MAX2038CCQ+T Datasheet MAX2038CCQ+T, MAX2038CCQ+, MAX2038CCQ+D | P13-P15

MAX2038

Ultrasound VGA Integrated

with CW Octal Mixer

______________________________________________________________________________________ 13

PIN NAME FUNCTION

70 VGOUT3+ VGA Channel 3 Noninverting Differential Output

71 VGOUT3- VGA Channel 3 Inverting Differential Output

73 LO2 CW LO Input for Channel 2. LO clock input for modes 3 and 4.

74 VGOUT2+ VGA Channel 2 Noninverting Differential Output

75 VGOUT2- VGA Channel 2 Inverting Differential Output

76 LO1 CW LO Input for Channel 1. LO clock input for modes 3 and 4.

77 VGOUT1+ VGA Channel 1 Noninverting Differential Output

78 VGOUT1- VGA Channel 1 Inverting Differential Output

80 DIN Serial Port Data Input. Data input to program the serial shift registers.

83 CLK Serial Port Data Clock. Clock input for programming the serial shift registers.

84 CW_M1

CW Mode Select Input 1. Input for programming beamforming mode 1, 2, 3, or 4. See Table 1 for

mode programming details.

85 CW_M2

CW Mode Select Input 2. Input for programming beamforming mode 1, 2, 3, or 4. See Table 1 for

mode programming details.

VG_CLAMP_

MODE

VGA Clamp Mode Enable. Drive VG_CLAMP_MODE low to enable VGA clamp mode. VGA output is

clamped at typically 2.4V

P-P

differential. Drive VG_CLAMP_MODE high to disable VGA clamp mode.

88 LOAD

Serial Port Load. Loads the data from the serial shift registers into the I/Q phase dividers. Pull LOAD

bus from high to low and from low to high for programming the I/Q phase dividers.

89 CW_QOUT+

CW Mixer Noninverting Differential Quadrature Output. CW Mixer output for eight quadrature mixers

combined.

90 CW_QOUT-

CW Mixer Inverting Differential Quadrature Output. CW mixer output for eight quadrature mixers

combined.

91 CW_IOUT- C W M i xer Inver ti ng D i ffer enti al In- P hase Outp ut. C W m i xer outp ut for ei g ht i n- p hase m i xer s com b i ned .

92 CW_IOUT+

CW Mixer Noninverting Differential In-Phase Output. CW Mixer output for eight in-phase mixers

combined.

94 VGIN1- VGA Channel 1 Inverting Differential Input

95 VGIN1+ VGA Channel 1 Noninverting Differential Input

97 CWIN1- CW Mixer Channel 1 Inverting Differential Input

98 CWIN1+ CW Mixer Channel 1 Noninverting Differential Input

99 VGIN2- VGA Channel 2 Inverting Differential Input

100 VGIN2+ VGA Channel 2 Noninverting Differential Input

—EP

Exposed Pad. Internally connected to GND. Connect EP to a large PCB ground plane to maximize

thermal performance.

Pin Description (continued)

MAX2038

Ultrasound VGA Integrated

with CW Octal Mixer

14 ______________________________________________________________________________________

Detailed Description

The MAX2038 is an 8-channel VGA integrated with a

programmable octal quadrature mixer array designed

for ultrasound imaging and Doppler applications. The

device is optimized for efficient power consumption,

high dynamic range, and for exceptionally low noise

performance. The VGA path features differential inputs,

analog variable gain control, differential outputs for

direct ADC drive, and a selectable output voltage

clamp to avoid ADC overdrive. The integrated octal

quadrature mixer array includes serial programmable

LO phase generators for CWD beamforming applica-

tions. The LO phase dividers can be programmed for 4,

8, or 16 quadrature phases. Lowpass filters are inte-

grated at the input paths of each CW mixer. The out-

puts for the mixers are summed into single I/Q

differential current outputs.

The MAX2038 also integrates an octal quadrature mixer

array and programmable LO phase generators for a

complete continuous wave (CW) Doppler beamforming

solution. The LO phase selection for each channel is

programmed using a digital serial interface and a sin-

gle high-frequency clock, or the LOs for each complex

mixer pair can be directly driven using separate 4 x LO

clocks. The serial interface is designed to allow multiple

devices to be easily daisy chained in order to minimize

program interface wiring. The LO phase dividers can

be programmed to allow 4, 8, or 16 quadrature phases.

The input path of each CW mixer consists of a selec-

table lowpass filter for optimal CWD noise performance.

The outputs of the mixers are summed into single I and

Q differential current outputs. The mixers and LO gen-

erators are designed to have exceptionally low noise

performance of -155dBc/Hz at 1kHz offset from a

1.25MHz carrier, measured with 900mV

P-P

differential

clutter signal.

Variable Gain Amplifier (VGA)

The MAX2038’s VGAs are optimized for high linearity,

high dynamic range, and low output-noise performance,

making this component ideal for ultrasound imaging

applications. The VGA paths also exhibit a channel-to-

channel crosstalk of -80dB at 10MHz and an absolute

gain error of less than ±0.25dB for minimal channel-to-

channel focusing error in an ultrasound system. Each

VGA path includes circuitry for adjusting analog gain, an

output buffer with differential output ports (VGOUT_+,

VGOUT_-) for driving ADCs, and differential input ports

(VGIN_+, VGIN_-), which are ideal for directly interfac-

ing to the MAX2034 quad LNA. See the

High-Level

Wave Mixer and Programmable Beamformer Functional

Diagram

for details.

The VGA has an adjustable gain range from -12.5dB to

+29.5dB, achieving a total dynamic range of 42dB

(typ). The VGA gain can be adjusted through the differ-

ential gain control inputs VG_CTL+ and VG_CTL-. Set

the differential gain-control input voltage at +2V for min-

imum gain and -2V for maximum gain. The differential

analog control common-mode voltage is 3V (typ).

GND

+5V

REF

VG_CTL+

VG_CTL-

VG_CLAMP_MODE

VGOUT1+

VGOUT1-

VGOUT8+

VGOUT8-

CW_IOUT+

CW_IOUT-

VGIN1+

VGIN1-

VGIN8+

VGIN8-

LOW_PWR

CW_VG

CW_FILTER

VGA

50Ω

•

+5V (LOW NOISE)

•

VGA

I&Q

50Ω

CWIN1+

CWIN1-

•

CW_QOUT+

CW_QOUT-

I&Q

CWIN8+

CWIN8-

MAX2038

High-Level Wave Mixer and

Programmable Beamformer

Functional Diagram

MAX2038

Ultrasound VGA Integrated

with CW Octal Mixer

______________________________________________________________________________________ 15

VGA Clamp

A clamp is provided to limit the VGA output signals to

avoid overdriving the ADC or to prevent ADC satura-

tion. Set VG_CLAMP_MODE low to clamp the VGA dif-

ferential outputs at 2.4V

P-P

. Set the VG_CLAMP_MODE

high to disable the clamp.

Power-Down

The device can also be powered down with PD. Set PD

to logic-high for power-down mode. In power-down

mode, the device draws a total supply current of 27mA.

Set PD to a logic-low for normal operation.

Overload Recovery

The device is also optimized for quick overload recovery

for operation under the large input-signal conditions that

are typically found in ultrasound input buffer imaging

applications. See the

Typical Operating Characteristics

for an illustration of the rapid recovery time from a trans-

mit-related overload.

Octal Continuous Wave (CW) Mixer

The MAX2038 CW mixers are designed using an active

double-balanced topology. The mixers achieve high

dynamic range and high linearity performance, with

exceptionally low noise, which is ideal for ultrasound

CWD signal reception. The octal quadrature mixer

array provides noise performance of -155dBc/Hz at

1kHz from a 1.25MHz carrier, and a two-tone third-

order ultrasound specific intermodulation product of

typically -50dBc. See the

Ultrasound-Specific IMD3

Specification

in the

Applications Information

section

The octal array exhibits quadrature and in-phase differ-

ential current outputs (CW_QOUT+, CW_QOUT-,

CW_IOUT+, CW_IOUT-) to produce the total CWD

beamformed signal. The maximum differential current

output is typically 3mA

P-P

and the mixer output-compli-

ance voltage ranges from 4.75V to 12V.

CHANNEL 1

I/Q

DIVIDER

PHASE

SELECTOR

5-BIT

IQ I Q

DIN

CLK

LO_LVDS+

LO_LVDS-

CWIN1

CWIN2

CWIN8

GNDCW_M2

CW_M1

CW_IOUT+

DOUT

LOW_PWR PD

CW_IOUT-

CW_QOUT-

CW_QOUT+

CW_IOUT2+

CW_QOUT2-

LOAD

LO1

LO2

LO8

REF

CW_FILTER M4_EN

•

MAX2038

I Q

CHANNEL 2

I/Q

DIVIDER

PHASE

SELECTOR

CHANNEL 8

I/Q

DIVIDER

PHASE

SELECTOR

High-Level CW Mixer and Programmable

Beamformer Functional Diagram

P1-P3 P4-P6 P7-P9 P10-P12 P13-P15 P16-P18 P19-P21 P22-P24

MAX2038CCQ+T

Mfr. #:

Buy MAX2038CCQ+T

Manufacturer:

Maxim Integrated

Description:

Instrumentation Amplifiers Ultrasound Variable Gain Amplifier

Lifecycle:

New from this manufacturer.

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MAX2038CCQ+T

MAX2038CCQ+T

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