Analog Devices has introduced a dc-coupled variable-gain amplifier (VGA) that is said to deliver the industry’s highest gain and bandwidth. The AD8336 may be the first VGA capable of processing high-frequency bipolar signals at high gain. It meets the demands of the industrial marketplace for a VGA with outstanding ac performance combined with stable dc characteristics over wide temperature and power supply voltage ranges.
The AD8336 also supports an extended industrial temperature range of –55 degrees C to 125 degrees C and a wide power supply range from 12 V. This is the voltage range used in applications such as automatic gain control, display drivers and radar receivers.
Designed for high-voltage and wide temperature applications, the AD8336 VGA provides 100 MHz bandwidth over a gain range of 60 dB — more than twice the bandwidth of competing VGAs that operate at much lower supply voltages. The AD8336 includes a voltage-feedback operational amplifier at its input that enables the gain to be externally adjusted. The nominal pre-amp gain is 4× (12 dB); a gain of 20× (26 dB) can be obtained at a reduced bandwidth. The AD8336 operates over a gain range of 0 dB to 60 dB with the pre-amp gain set to 26 dB.
The AD8336 is suitable for use with analog-to-digital converters such as the AD7656, AD7634, AD7951 and AD9460. Many types of digital-to-analog converters (DACs) can control the new VGA. These include unipolar and bipolar DACS, since the gain control input is differential to the AD8336 and the gain control common-mode voltage increases with increasing supply. The AD8336 is sampling and is available in a 4 mm x 4 mm, 16-lead lead frame chip-scale package (LFCSP) and will be available in volume production in October. The VGA is priced at $4.59 in 1000-piece quantities.