Power supply voltage detection and clamping circuit for 3-D integrated circuits

A circuit that detects and sets the power supply voltage of a given device plane in a 3-D IC is proposed. The circuit consists of 1) a ring oscillator in each voltage domain located in each device plane, and 2) a power module placed in a dedicated power plane. The power module consists of four components; a divide-by-40 clock divider, a frequency detector, a voltage ramp generator, and a voltage peak detector circuit. The power module provides a stable reference voltage equal to the power supply voltage of the targeted voltage domain in the device plane. SPICE simulations of the circuit indicate that power supply voltages of less than 1 V are successfully set and provided as a reference to an on-chip voltage regulator within 500 ns and with reference voltage variation of less than 1%. The power module is integrated with on-chip voltage regulators which require a precise voltage reference. The proposed implementation permits dynamic voltage and frequency scaling and point of load power delivery.