Coherent population trapping (CPT) atomic frequency standards are small-size and low-power consumption atomic frequency standards emerged in recent years.The frequency stability of a CPT atomic frequency heavily depends on the performance of its temperature control system.This article presents our optimization design scheme of the digital temperature control system.In the system the instrumentation amplifier is used to increase the resolution of the temperature measurement

the wavelet analysis de-noise method is used for signal de-noise process

the pulse width modulation (PWM) square wave is precisely modulated through

Δ-Σ

algorithm

the output resolution is increased

and the

harmonic interference is reduced.The realized temperature control system is a small size low power consumption circuit with good performance.With the improved circuit the frequency stability of the CPT atomic frequency standard is improved.This developed temperature control system specially suits for applications in small-size and low-power consumption CPT atomic frequency standards.