1. Field of Invention
The present invention generally relates to a voltage divider circuit and a voltage regulator having the voltage divider circuit, and more particularly to a voltage divider circuit with a fast rising speed and low current consumption.
2. Description of Prior Art
Along with the rapid development of science and technology at the present, semiconductor memories, such as major storage devices for large amount of data, are being developed to have larger and larger capacity. As the semiconductor technology is continuously scaled down to achieve high memory density, on-chip voltage regulators providing lower supply voltage for internal circuits are required to fulfill the requirements for device reliability and low power consumption. For the Dynamic Random Access Memory (DRAM), the bit line sensing, restoring and pre-charge operations in the memory cell arrays consume current abruptly and heavily. For high density DRAM chip, it is challenging to design on-chip voltage regulators for memory cell arrays providing a stable voltage level with sufficient and appropriate supplying current.
Referring to FIG. 1, FIG. 1 is a circuit diagram of a voltage divider circuit. The voltage divider circuit 10 comprises two resistors R1, R2, and two capacitors C1, C2. The first ends of the resistor R1 and capacitor C1 are coupled to an input voltage end of the voltage divider circuit 10, wherein the input voltage end receives the input voltage VIN from a power supply. The second ends of the resistor R1 and capacitor C1 are coupled to an output voltage end of the voltage divider circuit 10, and the first ends of the resistor R2 and capacitor C2 are also coupled to an output voltage end of the voltage divider circuit 10, wherein the output voltage end outputs the dividing voltage VOUT. The second ends of the resistor R2 and capacitor C2 are also coupled to a referencing voltage end of the voltage divider circuit 10, wherein the referencing voltage end is coupled to a referencing voltage VREF, and the referencing voltage VREF can be ground.
However, the power supply for the voltage divider circuit 10 can not be shut down due to the slow rising speed of the voltages on the resistors R1, R2, and thus the undesired current consumption in standby mode is always keeping. To put it concretely, the large resisting values of the resistors R1, R2 cause the large RC constants, and thus dramatically decreasing the rising speed of the voltages on the resistors R1, R2. Therefore, a circuit for increasing the rising speed of the voltage divider circuit 10 without the current consumptions should be provided.