公开(公告)号：US20190222203A1

公开(公告)日：2019-07-18

申请号：US16243455

申请日：2019-01-09

Applicant: STMicroelectronics S.r.l.

Inventor： Giovanni Carlo Tripoli ,  Cecilia Teresa Rita Gatti ,  Paul Georges Marie Rose ,  Roberto Faravelli

IPC: H03K3/03 ,  G05F1/577

CPC classification number: H03K3/0315 ,  G05F1/577 ,  H03K3/011 ,  H03K5/24

Abstract: An oscillator circuit including a ring oscillator and a reference current source is provided. The ring oscillator includes an odd number of inverter stages. Each inverter stage includes a first transistor having a first reference threshold that varies over temperature. The reference current source is configured to generate a plurality of currents, where a respective current is applied directly to the drain of a respective first transistor of a respective inverter stage. The reference current source includes a reference transistor that has a second reference threshold that varies over temperature; a resistor coupled between a gate and a source of the reference transistor; a second transistor having a source coupled to the gate of the reference transistor for generating a reference current that flows through the resistor to regulate a voltage of the resistor to the second threshold voltage; and a current mirror configured to generate the plurality of currents.