Inexpensive low phase noise high speed stabilized time base

• Main Author: MAYDER ROMI
• Format: Patent
• Language: English
• Published: 11.10.2007
• Subjects: BASIC ELECTRONIC CIRCUITRY; ELECTRICITY; GENERATION OF NOISE BY SUCH CIRCUITS; GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING,BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN ANON-SWITCHING MANNER; PULSE TECHNIQUE

A low phase noise high speed stabilized time base uses a crystal resonator that operates directly at a desired high frequency of one hundred to several hundred MHz. An inverted mesa AT-cut quartz crystal meets this criteria. To promote frequency stability the crystal and its oscillator circuit are thermally clamped to a convenient temperature that need be only loosely regulated, say, at about room temperature. In an exemplary ATE setting that already provides a water flow heat removal system whose supply side is 26° C.,±0.5° C., a 400 MHz inverted mesa AT-cut crystal is simply given its own loop within that water supply. Other temperature stabilization techniques for loose regulation, such as Peltier cells, may be used. The result is a high frequency time base having adequate frequency accuracy and stability, but with the extremely low timing jitter of just the crystal resonator, since there is no contributory timing jitter from a frequency multiplying PLL.