MAX2078(2009) 查看數據表（PDF） - Maxim Integrated

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MAX2078
(Rev.:2009)

Octal-Channel Ultrasound Front-End with CW Doppler Mixers

Maxim Integrated 

Octal-Channel Ultrasound Front-End

with CW Doppler Mixers

AC ELECTRICAL CHARACTERISTICS—SERIAL PERIPHERAL INTERFACE

(DOUT loaded with 60pF and 10MΩ, 2ns rise and fall edges on CLK.)

PARAMETER

Clock Speed

Mininimum Data-to-Clock Setup

Time

SYMBOL

tCS

CONDITIONS

MIN TYP MAX UNITS

10

MHz

5

ns

Mininimum Data-to-Clock Hold

Time

tCH

0

ns

Mininimum Clock-to-CS Setup

Time

tES

5

ns

CS Positive Mininimum Pulse

Width

tEW

1

ns

Mininimum Clock Pulse Width

Mininimum CS High to Mixer

Clock on

tCW

tMIXCS

2

ns

2

ns

Note 2: Minimum and maximum limits at TA = +25°C and +70°C are guaranteed by design, characterization, and/or production test.

Note 3: Noise performance of the device is dependent on the noise contribution from VREF. Use a low-noise supply for VREF.

Note 4: Note that the LVDS CWD LO clocks are DC-coupled. This is to ensure immediate synchronization when the clock is first

turned on. An AC-coupled LO is problematic in that the RC time constant associated with the coupling capacitors and the

input impedance of the pin causes a period of time (related to the RC time constant) when the DC level on the chip side of

the capacitor is outside the acceptable common-mode range and the LO swing does not excede both of the logic thresh-

olds required for proper operation. This problem associated with AC-coupling causes an inability to ensure synchronization

among beamforming channels. The LVDS signal is terminated differentially with an external 100Ω resistor on the board.

Note 5: An external 100Ω resistor terminates the LVDS differential signal path.

Note 6: Total on-chip power dissipation is calculated as PDISS = VCC1 x ICC1 + VCC2 x ICC2 + VREF x IREF + [11V - (I11V/4) x 162]

x I11V.

Note 7: This response time does not include the CW output highpass filter. When switching to VGA mode, the CW outputs stop

drawing current and the output voltage goes to the rail. If a highpass filter is used, the recovery time may be excessive

and a switching network is recommended, as shown in the Applications Information section.

Note 8: See the Ultrasound-Specific IMD3 Specification section.

Note 9: The reference input noise is given for 8 channels, knowing that the reference-noise contributions are correlated in all 8

channels. If more channels are used, the reference noise must be reduced to get the best noise performance.

Note 10: Channel-to-channel gain and phase matching measured on 30 pieces during engineering characterization at room tem-

perature. Each mixer is used as a phase detector and produces a DC voltage in the IQ plane. The phase is given by the

angle of the vector drawn on that plane. Multiple channels from multiple parts are compared to each other to produce the

phase variation.

Note 11: Voltage gain is measured by subtracting the output-voltage signal from the input-voltage signal. The output-voltage signal

is obtained by taking the differential CW I output and summing it in quadrature with the differential CW Q output. The input

voltage is defined as the differential voltage applied to the CW input pins.

Note 12: Mixer output-voltage compliance is the range of acceptable voltages allowed on the CW mixer outputs.

Note 13: Transconductance is defined as the quadrature-combined CW differential output current at baseband divided by the

mixer’s input voltage.

8 _______________________________________________________________________________________

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