General-Purpose, 55°C to +125°C,
Wide Bandwidth, DC-Coupled VGA
AD8336
Rev. C
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FEATURES
Low noise
Voltage noise: 3 nV/√Hz
Current noise: 3 pA/√Hz
Small-signal BW: 115 MHz
Large-signal BW: 2 V p-p = 80 MHz
Slew rate: 550 V/μs, 2 V p-p
Gain ranges (specified)
14 dB to +46 dB
0 dB to 60 dB
Gain scaling: 50 dB/V
DC-coupled
Single-ended input and output
Supplies:
±3 V to ±12 V
Temperature range: 55°C to +125°C
Power
150 mW @
±3 V, 55°C < T < +125°C
84 mW @ ±3 V, PWRA = 3 V
APPLICATIONS
Industrial process controls
High performance AGC systems
I/Q signal processing
Video
Industrial and medical ultrasound
Radar receivers
FUNCTIONAL BLOCK DIAGRAM
VGAI
VOUT
PRAO
GNEG
AD8336
VCOM
VPOS
GPOS
34dB
PrA
PWRA
ATTENUATOR
–60dB TO 0dB
GAIN CONTROL
INTERFACE
INPP
8
9
INPN
+
–
4
1
5
BIAS
2
06
22
8-
0
01
10
13
3
11
12
VNEG
Figure 1.
GENERAL DESCRIPTION
The
AD8336 is a low noise, single-ended, linear-in-dB, general-
purpose variable gain amplifier, usable over a large range of supply
voltages. It features an uncommitted preamplifier (preamp) with
a usable gain range of 6 dB to 26 dB established by external
resistors in the classical manner. The VGA gain range is 0 dB to
60 dB, and its absolute gain limits are 26 dB to +34 dB. When
the preamplifier gain is adjusted for 12 dB, the combined 3 dB
bandwidth of the preamp and VGA is 100 MHz, and the amplifier
is fully usable to 80 MHz. With ±5 V supplies, the maximum
output swing is 7 V p-p.
Thanks to its X-Amp architecture, excellent bandwidth uni-
formity is maintained across the entire gain range of the VGA.
Intended for a broad spectrum of applications, the differential
gain control interface provides precise linear-in-dB gain scaling
of 50 dB/V over the temperature span of 55°C to +125°C. The
differential gain control is easy to interface with a variety of
external circuits within the common-mode voltage limits of the
AD8336.
The large supply voltage range makes the AD8336 particularly
suited for industrial medical applications and for video circuits.
Dual-supply operation enables bipolar input signals, such as
those generated by photodiodes or photomultiplier tubes.
The fully independent voltage feedback preamp allows both
inverting and noninverting gain topologies, making it a fully
bipolar VGA. The AD8336 can be used within the specified
gain range of 14 dB to +60 dB by selecting a preamp gain
between 6 dB and 26 dB and choosing appropriate feedback
resistors. For the nominal preamp gain of 4×, the overall gain
range is 14 dB to +46 dB.
In critical applications, the quiescent power can be reduced by
about half by using the power adjust pin, PWRA. This is especially
useful when operating with high supply voltages of up to ±12 V,
or at high temperatures.
The operating temperature range is 55°C to +125°C. The
AD8336 is available in a 16-lead LFCSP (4 mm × 4 mm).