Datasheet

u
8CH_SNR
-
10
N
10 1 1
C
= x -
1CH_SNR
N + N 56 7
-
C
10
10
AFE5808
SLOS688C –SEPTEMBER 2010–REVISED APRIL 2012 www.ti.com
ELECTRICAL CHARACTERISTICS
AVDD_5V = 5V, AVDD = 3.3V, AVDD_ADC = 1.8V, DVDD = 1.8V, AC-coupled with 0.1µF at INP and bypassed to ground
with 15nF at INM, No active termination, V
CNTL
= 0V, f
IN
= 5MHz, LNA = 18dB, PGA = 24dB, 14Bit, sample rate = 65MSPS,
LPF Filter = 15MHz, low noise mode, V
OUT
= –1dBFS, internal 500Ω CW feedback resistor, CMOS CW clocks, ADC
configured in internal reference mode, Single-ended VCNTL mode, VCNTLM = GND, at ambient temperature T
A
= 25°C,
unless otherwise noted. Min and max values are specified across full-temperature range with AVDD_5V = 5V, AVDD = 3.3V,
AVDD_ADC = 1.8V, DVDD = 1.8V
PARAMETER TEST CONDITION MIN TYP MAX UNITS
TGC FULL SIGNAL CHANNEL (LNA+VCAT+LPF+ADC)
Rs = 0Ω, f = 2MHz, LNA = 24/18/12dB, PGA = 24dB 0.76/0.83/1.16
Input voltage noise over LNA Gain(low
nV/rtHz
noise mode)
Rs = 0Ω, f = 2MHz,LNA = 24/18/12dB, PGA = 30dB 0.75/0.86/1.12
Rs = 0Ω, f = 2MHz,LNA = 24/18/12dB, PGA = 24dB 1.1/1.2/1.45
Input voltage noise over LNA Gain(low
en (RTI) nV/rtHz
power mode)
Rs = 0Ω, f = 2MHz, LNA = 24/18/12dB, PGA = 30dB 1.1/1.2/1.45
Rs = 0Ω, f = 2MHz,LNA = 24/18/12dB, PGA = 24dB 1/1.05/1.25
Input Voltage Noise over LNA
nV/rtHz
Gain(Medium Power Mode)
Rs = 0Ω, f = 2MHz, LNA = 24/18/12dB, PGA = 30dB 0.95/1.0/1.2
Input referred current noise 2.7 pA/rtHz
Rs = 200Ω, 200Ω active termination, PGA = 24dB, LNA = 12/18/24dB 3.85/2.4/1.8 dB
NF Noise figure
Rs = 100Ω, 100Ω active termination, PGA = 24dB, LNA = 12/18/24dB 5.3/3.1/2.3 dB
V
MAX
Maximum Linear Input Voltage LNA gain = 24/18/12dB 250/500/1000
mVpp
V
CLAMP
Clamp Voltage Reg52[10:9] = 0, LNA = 24/18/12dB 350/600/1150
Low noise mode 24/30
PGA Gain dB
Medium/Low power mode 24/28.5
LNA = 24dB, PGA = 30dB, Low noise mode 54
Total gain LNA = 24dB, PGA = 30dB, Med power mode 52.5 dB
LNA = 24dB, PGA = 30dB, Low power mode 52.5
Ch-CH Noise Correlation Factor without
Summing of 8 channels 0
Signal
(1)
Full band (VCNTL = 0/0.8) 0.15/0.17
Ch-CH Noise Correlation Factor with
Signal
(1)
1MHz band over carrier (VCNTL= 0/0.8) 0.18/0.75
VCNTL= 0.6V(22 dB total channel gain) 68 70
Signal to Noise Ratio (SNR) VCNTL= 0, LNA = 18dB, PGA = 24dB 59.3 63 dBFS
VCNTL = 0, LNA = 24dB, PGA = 24dB 58
Narrow Band SNR SNR over 2MHz band around carrier at VCNTL=0.6V ( 22dB total gain) 75 77 dBFS
Input Common-mode Voltage At INP and INM pins 2.4 V
8 kΩ
Input resistance
Preset active termination enabled 50/100/200/400 Ω
Input capacitance 20 pF
Input Control Voltage VCNTLP-VCNTLM 0 1.5 V
Common-mode voltage VCNTLP and VCNTLM 0.75 V
Gain Range -40 dB
Gain Slope V
CNTL
= 0.1V to 1.1V 35 dB/V
Input Resistance Between VCNTLP and VCNTLM 200 KΩ
Input Capacitance Between VCNTLP and VCNTLM 1 pF
TGC Response Time VCNTL= 0V to 1.5V step function 1.5 µs
3rd order-Low-pass Filter 10, 15, 20, 30 MHz
Settling time for change in LNA gain 14 µs
Settling time for change in active
1 µs
termination setting
(1) Noise correlation factor is defined as Nc/(Nu+Nc), where Nc is the correlated noise power in single channel; and Nu is the uncorrelated
noise power in single channel. Its measurement follows the below equation, in which the SNR of single channel signal and the SNR of
summed eight channel signal are measured.
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