CML 公司的CMX994是 100-600MHz直接變換接收器，集成了高動態(tài)范圍I/Q解調(diào)器控制增益的寬帶LNA，接收器基帶部分包括放大器和精密的基帶濾波器，整數(shù)N PLL和VCO負阻放大器產(chǎn)生本地振蕩（LO），工作電壓3.3V，主要用在模擬/數(shù)字多模式無線電，SDR，數(shù)據(jù)遙測調(diào)制解調(diào)器，衛(wèi)星通信，笛卡爾反饋回路發(fā)送器，寬帶數(shù)據(jù)等。本文介紹了CMX994主要特性，方框圖，典型應(yīng)用框圖和EV9942評估板主要特性與功能，電路圖以及PCB布局圖。
The CMX994 is a direct conversion receiver IC. It includes a broadband LNA with gain control followed by a high dynamic range I/Q demodulator. The receiver baseband section includes amplifiers and precise baseband filter stages. LO generation is provided by an integer-N PLL and a VCO negative resistance amplifier; an external LO may also be used. LO dividers are provided for flexible multi-band operation.
The device operates from a single 3.3V supply over a temperature range of –40℃ to +85℃ and is available in a small 40-pin VQFN (Q4) package.
CMX994主要特性：
Rx Direct Conversion Receiver
o Direct conversion eliminates image responses
o LNA with gain control
o 100MHz to 600MHz I/Q demodulator
o Precise filtering with bandwidth setting and 1:2:4 bandwidth modes Local Oscillator
o LO synthesiser
o VCO negative resistance amplifier
o LO divide by 2, 4 or 6 modes
o Tx LO Output
3.3V Low-power Operation
Small size 40-pin VQFN Package
Low-power Mode
CMX994應(yīng)用：
Analogue/digital multimode radio
Software Defined Radio (SDR)
Data telemetry modems
Satellite communications
Constant envelope and linear Rx modulation
Rx function compatible with CMX998
Cartesian Feedback Loop Transmitter
Narrowband: e.g. 25kHz, 12.5kHz, 6.25kHz
Wideband Data
圖1。CMX994方框圖
圖2。CMX994典型應(yīng)用框圖
EV9942評估板
The EV9942 allows the user to investigate all aspects of the CMX994 integrated circuit, which implements a high-performance direct conversion receiver. The evaluation kit also includes additional circuits that may be used to evaluate system performance, a Fractional-N PLL and a high-frequency VCO.
Access is provided to all CMX994 RF, baseband and control signals by either connector or test points.
Test access points are available to accept common test equipments, such as RF and baseband signal generators and spectrum analysers. All signal paths are matched by suitable components. The overall frequency range of this evaluation kit is for RF frequencies between 100MHz and 600MHz, with default operation at 448MHz.
The CMX994 is controlled via its C-BUS serial interface. The PE0002 Interface Card is available separately to support PC-based control of the EV9942. The PE0002 uses ES9942xx.exe PC software, part of the ES9942xx.zip file, which is available from the CML website.
EV9942評估板主要特性：
CMX994 Evaluation Receiver:
o LNA
o I/Q Output
o Selectable Filters
Transmit LO Output
CMX994 Integer-N PLL
Interface for external Fractional-N PLL
19.2MHz VCTCXO
Flexible External VCO
On-board Voltage Regulators
PC Control Interface Available
Interfaces to PE0601, EV9810
or EV9100 Evaluation Kits
448MHz Default Operation
100MHz to 600MHz Evaluation
圖3。EV9942評估板外形圖
圖4。EV9942評估板方框圖
EV9942評估板功能：
The EV9942 functionality includes:
Demonstration of a linear direct conversion receiver from RF input to output in I/Q format including:
o LNA with gain control
o I/Q mixers
o first baseband filters
o first baseband amplifiers
o second baseband filters
o second baseband amplifiers.
VCO, Integer-N PLL and divider.
Tx LO Output.
Operation 100MHz to 600MHz (448MHz = default configuration).
19.2MHz VCTCXO.
On-board linear regulators for all necessary power rails.
The C-BUS Interface that allows the card to be connected to a host μController. A PC Interface board is separately available and allows control of all device functions, to support initial test and customer evaluation.
Interface to CMX7163 or CMX7164 evaluation boards (PE0601-7163 / PE0601-7164, not included) to allow demonstration/test of QAM and 2-FSK / 4-FSK demodulation.
Interface to CMX910 evaluation card (EV9100, not included) to allow demonstration/test with GMSK demodulation.
Interface to CMX981 evaluation card (EV9810, not included) allows demonstration of:
o Linear receiver
o Pi/4-DQPSK
In summary, the EV9942 allows the user to create experiments to investigate all aspects of the CMX994 device. The EV9942 is designed to allow user modification, to support the detailed investigation of the user’s specific and different applications. The evaluation platform also includes additional circuits that may be used to evaluate system performance, for example a fractional-N PLL (U8) and a high-frequency VCO (TR2/TR3).
圖5。EV9942評估板電路圖（1）
圖6。EV9942評估板電路圖（2）
圖7。EV9942評估板電路圖（4）
圖8。EV9942評估板電路圖（4）
圖9。EV9942評估板PCB布局圖：頂層
圖10。EV9942評估板PCB布局圖：底層
詳情請見：
http://www.cmlmicro.com/products/datasheets/Docs/CMX994ds.pdf
和
http://www.cmlmicro.com/products/datasheets/Docs/ev9942ds.pdf
