Series-resonance oscillator

Patent metadata

Field	Value
Publication number	US-10505525-B2
Application number	US-201715672343-A
Country	US
Kind code	B2
Filing date	Aug 9, 2017
Priority date	Apr 17, 2014
Publication date	Dec 10, 2019
Grant date	Dec 10, 2019

Abstract

An oscillator circuit ( 100 ) comprises a first tank circuit (T 1 ) comprising an inductive element (L) and a capacitive element (C) coupled in series between a first voltage rail ( 14 ) and a first drive node ( 12 ). A feedback stage (F) is coupled to a first tank output ( 13 ) of the first tank circuit (T 1 ) and to the first drive node ( 12 ). The feedback stage (F) is arranged to generate, responsive to a first oscillating tank voltage present at the first tank output ( 13 ), a first oscillating drive signal at the first drive node ( 12 ) in-phase with a first oscillating tank current flowing in the inductive element (L) and the capacitive element (C), thereby causing the oscillator ( 100 ) to oscillate in a series resonance mode of the inductive element (L) and the capacitive element (C).

First claim

The invention claimed is:

1. An oscillator circuit comprising:
a first tank circuit comprising an inductive element and a capacitive element coupled in series between a voltage rail and a first drive node and comprising a first tank output for outputting a voltage present at a node topologically located between the inductive element and the capacitive element in series; and
a feedback stage coupled to the first tank output of the first tank circuit and to the first drive node;
wherein the feedback stage is arranged to generate, responsive to a first oscillating tank voltage present at the first tank output, a first oscillating drive signal at the first drive node in-phase with an oscillating tank current flowing in the inductive element and the capacitive element, thereby causing the oscillator circuit to oscillate in a series resonance mode of the inductive element and the capacitive element.

2. The oscillator circuit as claimed in claim 1 , wherein the feedback stage is arranged to generate the first oscillating drive signal having a substantially rectangular waveform.

3. The oscillator circuit as claimed in claim 1 , wherein the first tank circuit is arranged to generate, responsive to the first oscillating drive signal, the first oscillating tank voltage in-phase with the first oscillating drive signal, and wherein the feedback stage comprises a first driver arranged to generate, responsive to the first oscillating tank voltage, the first oscillating drive signal in-phase with the first oscillating tank voltage.

4. The oscillator circuit as claimed in claim 3 , wherein the first tank circuit comprises a sensor device arranged to generate the first oscillating tank voltage responsive to the first oscillating tank current.

5. The oscillator circuit as claimed in claim 4 , wherein the sensor device comprises one of a resistive element and a transformer coupled in series with the inductive element and the capacitive element between the voltage rail and the first drive node.

6. The oscillator circuit as claimed in claim 4 , wherein the sensor device is magnetically coupled to the inductive element for generating by magnetic induction the first oscillating tank voltage responsive to the first oscillating tank current.

7. The oscillator circuit as claimed in claim 4 , wherein the capacitive element is coupled between the first drive node and the first tank output and the inductive element is coupled between the first tank output and the first voltage rail.

8. The oscillator circuit as claimed in claim 4 wherein the inductive element is coupled between the first drive node and the first tank output and the capacitive element is coupled between the first tank output and the first voltage rail.

9. The oscillator circuit as claimed in claim 3 , wherein the feedback stage includes a feedback stage tank circuit and the first driver comprises:
an input coupled to the feedback stage tank circuit;
an output coupled with the first drive node;
a transistor having a gate, a source, and a drain, wherein the source is coupled with the output and the drain is coupled with a power supply rail; and
a coupling capacitor coupled with the input and the gate.

10. The oscillator circuit as claimed in claim 1 , wherein
the first tank circuit is arranged to generate, responsive to the first oscillating drive signal, the first oscillating tank voltage one hundred and eighty degrees out-of-phase with the first oscillating drive signal, and wherein the feedback stage comprises a first driver arranged to generate, responsive to the first oscillating tank voltage, the first oscillating drive signal one hundred and eighty degrees out-of-phase with the first oscillating tank voltage by applying signal inversion to the first oscillating tank voltage.

11. The oscillator circuit as claimed in claim 10 , wherein the feedback stage comprises:
a feedback stage tank circuit having feedback stage tank circuit output, the feedback stage tank circuit coupled with the first driver; and
a variable capacitance element coupled with the first tank output and the feedback stage tank circuit output.

12. The oscillator circuit as claimed in claim 11 , wherein the feedback stage further comprises:
a first capacitor coupled between the feedback stage tank circuit output and the variable capacitance element; and
a second capacitor coupled between the variable capacitance element and the first tank output.

13. The oscillator circuit as claimed in claim 1 , wherein the first tank circuit is arranged to generate, responsive to the first oscillating drive signal, the first oscillating tank voltage in-phase with the first oscillating drive signal, and wherein the feedback stage comprises:
a second driver arranged to generate a second oscillating drive signal by applying signal inversion to the first oscillating tank voltage;
a second tank circuit arranged to generate, responsive to the second oscillating drive signal, a second oscillating tank voltage in-phase with the second oscillating drive signal; and
a first driver arranged to generate the first oscillating drive signal by applying signal inversion to the second oscillating tank voltage.

14. The oscillator circuit as claimed in claim 1 , wherein the first tank circuit is arranged to generate, responsive to the first oscillating drive signal, the first oscillating tank voltage one hundred and eighty degrees out-of-phase with the first oscillating drive signal, and wherein the feedback stage comprises:
a second driver arranged to generate a second oscillating drive signal by applying signal inversion to the first oscillating tank voltage;
a second tank circuit arranged to generate, responsive to the second oscillating drive signal, a second oscillating tank voltage in-phase with the second oscillating drive signal; and
a first driver arranged to generate the first oscillating drive signal in-phase with the second oscillating tank voltage.

15. The oscillator circuit as claimed in claim 1 , wherein the first tank circuit is arranged to generate, responsive to the first oscillating drive signal, the first oscillating tank voltage one hundred and eighty degrees out-of-phase with the first oscillating drive signal, and wherein the feedback stage comprises:
a second driver arranged to generate, responsive to the first oscillating tank voltage, a second oscillating drive signal in-phase with the first oscillating tank voltage;
a second tank circuit arranged to generate, responsive to the second oscillating drive signal, a second oscillating tank voltage one hundred and eighty degrees out-of-phase with the second oscillating drive signal; and
a first driver arranged to generate, responsive to the second oscillating tank voltage, the first oscillating drive signal in-phase with the second oscillating tank voltage.

16. The oscillator circuit as claimed in claim 1 , wherein
the first tank circuit is arranged to generate, responsive to the first oscillating drive signal, the first oscillating tank voltage having a phase lagging by ninety degrees a phase of the first oscillating drive signal, and wherein the feedback stage comprises a phase shifting stage arranged to generate a first intermediate oscillating voltage by applying a phase lag of ninety degrees to the first oscillating tank voltage and the oscillator circuit further comprises a first driver arranged to generate the first oscillating drive signal by applying signal inversion to the first intermediate oscillating voltage.

17. The oscillator circuit as claimed in claim 1 , wherein
the first tank circuit is arr

Assignees

• Ericsson Telefon Ab L M

Inventors

• Andreani Pietro
• Fanori Luca
• Mattsson Thomas

Classifications

• H03B5/24

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

• H03K2005/00286

  Phase shifter, i.e. the delay between the output and input pulse is dependent on the frequency, and such that a phase difference is obtained independent of the frequency · CPC title

• H03K5/145 Primary

  by the use of resonant circuits · CPC title

• H03L7/0995

  the oscillator comprising a ring oscillator · CPC title

• H03B5/18

  with frequency-determining element comprising distributed inductance and capacitance · CPC title