Dual Pre-trimmed Blackmer
®
Voltage Controlled Amplifier
THAT
2162
FEATURES
• Two Independent Channels
• Wide Dynamic Range: >118 dB
• Wide Gain Range: >130 dB
• Exponential (dB) Gain Control
• Low Distortion: 0.05% typ.
• Wide Supply Voltage Range:
±
2.25V ~
±
16V
• Low Supply Current: 5.2 mA typ. (
±
15V)
3 mA typ. (
±
5V)
• Dual Control Ports (pos/neg)
• Low Cost
• Small Package (16-pin QSOP)
• Faders
• Panners
• Compressors & Limiters
• Gates & Expanders
• Mixers
• Equalizers
• Filters
• Oscillators
APPLICATIONS
Description
THAT 2162 contains two high-performance
Blackmer
®
voltage-controlled amplifiers (VCAs).
With two opposing-polarity, voltage-sensitive
control ports, they offer wide-range exponential
control of gain and attenuation with low signal
distortion. Both VCAs are trimmed at wafer stage
to deliver low distortion and control-voltage
feedthrough
without
further
adjustment.
However, external symmetry adjustment is possi-
ble to further optimize distortion and control
feedthrough for critical applications.
The 2162 operates from a split power supply
up to ±16 Vdc, drawing only 5.2mA at ±15V and
3 mA at ±5V. The part can also operate at supply
voltages as low as ±2.25V, making it suitable for
battery-operated applications.
The two VCAs are independent of each other,
sharing only their power supply connections.
The 2162 is extremely flexible and capable of
being configured for a wide range of stereo or
multichannel applications. It is available in a
RoHS-compliant 16-pin QSOP package.
NC OUT 2 SYM 2 EC- 2 VCC EC+ 2 IN 2
16
15
14
13
12
11
10
EC+
IN
NC
9
EC-
OUT
VCA2
SYM
SYM
OUT
VCA1
IN
EC-
EC+
Pin Name
NC
OUT 1
SYM 1
Ec- 1
V
EE
Ec+ 1
IN 1
GND
NC
IN 2
Ec+ 2
V
CC
Ec- 2
SYM 2
OUT 2
NC
Pin Number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
1
2
3
4
5
6
7
NC OUT 1 SYM 1 EC- 1 VEE EC+ 1 IN 1
Figure 1. THAT 2162 Block Diagram
8
GND
Table 1. Pin Assignments
Package
16 pin QSOP
Order Number
2162Q16-U
Table 2. Ordering Information
THAT Corporation; 45 Sumner Street; Milford, MA 01757-1656; USA
Tel: +1 508 478 9200; Fax: +1 508 478 0990; Web: www.thatcorp.com
Copyright © 2007, THAT Corporation Document 600087 Rev 02
Document 600087 Rev 02
Page 2 of 11
2162 Dual Pre-trimmed Blackmer® VCA
SPECIFICATIONS
1
Absolute Maximum Ratings
2
Operating Temperature Range (TOP)
Junction Temperature (T
J
)
Storage Temperature Range (T
ST
)
-40 to +85 ºC
+125 ºC
-40 to +125 ºC
Supply Voltages (V
CC
, V
EE
)
VCA Control Voltage
Input or Output Voltage
±18V
±0.6 V
±0.5 V
Electrical Characteristics
3
Parameter
Positive Supply Voltage
Negative Supply Voltage
Supply Current
I
CC
I
EE
I
CC
I
EE
Equivalent Input Bias Current
Input Offset Voltage
I
B
V
OFF(IN)
Symbol
V
CC
V
EE
Conditions
Referenced to GND
Referenced to GND
No Signal
V
CC
=+15V, V
EE
= -15V
V
CC
=+15V, V
EE
= -15V
V
CC
=+5V, V
EE
= -5V
V
CC
=+5V, V
EE
= -5V
0 dB Gain
0 dB Gain
R
OUT
= 20 kΩ
0 dB gain
+15 dB gain
0 dB Gain
0 dB Gain, Rin = Rout = 20 kΩ, 100 Hz
Positive supply, 100 Hz
Negative supply, 100 Hz
V
CC
=+15V, V
EE
= -15V
V
CC
=+5V, V
EE
= -5V
VCA Gain Range
Gain-Control Constant
E
C+
/Gain (dB)
-60 dB < gain < +60 dB
V
CC
= +15V, V
EE
= -15V
V
CC
= +5V, V
EE
= -5V
Ref T
CHIP
=27ºC
-60 dB to +40 dB Gain
1 kHz, Ec+ = -0.45 V, Ec- = +0.45 V
e
N(OUT)
22Hz~22kHz, R
IN
= R
OUT
= 20 kΩ
0 dB gain
+15 dB gain
Crosstalk
1
2
Min
+2.25
-2.25
—
—
—
—
—
—
—
—
Typ
—
—
Max
+16
-16
Units
V
V
5.2
-5.2
3
-3
3
-7
7
-7
—
—
—
—
mA
mA
mA
mA
nA
mV
Output Offset Voltage Change
4
Δ
V
OFF(OUT)
±1
±3
20
±5
± 20
mV
mV
µA
Gain Cell Idling Current
Power Supply Rejection Ratio
I
IDLE
PSRR
—
—
80
75
± 1.5
± 815
—
—
dB
dB
mA
peak
µA
peak
Max. I/O Signal Current
i
IN(VCA)
+ i
OUT(VCA)
-70
—
—
—
—
—
—
+60
—
—
—
—
—
dB
6.4
6.1
+0.33
1
130
mV/dB
mV/dB
%/ºC
%
dB
Gain-Control Tempco
Gain Control Linearity
Off Isolation
Output Noise
ΔE
C
/ΔT
CHIP
—
—
—
-97.5
-86
110
-95
-84
—
dBV
dBV
1 kHz, 0 dB Gain, Rin = Rout = 20 kΩ
All specifications are subject to change without notice.
If the devices are subjected to stress above the Absolute Maximum Ratings, permanent damage may result. Sustained operation at or near the Absolute Maximum Ratings
conditions is not recommended. In particular, like all semiconductor devices, device reliability declines as operating temperat ure increases.
Unless otherwise noted, TA=25ºC, VCC=+15V, VEE= -15V.
Reference is to output offset with -40 dB VCA gain.
3
4
THAT Corporation; 45 Sumner Street; Milford, MA 01757-1656; USA
Tel: +1 508 478 9200; Fax: +1 508 478 0990; Web: www.thatcorp.com
Copyright © 2008, THAT Corporation; All rights reserved.
2162 Dual Pre-trimmed Blackmer® VCA
Page 3 of 11
Document 600087 Rev 02
Electrical Characteristics (con’t)
3
Parameter
Total Harmonic Distortion
Symbol
THD
Conditions
V
IN
= 0dBV, 1kHz, E
C+
= E
C-
= 0V
V
IN
= -5dBV, 1kHz, E
C+
= 0V, E
C-
= -90mV
V
IN
= +10dBV, 1kHz, E
C+
= 0V, E
C-
= 90mV
Slew Rate
Gain at 0V Control
G
0
0 dB Gain, Rin = Rout = 20 kΩ
E
C+
= E
C-
= 0V
Min
—
—
—
—
-1.0
Typ
0.05
0.09
0.09
6.5
0
Max
0.12
0.15
0.15
—
+1.0
Units
%
%
%
V/μs
dB
+15V
C3
6
EC+
12
VCC
7
IN
C1
22p
R2 NP0
20k0
2
2
1
3
100n
C2
R3
20k0
R4
6k8
In 1
10u
VCA1
OUT
SY M
3
4
Out 1
EC-
THAT2162
NJM4580
C4
100p
N/C
Ec- 1
C6
22p
NP0
11
EC+
N/C
14
SY M
VEE
THAT2162
15
6
R6
20k0
C7
In 2
10u
R7
20k0
R8
6k8
10
IN
VCA2
O UT
5
7
5
Out 2
EC-
13
C5
100n
NJM4580
C8
100p
-15V
Ec- 2
Figure 2. Typical Application Circuit
+2
dB
-60
+40dB
dBV
-70
-80
+1
+0
0dB
+20dB
-1
-90
-100
-110
Hz
100k
-2
20
100
1k
10k
-120
-90
-60
-30
0
Gain
dB
+30
Figure 3. 2162 Frequency Response Vs. Gain
Figure 4. 2162 Noise (22 kHz NBW) Vs. Gain
THAT Corporation; 45 Sumner Street; Milford, MA 01757-1656; USA
Tel: +1 508 478 9200; Fax: +1 508 478 0990; Web: www.thatcorp.com
Copyright © 2008, THAT Corporation; All rights reserved.
Document 600087 Rev 02
Page 4 of 11
2162 Dual Pre-trimmed Blackmer® VCA
Theory of Operation
The THAT 2162 VCA is designed for high
performance in audio-frequency applications requir-
ing exponential gain control, wide dynamic range,
low control-voltage feedthrough, and low cost. This
part controls gain by converting an input current
signal to a bipolar logged voltage, adding a dc control
voltage, and re-converting the summed voltage back
to a current through a bipolar antilog circuit.
Figure 5 presents a considerably simplified
internal circuit diagram of the IC. The ac input signal
current flows in pin 7 [10]
1
, the input pin. An inter-
nal operational transconductance amplifier (OTA)
works to maintain pin 7 [10] at a virtual ground
potential by driving the emitters of Q1 and (through
the Voltage Bias Generator) Q3. Q3/D3 and Q1/D1
act to log the input current, producing a voltage, V3,
which represents the bipolar logarithm of the input
current. The voltage at the junction of D1 and D2 is
the same as V3, but shifted by four forward Vbe
drops.
dBr
+40
+20
+0
-20
-40
-60
-80
-100
-576 -512
-384
-256
-128
+0
+128
mVdc
+256
Figure 6. Gain Vs. Control Voltage (Ec+) @ 1 kHz
dBr
+40
+20
0
-20
-40
-60
-80
-100
-256
-128
0
+128
+256
+384
mVdc
+512 +576
Gain Control
Since pin 2 [15], the output, is usually connected
to a virtual ground, Q2/D2 and Q4/D4 take the
bipolar antilog of V3, creating an output current
which is a precise replica of the input current. If pin
6 [11] (E
C+
) and pin 4 [13] (E
C-
) are held at ground,
the output current will equal the input current. For
pin 6 [11] positive or pin 4 [13] negative, the output
current will be scaled larger than the input current.
For pin 6 [11] negative or pin 4 [13] positive, the
output current is scaled smaller than the input.
The scale factor between the output and input
currents is the gain of the VCA. Either pin 6 [11]
(E
C+
) or pin 4 [13] (E
C-
), or both, may be used to
control gain. Gain is exponentially proportional to
the voltage at pin 6 [11], and exponentially
Figure 7. Gain Vs. Control Voltage (Ec-) @ 1 kHz
dB
50
40
30
20
10
0
-10
-20
-30
-40
-50
-256 -192 -128
+50
+25
0
mVdc
V+
12
-64
0
64
128
192
256
Iadj
D1
6[11]
D2
Figure 8. Gain Vs. Control Voltage (Ec-) with Temp (ºC)
Q1
Voltage
Bias
Generator
Q2
4[13]
Ec+
7[10]
2[15]
Ec-
OUT
IN
Iin
30
D3
Q3
Q4
3[14]
SYM
30
proportional to the negative of the voltage at pin 4
[13]. Therefore, pin 6 [11] (E
C+
) is the positive
control port, while pin 4 [13] (E
C-
) is the negative
control port. Because of the exponential characteris-
tic, the control voltage sets gain linearly in decibels.
Figure 6 shows the decibel current gain of a 2162
versus the voltage at E
C+
, while Figure 7 shows gain
versus E
C-
.
D4
Temperature Effects
The logging and antilogging in the VCA depends
on the logarithmic relationship between voltage and
current in a semiconductor junction (in particular,
between a transistor's Vbe and Ic). As is well known,
this relationship is temperature dependent. There-
fore, the gain of any log-antilog VCA depends on its
temperature.
V3
V+
5
Icell
V-
Figure 5. Simplified internal circuit
1
Pin number references are for VCA1, with VCA2 shown in brackets.
THAT Corporation; 45 Sumner Street; Milford, MA 01757-1656; USA
Tel: +1 508 478 9200; Fax: +1 508 478 0990; Web: www.thatcorp.com
Copyright © 2008, THAT Corporation; All rights reserved.
2162 Dual Pre-trimmed Blackmer® VCA
Page 5 of 11
Document 600087 Rev 02
Figure 8 shows the effect of temperature on the
negative control port. (The positive control port
behaves in the same manner.) Note that the gain at
E
C
= 0 V is 0 dB, regardless of temperature. Chang-
ing temperature changes the scale factor of the gain
by 0.33%/C, which pivots the curve about the 0 dB
point.
Mathematically, the 2162's gain characteristic is
E
C+
−E
C−
(0.0064)(1+0.0033
T)
,
10
1
0.1
0.01
%THD+N
Gain
=
Eq. 1
0.001
0.5
1
Vin
rms
10
where
ΔT
is the difference between room
temperature (25ºC) and the actual temperature, and
Gain is the gain in decibels. At room temperature,
this reduces to
Figure 11. THD+Noise Vs. Input Level, 0 dB Gain
%THD+N
Gain
=
E
C+
−E
C−
0.0064
10
,
Eq. 2
1
If only the positive control port is used, this
becomes
0.1
Gain
=
E
C+
0.0064
,
Eq. 3
0.01
If only the negative control port is used, this
becomes
0.001
0.1
0.5
1
Vin
rms
2
Gain
=
−E
C−
0.0064
.
Eq. 4
Figure 12. THD+Noise Vs. Input Level, +15 dB Gain
%THD+N
DC Bias Currents
The 2162 current consumption is determined by
an internal bias generator (I
CELL
), which varies its
current based on the power supply voltage. At
V
CC
=-V
EE
=15V, I
CELL
is approximately 2.25 mA; at
V
CC
=-V
EE
=5V, I
CELL
is approximately 1.15 mA.
Vdc
10
1
0.1
0.01
+0.02
+0.01
0
0.001
0.5
1
5
Vin
rms
10
Figure 13. THD+Noise Vs. Input Level, -15 dB Gain
-0.01
-0.02
-90
dB
+30
-60
-30
0
Another ~ 350
μA
is used to bias each OTA. I
CELL
is
split in two parts: about 250
μA
is necessary for the
bias generator, the rest is available for the sum of
input and output signal current.
Figure 9. Offset Vs. Gain (Ec+)
Vdc
Trimming
The VCA symmetry (actually, the combined V
BE
offsets of the gain cell transistors) is trimmed for low
distortion and control-voltage feedthrough during
wafer probe. However, limited trim resolution and
shifts during IC packaging limit the ultimate
pre-trimmed performance of the finished part. In
general, the second harmonic distortion and offset
change with gain can be reduced via external
trimming, as shown in the circuit of Figure 14. Pin 3
[14] (SYM) allows this adjustment. The 2162
includes on-chip 30Ω resistors between the SYM pins
and their respective E
C+
pins. The external trim
circuitry shown provides for up to
±
880
μV
offset
across these pins. Symmetry should be trimmed for
+0.02
+0.01
0
-0.01
-0.02
-90
-60
-30
0
dB
+30
Figure 10. Offset Vs. Gain (Ec-)
THAT Corporation; 45 Sumner Street; Milford, MA 01757-1656; USA
Tel: +1 508 478 9200; Fax: +1 508 478 0990; Web: www.thatcorp.com
Copyright © 2008, THAT Corporation; All rights reserved.
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