The frequency source can be said to be the heart of a communication system. The quality of the heart largely determines the health of a body, and the phase-locked loop is the main component of the frequency source. Therefore, the phase-locked loop chip with excellent performance is used for communication. The system is very important.
The phase noise of the phase-locked loop has a great impact on the performance of electronic devices and electronic systems. From the frequency domain, it is distributed on both sides of the carrier signal according to the power law spectrum distribution. Whenever the transmit excitation signal or the receiver local oscillator signal and various frequency references are used, these phase noises will appear in the demodulation process as well as the signal. Demodulation of the terminal causes a decrease in the baseband signal-to-noise ratio and an increase in the bit error rate.
Low phase noise HitTIte phase-locked loop products are divided into integrated VCO and no integrated VCO. The PLL chip with integrated VCO includes HMC820, HMC821, HMC826 and so on. The following is a comparison with similar products on the market, taking the working frequency band 1720~2080MHz as an example:
HMC820, HMC821 integrates the amplifier at the internal frequency output of the chip, so its output power is higher than that of similar products. In some cases, it can directly drive the mixer as LO output, eliminating a local oscillator buffer amplifier. The designer saves space and bom costs.
HMC820, HMC821 is a multi-band product that can work in three frequency bands. For example, the working frequency band of HMC821 includes 860~1040MHz, 1720~2080MHz, and 3440~4160MHz. Taking the 1800MHZ, 900MHZ GSM repeater as an example, since the HMC821 adopts an internal integrated frequency divider, only one HMC821 chip can be used, and the same loop filter circuit can meet the requirements of 900 and 1800MHz. This greatly speeds up the design process.
HitTIte's internal integrated VCO phase-locked loop chip features a unique switch design, as shown in the following figure.
The chip automatically selects the appropriate switch as needed. This design uses a small voltage to drive the VCO. It is not necessary to use an active circuit such as an op amp when designing the loop filter, and only a passive filter can be used. This makes the peripheral circuit simpler and reduces the burden on the RF engineer.
In the microwave band, HitTIte's integrated VCO PLL chip has HMC764, HMC765, HMC783, HMC807, and the working frequency range covers 7.3-13.4GHz. The phase noise of the HMC764 at a 10 kHz offset is approximately -102 dBc/Hz, and in fractional mode, the RMS Jitter is 196 fs.
If the customer has higher requirements for PLL performance, it can be implemented with a PLL chip without an integrated VCO and a suitable peripheral circuit. The PLL chip without integrated VCO includes HMC440, HMC698, HMC699, HMC700, HMC701, HMC702.
Taking the HMC700 as an example, the chip is internally composed of a phase detector, a charge pump, and an N, R divider. It uniquely supports serial port read and write functions. When the HMC700 peripheral circuit isolation is well designed, the spurs can be as low as -100dBc, which is much higher than the market-like level of -80dBc. The table below is a comparison of some other features.
If the designer has almost stringent requirements on the phase noise performance of the PLL chip, I believe that HitTIte's HMC440 can still help you. The chip is designed for low phase noise applications. When the reference frequency is 100MHz, the phase noise is as low as -153dBc/Hz at 10KHz frequency offset. The test results are as follows.
Hittite's innovative design makes its PLL products excellent in performance, excellent in phase noise and spurs, and its high integration makes peripheral circuits simple and easy to design. Therefore, with the development of electronic technology, the phase noise performance requirements of frequency sources are getting higher and higher. Hittite's low phase noise PLL is used in physics, astronomy, radio communication, radar, aviation, aerospace, precision metering, instruments, meters, etc. There will be great use in all fields.
Ups Lithium Ion Battery,Uninterruptible Power Battery,Stability Lithium Ion Battery,High Power Stability Battery
Wolong Electric Group Zhejiang Dengta Power Source Co.,Ltd , https://www.wldtbattery.com