General-Purpose, −55°C to +125°C,

Wide Bandwidth, DC-Coupled VGA

AD8336

Rev. 0

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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

VOUT

VGAI

PRAO

GNEG

AD8336

VCOM

VPOS

GPOS

34dB

PrA

PWRA

ATTENUATOR

–60dB TO 0dB

GAIN CONTROL

INTERFACE

INPP

INPN

+

–

BIAS

VNEG

4

5

2

13

3

11

12

1

10

9

8

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 2 V p-p.

Thanks to its X-Amp® architecture, excellent bandwidth

uniformity 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).