CONFIGURABLE VOLTAGE REGULATOR
Disclosed are voltage regulator circuits and techniques. Some embodiments employ an offset induced buffer to drive an N-type drive transistor.
1 . A voltage regulator circuit, comprising:
an error amplifier with a gain that is greater than unity;
an N-type output driver to provide a regulated output voltage; and
an offset induced voltage buffer coupled between the error amplifier and the output driver.
2 . The circuit of claim 1 , wherein the offset induced voltage buffer is to level shift the error amplifier upward for driving the N-type output driver.
3 . The circuit of claim 1 , wherein the offset induced voltage buffer includes a super source follower circuit.
4 . The circuit of claim 1 , wherein the offset induced voltage buffer includes a P-type transistor with an input that is coupled to a bias amplifier to induce an offset for the voltage buffer.
5 . The circuit of claim 4 , wherein the bias amplifier includes a first input coupled to the P-type transistor and a second input coupled to an offset voltage reference.
6 . The circuit of claim 5 , wherein the offset voltage reference is one-half of a voltage supply provided to the bias amplifier.
7 . The circuit of claim 1 , wherein the offset induced voltage buffer includes a P-type transistor with an input that is coupled to a voltage reference generation circuit to bias it and induce an offset for the voltage buffer.
8 . The circuit of claim 1 , wherein the error amplifier and N-type output driver each include one or more first supply nodes coupled to a first supply rail, and the offset induced voltage buffer includes a second supply node coupled to a second supply rail, wherein the first supply rail is to supply a lower voltage than the second supply rail.
9 . The circuit of claim 1 , wherein the error amplifier includes a differential amplifier and a common source amplifier.
10 . The circuit of claim 9 , wherein the common source amplifier includes a P-type transistor, and the error amplifier has a gain that is greater or equal to 40 dB.
11 . The circuit of claim 1 , wherein the offset induced voltage buffer includes a feedback circuit with an adaptive zero compensation circuit.
12 . The circuit of claim 11 , wherein the feedback circuit includes a current sensor coupled in series between the adaptive zero compensation circuit and an output of the offset inducing voltage buffer.
13 . The circuit of claim 1 , comprising a bypass transistor coupled to the N-type output driver for a low output voltage mode.
14 . An integrated circuit apparatus, comprising:
a first supply rail to provide a first supply voltage;
a second supply rail to provide a second supply voltage, wherein the second supply voltage is higher than the first supply voltage; and
a plurality of voltage regulators that include:
a differential amplifier with a differential amplifier supply node coupled to the first supply rail and a differential amplifier output node;
a voltage buffer with (i) a buffer input node that is coupled to the differential amplifier output node, (ii) a buffer supply node that is coupled to the second supply rail, and (iii) a buffer output node;
an output drive transistor with (i) a drive transistor input coupled to the buffer output node, and a drive transistor supply node coupled to the first supply rail, and
an adaptive zero compensation circuit coupled between the buffer input and buffer output nodes.
15 . The apparatus of claim 14 , wherein the voltage buffer is to level shift upward from the buffer input node to the buffer output node.
16 . The apparatus of claim 14 , wherein the voltage buffer includes a super source follower circuit.
17 . The apparatus of claim 16 , wherein the voltage buffer includes a P-type transistor with an input that is coupled to a bias amplifier to induce an offset into the voltage buffer.
18 . The circuit of claim 14 , wherein the voltage buffer includes a P-type transistor with an input that is coupled to a voltage reference generation circuit to bias it and induce an offset into the voltage buffer.
19 . A system, comprising:
a processor;
memory coupled to the processor; and
a field programmable gate array (FPGA) apparatus coupled to the processor, the FPGA including one or more voltage regulator circuits including:
an error amplifier with a gain that is greater than unity;
an output driver to provide a regulated output voltage; and
an offset induced voltage buffer coupled between the error amplifier and the output driver.
20 . The system of claim 19 , wherein the offset induced voltage buffer is to level shift the error amplifier upward for driving the N-type output driver.