Temperature-Compensated RC Delay Circuit for Stable Memory Timing

The patent applies parameter changes by utilizing the temperature-dependent characteristics of different circuit elements. Specifically, it combines PTAT (proportional to absolute temperature) delay circuitry with CTAT (complementary to absolute temperature) delay circuitry. The PTAT circuit elements exhibit delay that increases with temperature, while CTAT elements exhibit delay that decreases with temperature. By adjusting the ratio and configuration of these opposing temperature-dependent elements, the overall delay characteristic becomes substantially independent of temperature variations, thus maintaining reliable timing control across the full operating temperature range while supporting high-speed memory operation.

The patent changes the physical parameters of the delay circuit by combining elements with opposite temperature coefficients. The PTAT delay elements provide delay that scales positively with temperature, while CTAT delay elements provide delay that scales negatively with temperature. By carefully selecting the proportions and configurations of these elements, the circuit achieves a temperature-insensitive delay characteristic. This enables the use of tighter timing margins for higher productivity while maintaining sufficient timing stability across temperature variations.

The patent applies parameter changes to the delay circuitry used during ZQ calibration by combining PTAT and CTAT elements. During ZQ calibration, precise measurement of signal propagation delays is required to adjust impedance matching. The temperature-compensated delay circuit ensures that the calibration measurements are not skewed by temperature-dependent delay variations. This enables accurate and consistent ZQ calibration across the full operating temperature range, improving both measurement precision and calibration consistency.