AFE5807ZCF Datasheet, PDF (39/74 Pages) Texas Instruments – Fully Integrated, 8-Channel Ultrasound Analog Front End

AFE5807
www.ti.com
SLOS703C – SEPTEMBER 2010 – REVISED MAY 2013
Programmable Gain for CW Summing Amplifier
Different gain can be configured for the CW summing amplifier through the register 54[4:0]. By enabling and
disabling the feedback resistors between the summing amplifier inputs and outputs, the gain is adjustable
accordingly to maximize the dynamic range of CW path. Table 7 describes the relationship between the summing
amplifier gain and 54[4:0] settings.
54[4:0]/0x36[4:0]
00000
00001
00010
00100
01000
10000
Table 7. Register 54[4:0] Description
FUNCTION
No feedback resistor
Enables 250 Ω feedback resistor
Enables 250 Ω feedback resistor
Enables 500 Ω feedback resistor
Enables 1000 Ω feedback resistor
Enables 2000 Ω feedback resistor
54[4:0]/0x36[4:0]
CW I/V Gain
54[4:0]/0x36[4:0]
CW I/V Gain
54[4:0]/0x36[4:0]
CW I/V Gain
54[4:0]/0x36[4:0]
CW I/V Gain
Table 8. Register 54[4:0] vs Summing Amplifier Gain
00000
N/A
01000
2.00
10000
4.00
11000
1.33
00001
0.50
01001
0.40
10001
0.44
11001
0.36
00010
0.50
01010
0.40
10010
0.44
11010
0.36
00011
0.25
01011
0.22
10011
0.24
11011
0.21
00100
1.00
01100
0.67
10100
0.80
11100
0.57
00101
0.33
01101
0.29
10101
0.31
11101
0.27
00110
0.33
01110
0.29
10110
0.31
11110
0.27
00111
0.20
01111
0.18
10111
0.19
11111
0.17
Programmable Phase Delay for CW Mixer
Accurate CW beamforming is achieved through adjusting the phase delay of each channel. In the AFE5807, 16
different phase delays can be applied to each LNA output; and it meets the standard requirement of typical
1
λ
ultrasound beamformer, i.e. 16 beamformer resolution. Table 7 describes the relationship between the phase
delays and the register 55 and 56 settings.
CHX_CW_MIXER_PHASE
PHASE SHIFT
CHX_CW_MIXER_PHASE
PHASE SHIFT
Table 9. CW Mixer Phase Delay vs Register Settings
CH1 - 55[3:0], CH2 - 55[7:4], CH3 - 55[11:8], CH4 - 55[15:12],
CH5- 56[3:0], CH6 - 56[7:4], CH7 - 56[11:8], CH8 - 56[15:12],
0000
0
1000
180°
0001
22.5°
1001
202.5°
0010
45°
1010
225°
0011
67.5°
1011
247.5°
0100
90°
1100
270°
0101
112.5°
1101
292.5°
0110
135°
1110
315°
0111
157.5°
1111
337.5°
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