MAX9986 Evaluation Kit
9) Set DC supply to +5.0V, and set a current limit of
approximately 300mA, if possible. Disable the out-
put voltage and connect the supply to the EV kit
(through an ammeter, if desired). Enable the sup-
ply. Readjust the supply to get +5.0V at the EV kit.
There will be a voltage drop across the ammeter
when the mixer is drawing current.
10) Select LO1 by connecting LOSEL (TP3) to GND.
11) Enable the LO and the RF sources.
Testing the Mixer
Adjust the center and span of the spectrum analyzer to
observe the IF output tone at 160MHz. The level should
be approximately +2.0dBm (10dB conversion gain,
3dB pad loss). There is also a tone at 159MHz, which is
due to the LO signal applied to LO2. The amount of
suppression between the 160MHz and 159MHz signals
is the LO switch isolation. Note that the spectrum ana-
lyzer ’ s absolute magnitude accuracy is typically no bet-
ter than ±1dB. If accuracy is required, use the power
meter to measure the absolute single-tone power level.
Disconnect the GND connection to LOSEL. It is pulled
high by a pullup resistor on the board, selecting LO2.
Observe that the 159MHz signal increases while the
160MHz decreases. Reconfigure the test setup using a
combiner or hybrid to apply two RF signals at RFIN to
do a two-tone IP3 measurement, if desired. Terminate
the unused LO input in 50 ? .
Detailed Description
The MAX9986 is a high-linearity downconverter inte-
grated with RF and LO baluns, an LO buffer, an IF
amplifier, and an SPDT LO input select switch. The EV
kit circuit consists mostly of supply-decoupling capaci-
tors, DC-blocking capacitors, an IF balun, and induc-
tive chokes. The MAX9986 EV kit circuit allows for thor-
ough analysis and a simple design-in.
Supply-Decoupling Capacitors
Capacitors C2, C7, C8, and C11 are 82pF supply-
decoupling capacitors used to filter high-frequency
noise. C3, C6, and C9 are larger 0.01μF capacitors
used for filtering lower frequency noise on the supply.
DC-Blocking Capacitors
The MAX9986 has internal baluns at the RF and LO
inputs. These inputs have almost 0 ? resistance at DC,
so DC-blocking capacitors C1, C10, and C12 are used
to prevent any external bias from being shunted directly
to ground.
LO Bias and IF Bias
Bias currents for the integrated IF amplifier and the LO
buffer are set with resistors R1 (953 ? ± 1%) and R2
(619 ? ± 1%), respectively. These values were carefully
chosen during factory testing for optimum linearity
and minimal supply current. The DC currents can be
reduced by increasing the values of R1 and R2, but the
device would operate at reduced performance levels
(see the Modifying the EV Kit section).
Current-Limiting Resistor
Resistor R3 is used for current limiting at the supply,
and typically dissipates 60mW.
Tap Network
Capacitor C5 helps to terminate the second-order inter-
modulation products.
LEXT
The 30nH wire-wound inductor, L3, improves LO-to-IF
and RF-to-IF isolation. If isolation is not critical, then this
pin can be grounded.
IF ±
The MAX9986 employs a differential IF output to offer
increased IP2 system performance. The EV kit uses a
4:1 balun to transform the 200 ? differential output
impedance to a 50 ? single-ended output for easy
bench evaluation. Inductive chokes L1 and L2 provide
DC bias to the IF output amplifier, C13 and C14 for sup-
ply filtering, and R3 for current limiting.
As the differential IF outputs are relatively high imped-
ance (200 ? ), they are more susceptible to component
parasitics. It is often good practice to relieve the
ground plane directly underneath large components to
reduce associated shunt-C parasitics.
LOSEL
The EV kit includes a 47k ? pullup resistor for easy
selection of the LO port. Providing a ground at TP3
selects LO1, and leaving TP3 open selects LO2. To
drive TP3 from an external source, follow the limits
called out in the MAX9986 device data sheet. Logic
voltages should not be applied to LOSEL without the
+5V supply voltage. Doing so can cause the on-chip
ESD diodes to conduct and could damage the device.
_______________________________________________________________________________________
3
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相关代理商/技术参数
MAX9987EGP 制造商:Maxim Integrated Products 功能描述:14DBM TO 20DBM LO BUFFER/SPLITTER WITH +/-1DB - Rail/Tube
MAX9987EGP-T 制造商:Maxim Integrated Products 功能描述:14DBM TO 20DBM LO BUFFER/SPLITTER WITH +/-1DB - Tape and Reel
MAX9987ETP 功能描述:射频放大器 14dBm to 20dBm LO Buffer/Splitter RoHS:否 制造商:Skyworks Solutions, Inc. 类型:Low Noise Amplifier 工作频率:2.3 GHz to 2.8 GHz P1dB:18.5 dBm 输出截获点:37.5 dBm 功率增益类型:32 dB 噪声系数:0.85 dB 工作电源电压:5 V 电源电流:125 mA 测试频率:2.6 GHz 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:QFN-16 封装:Reel
MAX9987ETP+ 功能描述:射频放大器 14dBm to 20dBm LO Buffer/Splitter RoHS:否 制造商:Skyworks Solutions, Inc. 类型:Low Noise Amplifier 工作频率:2.3 GHz to 2.8 GHz P1dB:18.5 dBm 输出截获点:37.5 dBm 功率增益类型:32 dB 噪声系数:0.85 dB 工作电源电压:5 V 电源电流:125 mA 测试频率:2.6 GHz 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:QFN-16 封装:Reel
MAX9987ETP+T 功能描述:射频放大器 14dBm to 20dBm LO Buffer/Splitter RoHS:否 制造商:Skyworks Solutions, Inc. 类型:Low Noise Amplifier 工作频率:2.3 GHz to 2.8 GHz P1dB:18.5 dBm 输出截获点:37.5 dBm 功率增益类型:32 dB 噪声系数:0.85 dB 工作电源电压:5 V 电源电流:125 mA 测试频率:2.6 GHz 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:QFN-16 封装:Reel
MAX9987ETP-T 功能描述:射频放大器 14dBm to 20dBm LO Buffer/Splitter RoHS:否 制造商:Skyworks Solutions, Inc. 类型:Low Noise Amplifier 工作频率:2.3 GHz to 2.8 GHz P1dB:18.5 dBm 输出截获点:37.5 dBm 功率增益类型:32 dB 噪声系数:0.85 dB 工作电源电压:5 V 电源电流:125 mA 测试频率:2.6 GHz 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:QFN-16 封装:Reel
MAX9987EVKIT 功能描述:射频放大器 RoHS:否 制造商:Skyworks Solutions, Inc. 类型:Low Noise Amplifier 工作频率:2.3 GHz to 2.8 GHz P1dB:18.5 dBm 输出截获点:37.5 dBm 功率增益类型:32 dB 噪声系数:0.85 dB 工作电源电压:5 V 电源电流:125 mA 测试频率:2.6 GHz 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:QFN-16 封装:Reel
MAX9988EGP-T 制造商:Maxim Integrated Products 功能描述:14DBM TO 20DBM LO BUFFER/SPLITTER WITH +/-1DB - Tape and Reel