RF Amplifier Bias Circuit for Fast Operating-Point Startup

The patent applies preliminary action by pre-charging the capacitor in the inductive-capacitive resonance circuit before enabling the amplifier. When the reference voltage switches from low to high level, the pre-charged capacitor rapidly discharges through the inductor to pull up the DC bias level of the transistor, eliminating the need for slow conventional bias charging and reducing configuration time to nearly zero.

The patent utilizes periodic action through the inductive-capacitive resonance circuit, which operates as an oscillating system. The circuit is designed to resonate at a specific frequency, creating periodic current flow that rapidly charges the transistor bias node. This resonant oscillation provides a high initial current surge to quickly establish the operating point, then naturally dampens as the bias stabilizes.

The patent applies parameter changes by dynamically altering the impedance characteristics of the inductive-capacitive resonance circuit during the bias pull-up process. The circuit transitions from a high-impedance state (when capacitor is charged) to a low-impedance state (when capacitor discharges through inductor), creating a transient low-impedance path that enables rapid current flow and quick DC bias establishment without compromising final bias accuracy.

The patent utilizes mechanical vibration analogously through electrical resonance in the inductive-capacitive circuit. The resonant oscillation creates a high-amplitude periodic current that rapidly transfers charge to the transistor bias node, similar to how mechanical vibrations can rapidly transfer energy. This resonant current surge quickly pulls up the DC bias level to the required target, ensuring both speed and reliability.