ASK Demodulation in RF Transponders via Current Mirror Signals

The patent introduces an intermediary mechanism (capacitor voltage sampling and comparison circuitry) that mediates between the varying envelope signal and the demodulation decision. Instead of directly demodulating the ASK signal through envelope detection, the system samples the capacitor voltage at specific phases and compares it against a reference, effectively using the capacitor as an intermediary energy storage element that smooths out envelope variations while preserving data information.

The patent performs preliminary action by pre-charging capacitors during specific phases before the actual demodulation comparison. The capacitor voltages are prepared in advance during the first half-cycle of the RF signal, and then these pre-prepared voltages are compared against reference levels during the second half-cycle, allowing the system to anticipate and compensate for envelope variations before they affect demodulation accuracy.

The patent merges multiple antenna functions into a single integrated circuit structure. Multiple antenna elements and their associated demodulation circuitry are combined on a single semiconductor die, with shared components such as the reference voltage generation, capacitor arrays, and comparison logic. This merging approach allows the system to support multiple antennas for 3-D positioning while minimizing the total die area through resource sharing and integration.

The patent implements universal circuit blocks that can serve multiple antenna channels. The demodulation circuitry is designed with multi-functional components that can be selectively activated for different antenna elements, allowing a single set of circuitry to handle multiple antennas rather than requiring dedicated circuitry for each antenna, thus reducing overall die area while maintaining adaptability.