| US 7,486,129 B2 | ||
| Low power voltage reference | ||
| Stefano Pietri, Campinas (Brazil); Jader Alves De Lima Filho, Campinas (Brazil); and Alfredo Olmos, Campinas (Brazil) | ||
| Assigned to Freescale Semiconductor, Inc., Austin, Tex. (US) | ||
| Filed on Mar. 01, 2007, as Appl. No. 11/681,067. | ||
| Prior Publication US 2008/0218253 A1, Sep. 11, 2008 | ||
| Int. Cl. G05F 1/10 (2006.01); G05F 3/02 (2006.01) | ||
| U.S. Cl. 327—539 | 18 Claims |

| 1. A voltage reference, comprising:
a current mirror including a first node, a second node, a third node and a control input, wherein the first node of the current
mirror is coupled to a first power supply node associated with a first power supply;
a first cell including a diode-connected stack of insulated-gate field-effect transistors (IGFETs), wherein the first cell
is coupled between the second node of the current mirror and a second power supply node associated with the first power supply
and the diode-connected stack of IGFETs includes a first transistor that is biased in a triode weak inversion region;
a second cell including a diode-connected stack of IGFETs and a serially coupled resistor, wherein the second cell is coupled
between the third node of the current mirror and the second power supply node and the second cell is configured to provide
a reference voltage at a reference node; and
an amplifier including a first input, a second input and an output, wherein the first input of the amplifier is coupled to
a first intermediate node of the first cell, the second input of the amplifier is coupled to a first intermediate node of
the second cell and the output of the amplifier is coupled to the control input of the current mirror, and wherein the first
and second cells are configured to conduct respective proportional to absolute temperature(PTAT) currents and the amplifier
is configured to force the first intermediate nodes of the first and second cells to a substantially similar voltage.
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