Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

A LOW-HARMONIC HIGH-STABILITY RADIO FREQUENCY OSCILLATOR

IP.com Disclosure Number: IPCOM000008754D
Original Publication Date: 1998-Jun-01
Included in the Prior Art Database: 2002-Jul-10
Document File: 4 page(s) / 135K

Publishing Venue

Motorola

Related People

Hien Ma: AUTHOR [+4]

Abstract

A new RF oscillator is presented here. It gener- ates a low-level of undesired harmonics and it is more stable over temperature than existing oscillator circuits currently used in paging receivers.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 50% of the total text.

Page 1 of 4

0 M

MOTOROLA Technictrl bwdopments

A LOW-HARMONIC HIGH-STABILITY RADIO FREQUENCY OSCILLATOR

by Anh Nguyen, Argy Chatzipetros, Hien Ma and Steve Lloyd

ABSTRACT relatively simple circuit. However, its frequency stability is not as good as the Pierce oscillator. In A new RF oscillator is presented here. It gener- the UHF band this oscillator configuration usually ates a low-level of undesired harmonics and it is requires a TC capacitor. An additional problem more stable over temperature than existing oscillator of this oscillator is the "pull" frequency dependence circuits currently used in paging receivers. on the output load. This means that changes in the output load can cause a shift of the crystal 1 INTRODUCTION frequency.

A popular RF oscillator used in paging receivers is the Colpitts oscillator shown in Figure I. It is a

Fig. 1 Crystalized Colpitts Oscillator

  Another popular circuit is the Pierce oscillator the desired harmonic output. However, the with a buffer stage shown in Figure 2. It has a very undesired harmonic signals, generated at the buffer good short term frequency stability because the output, are strong, as shown in Figure 4. In external load, tied across the xtal, is mostly capaci- addition, the collector of Ql is connected to the tive rather than resistive, giving the crystal a high base of Q2. So, changes of the external load can in-circuit Q. It requires a buffer in order to generate potentially shift the crystal frequency.

ci Moioiola. Inc. 19YX 163 June 1998

[This page contains 15 pictures or other non-text objects]

Page 2 of 4

0 M

MOTOROLA Technical b!ve~opments

A

v -

Fig. 2 Ctystalized Pierce Oscillator with Buffer

HaZmic

Output

2

Fig. 3 Modified Ctystalized Pierce Oscillator

0 MOI"rOla. Inc. ,VYB 164 June 199X

[This page contains 15 pictures or other non-text objects]

Page 3 of 4

0 M

MOTOROLA Technicul Developments

Harmonic Contents

0 e "7 (D h 0 m 0 N D . "7 m

-s--,-F

Harmo...