that2162 THAT Corporation, that2162 Datasheet - Page 5

• Manufacturer Part Number: that2162
• Description: Dual Pre-trimmed Blackmer Voltage Controlled Amplifier
• Manufacturer: THAT Corporation

Document 600087 Rev 00G
negative control port. (The positive control port
behaves in the same manner.) Note that the gain at
E
ing temperature changes the scale factor of the gain
by 0.33%/C, which pivots the curve about the 0 dB
point.
temperature (25ºC) and the actual temperature, and
Gain is the gain in decibels. At room temperature,
this reduces to
becomes
becomes
DC Bias Currents
an internal bias generator (I
current based on the power supply voltage.
V
V
CC
CC
C
= 0 V is 0 dB, regardless of temperature. Chang-
=-V
=-V
Figure 7 shows the effect of temperature on the
Mathematically, the 2162's gain characteristic is
Gain =
where ΔT is the difference between room
Gain =
If only the positive control port is used, this
If only the negative control port is used, this
Gain =
The 2162 current consumption is determined by
Gain =
EE
EE
=15V, I
=5V, I
(0.0064)(1+0.0033 T)
E
0.0064
−E
0.0064
0.0064
Figure 8. Offset Vs. Gain (Ec+)
C+
Figure 9. Offset Vs. Gain (Ec-)
E
C−
−E
C+
CELL
E
CELL
C−
.
C+
,
−E
,
is approximately 2.25 mA; at
C−
is
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THAT Corporation; 45 Sumner Street; Milford, MA 01757-1656; USA
approximately 1.15 mA.
,
CELL
), which varies its
Copyright © 2007, THAT Corporation
Eq. 1
Eq. 2
Eq. 3
Eq. 4
At
Another ~ 350 μA is used to bias each OTA. I
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.
Trimming
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.
general, the second harmonic distortion and offset
change with gain can be reduced via external
trimming, as shown in the circuit of Figure 13. Pin 3
[14] (SYM) allows this adjustment. The 2162
includes on-chip 30Ω resistors between the SYM pins
and their respective E
circuitry shown provides for up to
across these pins. Symmetry should be trimmed for
Figure 11. THD+Noise Vs. Input Level, +15 dB Gain
Figure 12. THD+Noise Vs. Input Level, -15 dB Gain
The VCA symmetry (actually, the combined V
Figure 10. THD+Noise Vs. Input Level, 0 dB Gain
C+
pins.
The external trim
±
880 μV offset
Page 5 of 12
CELL
In
BE
is