The aggressive scaling of CMOS technologies and the widespread adoption of Internet of Things (IoT) systems demand highly power-efficient, temperature-robust, and frequency-stable on-chip power management and clock generation circuits. This work presents an integrated design of a low-power bandgap reference (BGR), a temperature-adaptive low-dropout regulator (LDO), and a low power crystal oscillator to achieve reliable timing under wide operating conditions. Finally, a low power crystal oscillator is implemented using a Pierce configuration with negative resistance of approximately 500Ω at 48MHz, satisfying the oscillation startup criterion of three times the crystal ESR. The oscillator achieves rail-to-rail output swing, startup time below 2ms, and total current consumption below 75µA, corresponding to power consumption of approximately 90µW at 1.2V. The combined architecture demonstrates that co-design of reference, regulation, and clock generation circuits significantly enhances frequency stability, reduces power dissipation, and improves system-level power efficiency, making the proposed framework highly suitable for next-generation IoT, wearable, and battery-operated edge devices.