The VCA2616 and VCA2611 are dual, Low-Noise Preamplifiers (LNP), plus low-noise Variable Gain Amplifiers (VGA). The VCA2611 is an upgraded version of the VCA2616. The only difference between the VCA2616 and the VCA2611 is the input structure to the LNP. The VCA2616 is limited to 0.3V negative-going input spikes; the VCA2611 is limited to 2.0V negative-going input spikes. This change allows the user to use slower and less expensive input clamping diodes prior to the LNP input. In some designs, input clamping may not be required.
The combination of Active Termination (AT) and Maximum Gain Select (MGS) allow for the best noise performance. The VCA2616 and VCA2611 also feature low crosstalk and outstanding distortion performance.
The LNP has differential input and output capability and is strappable for gains of 5dB, 17dB, 22dB, or 25dB. Low input impedance is achieved by AT, resulting in as much as a 4.6dB improvement in noise figure over conventional shunt termination. The termination value can also be switched to accommodate different sources. The output of the LNP is available for external signal processing.
The variable gain is controlled by an analog voltage whose gain varies from 0dB to the gain set by the MGS. The ability to program the variable gain also allows the user to optimize dynamic range. The VCA input can be switched from the LNP to external circuits for different applications. The output can be used in either a single-ended or differential mode to drive high-performance Analog-to-Digital (A/D) converters, and is cleanly limited for optimum overdrive recovery.
The combination of low noise, gain, and gain range programmability makes the VCA2616 and VCA2611 versatile building blocks in a number of applications where noise performance is critical. The VCA2616 and VCA2611 are available in a TQFP-48 package.
LOW-NOISE PREAMP:
Low Input Noise: 0.95nV/Hz
Active Termination Noise Reduction
Switchable Termination Value
80MHz Bandwidth
5dB to 25dB Gain
Differential In and Out
LOW-NOISE VARIABLE GAIN AMPLIFIER:
Low Noise VCA
Up to 40dB Gain Range
40MHz Bandwidth
Differential In and Out
LOW CROSSTALK: 66dB at Max Gain, 5MHz
HIGH-SPEED VARIABLE GAIN ADJUST
SWITCHABLE EXTERNAL PROCESSING
APPLICATIONS
ULTRASOUND SYSTEMS
WIRELESS RECEIVERS
TEST EQUIPMENT
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