Stepping temperature compensation method of crystal oscillator

Abstract

The invention discloses a stepping temperature compensation method of a crystal oscillator. The method adopts the closed-loop feedback compensation architecture, and comprises the following steps: firstly determining the binary coding B0i corresponding to a target frequency f0, and storing in a single chip microcomputer; when the temperature change is existent, sending a signal with a mode frequency of f(T) to an A/D converter to convert into the corresponding binary coding B1i, and inputting to the single chip microcomputer to compare with the binary coding B0i of the target frequency f0, setting the threshold range deltaB in the single chip microcomputer, comparing the B0i with the B1i, judging whether a comparison result B0i-B1i is in the threshold range; if the B0i-B1i is not in the threshold range, compensating by using the stepping binary coding B2i, and then sending into the single chip microcomputer to compare with the B0i after the compensation, cyclically compensating in this way until the comparison result B0i-B1i is in the threshold range, thereby finally realizing the temperature compensation. Compared with the existing temperature compensate crystal oscillator, the method disclosed by the invention is free from using a temperature sensor, a temperature hysteresis problem caused by asynchronous wafer temperature change of the temperature sensor and the crystal resonator in the existing TCXO is overcome.

Description

technical field [0001] The invention belongs to the technical field of crystal oscillators, and more specifically relates to a step temperature compensation method for crystal oscillators. Background technique [0002] Temperature Compensated Crystal Oscillator (TCXO, Temperature Compensate Xtal (crystal) Oscillator) is a kind of crystal oscillator that can work in a wide temperature range and maintain the output frequency of the crystal oscillator within a certain accuracy range (10 -6 ~10 -7 order of magnitude) crystal oscillator. It has the characteristics of low power, can work immediately after starting up, and has high stability. It is widely used in various communications, navigation, radar, satellite positioning systems, mobile communications, program-controlled telephone exchanges, and various electronic measuring instruments. [0003] The existing temperature-compensated crystal oscillator is essentially a voltage-controlled crystal oscillator (Voltage Controlled...

AI Technical Summary

Problems solved by technology

This method has advantages in phase noise characteristics when realizing high-frequency temperature-compensated crystal oscillators (TCXO), but the composition is relatively complicated and has not been widely used yet.

[0016] In summary, the existing temperature compensation methods for crystal oscillators all adopt an open-loop compensation framework, and a temperature sensor is used. The temperature sensor is as close as possible to the crystal resonator on the circuit, and the resonator chip of the crystal resonator It is packaged separately in a closed space, which inevitably produces a temperature hysteresis between the temperature sensor and the resonant chip, resulting in a failure to achieve a breakthrough in the frequency-temperature characteristics of the temperature-compensated crystal oscillator, that is, the TCXO.

Especially for crystal oscillators whose output signals are high frequency, this temperature hysteresis problem is more serious, and the compensation accuracy is limited

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