AD8336:  General-Purpose, −55°C to +125°C, Wide Bandwidth, DC-Coupled VGA

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 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).

Applications

• Industrial process controls
• High performance AGC systems
• I/Q signal processing
• Video
• Industrial and medical ultrasound
• Radar receivers