Importance

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Abstract

A heater controller for an atomic frequency standard provides accurate and stable temperature control for an assembly, such as a lamp assembly, by regulating a current flow through a heating device so as to maintain a substantially constant heating power output during start-up and by reducing the DC temperature errors of the system during normal operation. The heater controller includes an integrating amplifier which generates an amplified temperature signal based on the temperature of the lamp assembly. The heater controller further includes a device for receiving the amplified signal from the integrating amplifier and establishing a control voltage having an upper limit based on a voltage of the heater power supply. An attenuator is provided for attenuating an output signal from the receiving device by an attenuation factor sufficient to offset a substantial portion of the amplified temperature signal, as required for thermal control loop stability at a frequency above the gain transition frequency, wherein the attenuation factor permits an increase in the gain of the integrating amplifier above the gain transition frequency, and wherein the increase in gain is achieved by decreasing the value of the input resistor of the integrating amplifier. In turn, the reduction in value of the input resistor results in a decrease in an amount of DC temperature error generated by the lamp assembly, wherein the temperature error is a result of leakage currents and offset currents flowing in the integrating amplifier.

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First Claim