const min_price_variant_href = (data.min_price_variant && data.min_price_variant.available) ? data.min_price_variant.url : data.url; The next PLL circuit element to be considered in our circuit is the voltage controlled oscillator. With VCOs, a fundamental trade-off between phase noise, frequency coverage, and power consumption is necessary. The higher the quality factor (Q) of the oscillator, the lower the VCO phase noise is. However, higher Q circuits have narrower frequency ranges. Increasing the power supply will also lower the phase noise. Looking at the Analog Devices family of VCOs, the HMC507 covers a range of 6650 MHz to 7650 MHz and the VCO noise at 100 kHz is approximately –115 dBc/Hz. By contrast, the HMC586covers a full octave from 4000 MHz to 8000 MHz, but has higher phase noise of –100 dBc/Hz. One strategy for minimizing phase noise in such VCOs is to increase the voltage tuning range of the V TUNE to the VCO (up to 20 V or greater). This increases PLL circuit complexity, as most PLL charge pumps can only tune to 5 V, so an active filter using operational amplifiers is used to increase the tuning voltage of the PLL circuit on its own. Multiband Integrated PLLs and VCOs Care needs to be taken with fractional-N PLLs to ensure that spurious tones do not degrade system performance. On PLLs such as the HMC704, integer boundary spurs (generated when the fractional portion of the N value approaches 0 or 1, like 147.98 or 148.02 are very close to the integer value of 148) generate the most concern. This can be mitigated by buffering the VCO output to the RF input, and/or careful frequency planning in which the REF IN can be changed to avoid these more problematic frequencies. A door latch is a mechanism that connects the door to the door frame. Generally, the latch fits into a pre-cut hole in the door frame, but can also attach to a catch on the outside of a frame. The door latch ensures the door remains in place when closed.

To generate a range of higher frequencies, a VCO is used, which tunes over a wider range than a VCXO. This is regularly used in frequency hopping or in spread spectrum frequency hopping (FHSS) applications. In such PLLs, the output is a high multiple of the reference frequency. Voltage controlled oscillators contain a variable tuning element, such as a varactor diode, which varies its capacitance with input voltage, allowing a tuneable resonant circuit, which permits a range of frequencies to be generated (Figure 9). The PLL can be thought of as a control system for this VCO. To solve this issue, we must enable AOF with the fsync=always option before setting the key in Redis. Note that enabling this option has some performance impact on Redis, but we need this option for strong consistency. Redis Database (RDB): performs point-in-time snapshots of your dataset at specified intervals and store on the disk.

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For example, the first line means if we have one write operation in 900 seconds (15 minutes), then It should be saved on the disk. Append-only File (AOF): logs every write operation received by the server, that will be played again at server startup, reconstructing the original dataset. Atomic operations: Redis provides atomic commands that allow you to perform complex operations in a single, uninterruptible step. Easy scalability: Redis can be easily scaled horizontally, making it suitable for large-scale distributed systems.

In the next section, I will show how we can extend this solution when having a master-replica. Third Scenario: Master-Replica The key performance parameters of PLLs are phase noise, unwanted by-products of the frequency synthesis process, or spurious frequencies (spurs for short). For integer-N PLLs, spurious frequencies are generated by the PFD frequency. A leakage current from the charge pump will modulate the tuning port of the VCO. This effect is lessened by the low-pass filter and the narrower this is, the greater the filtering of the spurious frequency. An ideal tone would have no noise or additional spurious frequency (Figure 10), but in practice phase noise appears as a skirt around a carrier, as shown in Figure 11. Single sideband phase noise is the relative noise power to the carrier in a 1 Hz bandwidth, specified at a frequency offset from the carrier. Figure 10. Ideal LO spectrum. Figure 11. Single sideband phase noise. Integer-N and Fractional-N Divider Designing Data-Intensive Applications: The Big Ideas Behind Reliable, Scalable, and Maintainable Systems,Martin KleppmannImagine you want to go on a vaction; how do you prefer to control your home and property while you are away? Do you have any dogs to watch your house, or do you ask some neighbors to protect your property? These ways of controlling the home and property are old-fashioned.

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For the majority of PLLs the in-band noise is highly dependent on the N value, and also on the PFD frequency. Subtracting 20log (N) and 10log (F PFD) from the flat portion of an in-band phase noise measurement yields the figure of merit (FOM). A common metric for choosing PLLs is to compare the FOM. Another factor that influences the in-band noise is the 1/f noise, which is dependent on the output frequency of the device. The FOM contribution and the 1/f noise, together with the reference noise, dominate the in-band noise of a PLL system. Narrow-Band LO for 5G Communications In this configuration, we have one or more instances (usually referred to as the slaves or replica) that are an exact copy of the master. To solve this problem, we can set a timeout for Redis clients, and it should be less than the lease time. But there is another problem, what would happen if Redis restarted (due to a crash or power outage) before it can persist data on the disk? We consider it in the next section. Second Scenario: Single Instance of Redis and Node Outage Setting a TTL on a key in Redis can be done using the PEXPIRE command, and can be issued by your thread immediately after the SETNX in a MULTI/EXEC transaction, like this: const hasChild = linkList.some(link => !!(link.children && link.children.length