TC-OCXO Technology
OCXO stability at TCXO power and package size
The world’s first TC-OCXOs (temperature-compensated oven-controlled crystal oscillators) are designed to deliver the high stability of an OCXO from a device with low power consumption, small size and light weight comparable to those of a TCXO. Known as Triton™, it is capable of stabilities better than ±0.05 ppm over operating temperature range, and is aimed at mobile, battery powered and remote applications such as GPS, satellite comms, distress beacons and secure radio.
Ambient temperature variation is one of the main causes of frequency variation in a crystal oscillator. To overcome this, TC-OCXOs use a hybrid combination of limited temperature control, by use of an oven, and further reduction of the remaining frequency error through proprietary Pluto temperature compensation technology.
Previous attempts by various parties to combine temperature compensation with oven control have taken a crude ‘heating a TCXO’ approach — a heater has been used to reduce the temperature range seen by the TCXO. The result has been oscillators with good power consumption but significantly inferior stability to existing OCXOs.
Triton’s™ proprietary approach uses a miniature oven with crude temperature control to keep the crystal oscillator at an approximately constant temperature slightly above its specified operating temperature range — e.g. between 90° and 95°C for a device with operating temperature range specified as –40° to +85°C. Any residual frequency errors occurring over the oven’s limited temperature range are then minimized using the Pluto’s analogue compensation circuitry.
The result is an oscillator with overall stability nearly an order of magnitude better than the most stable TCXOs — i.e. comparable to that of an OCXO — but with better power consumption, smaller and lighter package size and faster warm-up. For example, a typical specification might offer ±0.05 ppm stability over temperature range of –20° to +70°C, at standard frequencies from 5 to 20 MHz, with a highly linear ±5 ppm frequency adjustment for ageing effects, power consumption =400 mW at –20°C steady state or =1.0 W during warm-up, from a 3.3 V supply, in an industry standard 20.7 x 13.08 mm DIL package.
™ - Triton is a registered trademark of Rakon Limited.