POWER AND LINEAR IC SOLUTIONS

800MHz Analogue Control, Variable Gain Amplifier

The LTC6412 is a fully differential, analogue control, Variable Gain Amplifier (VGA) with high levels of stability and consistency across its entire frequency, temperature and gain ranges.

With a -3dB bandwidth of 800MHz, it is optimised for operation with input signals from 1MHz to 500MHz and provides continuous gain adjustment from -14dB to 17dB.

The device has a third-order Output Intercept Point (OIP3) of 35dBm at 240MHz across all gain settings. It also achieves constant-output noise level over the entire gain range, with a Noise Figure (NF) of just 10dB at the maximum gain setting. This results in a constant Spurious Free Dynamic Range (SFDR) characteristic remaining greater than 120dB at 240MHz over the full gain control range. This makes the device highly suitable for Automatic Gain Control (AGC) in receiver IF chains.



Gain is controlled with either a positive or negative slope control voltage. Using negative gain-slope mode, the gain control slope is approximately -32dB/V at 140MHz with a control range of 0.1V to 1.1V. The figure shows the gain conformance of the LTC6412 over its gain and temperature range; this is guaranteed to be 0.45dB or less over a control voltage range of 0.2V to 1.0V.



The LTC6412 also achieves a high degree of gain flatness over the entire frequency and gain ranges. It features 50Ω and 200Ω input and output impedances, respectively. Consuming just 110mA on a 3.3V supply, the device enables a low power, compact solution to be developed when paired with suitable voltage mixers, ADCs and ADC drivers.

It is available in a 4mm x 4mm QFN package and is fully specified over the commercial and industrial temperature ranges.

Features

• 800MHz –3dB small-signal bandwidth
• Continuously adjustable gain control
• –14dB to +17dB linear gain range
• 35dBm OIP3 at 240MHz (for all gain settings)
• 10dB noise figure at maximum gain
• 2.7nV/√Hz input referred noise
• Differential inputs and outputs
• 50Ω input impedance (for all gain settings)
• Single supply operation: 3.0V to 3.6V
• 110mA supply current

Applications

• IF signal chain AGC
• 2.5G and 3G base station transceivers
• WiMAX, WiBro, WLAN wireless receivers
• GPS and satellite receiver IF

For further information, to register your interest in a Free Demo Board*, or to obtain a copy of the latest Altera/LTC Development Tools Brochure, please click here

* Free demo boards are limited to current or potential Arrow customers with valid opportunities and are at the discretion of local Arrow representatives.