DQPSK Demodulator Bias Point Control via Digital Feedback

The patent replaces the analog circuit implementation with a digital circuit implementation. The digital circuit processes the differential current signals through filtering and computational operations to determine bias point real-time values, eliminating the vulnerabilities of analog circuits to external environmental factors such as temperature drift, noise, and component aging. This substitution fundamentally improves reliability by using digital logic and algorithms that are inherently more stable and less susceptible to environmental variations.

The patent implements a dynamic bias point control mechanism where the bias point real-time values for the I-path and Q-path can be independently adjusted to any expected values, not fixed at π/4 and -π/4. The digital circuit calculates real-time bias point values based on filtering the differential current signals and applies feedback control to lock at these dynamically determined values. This dynamic approach enables the system to adapt to different operating conditions and requirements while maintaining control simplicity through automated digital processing.

The patent employs digital signal processing techniques including filtering operations on the differential current signals and computational algorithms to determine bias point real-time values with high precision. The digital circuit architecture provides superior resolution and accuracy compared to analog methods, as digital systems can represent and process values with arbitrary precision limited only by the number of bits used. The increased complexity is offset by the use of standard digital logic components and algorithms that provide robust and repeatable precision control.