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US 2010/0134087 A1Published application
Low noise reference circuit of improving frequency variation of ring oscillator
AssigneeFci
InventorsIn-chul Hwang, Myung-woon Hwang, Je-cheol Moon, Hyun-ha Jo
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Abstract
A low noise reference voltage circuit without using an amplifier inside is capable of transforming a current IPTAT in positive proportion to absolute temperature into a voltage VPTAT in positive proportion to absolute temperature, and outputting it to a ring oscillator. The low noise reference voltage circuit improves a degradation of noise performance compared with a conventional band-gap reference voltage circuit and is in characteristic of low noise and higher PSRR.
Claims6
A low noise reference voltage circuit for improving the frequency variation of a ring oscillator, comprising:
- a PTAT (proportional to absolute temperature) current generating unit configured to generate a PTAT current in positive proportion to absolute temperature;
- a PTAT voltage transforming unit configured to transform the PTAT current into a PTAT voltage and to output the PTAT voltage to a linear regulator, wherein the PTAT voltage transforming unit includes a transistor of a current mirror and a diode connected thereto;
- and
- a power supply rejection ratio (PSRR) improving resistor connected to one terminal of the transistor and configured to improve the variation of a power voltage.
1 more element
Dependencies are inferred from the claim text.