When DUT Clock performance is needed on the UltraFLEX at frequencies significantly higher than the UltraWave24 DUT Clock instrument capability and frequency locked to the tester, an application circuit can be provided to address the issue. For wireless systems, a reference clock is used to frequency lock many functional circuit blocks including Analog to Digital Converters (ADCs), Digital to Analog Converters (DACs) and synthesizers. The overall wireless system performance can be degraded or impaired by phase noise or jitter present on the reference clock. Usually, the device under test (DUT) will have one fixed operating frequency for the reference clock. Further, it is common that the DUT clock input is digital and will experience less jitter on the clock with faster slew rate clock input (e.g., square wave input). This presentation will describe a DIB application solution that provides an ultra-low phase noise, square wave, DUT reference clock signal, frequency locked with the UltraFLEX tester, at two available Vpp amplitudes, at a frequency above the UltraWave24 DUT clock maximum frequency of 105MHz.