A Temperature Compensated High Frequency Crystal Oscillator Based on Analog Compensation

Abstract

The invention discloses a temperature-compensated high-frequency crystal oscillator based on analog compensation, which adopts a closed-loop feedback compensation framework. The deviation calculation module calculates the frequency deviation between the frequency of the voltage-controlled crystal oscillator and the desired target frequency when it is not compensated. The frequency-voltage conversion module uses an analog circuit to obtain the compensation voltage according to the frequency deviation, and then passes the filter to the compensation voltage signal After filtering, it is fed back to the input terminal of the compensation voltage signal of the voltage-controlled crystal oscillator for compensation, so that the voltage-controlled crystal oscillator outputs the desired target frequency. The present invention does not need a temperature sensor, but directly converts the frequency deviation related to the real-time temperature into a compensation voltage corresponding to it in a one-to-one mapping relationship for temperature compensation, and overcomes the temperature hysteresis problem in the existing temperature-compensated high-frequency crystal oscillator .

Description

technical field [0001] The invention belongs to the technical field of crystal oscillators, and more specifically relates to a temperature-compensated crystal oscillator based on analog compensation. 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...

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Problems solved by technology

The structure of the temperature compensated crystal oscillator in this way is complicated, and large-scale circuit integration can be used, and the cost is relatively high.

In addition, the analog temperature-compensated crystal oscillator implemented in this way also adopts an open-loop compensation method, which requires a separate temperature sensor to sense the external environment temperature, so that there is inevitably a temperature difference and temperature hysteresis effect between the sensor and the crystal. So that the compensation accuracy is affected

[0016] To sum up, the existing temperature-compensated crystal oscillators, namely TCXO, all adopt an open-loop compensation architecture, and temperature sensing is used. The temperature sensor is as close as possible to the crystal resonator on the circuit, and the crystal resonator The resonant chip is individually packaged 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.

Especially for crystal oscillators with high-frequency output signals, this temperature hysteresis problem is more obvious, which seriously restricts the frequency compensation accuracy of temperature-compensated high-frequency crystal oscillators

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