SNAS783C June 2020 – February 2021 LMX2820
PRODUCTION DATA
To reduce the VCO tuning gain and therefore improve the VCO phase-noise performance, the VCO frequency range is divided into several different frequency bands. The entire range, 5.65 to 11.3 GHz covers an octave that allows the divider to take care of frequencies below the lower bound. This creates the need for frequency calibration to determine the correct frequency band given a desired output frequency. The frequency calibration routine is activated any time that the R0 register is programmed with the FCAL_EN = 1. It is important that a valid OSCIN signal must present before VCO calibration begins. The VCO also has an internal amplitude calibration algorithm to optimize the phase noise which is also activated any time the R0 register is programmed. The optimum internal settings for this are temperature dependent. The maximum allowable drift for continuous lock, ΔTCL, is stated in the electrical specifications. For this device, a number of 125 °C means the device never loses lock if the device is operated under the Recommended Operating Conditions.