Oscillator amplifier with input clock detection and method therefor
US7924108B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 14, 2009 |
| Grant date | Apr 12, 2011 |
| Priority date | — |
| Expiry date | Oct 29, 2029 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03B5/362
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An oscillator circuit has a crystal oscillator amplifier having only two clock input terminals, one being an input terminal and the other being an output terminal. The input terminal allows a user of the integrated circuit to choose between connecting a first clock signal generated from a crystal or a second clock signal generated by a non-crystal source to the input terminal. Control circuitry has a capacitor coupled in parallel with a transistor. Both are coupled in series with a resistive device at an output of the control circuitry to provide a control signal. Clock generation circuitry coupled to the crystal oscillator amplifier provides an oscillating output signal in response to an enable signal. In one form a comparator circuit provides the oscillating output signal. The control signal is used to ensure that inputs to the comparator circuit repeatedly cross each other over time.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.