Can someone explain or point to some documentation that explains how the RF front-end works for BLE chips? Specifically, I am confused about why the VCO runs at 4.8Ghz and is then divided by 2. I have a background in EE but not much RF.
Reading here I get this but want to confirm if there are other things to consider:
"Typically, VCO performance is poor when the control voltage hovers close to the threshold voltage of the transistors in the Voltage-to-Current (V2I) converter and is also poor at high control voltages when the V2I current sources are pulledout of saturation. So, it may be beneficial to divide the VCO by 2 at low frequencies and divide by 1 at high frequencies to keep the control voltage in the VCO's "sweet spot"."
I see images similar to this online: