that2162 THAT Corporation, that2162 Datasheet - Page 6

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

Page 6 of 12
minimum THD with a modest level (e.g., ~1 Vrms),
middle-frequency (e.g., ~1 kHz) sine wave input.
combined V
constant that varies depending on the specific IC
involved.
supply voltage, though the setting will vary slightly
with power supply voltage. Note that the on-board
trim is set with ±15 V power supply rails. Typically,
the 1 kHz THD+N at 0 dB gain and 1 Vrms input will
The parameter that is being trimmed here (the
It is substantially independent of power
Figure 13. External trimming circuit
BE
offset of the gain cell transistors) is a
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vary by approximately 0.003% - 0.005% per 5 V
change in the supply voltage from ±15 V.
adjustment. But, in the circuit of Figure 13, the avail-
able range of adjustment is directly proportional to
the power supply voltage. For best results, R1 should
be scaled proportional to the supply voltage.
pins 3 and 14 should be left open, as shown in
Figure 2.
DC Feedthrough
2 [15] (the output). When the gain is changed, the dc
term
increases with gain. See Figures 8 and 9 for typical
curves for dc offset vs. gain. As noted above, dc
feedthrough is affected by the symmetry trim.
Audio Performance
ensure good audio performance when used as
recommended. In particular, the 2162 maintains low
distortion over a wide range of gain, cut and signal
levels. Figures 10 through 12 show typical distortion
performance for representative samples of the part.
Most parts will require less than 600 μV of trim
If the external symmetry circuitry is omitted,
Normally, a small dc error term flows in pin
The 2162 VCA design, fabrication and testing
changes.
2162 Dual Pre-trimmed Blackmer® VCA
This
control-voltage
feedthrough