SNAU259 August 2021 LMK1D1208
The LMK1D1208 can receive either a differential or single-ended clock as clock input. The default board configuration is for a differential signal at both device inputs. The inputs can be applied through the SMAs, J1, J3 or J4, J6. These inputs are AC-coupled to the device. The common-mode voltage is provided by the device on-chip bias generator (VAC_REF) pins.
LMK1D1208: Either of the two input clocks can be selected using the jumper J5. When J5 is connecting IN_SEL to GND, IN0 is selected. When J5 is connecting IN_SEL to VDD, IN1 is selected.