MAX2034
Quad-Channel, Ultra-Low-Noise Amplifier with
Digitally Programmable Input Impedance
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Figure 2. Typical Single-Channel Ultrasound Application Circuit
Ultrasound-Specific IMD3 Specification
Unlike typical communications specs, the two input
tones are not equal in magnitude for the ultrasound-
specific IMD3 two-tone specification. In this measure-
ment, F1 represents reflections from tissue and F2
represents reflections from blood. The latter reflections
are typically 25dB lower in magnitude, and hence the
measurement is defined with one input tone 25dB lower
than the other. The IMD3 product of interest (F1 - (F2 -
F1)) presents itself as an undesired Doppler error sig-
nal in ultrasound applications. See Figure 1.
