Temperature-compensated crystal oscillator based on digital circuit

Patent metadata

Field	Value
Publication number	US-10367451-B2
Application number	US-201715696533-A
Country	US
Kind code	B2
Filing date	Sep 6, 2017
Priority date	May 17, 2017
Publication date	Jul 30, 2019
Grant date	Jul 30, 2019

Abstract

The present invention provides a temperature-compensated crystal oscillator based on digital circuit, a closed-loop compensation architecture is employed to realize the high precision compensation of the crystal oscillator. The output frequency f(T) of the TCXO to be compensated is directly connected with the compensation voltage Vc(T) in real time, and the compensation voltage is fed back to the voltage control terminal of the VCXO to be compensated to compensate, so that the output frequency after compensation is equal to the target frequency signal, thus avoiding the frequency shift of output signal caused by temperature hysteresis, i.e. the discrepancy between the temperature acquired by a temperature sensor and the real temperature of the resonant wafer in the prior art.

First claim

What is claimed is:

1. A temperature-compensated crystal oscillator based on digital circuit, comprising:
a VCXO for generating a signal with desired frequency;
a compensation network for generating a desired compensation voltage based on a compensation voltage value and sending the desired compensation voltage to the voltage control terminal of the VCXO to make the VCXO generate a stable signal with desired frequency;
wherein further comprising a power divider, an analog-to-digital converter and a microprocessor;
where the power divider divides the signal with desired frequency signal into two signals: one is used as the output of the TCXO and the other is sent to the analog-to-digital converter;
the analog-to-digital converter converts the signal with desired frequency into a corresponding frequency value with binary form, and sends the corresponding frequency value to the microprocessor;
a binary coding table, in which a plurality of frequency values and their respective corresponding compensation voltage values are filled is stored in the microprocessor, the microprocessor finds a compensation voltage value in the binary coding table according to the frequency value sent by the analog-to-digital converter, and sends it to the compensation network; and
wherein the compensation network comprises a digital-to-analog converter, a signal conditioning circuit and a filter, the digital-to-analog converter converts the compensation voltage value into a corresponding analog voltage signal, and the signal conditioning circuit modulates the analog voltage signal to generate a compensation voltage V c (T), the filter filters the compensation voltage V c (T), and sends the compensation voltage V c (T) to the voltage control terminal of the VCXO to make the VCXO generate a stable signal with desired frequency.

Assignees

• Univ Electronic Sci & Tech China

Inventors

• Ye Peng
• Tan Feng
• Liu Xingqi
• Qiu Duyu
• Guo Lianping
• Yang Kuojun
• Zhang Qinchuan
• Pan Huiqing

Classifications

• H03B5/32 Primary

  being a piezoelectric resonator (selection of piezoelectric material H10N30/00) · CPC title

• H03B5/04 Primary

  Modifications of generator to compensate for variations in physical values, e.g. power supply, load, temperature · CPC title

• H03L1/02

  against variations of temperature only · CPC title

• H03L1/022 Primary

  by indirect stabilisation, i.e. by generating an electrical correction signal which is a function of the temperature (H03L1/021 takes precedence) · CPC title

• H03L1/028

  of generators comprising piezoelectric resonators (H03L1/021, H03L1/022 take precedence; oscillation generators with a piezoelectric resonator H03B5/32) · CPC title