Datasheet

S0501-01
I/VSum
Amp
CW_AMPINP CW_OUTM
CW_AMPINM CW_OUTP
C
EXT
C
EXT
R
EXT
R
EXT
R
INT
R
INT
2000Ω
2000Ω
1000Ω
1000Ω
500Ω
500Ω
250Ω
250Ω
250Ω
250Ω
AFE5808
SLOS688C –SEPTEMBER 2010–REVISED APRIL 2012 www.ti.com
Figure 86. CW Summing Amplifier Block Diagram
Multiple AFE5808s are usually utilized in parallel to expand CW beamformer channel count. These AFE5808s’
CW outputs can be summed and filtered externally further to achieve desired gain and filter response. AC
coupling capacitors CAC are required to block DC component of the CW carrier signal. CAC can vary from 1uF
to 10s μF depending on the desired low frequency Doppler signal from slow blood flow. Multiple AFE5808s’ I/Q
outputs can be summed together with a low noise external differential amplifiers before 16/18-bit differential
audio ADCs. TI’s ultralow noise differential precision amplifier OPA1632 and THS4130 are suitable devices.
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