Crystal oscillator circuit having transistor with back gate voltage control
AssigneeSeiko Epson Corporation
InventorsTadao Kadowaki, Yoshiki Makiuchi, Shinji Nakamiya
Life of this patent
Estimating the term…
Abstract
An oscillation circuit comprising a control circuit that utilizes the body effect of a substrate bias to control the source potential of a MOSFET that configures a signal inversion amplifier. This control circuit controls the threshold voltage of this MOSFET to be low when power is first applied to the oscillation circuit, and controls the threshold voltage of the MOSFET to be high after the oscillation of the oscillation circuit has stabilized. This makes it possible to ensure that the oscillation circuit oscillates stably and at a low power consumption.
Claims36
An oscillation circuit comprising:
- a signal inversion amplifier comprising a first transistor and a second transistor;
- a feedback circuit having a crystal oscillator, for inverting the phase of an output signal of said signal inversion amplifier and feeding said inverted signal back as an input to said signal amplifier;
- and
- a control circuit for controlling a back gate voltage between the back gate and source of said second transistor;
- wherein the back gate of said second transistor is set to a predetermined potential;
- and
- wherein said control circuit comprises:
- a rectifier element circuit connected to the source of said second transistor;
- a switching element that forms a bypass circuit for said rectifier element circuit;
- and
- a switching circuit for selectively switching a back gate voltage of said second transistor over at least two stages, by on/off control of said switching element.
An oscillation circuit comprising:
- a signal inversion amplifier comprising a first transistor and a second transistor;
- a feedback circuit having a crystal oscillator, for inverting the phase of an output signal of said signal inversion amplifier and feeding said inverted signal back as an input to said signal amplifier;
- and
- a control circuit for controlling a back gate voltage between the back gate and source of said second transistor;
- wherein the source of said second transistor is set to a predetermined potential;
- and
- wherein said control circuit comprises;
- a rectifier element circuit connected to the back gate of said second transistor;
- a switching element that forms a bypass circuit for said rectifier element circuit;
- and
- a switching circuit for selectively switching a back gate voltage of said second transistor over at least two stages, by outputting on/off control signals of said switching element.
Dependencies are inferred from the claim text.