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RF2690 参数 Datasheet PDF下载

RF2690图片预览
型号: RF2690
PDF下载: 下载PDF文件 查看货源
内容描述: W-CDMA的接收自动增益控制和解调器 [W-CDMA RECEIVE AGC AND DEMODULATOR]
分类和应用: 电信集成电路信息通信管理
文件页数/大小: 16 页 / 261 K
品牌: RFMD [ RF MICRO DEVICES ]
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Preliminary  
RF2690  
Since the power gain to the input of the Op-Amp GP’=αGP, where GP is the power gain of demodulator for matched load.  
Therefore, the demodulator power gain is 65+15=80dB.  
AC Coupling in Evaluation Board  
The output I and Q baseband signal is AC coupled for evaluation purposes only. The high-pass corner frequency is at  
1/(2π RC)=1/(6.28*30k*100nF)=56Hz.  
I and Q Output DC Voltage and Its Offset  
Although the I and Q output is AC coupled on the evaluation board, in most applications, it would be DC coupled to the  
ADC input buffer. The DC voltage at the IC output is VCC-1.6V with a possible variation of ±0.3V due to temperature and  
tolerance. The differential circuit asymmetry would cause common mode DC offset to the extent of ±40mV.  
Baseband Filter Calibration Process  
The BB (baseband) filter calibration process is same for both WCDMA and GSM/DCS. After calibration is done, the  
WCDMA mode sets the circuitry to have a 3dB bandwidth of 2.5MHz, the GSM/DCS mode (if the chip has GSM/DCS  
mode) sets the circuitry to have a 3dB bandwidth of 250kHz.  
The BB filter in the I and Q path needs to be calculated every time after power down. When the FCLK pin is connected to  
a signal generator with 0dBm output level at 13.0MHz, a logic high at CALEN pin for 200µs will calibrate the filter to have  
2.5MHz bandwidth with 10% accuracy when WCDMA mode is set, or to 250kHz bandwidth with 10% accuracy when  
GSM mode is set. The calibration is done when the chip is powered on only. Calibration is independent from all other  
conditions, e.g. the chip enable could be off.  
7
The calibration circuitry consumes 400µA. When the calibration sequence is complete after 200µs, the ICC drops to  
0mA.  
The 3dB bandwidth is defined to be from the reference level at 1MHz for WCDMA and at 50kHz for GSM/DCS. The 3dB  
bandwidth is independent of VGC and VCC  
.
The filter can also be calibrated with different clock frequencies from 10MHz to 30MHz to tune the bandwidth over -40%  
to +60% from its default 3dB bandwidth (2.5MHz for WCDMA and 250kHz for GSM). The 3dB bandwidth is linear with  
clock frequency.  
7-46  
Rev A4 010918