In the past, hardware designers had to use multiple fixed frequency XO, VCXO or voltage controlled SAW oscillators (VCSO) to develop the frequency conversion architecture of complex systems and make them work at different frequencies. However, the cost of this method is very high, which requires complex analog phase-locked loop (PLL) design and layout, and will also prolong the time to market of newly developed products.
The elastic oscillators of Si570/ 1 programmable XO and VCXO can generate any frequency from 10MHz to 1.4GHz. Such a device can replace multiple fixed-frequency oscillators, which not only simplifies the design and layout of PLL, but also greatly reduces the number of components, system cost and circuit board area. In addition, because Si570/ 1 saves many fixed-frequency oscillators that may become fault points, the system will become more reliable.
Si570/ 1 can set the working frequency through the industrial standard I2C interface, which makes it easier to program and reconfigure the device. Si570/ 1 can also be reprogrammed infinitely, allowing system designers to reuse the same set of clock frequency architectures for different end applications, thus simplifying the design and speeding up the time to market. Si570/ 1 is packaged in an industrial standard and RoHS-compatible 5× 7mm surface mount package, which supports all common output signal formats (LVPECL, LVDS, CMOS and CML). This series includes three devices with different speed levels, namely 10MHz- 1.4GHz, 10-8 10MHz and10-2/5mhz. There are two different specifications of temperature stability for Si570 synchronous oscillator with arbitrary frequency, namely 20 ppm and 50ppm. Si57 1 voltage controlled synchronous oscillator with any frequency includes devices with different absolute Pull ranges from 12 ppm to 375ppm, so that designers can flexibly choose the devices that are most suitable for their applications. The working temperature range of Si570/ 1 is -40 to +85℃.
Nominal frequency: the center frequency or nominal value of the oscillator output frequency.
Optional frequency range: We can provide the achievable frequency output of the oscillator with specific specifications.
Frequency temperature stability: the maximum allowable frequency deviation of the measured value when the output frequency of the oscillator is relative to 25°C within the specified temperature range.
Aging: the relative change of output frequency within a certain period of time.
Output: the waveform and power output by the oscillator.
Duty ratio: It reflects the symmetry of output waveform, that is, the ratio of high level to low level in a period.
Rise time: the time when a square wave changes from low level to high level.
Falling time: the time when the square wave changes from high level to low level.
Harmonic: Suppress the oscillator at the resonance point relative to the output frequency. Non-harmonic: Suppress the oscillator at a non-resonant point relative to the output frequency.
Short-term frequency stability: the stability of oscillator output frequency in a short time, usually 1 sec.
Phase noise: used to describe the short-term frequency fluctuation of oscillator. It is usually defined as the single sideband power density with frequency offset of 1Hz, and the unit is dBc/Hz.
Power supply voltage: the voltage applied to the power supply terminal (Vcc) of the oscillator to make the oscillator work normally.
Power supply current: the total current flowing through the power supply terminal (Vcc) of the oscillator.
Operating temperature range: the temperature range that can ensure the output frequency and other characteristics of the oscillator to meet the requirements of the index.
Characteristics of quartz crystal oscillator
Z At the oscillation frequency, the phase shift of the closed loop is 2nπ.
Z When the power supply is started, the only signal in the circuit is noise. The frequency noise component satisfying the oscillation phase condition increases.
Large amplitude transmission in the loop, the increasing rate consists of additional components, namely small signal, loop gain and crystal network.
Bandwidth of decision.
The Z amplitude continues to increase until the amplifier gain decreases due to the nonlinearity (self-current limiting) of the active device or for some reason.
Automatic horizontal control.
When z is in steady state, the closed-loop gain is 1. According to the situation of the extraction electrode, quartz resonator can be divided into two-electrode type, three-electrode type and double-counter-electrode type. Figure 1 shows the shape of a two-electrode quartz resonator. Although their volumes are large or small and their natural oscillation frequencies are high or low, they are all represented by the symbol +0 (b) in the circuit diagram. The symbols of three-electrode quartz resonator and two-electrode quartz resonator are shown in the figure. 2。
Such as the color subcarrier oscillator of color TV, the time base oscillator of electronic clock and the clock pulse oscillator in game machine, the cost of the clock crystal is high, so ceramic resonant elements are generally used in circuits with low requirements.