SU1390770A1 - Device for temperature compensation of crystal oscillator - Google Patents

Abstract

The invention relates to radio engineering and improves the accuracy of thermal compensation. The device contains a sensor 1 t-ry, an analog-to-digital converter (ADC) 2, a block of 3 memory, a digital-to-analog converter (DAC) 4, a quartz oscillator 5. Shapes (F) 6 and 7 of the voltage module, subtractor 8, amplifier 9 with adjustable transmission coefficient, unit 10pam, analog adder P. From sensor 1, the temperature-dependent voltage is removed. It goes to F 6 and A / D converter 2. A digital code with A / D converter 2 is an address for blocks 3 and 10. Block 3, in which the temperature compensation data is stored in the form of digital values of a certain size, is associated with 4 , From the analog output of the ADC 2, stepwise varying voltage is fed to input F 7. At outputs F 6 and 7, a piecewise-linear voltage is formed with a break point corresponding to the extremum of temperature-frequency x-ki. generator 5. At the output of the F 7 a signal is generated with a discrete change in voltage, and at the output of F 6 a signal with a continuous change of voltage. In the subtractor 8, a differential signal is formed in the form of a saw-tooth, for example -: bridging. Next, the signal goes to the amplifier 9. Koef. the amplification of the amplifier 9 ... is programmed with a digital code from block 10, corresponding to each address of the difference between two adjacent digital words of block 3. Thus, the voltage from amplifier 9 is in the form of a sawtooth voltage with an amplitude of teeth proportional to the amplification factor of amplifier 9 at each address t-ry, goes to the adder 1, the other input of which receives the voltage from the DAC 4. At the output of the adder 11, a voltage is formed with a piecewise-linear approximation. 1 il. § (L с: со со о со

Description

eleven

The invention relates to radio engineering and can be used in sources of highly stable electrical oscillations.

The purpose of the invention is to improve the accuracy of thermal compensation.

The drawing shows the structural: shektrichesky scheme of the thermal compensation device of the quartz oscillator.

The device contains a temperature sensor 1, an analog-to-digital converter (ADC) 2, the first memory block 3, a digital-to-analog converter (DAC) 4, a crystal oscillator 5, the first 6 and second 7 drivers of a voltage module, a subtractor 8, an amplifier 9 with an adjustable factor transmissions, second memory block 10, analogue adder 11.

The device works as follows

Temperature 1 is removed from sensor 1. The dependent voltage from the first driver 6 and the A / D converter 2. A / D converter 2 converts the analog signal from sensor I to a digital code, which is the address for First 3 and second 10 memory blocks. The first memory block 3, in which thermal compensation data is stored in the form of digital words of a certain size, is associated with a DAC. A, which converts digital information into an analog signal, whose value is changed only by changing the digital temperature code, the analog output of the ADC is 2 steps, the varying voltage is fed to the input of the second driver 7, and the outputs of the first 6 and second 7 drivers are piecewise a linear voltage with a breakpoint corresponding to the extremum of the temperature-frequency characteristic of the quartz oscillator 5; In this case, a signal with a discrete voltage variation is formed at the output of the second shaper 7 (In the form of steps}, and in. The first output signal shaper 6 with a continuous direct voltage change,

In the subtractor 8, a differential signal is generated in the form of a sawtooth, with the saw falling linearly in the min-temperature zone, and to the right of the extremum, the saw growing linearly. Output signal

0

0

five

0

five

five

0

five

0

five

the subtractor 8 is fed to the input of the amplifier 9; the gain factor of the amplifier 9 is programmed with a digital code from the output of the third memory block 10. The number of addresses of the second memory block 10 is equal to the number of addresses of the first memory block 3. The gain of amplifier 9 is determined by the digital code from the output of the second block 10, the memory corresponding to each difference address of two adjacent digital words of the first block

3 memories.

Claims (1)

Thus, the voltage from the output of the amplifier 9 in the form of a sawtooth voltage with the amplitude of the teeth, is proportional to the gain; the amplifier 9 at each temperature address is fed to the analog adder 11, to the other input of which a voltage varies stepwise from the DAC 4. A piecewise-linear approximation voltage is formed at the output of the analog adder. In this case, the slope of the straight sections is determined by the difference in voltages between adjacent steps. Invention Formula A thermal compensation device for a crystal oscillator containing a crystal oscillator, a series-connected temperature sensor, an analog-to-digital converter, the first: a memory unit and a digital-to-analog converter, characterized in that, in order to improve the accuracy of thermal compensation, a series-connected subtractor, an amplifier with an adjustable transmission coefficient, and an analog are introduced the adder, the output of which is connected to the control input of the quartz oscillator, chen between the temperature sensor output and the first input of the subtractor, vtoroy.formirovatel modulation voltage, which is connected between the analog output of analog-to-digital converter and a second input calc Tutelo second. a memory unit that is connected between the analogue-digital digital output. converter and control input. an amplifier with an adjustable transmission ratio; the output of the D / A converter is connected to the second input of the analog adder.