AFE5818 Datasheet, PDF (23/156 Pages) Texas Instruments – 16-Channel, Ultrasound, Analog Front-End

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AFE5818
SBAS687B – FEBRUARY 2015 – REVISED AUGUST 2015
Typical Characteristics (continued)
At T_A = 25°C, AVDD_1P8 = 1.8 V, AVDD_3P3 = 3.3 V, AVDD_5V = 5 V, DVDD_1P2 = 1.2 V, DVDD_1P8 = 1.8 V, ac-
coupled with a 0.1-µF capacitor at INP, 15-nF capacitor to ground at INM, no active termination, VCNTLP = VCNTLM = 0 V,
LNA = 18 dB, PGA = 24 dB, LPF filter = 15 MHz, low-noise mode, internal 500-Ω CW feedback resistor, 14-bit ADC
resolution, ADC_CLKP and ADC_CLKM = 50-MHz differential, LVDS mode to capture ADC data, input signal frequency f_IN =
5 MHz, and output amplitude V_OUT = –1 dBFS, unless otherwise noted. Minimum and maximum values are specified across
the full temperature range.
12000
10000
10
Open
0
-10
Open
8000
-20
-30
6000
-40
-50
4000
-60
2000
-70
-80
0
0.5
4.5
8.5
12.5
16.5
20.5
Frequency (MHz)
D008
Without active termination
-90
0.5
4.5
8.5
12.5
16.5
Frequency (MHz)
Without active termination
20.5
D009
Figure 8. Input Impedance Magnitude vs Frequency
550
500
50 :
100 :
450
200 :
400
400 :
350
300
250
200
150
100
50
0
0
5
10
15
20
25
Frequency (MHz)
D010
Across active termination
Figure 9. Input Impedance Phase vs Frequency
10
0
-10
-20
-30
-40
-50
-60
-70
-80
-90
0.5
50 :
100 :
200 :
400 :
4.5
8.5
12.5
16.5
Frequency (MHz)
Across active termination
20.5
D011
Figure 10. Input Impedance Magnitude vs Frequency
5
0
-5
-10
-15
-20
-25
-30
-35
-40
0
10 MHz
15 MHz
20 MHz
30 MHz
35 MHz
50 MHz
10 20 30 40 50 60 70 80 90
Frequency (MHz)
D012
Across LPF corner settings
Figure 11. Input Impedance Phase vs Frequency
3
0
-3
-6
-9
-12
-15
-18
-21
Register 203[3:2], 205[8] = 01, 1
Register 203[3:2], 205[8] = 01, 0
-24
Register 203[3:2], 205[8] = 00, 0
-27
Register 203[3:2], 205[8] = 11, 0
Register 203[3:2], 205[8] = 10, 0
-30
10
20 30 40 50 70 100
200 300 500
Frequency (kHz)
D013
Across LNA_HPF_PROG (register 203, bits 3-2) and
RED_LNA_HPF_3X (register 205, bit 8)
Figure 12. Full-Channel Amplitude Response vs Frequency
Figure 13. LNA High-Pass Filter Amplitude Response vs
Frequency
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