myicejade
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lmx2326 datasheet
Hi, I am troubleshooting a 2000MHz PLL design using National Semiconductor LM2326 2.8GHz PLL IC. My design parameter is:
My design parameters:
Fmax: 1970MHz
Fmin: 2030MHz
Loop BW: 3KHz
Fcomp: 50KHz
Fref: 12.8MHz
VCO: Vari-l Narrowband 5V VCO 1805-1880MHz
VCO Gain: 15MHz/V
VCO tuning Range: 0.5V-4.5V
I am using a 3nd order passive loop filter. The charge pump voltage Vp is at 5V, while the PLL Vcc1&Vcc2 is at 3.3V.
I have done some Frequency synthesizers with LMX2326,most of them is good ,but only few is bad ,the phenomena are as follows
first:the charge pump output voltage in R3 is 0V
second: the charge pump output voltage in R3is 5.0V(Vp=5.0V)
why????
I dont know how to resolve them , and I have checked my design circuits again and again,and I am sure that they are good,but the results is disappointed,how I do it ? please help me ? thank you very much!!!!
Warmest Regards
zhangjincai
Hi, I am troubleshooting a 2000MHz PLL design using National Semiconductor LM2326 2.8GHz PLL IC. My design parameter is:
My design parameters:
Fmax: 1970MHz
Fmin: 2030MHz
Loop BW: 3KHz
Fcomp: 50KHz
Fref: 12.8MHz
VCO: Vari-l Narrowband 5V VCO 1805-1880MHz
VCO Gain: 15MHz/V
VCO tuning Range: 0.5V-4.5V
I am using a 3nd order passive loop filter. The charge pump voltage Vp is at 5V, while the PLL Vcc1&Vcc2 is at 3.3V.
I have done some Frequency synthesizers with LMX2326,most of them is good ,but only few is bad ,the phenomena are as follows
first:the charge pump output voltage in R3 is 0V
second: the charge pump output voltage in R3is 5.0V(Vp=5.0V)
why????
I dont know how to resolve them , and I have checked my design circuits again and again,and I am sure that they are good,but the results is disappointed,how I do it ? please help me ? thank you very much!!!!
Warmest Regards
zhangjincai