RC oscillator with additional inverter in series with capacitor

Patent metadata

Field	Value
Publication number	US-9300247-B2
Application number	US-201313887434-A
Country	US
Kind code	B2
Filing date	May 6, 2013
Priority date	May 6, 2013
Publication date	Mar 29, 2016
Grant date	Mar 29, 2016

Abstract

In an electronic device, an RC oscillator generally includes a resistor, a capacitor and at least one inverter. The resistor and capacitor generate a time-varying voltage. The time-varying voltage is provided to the at least one inverter to cause a clock signal to propagate therethrough. The clock signal propagates with a time delay that is at least partially dependent on a supply voltage. The supply voltage is adjusted to maintain the time delay at almost a constant value.

First claim

The invention claimed is:

1. A local power supply circuit comprising:
a supply voltage input and a supply voltage return lead;
a current source having an input coupled to the supply voltage input and an output;
a current mirror having a first input coupled to the supply voltage input, a second input coupled to the output of the current source, a first output, and a local power supply output; and
a first self-biased inverter having a third input coupled to the first output and an output coupled to the supply voltage return lead, the first self-biased inverter including a third transistor having a control node, a first node, and a second node and a fourth transistor having a control node, a first node, and a second node, the first and second nodes of the third and fourth transistors being coupled in series between the third input and the supply voltage return lead, the control node of the third transistor being connected to the local power supply output, and the control node of the fourth transistor being connected to the supply voltage return lead, and including a capacitor coupled between the local power supply output and the supply voltage return lead.

2. The local power supply circuit of claim 1 in which the current mirror includes a first transistor having a control node coupled to the second input, and having two other nodes coupled between the second input and the first output, and a second transistor having a control node coupled to the second input and two other nodes coupled between the first input and the local power supply output.

3. The local power supply circuit of claim 2 in which the first and second transistors are NMOS transistors.

4. A local power supply circuit comprising:
a supply voltage input and a supply voltage return lead;
a current source having an input coupled to the supply voltage input and an output;
a current mirror having a first input coupled to the supply voltage input, a second input coupled to the output of the current source, a first output, and a local power supply output;
a first self-biased inverter having a third input coupled to the first output and an output coupled to the supply voltage return lead, the first self-biased inverter including third and fourth transistors coupled between the third input and the supply voltage return lead, and a control node of the third transistor coupled to a node between the third and fourth transistors; and
a second self-biased inverter coupled between the local power supply output and the supply voltage return lead, the second self-biased inverter includes fifth and sixth transistors coupled between the local power supply output and the supply voltage return lead, and a control node of each of the fifth and sixth transistors coupled together and to a node between the fifth and sixth transistors and to a control node of the fourth transistor.

5. The local power supply circuit of claim 4 in which the third and fifth transistors are PMOS transistors and the fourth and sixth transistors are NMOS transistors.

6. The local power supply circuit of claim 4 in which the current mirror includes a first transistor having a control node coupled to the second input, and having two other nodes coupled between the second input and the first output, and a second transistor having a control node coupled to the second input and two other nodes coupled between the first input and the local power supply output.

Assignees

• Texas Instruments Inc

Inventors

• Roine Per Torstein
• Griffith Danielle L
• Smith Ryan A

Classifications

• H03L7/099

  concerning mainly the controlled oscillator of the loop · CPC title

• H03K3/354

  Astable circuits · CPC title

• H03K3/0315

  Ring oscillators · CPC title

• H03K3/03

  Astable circuits · CPC title

• H03B5/24 Primary

  active element in amplifier being semiconductor device (H03B5/26 takes precedence) · CPC title