Datasheet Texas Instruments VCA2612Y/250 — Datenblatt

VCA VCA2612 261 2 SBOS117C – SEPTEMBER 2000 – REVISED APRIL 2004 Dual, VARIABLE GAIN AMPLIFIER
with Low Noise Preamp
FEATURES DESCRIPTION в—Џ LOW NOISE PREAMP: Low Input Noise: 1.25nV/в€љHz Active Termination Noise Reduction Switchable Termination Value 80MHz Bandwidth 5dB to 25dB Gain Range Differential Input /Output
в—Џ LOW NOISE VARIABLE GAIN AMPLIFIER: Low Noise VCA: 3.3nV/в€љHz, Differential
Programming Optimizes Noise Figure 24dB to 45dB Gain 40MHz Bandwidth Differential Input /Output
в—Џ LOW CROSSTALK: 52dB at Max Gain, 5MHz
в—Џ HIGH-SPEED VARIABLE GAIN ADJUST
в—Џ SWITCHABLE EXTERNAL PROCESSING The VCA2612 is a highly integrated, dual receive channel,
signal processing subsystem. Each channel of the product
consists of a low noise preamplifier (LNP) and a Variable
Gain Amplifier (VGA). The LNP circuit provides the necessary connections to implement Active Termination (AT), a
method of cable termination which results in up to 4.6dB
noise figure improvement. Different cable termination characteristics can be accommodated by utilizing the VCA2612’s
switchable LNA feedback pins. The LNP has the ability to
accept both differential and single-ended inputs, and generates a differential output signal. The LNP provides strappable
gains of 5dB, 17dB, 22dB, and 25dB.
The output of the LNP can be accessed externally for further
signal processing, or fed directly into the VGA. The VCA2612’s
VGA section consists of two parts: the Voltage Controlled
Attenuator (VCA) and the Programmable Gain Amplifier
(PGA). The gain and gain range of the PGA can be digitally
programmed. The combination of these two programmable
elements results in a variable gain ranging from 0dB up to a …