AD8432 Datasheet, PDF (1/28 Pages) Analog Devices – Dual-Channel Ultralow Noise Amplifier with Selectable Gain and Input Impedance

Dual-Channel Ultralow Noise Amplifier with
Selectable Gain and Input Impedance
AD8432
FEATURES
Low noise
Input voltage noise: 0.85 nV/√Hz
Current noise: 2.0 pA/√Hz
Excellent ac specifications
200 MHz bandwidth (G = 12.04 dB)
295 V/μs slew rate
Selectable gain
G = 12.04 dB (×4)
G = 18.06 dB (×8)
G = 21.58 dB (×12)
G = 24.08 dB (×16)
Active input impedance matching
Integrated input clamp diodes
Single-ended input, differential output
Supply range: 4.5 V to 5.5 V
Low power: 60 mW/channel
APPLICATIONS
CW Doppler ultrasound front ends
Low noise preamplification
Predriver for I/Q demodulators and phase shifters
Wideband analog-to-digital drivers
FUNCTIONAL BLOCK DIAGRAM
ENB
VPS1
VPS2 COMM
INH1
IND1
INL1
INH2
IND2
INL2
BIAS
AD8432
LNA1
LNA2
OPH1
OPL1
GMH1
GOH1
GOL1
GML1
OPH2
OPL2
GMH2
GOH2
GOL2
GML2
Figure 1.
GENERAL DESCRIPTION
The AD8432 is a dual-channel, low power, ultralow noise
amplifier with selectable gain and active impedance matching.
Each amplifier has a single-ended input, differential output, and
integrated input clamps. By pin strapping the gain setting pins, four
accurate gains of G = 12.04 dB, 18.06 dB, 21.58 dB, and 24.08 dB
(×4, ×8, ×12, and ×16) are possible. A bandwidth of 200 MHz at
G = 12.04 dB makes this amplifier well suited for many high speed
applications.
The exceptional noise performance of the AD8432 is made
possible by the active impedance matching. Using a feedback
network, the input impedance of the amplifiers can be adjusted
to match the signal source impedance without compromising
the noise performance. Impedance matching and low noise of
the AD8432 allow designers to create wider dynamic range
systems that are able to detect even very low level signals.
The AD8432 achieves 0.85 nV/√Hz input referred voltage noise for
a gain of 12.04 dB. The AD8432’s ultralow noise, low distortion,
excellent gain accuracy, and channel-to-channel matching are ideal
for high performance ultrasound systems and for processing I/Q
demodulator signals.
The AD8432 operates on a single supply of 5 V at 24 mA. It is
available in a 4 mm × 4 mm, 24-lead LFSCP. The LFCSP features
an exposed paddle that provides a low thermal resistance path to
the PCB, which enables more efficient heat transfer and increases
reliability. The operating temperature range is −40°C to +85°C.
Rev. 0
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