The information below is taken from MDK v.0.2
The contactless media converter (CMC) allows high-speed and contactless transmission of data between modules and the Endo. The CMC (which can either be integrated into the M-PHY IP block natively, into a bridge ASIC, or as a stand-alone CMC discrete component) removes the need for a data connector, saving space and cost, and increasing durability. The Ara platform uses contactless, inductively-coupled data communication between modules and the Endo. This AC-coupled interface replaces the mechanical connector with traces on a printed circuit board.
Figure below shows a pair of inductive loops on adjacent printed circuit boards. The lower loop is connected to the transmitter IC, and the upper loop is connected to the receiver IC, using microsctrip transmission lines. The two coaxial loops taken together form a signal transformer: a time-varying current in the lower loop creates a time-varying magnetic field in air space between the boards, inducing a time-varying voltage in the upper loop.
Figure below presents a high-level view of the contactless media converter circuit. To allow lowspeed data transmission, the DC level of the signal is restored in the receiver first by a variable gain amplifier (VGA), followed a continuous time linear equalizer (CTLE), and a hysteresis comparator, which restore data pattern from the transmission.
The contactless media converter will operate over the 0.125 – 0.5 mm (+/- 0.05 mm) (TBD) airgap between the module and Endo. It will support all M-PHY transmission rates and modes implemented by the Ara network (see M-PHY specifications section). See the draft CMC Specification document in the reference materials for more detailed specifications.
MDK 0.2: A reference implementation for the contactless media converter is under development. The contactless media converter will also be part of a future version of the Toshiba Bridge ASICs and also available as a stand-alone discrete component that can be used as an add-on to a device enabled with conventional M-PHY MPORTs.
The Ara network stack uses MIPI M-PHY (V3.0 26-July-2013) at Layer 1. M-PHY is a serial interface that supports multiple transmission rates for high and low bandwidth applications. MPHY uses 8b/10b encoding and an embedded clock signal. M-PHY also has multiple power saving modes to support low power embedded devices.
M-PHY operating with the contactless media converter defined in the previous section can support up to HS-GEAR 3 (at 3A/3B Bandwidth and 4.99/5.82 Gbps per lane) and PWM-GEAR 1 to PWM-GEAR 2 (at 9/18 Mbps per lane).