switching command signal ST).
Further, the timing circuit 13 outputs the volume switching instruction S
This is a block for generating switching timing of two sets of resistance ladder switch element groups A and B when T (trigger) is input.

FIG. 2 is a diagram showing a specific circuit configuration of the timing circuit section TC in FIG. 1, and FIG. 3 is a diagram showing a specific circuit configuration of the bias switching circuit 11. Using Figure 2,
A more detailed operation will be described. In the figure, 1 is serial data input from the microcomputer, 2 is VOLbit,
3 is ENbit.

A general electronic volume is controlled by serial data 1 input from a microcomputer (not shown). ENbit2 is a bit called an enable bit for selecting an operation function of input data. In this example, 3 bits are assigned. VOLbit is a bit for determining the amount of attenuation of the volume.
Bits are allocated.

After the serial data 1 is input in a predetermined format, one pulse is input to the first-stage AND circuit 4 as a volume switching command signal ST serving as a trigger input for volume setting.

Another input of the AND circuit 4 is "Hi".
That is, when selected by ENbit3, a pulse similar to the signal ST is output to the output, and is input to the T input of the next stage D-FF5. The output "-Q" of this D-FF5
(= Inverted Q signal) and the D input are connected, and each time a pulse is input to the T input, the output “Q”,
“−Q” changes from the previous state “Hi” or “Low” to “L”.
ow "or" Hi ". Outputs “Q” and “−Q” of the D-FF 5 are input to T inputs of D-FFs (edge trigger type) 6 and 7 at the next stage, respectively.

The D inputs of the D-FFs 6 and 7 are supplied to the power supply,
Q ”input is a delay element Delay having a constant delay.
8 to the R input (reset). Therefore, the T inputs of the D-FFs 6 and 7 change from “Low” to “Hi”.
, The “Q” output becomes “Hi” and “−Q”
The output becomes “Low”. Further, the “−Q” output is input to the next Delay element 8, but after a certain time,
Since "Low" is input to the R input of the D-FF,
The “Q” output changes from “Hi” to “Low”. That is, an edge one-shot pulse circuit is formed.
The outputs of the D-FFs 7 and 8 are input to the trigger input terminals of the latch B circuit 9B and the latch A circuit 9A as signals TB and TA, respectively.

The latch A and latch B circuits 9A and 9B store volume setting bits 2 of serial data 1 as data.
At the pulse input timing of the trigger inputs TA and TB,
It is set and held until the next trigger input TA or TB comes. The held 5-bit data is such that only one of the data outputs (A1 to An) and (B1 to Bn) is "Hi" or "Low" at the next stage decoder A: 10A and decoder B: 10B. To get the output These data outputs (A1 to An) and (B1 to Bn) are shown in FIG.
For controlling the switch groups A and B of the resistance ladder section RL.

On the other hand, the D-FF 12 is the D-FF 5
Performs the same operation as the above, but is a falling edge trigger type. The output Q of the D-FF 12 is input to the trigger input TS of the bias switching circuit 11. The TS input is first input to the gate of the first-stage NchMOS transistor Qs, and ON / OFF-controls the transistor Qs. When the transistor Qs is OFF, the capacitor Cs is charged by the constant current source Is, and becomes the potential Vcc.

Next, when the transistor Qs is turned on, the capacitor Cs is discharged via the resistor Rs and the transistor Qs, and transitions from the Vcc potential to the GND potential with a time constant. Due to this change in potential, the bias currents IA and IB change from the "flowing state (current high level)" to the "current zero state (current zero level)" with the respective time constants by the next stage comparator.

The above operation timings are shown in FIG. 4 in terms of the terminal waveforms and the switching states of the groups A and B. As can be seen from this timing chart, the switch group A, B on the side not selected by the operational amplifier with switch SA is always switched to the switch at the next volume position at the rising edge of the volume switching command signal ST.
Further, at the falling edge of the signal ST, switching is performed so that the volume setting by the switch of the next volume position is made valid. At this time, the switch on the non-selection side is always switched as described above.

That is, in FIG. 4, in the left end state shown in the figure, the bias currents IA and IB of the differential transistors in the operational amplifier SA with switch are such that the bias current IA is at a high level and the bias current IB is at a zero level. is there. When the bias current IA is at a high level, the switch element group A is selected, and the switch element group B is in a non-selected state.

The switch element group A includes a switch element Ax
(One of the switch elements A1 to An) is turned on, the set resistance value of the resistance element group R corresponding to the switch element Ax is validated, and the volume value is determined accordingly. Here, the switch element group A includes a control signal Ax (control signals A1 to An) which has been latched by a latch signal TA applied to the latch circuit A: 9A before that.
Is output from the decoder A: 10A. On the other hand, the switch element group B outputs one of the control signals B1 to Bn previously latched by the latch signal TB applied to the latch circuit B: 9B from the decoder B: 10B, and outputs the switch element B1. To Bn are in the ON state, but are not involved in the determination of the volume value based on the set resistance value of the resistance element group R due to the non-selected state.

In this state, when switching to the volume value corresponding to the switch element m (one of the switch elements A1 to An and B1 to Bn), the volume setting bit 2 corresponding to the volume value to be switched is set. After the serial data 1 having the set value is input, a volume switching signal ST serving as a trigger for volume setting is input (see FIG. 2). Since the input of the serial data 1 from the ENbit 3 to the AND circuit 4 is “Hi”, the AND circuit 4 outputs a pulse signal similar to the volume switching signal ST. In response to the rising edge of the pulse signal, that is, the rising edge of the volume switching signal ST, the flip-flop 5 operates to set its Q output to "Hi", thereby operating the flip-flop 6 and outputting the latch signal TB from the flip-flop 6.

The latch circuit B: 9B newly latches a data signal corresponding to the volume switching expected value in VOLbit 2 of the serial data 1 by the latch signal TB input to the latch circuit B: 9B, and the decoder circuit B:
The output of 10B is Bm corresponding to the scheduled volume switching value.
(One of the outputs B1 to Bn) and the switching element B
m (one of the switch elements B1 to Bn) is switched to the ON state.

At the timing of the rising edge of the volume switching signal ST, the bias current IA is maintained at a full level, and the bias current IB is in a standby state in which it is maintained at a zero level. In this state where the bias current IB is maintained at the zero level, the switch element group B is in the non-selected state, and the volume set value by this switch element Bm (one of the switch elements B1 to Bn) is effective. is not.

Next, the flip-flop 12 operates in response to the fall of the volume switching signal ST, and outputs a trigger input signal TS to the bias switching circuit 11. Upon application of the trigger input signal TS, the bias switching circuit 11 switches the bias currents IA and IB according to the time constant of the resistor Rs and the capacitor Cs, and gradually shifts the bias current IA from full level to zero level with the time constant. The bias current IB is gradually shifted from the zero level to the full level with the time constant.

When the bias current IB shifts to the full level, the volume set value by the switch element Bm (one of the switch elements B1 to Bn) in which the switch element group B is in the ON state is selected, and is set to be valid. Become. Then, by the shift of the bias current IA to the zero level,
The switch element group A is in a non-selected state.

In this state, when switching to the volume value corresponding to the switch element n (one of the switch elements A1 to An and B1 to Bn), the volume setting bit 2 corresponding to the volume value to be switched is set. After the serial data 1 having the set value is input, a volume switching signal ST serving as a trigger for volume setting is input (see FIG. 2). Since the input of the serial data 1 from the ENbit 3 to the AND circuit 4 is “Hi”, the AND circuit 4 outputs a pulse signal similar to the volume switching signal ST. In response to the rising edge of this pulse signal, that is, the volume switching signal ST, the flip-flop 5 operates and its Q output is set to "Low", thereby operating the flip-flop 6 and outputting the latch signal TA from the flip-flop 7.

The latch circuit A: 9A newly latches a data signal corresponding to the expected volume switching value in VOLbit 2 of the serial data 1 by the latch signal TA input to the latch circuit A: 9A.
The output of 10A becomes An corresponding to the scheduled volume switching value, and is switched so that the switch element An is turned on.

At the timing of the rising edge of the volume switching signal ST, the bias current IA is maintained at zero level, and the bias current IB is in a standby state in which it is maintained at full level. In this state where the bias current IA is maintained at the zero level, the switch element group A is in the non-selected state, and the volume set value by this switch element An is not valid.

Next, the flip-flop 12 operates in response to the fall of the volume switching signal ST, and outputs a trigger input signal TS to the bias switching circuit 11. Upon application of the trigger input signal TS, the bias switching circuit 11 switches the bias currents IA and IB according to the time constant of the resistor Rs and the capacitor Cs, and gradually shifts the bias current IA from zero level to the full level with the time constant. The bias current IB is gradually shifted from the full level to the zero level with the time constant.

When the bias current IA shifts to the full level, the volume set value by the switch element An in which the switch element group A is ON is selected and becomes effective. When the bias current IB shifts to the zero level, the switch element group B is deselected.

Further, when a volume switching signal ST is issued as a switching element l switching command, the switching element B1 (switch element B1) is operated by the same operation as described above.
To Bn) are turned ON, and the switch element group B is selected.

Since the operational amplifier connected to the switch groups A and B, which are always switched, is in a non-selected state, shock noise caused by the parasitic capacitance of the switch is not affected at all by the output of the operational amplifier SA. . In addition, since the switching of the operational amplifier SA is gently changed by the time constant of the bias switching circuit 11, shock noise caused by the input bias current of the operational amplifier SA is prevented.

According to the embodiment of the present invention, a plurality of resistance elements R1, R2, R3, R
, Rn, and a plurality of switch elements A1, A connected to the resistance elements, respectively.
2, A3, A4, A5,..., An, a first switch element group A for setting the resistance value of the resistance element group according to the switching operation of each switch element, and the first switch A plurality of switch elements B1, B2, B3 connected in parallel to the plurality of switch elements A1, A2, A3, A4, A5,.
, Bn, and a second pair for setting the resistance value of the resistor element group R in accordance with the switching operation of each switch element, forming a pair with the first switch element group A. A switch element group B and one of the first and second switch element groups A and B are selected to derive a current passing through the switch element, and the first and second switch element groups A and B are selected. A stage for validating the setting of the resistance value in one of the above, when the resistance value of the resistance element group R is changed by the switching operation of the switching means to change the volume value, the switching means is not selected by the switching means Setting the other set resistance value of the first and second switch element groups A and B to a value corresponding to a volume value to be changed;
The switching means is constituted by an operational amplifier SA with a switch to which a bias current is supplied by first and second bias current sources, and the first and second bias current sources are used to increase and decrease the bias current. By changing the current passing through the switch element in one and the other of the second switch element groups A and B from zero level to high level or from high level to zero level with a predetermined time constant, the first and second switch elements are changed. Since the setting of the resistance value on the other side of the group is made valid, it is possible to obtain an electronic volume that can more accurately prevent noise during volume switching by adjusting the bias current.

According to the embodiment of the present invention, the timing for setting the switching timing from one of the first and second switch element groups A and B to the other or the other from one in response to the volume switching command ST. Circuit and the operational amplifier with switch S according to a volume switching command.
And a bias switching circuit 11 for changing a bias current in the first and second bias current sources of the switching means having a predetermined time constant with a predetermined time constant. The switch element groups A and B are switched. The respective bias currents are set to a predetermined standby state, and the first and second switch element groups are activated by operating the bias switching circuit 11 at the falling edge of the volume switching command signal. Since A and B are switched, the bias currents IA and I by the bias switching circuit which are brought into a predetermined standby state when switching are performed.
By switching B, it is possible to obtain an electronic volume that can more accurately prevent noise during volume switching.

According to the embodiment of the present invention, the first and second switching element groups A and B are responsive to the rising edge of the volume switching command signal ST.
And a bias switching circuit 1 in response to the falling edge of the volume switching command signal ST.
1 to activate the first and second switch element groups A, B
Is provided, the second flip-flop 12 is provided to switch between the bias currents IA and IB by the bias switching circuit operated by the flip-flop, thereby obtaining an electronic volume that can more accurately prevent noise at the time of volume switching. it can.

[0043]

According to the first aspect of the present invention, there are provided a resistor element group including a plurality of resistor elements connected in series to each other, and a plurality of switch elements respectively connected to the resistor elements.
A first switch element group for setting a resistance value of the resistor element group according to a switching operation of each switch element, and a plurality of switch elements connected in parallel to the plurality of switch elements in the first switch element group, respectively. A second switch element group for pairing with the first switch element group and setting a resistance value of the resistor element group in accordance with a switching operation of each switch element; and A switch for selecting one of the first and second switch element groups to derive a current passing through the switch element, and enabling the setting of the resistance value in one of the first and second switch element groups Means for switching one of the first and second switch element groups when one of the first and second switch element groups is switched to the other. The current passing through the switch element changes from a high level to a zero level with a predetermined time constant, and the current passing through the switch element in the other one of the first and second switch element groups changes from a zero level to a high level with a predetermined time constant. The setting of the resistance value in the other of the first and second switch element groups is made effective by changing the above, so that it is possible to obtain an electronic volume that can accurately prevent noise during volume switching. .

According to the second aspect of the present invention, the resistance element group includes a plurality of resistance elements connected in series to each other, and a plurality of switch elements connected to the resistance elements. A first switch element group for setting a resistance value of the resistance element group in accordance with the first switch element group, and a plurality of switch elements respectively connected in parallel to the plurality of switch elements in the first switch element group. A second switch element group for forming a pair with the first switch element group and setting a resistance value of the resistance element group in accordance with a switching operation of each switch element; and the first and second switch elements. Selecting one of the groups to derive a current through the switch element and enabling the setting of the resistance value in one of the first and second switch elements Switching means for changing the resistance value of the resistor element group by the switching operation of the switching means to change the volume value, when the first and second switch element groups not selected by the switching means are changed. The other set resistance value is set to a value corresponding to the volume value to be changed, and the switching means is configured to switch the first and second resistance values.
In response to switching from one of the switch element groups to the other, the current passing through the switch element in one of the first and second switch element groups changes from a high level to a zero level with a predetermined time constant, and The resistance value in the other of the first and second switch element groups is changed by changing the current passing through the switch element in the other of the first and second switch element groups from a zero level to a high level with a predetermined time constant. Since the setting is made effective, it is possible to obtain an electronic volume that can more accurately prevent noise during volume switching.

According to the third invention, the switching means is provided with the first switch.
And an operational amplifier with a switch to which a bias current is supplied by a second bias current source, wherein one of the first and second switch element groups and one of the first and second switch element groups are provided by increasing or decreasing the bias current by the first and second bias current sources. Since the current passing through the switch element on the other side is changed from zero level to high level or from high level to zero level with a predetermined time constant, it is possible to obtain an electronic volume that can more accurately prevent noise during volume switching. .

According to the fourth invention, a timing circuit for setting a switching timing from one of the first and second resistance element groups to the other or from the other to one in response to a volume switching command, And a bias switching circuit for changing the bias current in the first and second bias current sources of the switching means comprising the operational amplifier with a switch with a predetermined time constant, so that noise at the time of volume switching can be more accurately prevented. You can get an electronic volume.

According to the fifth aspect, at the rising edge of the volume switching command signal, the first and second switch element groups are switched, the respective bias currents are set to a predetermined standby state, and the volume switching command signal is switched. At the falling edge of, the bias switching circuit is activated and the first
Further, since the second switch element group is switched, it is possible to obtain an electronic volume that can more accurately prevent noise at the time of volume switching.

According to the sixth aspect, in response to the rising edge of the volume switching command signal, one of the first and second switching element groups is made operable and the other is made inoperative. Since the flip-flop and the second flip-flop for switching the first and second switch element groups by operating the bias switching circuit in response to the falling edge of the volume switching command signal are provided,
It is possible to obtain an electronic volume that can more accurately prevent noise during volume switching.

[Brief description of the drawings]

FIG. 1 is a connection diagram showing an embodiment according to the present invention.

FIG. 2 is a connection diagram showing a timing generation circuit in the embodiment according to the present invention;

FIG. 3 is a connection diagram showing a bias switching circuit in the embodiment according to the present invention.

FIG. 4 is an explanatory diagram of operation timing in the embodiment according to the present invention.

FIG. 5 is a connection diagram showing a configuration example in a conventional technique.

FIG. 6 is an explanatory diagram showing a configuration of a CMOS switch, an equivalent circuit, and an influence of a parasitic capacitance.

[Explanation of symbols]

RL resistor ladder section, operational amplifier section with SA switch,
TC timing circuit section, Vin input terminal, R resistance element group, R1, R2, R3, R4, R5,..., Rn resistance element, A switch element group, A1, A2, A3, A4
A5,..., An, B switch element group, B1, B2, B
3, B4, B5,..., Bn switch element, Vout output terminal, 11 bias switching circuit, 13 timing circuit.

 ──────────────────────────────────────────────────の Continued on the front page F term (reference) 5J092 AA01 AA47 CA41 FA20 FR15 HA08 HA10 HA17 HA18 HA25 HA29 HA39 KA00 KA02 KA05 KA07 KA12 KA17 KA25 KA33 KA36 SA05 TA01 TA06 5J100 AA15 BA10 BB10 BB21 CA05 CA01 CA02 CA23 CA29 DA06 EA02 FA05

Claims (6)

[Claims] 1. A resistive element group comprising a plurality of resistive elements connected in series to each other and a plurality of switch elements respectively connected to the resistive elements, wherein the resistive element group depends on the switching operation of each switch element. A first switch element group for setting the resistance value of the first switch element group, and a plurality of switch elements connected in parallel to the plurality of switch elements in the first switch element group. Forming a pair, a second switch element group for setting the resistance value of the resistor element group according to the switching operation of each switch element, and one of the first and second switch element groups. Switching means for selecting and deriving a current passing through the switch element, and enabling the setting of the resistance value in one of the first and second switch element groups. The switching means is configured to switch from one of the first and second switch element groups to the other,
The current passing through the switch element in one of the first and second switch element groups changes from a high level to a zero level with a predetermined time constant, and the switch element in the other of the first and second switch element groups is An electronic device wherein the setting of the resistance value in the other of the first and second switch element groups is made effective by changing a passing current from a zero level to a high level with a predetermined time constant. volume. 2. A resistive element group comprising a plurality of resistive elements connected in series to each other, and a plurality of switch elements respectively connected to said resistive elements, wherein said resistive element group according to a switching operation of each switch element. A first switch element group for setting the resistance value of the first switch element group, and a plurality of switch elements connected in parallel to the plurality of switch elements in the first switch element group. Forming a pair, a second switch element group for setting the resistance value of the resistor element group according to the switching operation of each switch element, and one of the first and second switch element groups. Switching means for selecting and deriving a current passing through the switch element, and enabling the setting of the resistance value in one of the first and second switch element groups. When the volume of the resistance element group is changed by changing the resistance value of the resistance element group by the switching operation of the switching means, the first signal not selected by the switching means is selected.
And the other set resistance value of the second switch element group is set to a value corresponding to a volume value to be changed, and the switching means is configured to switch from one of the first and second switch element groups to the other. In response to the switching, the current passing through the switch element in one of the first and second switch element groups is changed from a high level to a zero level with a predetermined time constant, and the current of the first and second switch element groups is changed. The setting of the resistance value in the other of the first and second switch element groups is made valid by changing the current passing through the switch element on the other side from a zero level to a high level with a predetermined time constant. Electronic volume characterized by. 3. The switching means comprises an operational amplifier with a switch to which a bias current is supplied by first and second bias current sources, and wherein the first and second bias current sources increase or decrease the bias current to increase or decrease the bias current. 3. The method according to claim 2, wherein the current passing through the switch element in one or the other of the first and second switch element groups is changed from a zero level to a high level or from a high level to a zero level with a predetermined time constant. Electronic volume described. 4. A timing circuit for setting a switching timing from one of the first and second switch element groups to the other or the other from the one according to a volume switching command, and from the operational amplifier with switch according to a volume switching command. 4. The electronic volume according to claim 3, further comprising a bias switching circuit for changing a bias current in the first and second bias current sources of the switching means with a predetermined time constant. 5. A method according to claim 1, wherein the first and second switch element groups are switched at a rising edge of a volume switching command signal, each bias current is set to a predetermined standby state, and at a falling edge of the volume switching command signal,
The electronic volume according to claim 4, wherein a bias switching circuit is operated to switch the first and second switch element groups. 6. A first flip-flop that sets one of the first and second switching elements to an operable state and the other to an inoperative state in response to a rising edge of a volume switching command signal, and a volume switch. 5. The semiconductor device according to claim 4, further comprising a second flip-flop that operates a bias switching circuit in response to a falling edge of the command signal to switch between the first and second switch element groups.
Electronic volume as described in.