The blue trace (3) and purple trace (4) are on either side of R1 and show the clock signal going directly into the AD8333. As shown they have an offset of ~1.2V and and amplitudes of ~460mVpp. The light pink signal (M1) is the differential signal (trace 3 - trace 4). The frequency is 20MHz. I am confident his clock is working effectively. If I alter the input RF signal so that LO != 4*RF, then I see sinusoidal oscillations on I1 and Q1, as expected. All the results shown in this example are taken when LO = 4*RF and no oscillations are seen on I1 and Q1.