參數(shù)資料
型號(hào)： MAX2078CTK+
廠商： Maxim Integrated Products
文件頁(yè)數(shù)： 15/26頁(yè)
文件大?。?/td> 0K
描述： IC FRNT-END ULTRASOUND 8CH 68QFN
應(yīng)用說明： Ultrasound Imaging Systems Application Note
產(chǎn)品培訓(xùn)模塊： Lead (SnPb) Finish for COTS
Obsolescence Mitigation Program
特色產(chǎn)品： MAX2078 Octal-Channel Ultrasound Front-End with CW Doppler Mixers
標(biāo)準(zhǔn)包裝： 30
類型： 超聲波接收器
應(yīng)用： 醫(yī)療用超聲波成像，聲納
安裝類型： 表面貼裝
封裝/外殼： 68-TQFN 裸露焊盤
供應(yīng)商設(shè)備封裝： 68-TQFN-EP（10x10）
包裝： 管件
MAX2078
Octal-Channel Ultrasound Front-End
with CW Doppler Mixers
22
______________________________________________________________________________________
Ultrasound Front-End CWD Beamformer
The user provides an LO frequency of 16MHz to
120MHz. This high clock frequency requires a differential
LVDS input. 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 results in a period of time (related to the RC time con-
stant) when the DC level on the chip side of the capaci-
tor is outside the acceptable common-mode range and
the LO swing cannot overcome both of the logic thresh-
olds required for proper operation. This problem associ-
ated with AC coupling would cause an inability to ensure
synchronization among beamforming channels.
The LVDS signal is terminated differentially with an
external 100
Ω resistor on the board. The LO input is
divided internally by 16 to produce 16 phases at a fre-
quency of 1MHz to 7.5MHz. There is one divider per
channel. Each channel has a corresponding 5-bit shift
register (4 bits for phase programming and 1 bit for
channel enable) that is used to program the output
phase of the divide-by-16 circuit. The first 4 bits of the
shift register are for programming the 16 phases, and
the fifth bit can be used to turn on/off each channel
individually through the serial bus.
CW Mixer Output Summation
The maximum differential current output is typically
3mAP-P and the mixer output-compliance voltage
ranges from 4.5V to 12V per mixer channel. The mixer
common-mode current in each of the differential mixer
outputs is typically 2.83mA. The total summed current
would equal N x 2.83mA in each of the 162
Ω load resis-
tors (where N = number of channels). In this case, the
quiescent output voltage at +VSUM and -VSUM outputs
would be 11V - (N x 2.83mA x 162
Ω) = 11V - (8 x
2.83mA x 162
Ω) = 7.34V. The voltage swing at each
output, with one channel driven at maximum output cur-
rent (differential 2.8mAP-P) while the other channels are
not driven, would be 1.4mAP-P x 162Ω or 226mVP-P
and the differential voltage would be 452mVP-P. The
voltage compliance range is defined as the valid range
for +VSUM and -VSUM in this example.
Active Impedance Matching
To provide exceptional noise-figure characteristics, the
input impedance of each amplifier uses a feedback
topology for active impedance matching. A feedback
resistor of the value (1 + (A/2)) x RS is added between
the inverting input of the amplifier to the output. The
input impedance is the feedback resistor (ZF) divided
by 1 + (A/2). The factor of two is due to the gain of the
amplifier (A) being defined with a differential output. For
common input impedances, the internal digitally pro-
grammed impedances can be used (see Tables 1 and
2). For other input impedances, program the imped-
ance for external resistor operation, and then use an
externally supplied resistor to set the input impedance
according to the above formula.
Noise Figure
The MAX2078 is designed to provide maximum input
sensitivity with exceptionally low noise figure. The input
active devices are selected for very-low-equivalent
input noise voltage and current, optimized for source
impedances from 50
Ω to 1000Ω. Additionally, the noise
contribution of the matching resistor is effectively divid-
ed by 1 + (A/2). Using this scheme, typical noise figure
of the amplifier is approximately 2.4dB for RIN = RS =
200
Ω. Table 6 illustrates the noise figure for other input
impedances.
Input Clamp
The MAX2078 includes configurable integrated input-
clamping diodes. The diodes are clamped to ground at
±0.8V. The input-clamping diodes can be used to pre-
vent large transmit signals from overdriving the inputs of
the amplifiers. Overdriving the inputs could possibly
place charge on the input-coupling capacitor, causing
longer transmit overload recovery times. Input signals
are AC-coupled to the single-ended inputs IN1–IN8, but
are clamped with the INC1–INC8 inputs. See the
Typical
Application Circuit. If external clamping devices are pre-
ferred, simply leave INC1–INC8 unconnected.
Analog Output Coupling
The differential outputs of the VGA are capable of dri-
ving a differential load capacitance to GND at each of
the differential outputs of 25pF, and the differential
capacitance across the VGA outputs is 15pF, RL =
1k
Ω. The differential outputs have a common-mode
bias of approximately 1.73V. AC-couple these differen-
tial outputs if the next stage has a different common-
mode input range.
RS (
Ω)RIN (Ω)
NF (dB)
50
4.5
100
3.4
200
2.4
1000
2.1
Table 6. Noise Figure vs. Source and
Input Impedances
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MAX2078CTK+ 功能描述:射頻前端 8Ch Ultrasound Front-End RoHS:否 制造商:Skyworks Solutions, Inc. 類型: 工作頻率:2.4 GHz, 5 GHz 最大數(shù)據(jù)速率:54 Mbps 噪聲系數(shù): 工作電源電壓:3.3 V 電源電流:180 mA 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-32
MAX2078CTK+T 功能描述:射頻前端 8Ch Ultrasound Front-End RoHS:否 制造商:Skyworks Solutions, Inc. 類型: 工作頻率:2.4 GHz, 5 GHz 最大數(shù)據(jù)速率:54 Mbps 噪聲系數(shù): 工作電源電壓:3.3 V 電源電流:180 mA 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-32
MAX2078EVKIT 功能描述:射頻前端 Ultrasound Integrated Analog Front End Octal LNA RoHS:否 制造商:Skyworks Solutions, Inc. 類型: 工作頻率:2.4 GHz, 5 GHz 最大數(shù)據(jù)速率:54 Mbps 噪聲系數(shù): 工作電源電壓:3.3 V 電源電流:180 mA 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-32
MAX2079 制造商:未知廠家 制造商全稱:未知廠家 功能描述:每個(gè)通道具有獨(dú)立的混頻器，以優(yōu)化CWD靈敏度
MAX2079CXE+ 功能描述:射頻接收器 8Ch Ultrasound Front End w/ADC+CW Doppler RoHS:否 制造商:Skyworks Solutions, Inc. 類型:GPS Receiver 封裝 / 箱體:QFN-24 工作頻率:4.092 MHz 工作電源電壓:3.3 V 封裝:Reel
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