Abstract: A hybrid fiber coax (HFC) circuit comprises a diplexer and laser. The diplexer has an input terminal receiving a downstream radio-frequency (RF) signal from a passive optical network (PON). The diplexer outputs this signal from its common terminal onto a cable distribution network (CDN) covering the “last mile” to the customer. The diplexer receives on the common terminal an upstream radio-frequency (RF) signal from the CDN which it outputs on its output terminal. The laser connects to receive the upstream RF signal from the output terminal and uses this signal to generate an optical upstream RF signal transmitted to the head-end or hub via the PON. The HFC circuit can also comprise an RF amplifier, equalizer, or pod adjustment unit. Elements of the HFC circuit can be mounted on a substrate with an interface connection configured to fit into an optical network terminal (ONT). A related system is also disclosed.