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Dual Output Oscillator with Adjustable Phase and Duty-cycle

IP.com Disclosure Number: IPCOM000168305D
Publication Date: 2008-Mar-05
Document File: 5 page(s) / 61K

Publishing Venue

The IP.com Prior Art Database

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Page 1 of 5

     Dual Output Oscillator
with Adjustable Phase and Duty-cycle

Summary

When a dual output oscillator is needed, it is desirable to be able to adjust the phase between the two outputs, while the duty cycles of each output remains adjustable and independent of the phase adjustment.

Description of the Invention

What is the problem to be solved?

How to generate two outputs from a single oscillator with the two outputs being phase shifted with identical duty cycle?

1MHz Oscillator core principle:

Threshold

generation

cmd_gbr

threshold1

Higher threshold

R

R

Filter 1

threshold2

Lower threshold

Filter 2

Multiplexer

Upper Threshold

Lower Threshold

Vcc level

Ground level

1

0

1

Pump up

Pump down

V+>V- NodeCmp = 1

V-<V+ NodeCmp = 0

0

0

NodeCapa

1

NodeCmp

Cosc

Comparator

Internal Driver

Output Driver

1

0

EnOSC

OutputEN

1

0

cmd_gri

OutputOsc

Figure 1. Principle of a simple 1MHz oscillator.

Page 2 of 5

OutputOsc

t2

t1

t1

Phase shift

levint O

t1

t2

t2

Figure 2. The OutputOsc signal shape versus time and the phase shifter signal to be generated.

A new schematic will be presented to generate the OutputShifted signal from the OutputOsc signal.

This new proposed schematic takes into account process variations of the simple oscillator shown in Figure 1, and does not alter its behavior even if a new structure is added.

Again, the overall architecture needs to operate regardless of external noise and current spike size and shape.

DBLO Block Diagram

Voltage level definition:
levhig = threshold1 ; levlow=threshold2 ; levlow < levint < levhig

CompCapInt

Figure 3. Logical structures.

levint

NodeCapa > levint

NodeCpsh < levlow...