a
FEATURES
117 dB Dynamic Range
0.006% Typical THD+N (@ 1 kHz, Unity Gain)
140 dB Gain Range
No External Trimming Required
Differential Inputs
Complementary Gain Outputs
Buffered Control Port
I–V Converter On-Chip (SSM2018T)
Differential Current Outputs (SSM2118T)
Low External Parts Count
Low Cost
GENERAL DESCRIPTION
Trimless
Voltage Controlled Amplifiers
SSM2018T/SSM2118T*
FUNCTIONAL BLOCK DIAGRAMS
V
C
SSM-2018T
G
V
G
+IN
–IN
GAIN
CORE
–I
G
1–G
V
1–G
–I
1–G
The SSM2018T and SSM2118T represent continuing evolu-
tion of the Frey Operational Voltage Controlled Element
(OVCE) topology that permits flexibility in the design of high
performance volume control systems. Voltage (SSM2018T)
and differential current (SSM2118T) output versions are of-
fered, both laser-trimmed for gain core symmetry and offset. As
a result, the SSM2018T is the first professional audio quality
VCA to offer trimless operation. The SSM2118T is ideal for
low noise summing in large VCA based systems.
Due to careful gain core layout, the SSM2018T/SSM2118T
combine the low noise of Class AB topologies with the low dis-
tortion of Class A circuits to offer an unprecedented level of
sonic transparency. Additional features include differential in-
puts, a 140 dB gain range, and a high impedance control port.
The SSM2018T provides an internal current-to-voltage con-
verter; thus no external active components are required. The
SSM2118T has fully differential current outputs that permit
high noise-immunity summing of multiple channels.
Both devices are offered in 16-pin plastic DIP and SOIC pack-
ages and guaranteed for operation over the extended industrial
temperature range of –40°C to +85°C.
V
C
SSM-2118T
+I
G
G
–I
G
+IN
–IN
1–G
V
1–G
GAIN
CORE
–I
1–G
*Protected
by U.S. Patent Nos. 4,471,320 and 4,560,947.
REV. A
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood. MA 02062-9106,
U.S.A. Tel: 617/329-4700
Fax: 617/326-8703
SSM1018T/SSM2118T–SPECIFICATIONS
ELECTRICAL SPECIFICATIONS
[V =
±15
V, A = 0 dB, R = 100 kΩ, f = 1 kHz, 0 dBu = 0.775 V rms, simple VCA application
S
V
L
circuit with 18 kΩ resistors, –V
IN
floating, and Class AB gain core bias (R
B
= 150 kΩ), –40°C < T
A
< +85°C, unless otherwise noted. Typical
specifications apply at T
A
= +25°C.]
Parameter
AUDIO PERFORMANCE
1
Noise
Headroom
Total Harmonic Distortion plus Noise
Conditions
V
IN
= GND, 20 kHz Bandwidth
Clip Point = 1% THD+N
2nd and 3rd Harmonics Only (+25°C to +85°C)
A
V
= 0 dB, V
IN
= +10 dBu
A
V
= +20 dB, V
IN
= –10 dBu
A
V
= –20 dB, V
IN
= +10 dBu
2
V
CM
= 0 V
V
CM
= 0 V
V
CM
= 0 V
VCA Configuration
VCP Configuration
Min
Typ
–95
+22
0.006
0.013
0.013
0.25
1
10
4
±
13
0.7
14
5
1.0
+10
–10
+13
–14
9
0.36
1
1
–30
–3500
±
1
±
4
100
±
5
11
80
±
18
15
Max
–93
Units
dBu
dBu
%
%
%
µA
mV
nA
MΩ
V
MHz
MHz
V/µs
mV
V
V
kΩ
µA
MΩ
mV/dB
ppm/°C
mV
dB
V
mA
dB
0.025
0.04
0.04
1
15
100
INPUT AMPLIFIER
Bias Current
Offset Voltage
Offset Current
Input Impedance
Common-Mode Range
Gain Bandwidth
Slew Rate
OUTPUT AMPLIFIER (SSM2018T)
Offset Voltage
Output Voltage Swing
Minimum Load Resistance
CONTROL PORT
Bias Current
Input Impedance
Gain Constant
Gain Constant Temperature Coefficient
Control Feedthrough
Maximum Attenuation
POWER SUPPLIES
Supply Voltage Range
Supply Current
Power Supply Rejection Ratio
V
IN
= 0 V, V
C
= +4 V
I
OUT
= 1.5 mA
Positive
Negative
For Full Output Swing
15
Device Powered in Socket > 60 sec
0 dB to –40 dB Gain Range
V
C
= +4 V
NOTES
1
SSM2118T tested and characterized using OP275 as current-to-voltage converter, see figure next page.
2
Guaranteed by characterization data and testing at A
V
= 0 dB.
Specifications subject to change without notice.
–2–
REV. A
SSM2018T/SSM2118T
ABSOLUTE MAXIMUM RATINGS
1
Supply Voltage
Dual Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .± 18 V
Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
±
V
S
Operating Temperature Range . . . . . . . . . . . . . –40°C to +85°C
Storage Temperature . . . . . . . . . . . . . . . . . . . –65°C to +150°C
Junction Temperature (T
J
) . . . . . . . . . . . . . . . . . . . . . +150°C
Lead Temperature (Soldering, 60 sec) . . . . . . . . . . . . . +300°C
THERMAL CHARACTERISTICS
PIN CONFIGURATIONS
16-Lead Plastic DIP
16-Lead Plastic DIP
and SOL
and SOL
+I
1–G
V+
–I
G
–I
1–G
COMP 1
+IN
–IN
COMP 2
1
2
3
4
5
6
7
8
16 V
1–G
15
BAL
BAL
V
1–G
+I
1–G
–I
1–G
COMP 1
+IN
–IN
COMP 2
1
2
3
4
5
6
7
8
16 V+
15
14
–I
G
+I
G
14 V
G
SSM2018T
Thermal Resistance
16-Pin Plastic DIP
θ
JA
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76°C/W
θ
JC
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33°C/W
16-Pin SOIC
θ
JA
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92°C/W
θ
JC
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27°C/W
TRANSISTOR COUNT
2
13
TOP VIEW
12
(Not to Scale)
11
GND
MODE
V
C
SSM2118T
13 GND
TOP VIEW
12 MODE
(Not to Scale)
11 V
C
10 V–
9
COMP 3
10 V–
9
COMP 3
ORDERING GUIDE
Number of Transistors
SSM2018T . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
SSM2118T . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
ESD RATINGS
Model
SSM2018TP
SSM2018TS
SSM2118TP
SSM2118TS
Temperature Range
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
Package Option*
N-16
R-16
N-16
R-16
883 (Human Body) Model . . . . . . . . . . . . . . . . . . . . . . . 500 V
EIAJ Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 V
1
Stresses above those listed under “Absolute Maximum Ratings” may cause
permanent damage to the device. This is a stress rating only and functional
operation of the device at these or any other conditions above those indicated in the
operation section of this specification is not implied. Exposure to absolute maxi-
mum rating conditions for extended periods may affect device reliability.
2
θ
JA
is specified for worst-case conditions, i.e.,
θ
JA
is specified for device in socket
for P-DIP and device soldered in circuit board for SOIC package.
50pF
18k
V
OUT
1
V+
2
3
4
1µF
V
IN+
V
IN–
1µF 18k
47pF
18k
5
6
7
8
16
15
V–
*N = Plastic DIP; R = SOL.
FROM
ADDITIONAL
SSM2118Ts
OPTIONAL
TRIM
GLOBAL
SYMMETRY
TRIM
50pF
500k
18k
47k
470k
V+
47k
A2
50pF
*
V
OUT
10k
18k
10k
1
V–
2
3
16
15
14
150k
14
SSM2018T
13
12
11
10
9
150k
V+
3k
1µF
1k
V
CONTROL
V
IN+
V
IN–
1µF 18k
47pF
1µF 18k
4
SSM2118T
13
5
6
7
8
12
11
V–
10
9
A1
A1, A2: OP275
3k
V
CONTROL
1µF
1k
*
FOR MORE THAN 2 SSM2118Ts
SSM2018T Typical Application Circuit
SSM2118T Typical Application Circuit
CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily
accumulate on the human body and test equipment and can discharge without detection.
Although the SSM2018T/SSM2118T features proprietary ESD protection circuitry, permanent
damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper
ESD precautions are recommended to avoid performance degradation or loss of functionality.
WARNING!
ESD SENSITIVE DEVICE
REV. A
–3–
SSM2018T/SSM2118T–Typical Characteristics
0.1
T
A
= +25°C
V
S
=
±15V
R
F
= 18kΩ
1
T
A
= +25°C
V
S
=
±15V
R
F
= 18kΩ
AV = +20dB
0.1
THD + N – %
THD + N – %
0.010
AV = –20dB
0.010
AV = 0dB
0.001
20
100
1k
FREQUENCY – Hz
10k
20k
0.001
10m
0.1
AMPLITUDE – V
RMS
1
2
Figure 1. SSM2018T THD + N Frequency (80 kHz Low-Pass
Filter, for A
V
= 0 dB, V
IN
= 3 V rms; for A
V
= +20 dB,
V
IN
= 0.3 V rms; for A
V
= –20 dB, V
IN
= 3 V rms)
Figure 4. SSM2018T THD + N vs. Amplitude
(Gain = +20 dB, f
IN
=1 kHz, 80 kHz Low-Pass Filter)
100
90
80
70
60
T
A
= +25°C
A
V
= 0dB
300 UNITS
V
IN
= 10dBu
V
S
=
±15V
1.0
T
A
= +25°C
V
S
=
±15V
R
F
= 18kΩ
0.1
THD + N – %
UNITS
50
40
30
20
10
0
0.000
0.005
0.010
0.015
0.020
0.025
0.01
0.001
–60
–40
DISTORTION – %
–20
0
GAIN – dB
20
40
Figure 2. SSM2018T Distortion Distribution
Figure 5. SSM2018T THD + N vs. Gain (f
IN
= 1 kHz;
for –60 dB
≤
A
V
≤
–20 dB, V
IN
= 10 V rms;
for 0 dB
≤
A
V
≤
+20 dB, V
IN
= 1 V rms)
1
T
A
= +25°C
R
F
= 18kΩ
V
S
=
±15V
0.1
T
A
= +25°C
R
F
= 18kΩ
0.1
THD + N – %
THD + N – %
0.01
0.010
0.001
0.1
1
AMPLITUDE – V
RMS
10
20
0.001
0
±3
±6
±9
±12
±15
±18
SUPPLY VOLTAGE – Volts
Figure 3. SSM2018T THD + N vs. Amplitude (Gain = 0 dB,
f
IN
= 1 kHz, 80 kHz Low-Pass Filter)
Figure 6. SSM2018T THD + N vs. Supply Voltage
(A
V
= 0 dB, V
IN
= 1 V rms, f
IN
= 1 kHz, 80 kHz
Low-Pass Filter)
–4–
REV. A
SSM2018T/SSM2118T
500
MAXIMUM OUTPUT SWING – V
PEAK
±15
T
A
= +25°C
V
S
=
±15V
400
±12
R
F
= 18kΩ
T
A
= +25°C
V
S
=
±15V
NOISE DENSITY – nV/√Hz
300
±9
±6
200
±3
100
0
10
100
1k
FREQUENCY – Hz
10k
100k
0
100
1k
10k
100k
LOAD RESISTANCE –
Ω
Figure 7. SSM2018T Noise Density vs. Frequency
Figure 10. SSM2018T Maximum Output Swing vs.
Load Resistance, (THD = 1 % max)
100
R
F
= 18kΩ
T
A
= +25°C
±20
90
80
OUTPUT OFFSET – mV
R
L
=
∞Ω
OUTPUT VOLTAGE SWING – V
PEAK
T
A
= +25°C
V
S
=
±15V
70
60
50
40
30
20
10
±15
±10
R
L
= 10kΩ
±5
0
0
±5
±10
±15
±20
0
–80
–60
–40
–20
GAIN – dB
0
20
40
SUPPLY VOLTAGE – Volts
Figure 8. SSM2018T Maximum Output Swing vs.
Supply Voltage (THD = 1% max)
Figure 11. SSM2018T Output Offset vs. Gain
+10
MAXIMUM OUTPUT SWING – V
PEAK
±15
R
F
= 18kΩ
T
A
= +25°C
V
S
=
±15V
R
L
=
∞
T
A
= +25°C
V
S
=
±15V
+5
GAIN – dB
R
L
= 10k
±9
0
GAIN
PHASE
–5
0
–45
±6
±3
–10
–90
0
1k
10k
FREQUENCY – Hz
100k
–15
100
–135
1k
10k
FREQUENCY – Hz
100k
1M
Figure 9. SSM2018T Maximum Output Swing vs.
Frequency (THD = 1 % max)
Figure 12. SSM2018T Gain/Phase vs. Frequency
REV. A
–5–
PHASE – Degrees
±12
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