ROHM BA6110FS Datasheet

BA6110FS

Standard ICs

Voltage controlled operational amplifier

BA6110FS

The BA6110FS is a low-noise, low-offset programmable operational amplifier. Offering superb linearity over a broad
range, this IC is designed so that the forward direction conductivity (g
such as voltage control amplifiers (VCA), voltage control filters (VCF) and voltage control oscillators (VCO).
Distortion reduction circuitry improves the signal-to-noise ratio by a significant 10dB at a distortion rate of 0.5% in
comparison with products not equipped with this feature. When used as a voltage control amplifier (VCA), a high S / N
ratio of 86dB can be achieved at a distortion rate of 0.5%.
The open loop gain is determined by the control current and an attached gain determining resistance R
range of settings.
In addition, a built-in low-impedance output buffer circuit reduces the number of attachments.

Applications

!

Electronic volume controls
Voltage-controlled impedances
Voltage-controlled amplifiers (VCA)
Voltage-controlled filters (VCF)
Voltage-controlled oscillators (VCO)
Multipliers
Sample holds
Schmitt triggers

m

) can be changed, making it ideal for applications

L

, enabling a wide

Features

!

1) Low distortion rate.
(built-in distortion reduction bias diode)

2) Low noise.

3) Low offset voltage. (V

Block diagram

!!!!

IO

= 3m V

Max

).

BA6110FS

4) Built-in output buffer.

5) Variable g

m

with superb linearity across three decade

fields.

CC

V

N.C.

16 15 14 13 12 11 10

–

+

12345678

N.C.

POSITIVE INPUT

N.C.

BUFFER OUTPUT

1 / 2

1 / 2

N.C.

NEGATIVE INPUT

BUFFER INPUT

VCA OUTPUT

V

CC

N.C.

INPUT BIAS

EE

N.C.

– V

9

BUFFER

N.C.

CONTROL INPUT

Standard ICs

Internal circuit configuration

!!!!

Q

5

Q

4

CC

Pd

Topr
Tstg

C Max.

Current mirror (2)

Q

13

Current mirror (3)

R

1

Q

6

Q

9

Q

7

Q

8

Control pin

7

300

– 20 ~ + 70

– 55 ~ + 125

Q

14

R

2

Q10Q

12

Q

11

Fig.1

34 V

1

∗

Current mirror (1)

Input bias

1

D

1

D

2

3

5

Q

Q

1

(Ta = 25°C)

3

Q

2

Positive input

Negative input

Absolute maximum ratings

!!!!

Parameter Symbol Limits Unit

Power supply voltage V
Power dissipation
Operating temperature ˚C

Storage temperature ˚C
Maximum control current 500 µAI

1 Reduced by 3mW for each increase in Ta of 1˚C each 25˚C.

*

11

OUT

Current mirror (4)

Q

15

Current mirror (5)

mW

R

12

3

Buffer IN

R

4

Q

Q

BA6110FS

15

V

CC

R

5

14

Buffer OUT

17

Q

18

16

9

EE

V

Electrical characteristics

!!!!

Parameter Symbol Min. Typ. Max. Unit Conditions

Quiescent current I
Pin 7 bias current I
Distortion THD — 0.2 1 % Fig.2
Forward transmission conductance g
Pin 6 maximum output voltage | V
Pin 8 maximum output voltage 911— VR
Pin 6 maximum output current 300 500 650 µAI

Residual noise 1 VN

Residual noise 2 VN

Discontinuous noise VNP

Leakage level —– 94 – 75 dBm

(unless otherwise noted, Ta = 25°C, VCC = 15V, VEE = – 15V)

Q

7PIN

m

OM6

OM8

| V

OM6

| I

1

2

L (Leak)

0.9 3.0 6.0 mA I
— 0.8 5 µA — Fig.2

4800 8000 12000 µsI

12 14 — VI

|
|

|

—– 94 – 90 dBm Fig.2

—– 74 – 66 dBm Fig.2

2

— 10.5 11.5 dB Fig.2

CONTROL

= 0µA Fig.2

I

CONTROL

= 200µA, VI = 5mVrms

CONTROL

= 500µA Fig.2

CONTROL

= 500µA Fig.2

L

= 47kΩ Fig.2

CONTROL

= 500µA Fig.2

CONTROL

= 0µA, BPF

I
(30 ~ 320kHz, 3dB, 6dB / OCT)

CONTROL

= 200µA, BPF

I
(30 ~ 20kHz, 3dB, 6dB / OCT)

CONTROL

= 200µA, BPF

I
(30 ~ 20kHz, 3dB, 6dB / OCT)

I

CONTROL

= 0µA, VIN = – 30dBm

IN

= 20kHz

f

Measurement

circuit

Fig.2

Standard ICs

Measurement circuit

!!!!

BA6110FS

D.V

4

S

27kΩ

Circuit discription

!!!!

10µF

V

600Ω

1

1kΩ

1

S

+

1
2

2

S

1V

1

3

1kΩ

S

3

2

500µA→

11

12

BA6110FS

7

3

1

3

2

200µA→

5

S

15

5

9

7

S

1

The BA6110FS is configured of an operational amplifier
which can control the forward propagation conductance

m

(g

) using the control current, an input bias­compensating diode used to eliminate distortion created
by the amplifier’s differential input, a bias setter, and an
output buffer.
In the operational amplifier, Pin 1 is the positive input and
Pin 3 is the negative input. Pin 7 is the control pin which
determines the differential current. Pin 11 is the output pin
which determines the open loop gain using the external
resistor and the control current.
This section describes the circuit operation of this
operational amplifier.
Transistors Q
operational amplifier, while transistors Q

13

and Q14 form the differential input for the

7

to Q12 are
composed of the current mirror circuits. The current
mirror absorbs current from the differential input common
emitter which is equal to the control current flowing into
the Pin 7 control pin. If the differential input V
point, then 1 / 2 Ic is supplied to the Q

IN

= 0 at this

13

and Q
collectors and the other half passes through the current
mirrors (3) and (4). The output of current mirror (3) which
is the differential active load is inverted by current mirror
(5), and is balanced with the output of current mirror (4),
also an active load.
If the differential input changes, the current balance
changes. The output current is on Pin 11. An output
voltage can be generated using an external resistance.

2

150kΩ

Fig.2

mA

S

0

1

30 ~ 20kHz

BPF

47kΩ

VEE = – 10V

2

S

6-1

14

CC

V

1

S

6-2

2

40dB AMP

= + 10V

V.V

THD

Vmp

DV

For the open loop gain of this operational amplifier, if the
Pin 7 control current is I
resistance is R

O

, then:

Av = gm · RO =

CONTROL

and the Pin 11 external

CONTROL

× R

I

KT

2

q

To eliminate the distortion created by the differential input,
the input bias diode and its bias circuit consist of the
following: bias diodes D

1

and D2, current mirrors (1) and
(2), and the Pin 5 bias pin current mirror that consists of
the transistors Q

1

to Q6 and the resistance R1.
This circuit eliminates the distortion that occurs as a
result of using the differential input open loop.
In the buffer circuit, Pin 12 is the buffer input and Pin 14 is
the buffer output.
In the buffer circuit, the emitter follower consists of the
active load of the NPN transistor, Q

16

Q

. The VF difference created by the emitter follower is

17

, and its active load,

eliminated by the emitter follower which consists of the

14

PNP transistor Q

18

and resistor R5. Also, the gain is

determined by the ratio of the signal source resistance

IN

R

and the diode impedance.

O

Standard ICs

BA6110FS

Attached components

!!!!

(1) Positive input (Pin 1)
This is the differential positive input pin. To minimize the
distortion due to the diode bias, an input resistor is
connected in series with the signal source. By increasing
the input resistance, distortion is minimized.
However, the degree of improvement for resistances
greater than 10kΩ is about the same. An input resistance
of 1kΩ to 20kΩ is recommended.
(2) Negative input (Pin 3)
This is the differential negative input pin. It is grounded
with roughly the same resistance value as that of the
positive input pin. The offset adjustment is also
connected to this pin. Make sure a sufficiently high
resistance is used, so as not to disturb the balance of the
input resistance (see Figure 3).
(3) Input bias diode (Pin 5)
The input bias diode current (I

D

) is determined by this pin.
The IC input impedance when the diode is biased, if the
diode bias current is I

D

, is expressed as follows:

I

D

26

(mA)

Rd = (Ω)

(4) Control (Pin 7)
This pin controls the differential current. By changing the
current which flows into this pin, the gain of the differential
amplifier can be changed.
(5) Output (Pin 11)
The differential amplifier gain (A
resistor R

O

connected between the output terminal and

V

) is determined by the

the Pin 7 control terminal, as follows:

I

CONTROL

Av = gm · RO =

52 (mV)

(mA)

× R

O

Make sure the resistor is selected based on the desired
maximum output and gain.
(6) Buffer input (Pin 12)
The buffer input consists of the PNP and NPN emitter
follower. The bias current is normally about 0.8µA.
Consequently, when used within a small region of control
current, we recommend using the high input impedance
FET buffer.
(7) Buffer output resistance (Pin 14)
An 11kΩ resistor is connected between V

CC

and the
output within the IC. When adding an external resistance
between the GND and the output, make sure the resistor

L

R

= 33kΩ.

Application example

!!!!

(1) Fig.3 shows a voltage-controlled amplifier (AM
modulation) as an example of an application of the
BA6110FS.

By changing the I
gain can be changed. The gain (A
Pin 11 is R

CONTROL

current on Pin 7, the differential

V

), if the resistance of

O

, is determined by the following equation:

CONTROL

(mA)

Av = gm · RO =

I

52 (mV)

× R

O

Good linearity can be achieved when controlling over
three decades.
By connecting Pin 5 to the V

CC

by way of a resistor, the
input is biased at the diode and distortion is reduced.
The gain in this case is given by the diode impedance Rd
and the ratio of the input resistance R

IN

, as shown in the

following:

d

Av = gm · RO ×

R

Rd × R

IN

The diode impedance Rd = (26 / ID (mA) ) Ω, so that the
Pin 5 bias current I

D

= (VCC - 1V) / R (Pin 5). The graph in
Fig. 6 shows the control current in relation to the open
loop gain at the diode bias. In the same way, Fig.7 shows
the control current in relation to the THD = 0.5% output at
the bias point.
Fig. 8 shows a graph of the control current in relation to
the open gain with no diode bias.
Fig. 9 shows a graph of the control current in relation to
the SN ratio.
Fig. 10 shows a graph of the diode bias current in relation
to the SN ratio.
Fig. 11 shows a graph of the power supply voltage
characteristics.
(2) Fig. 4 shows a low pass filter as an example of an
application of the BA6110FS.
The cutoff frequency f

O

can be changed by changing the
Pin 7 control current.
The cutoff frequency f

O

is expressed as:

R

fO =

(R + RA) 2πC

A

· g

m

This is attenuated by -6dB / OCT.
Fig. 12 shows a graph of the I

CONTROL

in relation to the
output characteristics.
(3) Fig. 5 shows a voltage-controlled secondary low
passfilter as an example of an application of the
BA6110FS.
The cutoff frequency f

O

can be changed by changing

thePin 7 control current.

R

A

· g

m

fO =

(R + RA) · 2πC

This is attenuated by - 12dB / OCT.
Fig. 13 shows a graph of the I

CONTROL

output

characteristic.

Standard ICs

BA6110FS

V

CC =

15V

0

V

IN

R

IN

10k

1

150k

I

5

15

100k
(Offset adjustment)

IN

V

330k

V

R

10k

R

IN

3

BA6110FS

11

9

14

7

12

I

CONTROL

30kΩ

R0 = 27kΩ

Fig.3 Voltage-controlled amplifier (electronic volume control)

IC

100k

20kΩ

7

14

9

5

R

100k

200Ω

15

1

BA6110FS

3

12

11

150pF

VEE = – 15V

C

V

OUT

V

V

OUT

CC

EE

= 15V

= – 15V

Fig.4 Voltage control low pass filter

CC

15V

V

CONTROL

I

20kΩ

100kΩ

1

BA6110FS

3

5

R

15

7

14

12

11

9

2C
200pF

15

9

100kΩ

100kΩ

7

200Ω

14

12

11

R

A

200

R

C 100pF

100kΩ

IN

V

1

200

R
200Ω

A

BA6110FS

3

5

Fig.5 Voltage-controlled secondary low pass filter

V

VEE15V

C

V

Standard ICs

Electrical characteristic curves

!!!!

VCC = 15V
V

EE

R

IN

I

D

20

(dB)

V

10

0

– 10
– 20
– 30

OPEN LOOP GAIN: G

– 40

For diode bias of 200µA

= – 15V

= 10kΩ

= 200µA

R0 = 50kΩ

R0 = 27kΩ

R

I

D

200µA

+ 15V

+

–

V

IN

10kΩ

2 5 10 20 50 100 200 500 1000
CONTROL CURRENT: I

15V

CONTROL

Fig.6 Open loop gain control

current characteristics

0

= 10kΩ

I

CONTROL

R0 = 27kΩ

V

A

V

V

(µA)

V

O

O
IN

VCC = 15V
V

EE

= – 15V

10

R

IN

= 10kΩ

)

5

I

D

= 200µA

rms

fin = 1kHz

(V

O

Output when THD = 0.5%

2

With diode bias

R0 = 27kΩ

R0 = 50kΩ

1

0.5

0.2

0.1

OUTPUT VOLTAGE: V

0.05

0.02
21 5 10 20 50 100 200 5001000

CONTROL CURRENT: I

Fig.7 THD 0.5% output control

current characteristics

R0 = 10kΩ

CONTROL

(µA)

BA6110FS

VCC = 15V
V

EE

= – 15V

R

IN

= 10kΩ

I

o

= 0

60

(dB)

V

50
40
30
20
10

OPEN LOOP GAIN: G

0

– 10

21 5 10 20 50 100 200 5001000
CONTROL CURRENT: I

Fig.8 Open loop gain control current

characteristics

No diode bias

R0 = 270kΩ

R0 = 50kΩ

R0 = 10kΩ

CONTROL

R0 = 27kΩ

(µA)

NOISE B.P.F20 ~ 20kHz

VCC = 15V

SN ratio when THD = 0.5%

V

EE = – 15V

R

IN = 10kΩ

R

O = 27kΩ

f

in = 1kHz

80

70

SIGNAL TO NOISE RATIO: S / N (dB)

60

ID = 200µA

IO = 0

5 10 20 50 100 200 500 1mA
CONTROL CURRENT: I

CONTROL (µA)

Fig.9 SN ratio vs. control current

VCC = 15V
V

EE

= – 15V

6pin C = 150pF

(dB)

V

0

– 4

I

CONTROL

= 100µA

– 8

– 12

I

CONTROL

6dB / OCT

= 10µA

– 16
– 20

VOLTAGE GAIN: G

– 24
– 28

100200 500 1k 2k 5k 10k20k 100k50k

FREQUENCY: f (Hz)

Fig.12 Low pass filter characteristics

I

CONTROL

RIN = 50kΩ

80

RIN = 2kΩ

RIN =
10kΩ

70

SIGNAL TO NOISE RATIO: S / N (dB)

60

510

I

CONTROL

VCC =

15V

V

EE

= –

O

=

27kΩ

R
f

in

=

1kHz

NOISE B.P.F20Hz ~ 20kHz

CONTROL

I
SN ratio when THD

20 50 100

BIAS CURRENT: I

Fig.10 SN ratio vs. diode bias current

VCC = 15V
V

EE

= – 15V

0

(dB)

V

– 4
– 8

– 12

I

CONTROL

– 16
– 20

VOLTAGE GAIN: G

= 10µA

– 12dB / OCT

– 24
– 28

100200 500 1k 2k 5k 10k 20k 100k50k

FREQUENCY: f (Hz)

Fig.13 Secondary low pass filter

characteristics

I

= 200µA

= 500µA

15V

=

200µA

=

200 500 1mA

D

(µA)

CONTROL

= 100µA

0.5%

15

R0 = ∞

12

(V)

Pin 8 voltage

10

OM

8
6
4
2
0

– 2
– 4
– 6

– 8
– 10
– 12
– 14

MAXIMUM OUTPUT VOLTAGE: V

± 2 ± 4 ± 6 ± 8 ± 10 ± 12 ± 14
POWER SUPPLY VOLTAGE: V

Fig.11 Maximum output voltage vs.
power supply voltage

V

OM

V

OM

CC

(V)

Standard ICs

External dimensions

!!!!

BA6110FS

6.6 ± 0.2

16

4.4 ± 0.2

6.2 ± 0.31.5 ± 0.1

1

0.11

(Units : mm)

9

8

0.36 ± 0.10.8

SSOP-A16

BA6110FS

0.15 ± 0.1

0.3Min.

0.15