arefeidi
Member level 4
kd pll gain
Hi,
I've got a few questions regarding PLL's and VCO's. In my project I'm going to use a synthesizer like the ADF4111 from Analog Devices. Output frequency about 900MHz (ZComm or Minicircuits VCO), crystal oscillator 10 MHz (if that's of interest).
1. Which frequency are the charge pump impulses - I suppose (f_vco / N). Am I right? So when I double the divider N, the rate of the impulses changes gets halved?
2. The output resistance of the synthesizers charge pump (current source) should be as large as possible, right? Is it usually big enough to be able to calculate with an output resistance of ∞ (infinite)?
3. What is the usual input impedance for a VCO (for the tuning voltage input)?
Thanks in advance for any help!
Hi,
I've got a few questions regarding PLL's and VCO's. In my project I'm going to use a synthesizer like the ADF4111 from Analog Devices. Output frequency about 900MHz (ZComm or Minicircuits VCO), crystal oscillator 10 MHz (if that's of interest).
1. Which frequency are the charge pump impulses - I suppose (f_vco / N). Am I right? So when I double the divider N, the rate of the impulses changes gets halved?
2. The output resistance of the synthesizers charge pump (current source) should be as large as possible, right? Is it usually big enough to be able to calculate with an output resistance of ∞ (infinite)?
3. What is the usual input impedance for a VCO (for the tuning voltage input)?
Thanks in advance for any help!