Berkeley Audio Design’s “proprietary RF waveguide isolation” in the Alpha Reference DAC 3P is not a conventional microwave waveguide in the radar/telecom sense, but rather a carefully engineered on-board and in-chassis RF containment/absorption structure that prevents internally generated and externally coupled RF energy from modulating the ultra‑low‑noise clocking, digital processing, and analog output stages.
Likely physical implementation inside the 3P
Given Berkeley’s design approach and standard RF isolation techniques, the “RF waveguide isolation” in the 3P almost certainly combines several of the following:
On‑board RF “waveguide” structures around critical sections
In RF/mixed‑signal PCB design, a “waveguide” can be realized as:
Grounded coplanar waveguides and slot structures: a center signal trace flanked by grounded copper, with periodic via fences to form an effective waveguide that confines fields and reduces coupling.
Via fences / cavity isolation: dense rows of grounded vias forming walls around sensitive blocks (clock distribution, DAC core, analog output stage) to create a quasi‑waveguide cavity that traps RF and prevents lateral propagation.
In the 3P, these structures are likely used:
Around the ultra‑low phase‑noise clock network and reclocking circuits, where any RF coupling directly translates to jitter and time‑domain distortion.
Around the digital processing section (FPGA / custom logic) that generates high‑frequency switching noise.
Between digital and analog sections to ensure that RF generated by digital circuitry cannot couple into the analog output path.
