Internal supply voltage generator for delay locked loop circuit
Provided is directed to an internal supply voltage generator for a delay locked loop circuit which can prevent a tAC for a next read command from being outputted with a delay, by blocking a supply voltage VDLL from a transient lowering regardless of a reacting speed of a VDLL supply voltage generator by means of maximizing a driving power of the VDLL supply voltage generator which generates the supply voltage VDLL of a delay locked loop during entering time from a power down period to a power up period. Furthermore, as the supply voltage VDLL is prevented from lowering without rising the reacting speed of the VDLL supply voltage generator, it is advantageous to prevent a distorting phenomenon of the supply voltage VDLL in response to a fast reacting speed of the VDLL supply voltage generator.
1. An internal supply voltage generator for a delay locked loop circuit, including:
a comparator of which a reference voltage is applied to a first input terminal and an output terminal of the internal supply voltage generator is connected to a second input terminal;
an output switching device which is connected between the output terminal and an external supply voltage terminal, and operates according to an output signal of the comparator; and
an output controller which blocks the output signal of the comparator and the external supply voltage transferred to the output switching device and sets to turn on the output switching device, in a power down period according to a control signal, and which transfers the output signal of the comparator and the external supply voltage to the output switching device.
2. The internal supply voltage generator of claim 1 , wherein the output switching device is performed by an analog-type operation according to the output signal of the comparator.
3. The internal supply voltage generator of claim 1 , wherein the output switching device is comprised of a PMOS transistor.
4. The internal supply voltage generator of claim 1 , wherein the output controller includes:
a first switching device which is connected between the external supply voltage terminal and the output switching device, and blocks the external supply voltage in the power period according to the control signal;
a second switching device setting to turn on the output switching device in the power down period by switching a ground voltage according to the control signal; and
switching units blocking the output signal of the comparator in the power down period according to the control signal.
5. The internal supply voltage generator of claim 4 , wherein the switching units includes:
an inverter for inverting the control signal; and
a transmission gate operating according to an output signal of the inverter and the control signal.