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CMX992Q3 参数 Datasheet PDF下载

CMX992Q3图片预览
型号: CMX992Q3
PDF下载: 下载PDF文件 查看货源
内容描述: [Telecom Circuit, 1-Func, VQFN-48]
分类和应用: 电信电信集成电路
文件页数/大小: 56 页 / 1937 K
品牌: CMLMICRO [ CML MICROCIRCUITS ]
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RF Quadrature Transceiver / RF Quadrature Receiver  
CMX991/CMX992  
4
External Components  
4.1  
Power Supply Decoupling  
The CMX991/CMX992 has separate supply pins for the analogue and digital circuitry: a 3.3V nominal  
supply is recommended for all circuits but a different voltage for VDDIO may be used (see section 5.6).  
DVDD  
DVDD  
R5  
VDDIO  
R4  
VCCRF  
R3  
VCCIF  
R2  
AVDD  
VCCSYNTH  
R1  
C5  
C4  
C3  
C2  
C1  
GND Plane for: AGND  
GND for: DGND  
GND  
Figure 5 Recommended Power Supply Connections and Decoupling  
C1 10nF  
C2 10nF  
C3 10nF  
C4 10nF  
C5 10nF  
R1 3.3 Ω  
R2 3.3 Ω  
R3 3.3 Ω  
R4 10 Ω  
R5 10 Ω  
Table 3 Decoupling Components  
Notes:  
1. Maximum Tolerances: Resistors 5%, capacitors 20% unless otherwise stated  
2. It is expected that any low frequency interference on the 3.3 Volt supply will be removed by active  
regulation; a large capacitor is an alternative but may require more board space and so may not  
be preferred. It is particularly important to ensure that there is no interference from the VDDIO  
(which supplies the digital I/O) or from any other circuit that may use the DVDD supply (such as a  
microprocessor), to sensitive analogue supplies (AVDD). It is therefore advisable to use separate  
power supplies for the digital and analogue circuitry.  
3. The supply decoupling shown is intended for RF noise suppression. It is necessary to have a  
small series impedance prior to the decoupling capacitor for the decoupling to work well; this may  
be cost effectively done with the resistor and capacitor values shown. The use of resistors results  
in small dc voltage drops (up to approx 0.1V). Choosing resistor values approximately inversely  
proportional to the dc current requirements of each supply ensures the dc voltage drop on each  
supply are reasonably matched. In any case, the dc voltage change that results is well within the  
design tolerance of the device. If higher impedance resistors are used (not recommended) then  
greater care will be needed to ensure the supply voltages are maintained within tolerance, even  
when parts of the device are enabled or disabled.  
4. It is advisable to have separate ground planes for the analogue and digital circuits.  
2012 CML Microsystems Plc  
10  
D/991_992/18