Unexpected high-frequency VSINE output in low-voltage mode

### Unexpected high-frequency VSINE output in low-voltage mode

We are currently testing 3 lick detector boards and have observed unexpected behaviour on the VSINE output when the low-voltage mode is selected.

Measurement point:

* Scope probe on J1, pin 6, labelled VSINE
* Ground reference: H1 ground tab
* 10× oscilloscope probe used

Note: lick detection appears to function normally in both voltage modes.

In the higher-voltage mode, the output appears to work as expected:

* VSINE: 100 kHz sine wave, approximately 2 Vpp
* See attached image: `2V Mode`

However, when the low-voltage mode is selected and the board is power-cycled, we would expect to see:

* VSINE: 100 kHz sine wave, approximately 20 mV

Instead, on all boards tested, we are seeing:

* Approximately 1 Vpp
* Very high-frequency signal above 35 MHz
* See attached image: `20mV Mode`

Could you confirm whether the expected low-voltage VSINE output at J1 pin 6 should be a 100 kHz / 20 mV sine wave?

Have you seen this high-frequency behaviour before in low-voltage mode?