Datasheet

MAX2078
Octal-Channel Ultrasound Front-End
with CW Doppler Mixers
4 _______________________________________________________________________________________
AC ELECTRICAL CHARACTERISTICS
( Typical Application Circuit , V
REF
= 2.475V to 2.525V, V
CC1
= 3.13V to 3.47V, V
CC2
= 4.5V to 5.25V, T
A
= 0°C to +70°C, V
GND
= 0V,
NP = 0, PD = 0, D43/D42/D41/D40 = 1/0/1/0 (R
IN
= 200Ω, LNA gain = 18.5dB, D45/D44 = 1/1 (f
C
= 18MHz), f
RF
= f
LO
/16 = 5MHz,
capacitance to GND at each of the VGA differential outputs is 25pF, differential capacitance across VGA outputs is 15pF, R
L
= 1kΩ
differential, reference noise less than 10nV/√Hz from 1kHz to 20MHz, DOUT loaded with 10MΩ and 60pF. Typical values are at V
CC1
= 3.3V, V
CC2
= 4.75V, T
A
= +25°C, unless otherwise noted.) (Note 5)
PARAMETER CONDITIONS MIN TYP MAX UNITS
V/C stepped from 0 to 1, DC stable within 10% 1
Mode Select Response Time
(Note 10)
V/C stepped from 1 to 0, DC stable within 10% 1
µs
High Gain Maximum Input-
Voltage Range
High LNA gain D43/D42/D41/D40 = 1/0/1/0 0.33
V
P-P
differential
Low Gain Maximum Input-Voltage
Range
Low LNA gain D43/D42/D41/D40 = 0/0/0/1 0.6
V
P-P
differential
AC ELECTRICAL CHARACTERISTICS—VGA MODE
( Typical Application Circuit , V
REF
= 2.475V to 2.525V, V
CC1
= 3.13V to 3.47V, V
CC2
= 4.5V to 5.25V, T
A
= 0°C to +70°C, V
GND
= 0V,
V/C = 1, NP = 0, PD = 0, D43/D42/D41/D40 = 1/0/1/0 (R
IN
= 200Ω, LNA gain = 18.5dB), D45/D44 = 1/1 (f
C
= 18MHz), f
RF
= 5MHz,
capacitance to GND at each of the VGA differential outputs is 25pF, differential capacitance across VGA outputs is 15pF, R
L
= 1kΩ
differential, reference noise less than 10nV/√Hz from 1kHz to 20MHz, DOUT loaded with 10MΩ and 60pF. Typical values are at V
CC1
= 3.3V, V
CC2
= 4.75V, T
A
= +25°C, unless otherwise noted.) (Note 5)
PARAMETER CONDITIONS MIN TYP MAX UNITS
D42/D41/D40 = 0/0/0, R
IN
= 50Ω 47.5 50 60
D42/D41/D40 = 0/0/1, R
IN
= 100Ω 90 100 110
D42/D41/D40 = 0/1/0, R
IN
= 200Ω 180 200 220
Input Impedance
D42/D41/D40 = 0/1/1, R
IN
= 1000Ω, f
RF
= 2MHz 700 830 1000
Ω
R
S
= R
IN
= 50Ω, VG+ - VG- = +3V 4.5
R
S
= R
IN
=100Ω, VG+ - VG- = +3V 3.4
R
S
= R
IN
= 200Ω, VG+ - VG- = +3V 2.4
Noise Figure
R
S
= R
IN
= 1000Ω, VG+ - VG- = +3V 2.1
dB
Low-Gain Noise Figure
D43/D42/D41/D40 = 0/0/0/1, LNA gain = 12.5dB,
R
S
= R
IN
= 200Ω, VG+ - VG- = +3V
3.9 dB
Input-Referred Noise Voltage D43/D42/D41/D40 = 1/1/1/0 0.9 nV/√Hz
Input-Referred Noise Current D43/D42/D41/D40 = 1/1/1/0 2.1 pA/√Hz
M axi m um Gai n, H i g h G ai n S etti ng VG+ - VG- = +3V 41 42.8 45 dB
Minimum Gain, High Gain Setting VG+ - VG- = -3V 8.5 10 11 dB
Maximum Gain, Low Gain Setting D43/D42/D41/D40 = 0/0/0/1, VG+ - VG- = +3V 35 36.8 38 dB
Minimum Gain, Low Gain Setting D43/D42/D41/D40 = 0/0/0/1, VG+ - VG- = -3V 2.5 4 6 dB
D45/D44 = 0/0, f
C
= 9MHz 9
D45/D44 = 0/1, f
C
= 10MHz 10
D45/D44 = 1/0, f
C
= 15MHz 15
Anti-Aliasing Filter 3dB Corner
Frequency
D45/D44 = 1/1, f
C
= 18MHz 18
MHz
Gain Range VG+ - VG- = -3V to +3V 33 dB