CN102075141A

CN102075141A - Oven controlled crystal oscillator (OCXO) with acceleration compensation

Info

Publication number: CN102075141A
Application number: CN2010106087316A
Authority: CN
Inventors: 单庆晓
Original assignee: Individual
Current assignee: Individual
Priority date: 2010-12-28
Filing date: 2010-12-28
Publication date: 2011-05-25

Abstract

The invention relates to an oven controlled crystal oscillator (OCXO) with acceleration compensation. An acceleration compensation part is added into an internal part of the OCXO provided by the invention, wherein the part mainly comprises a three-dimensional MEMS (Micro Electro Mechanical System) acceleration transducer, a FPGA (Field-programmable Gate Array)-based digital controlled circuit and a digital-to-analog converter circuit. The OCXO provided by the invention is realized by using digital compensation techniques through digital algorithm, and disadvantages that an analog circuit is easily influenced by the environment temperature and has unstable performance are overcome, so that the OCXO provided by the invention has broad application prospect.

Description

A kind of constant-temperature crystal oscillator with acceleration compensation

Technical field

The present invention carries out vibration compensation to constant-temperature crystal oscillator, need to be applied to high accuracy frequency reference occasion, particularly needs the high accuracy frequency reference under vibration environment; The sophisticated electronics that carries as airborne sophisticated electronics, spacecraft sophisticated electronics and various motion carrier.

Background technology

Constant-temperature crystal oscillator (OCXO) obtains extensive use because output frequency is stabilized in the various high accuracy frequency reference occasions that need.Because quartz oscillator is to acceleration sensitive, output frequency changes under vibration environment, and phase noise increases, and has reduced the performance of electronic equipment.

People have done research on mechanical structure at present, mechanically take various buffer technologys, reduce the influence of impacting crystal oscillator.Yet buffering mechanically can only reduce the impact of short-term, can't solve for the acceleration of low frequency.And impact mitigation measure mechanically increases equipment volume and weight, is unfavorable for miniaturization.

People have also adopted various compensation methodes.Compensation comprises passive compensation and Active Compensation.Gagnepain etc. connect two oscillator inverse parallels mechanically again on electric, thereby have realized passive compensation; Have the scholar to adopt twin crystal to shake, degree of will speed up sensitization capacitance is added in the tuning circuit, utilizes acceleration sensitive electric capacity to compensate.Also have the scholar to adopt the method for Active Compensation, degree of will speed up meter is installed on the crystal, and detected value feed-in analog circuit is realized the frequency adjustment.These compensation methodes are the analog compensation method, because the acceleration change scope is big, guarantee that the linearity of analog circuit in wide region is very difficult.

【1】Martin?Bloch，”Method?for?achieving?highly?reproducible?acceleration?insensitive?quartz?crystal?oscillators”，U.S.Patent?No?7,106,143，2006

【2】John?A.Kosinski，”Acceleration?insensitive?piezo-microresonator”，U.S.Patent?No?7,154,212，2006

【3】Marvin?E.Frerking，“Vibration?compensated?crystal?oscillator”，U.S.Patent?No4,891,611，1990

Summary of the invention

The present invention proposes a kind of constant-temperature crystal oscillator that adopts the digital form compensation.The three-dimensional MEMS acceleration transducer is installed in the position approaching with crystal oscillator, detects three-dimensional acceleration in real time.Adopt digital processing chip to obtain the three-dimensional acceleration value, produce control voltage by numerical calculation, this voltage is applied to the voltage-controlled end of constant-temperature crystal oscillator, the frequency change that compensated acceleration is brought.

Digital compensation technology is adopted in this invention, utilizes digital algorithm to realize, has overcome that analog circuit is easily influenced by ambient temperature, the shortcoming of unstable properties, is with a wide range of applications.

Description of drawings

Fig. 1 is the constant-temperature crystal oscillator schematic diagram of band acceleration compensation.

Fig. 2 is acceleration figure.

Fig. 3 is an acceleration compensation circuit board schematic diagram.

Fig. 4 is the scheme of installation of acceleration compensation circuit board.

Fig. 5 is the floor map of acceleration compensation circuit board, wherein the 1-MEMS acceleration transducer; 2-FPGA; The 3-power module; The 4-D/A chip.

Embodiment

Constant-temperature crystal oscillator (being called for short OCXO) generally has the temperature that temperature control circuit is accurately controlled crystal, and OCXO also has a voltage-controlled circuit, can adjust output frequency by the voltage that changes voltage-controlled end.The present invention adds the acceleration compensation part in OCXO inside, and this part mainly comprises a three-dimensional MEMS acceleration transducer, the digital control circuit based on FPGA, D/A converting circuit (being called for short D/A).OCXO with acceleration compensation forms as shown in Figure 1.

OCXO has an intrinsic acceleration sensitive direction, and this direction can obtain by method of testing for what determine.If this direction and x, y, the angle that z is three is

A mistake! Do not find Reference source.。If the three-dimensional MEMS acceleration transducer detects the acceleration of three directions in real time, 3-axis acceleration is respectively a _x, a _y, a _zA mistake! Do not find Reference source., then the sensitive acceleration vector is

A mistake! Do not find Reference source.(1)

The detected value a of acceleration transducer _x, a _y, a _zGive FPGA, through type (1) calculate sensitive acceleration value a _m, the voltage-controlled coefficient of establishing OXCO is k _v, the acceleration sensitive coefficient is k _a, then the voltage of digital-to-analogue conversion output is

Δv = \frac{k_{a} \cdot a_{m}}{k_{v}}

Acceleration compensation circuit board principle as shown in Figure 3, the power supply of OCXO is 12V, for D/A provides reference voltage, for the work of FPGA provides frequency output.Power conversion part is the various voltages of FPGA need of work with the 12V power conversion.FPGA reads the numerical value of MEMS acceleration transducer by digital interface, by computing control D/A output voltage the output frequency of OCXO is regulated.

The installation pad of acceleration compensation circuit board is corresponding with the pin of OCXO, can directly be welded in the bottom of OCXO, as shown in Figure 4; Fig. 5 is the floor map of circuit board, and acceleration transducer 1 is installed in the middle part of circuit board, the acceleration of being convenient to truly to reflect OCXO and being born.

Claims

1. the constant-temperature crystal oscillator with acceleration compensation is characterized in that comprising a three-dimensional MEMS acceleration transducer, the digital control circuit based on FPGA, D/A converting circuit; The output of digital to analog converter is connected to the voltage-controlled pin of constant-temperature crystal oscillator.

2. a kind of constant-temperature crystal oscillator with acceleration compensation according to claim 1 is characterized in that the compensating circuit plate is directly installed on the pin of OCXO, is convenient to install.