AD835-Based Squaring Circuit Does Not Go to Zero When Input Goes to Zero

I'm using an AD835 as a simple OOK square-law detector. My LTSpice simulations look perfect, but my real-world PCB results do not. On the real PCB, the multiplier output does not go to zero when the carrier goes to zero. Zero squared is zero. It goes to zero in the simulations as it should. Can you tell me what's wrong with the PCB circuit? It looks the same as the simulation circuit to me. I've pasted in the simulation circuit and results along with the actual circuit and results. Carrier frequency is about 20 MHz. Thanks.

Simulation Circuit and Results -- Blue = Squarer Input, Green = Squarer Output

Real-World Schematic and Results -- Left Scope Capture = Squarer Input, Right Scope Capture = Squarer Output