Artificial Intelligence
Introduction of PLL chip technology for phase-locked loop products
The frequency source is often considered the heart of a communication system. Just as the health of the body depends on the quality of the heart, the performance of a communication system largely relies on the stability and accuracy of its frequency source. At the core of this frequency source lies the phase-locked loop (PLL), which plays a critical role in maintaining signal integrity and system reliability. Therefore, using high-performance PLL chips is essential for modern communication systems.
Phase noise, an important parameter of the PLL, significantly affects the overall performance of electronic devices and systems. In the frequency domain, it spreads symmetrically around the carrier signal according to a power-law spectrum. This noise can appear during demodulation when transmit excitation signals, receiver local oscillator signals, or various frequency references are involved. As a result, the baseband signal-to-noise ratio decreases, and the bit error rate increases, degrading system performance.
HitTIte offers low-phase-noise PLL products, which can be categorized into two types: those with integrated VCOs and those without. Integrated VCO PLL chips such as HMC820, HMC821, and HMC826 provide higher output power due to internal amplifiers, allowing them to directly drive mixers as LO outputs, thus reducing the need for additional buffer amplifiers. This not only saves space but also lowers BOM costs.
These chips are multi-band capable, enabling operation across different frequency ranges. For instance, HMC821 supports 860–1040 MHz, 1720–2080 MHz, and 3440–4160 MHz. This flexibility allows a single chip to meet the requirements of multiple frequency bands, such as in GSM repeaters operating at 900 MHz and 1800 MHz. The internal frequency divider simplifies the design process and reduces development time.
HitTIte’s integrated VCO PLL chips feature a unique switch design that automatically selects the appropriate configuration. This design uses a small voltage to drive the VCO, eliminating the need for active components like operational amplifiers in the loop filter. A passive filter alone is sufficient, resulting in a simpler peripheral circuit and less complexity for RF engineers.
In the microwave band, HitTIte offers several high-performance PLL chips, including HMC764, HMC765, HMC783, and HMC807, covering frequencies from 7.3 GHz to 13.4 GHz. These chips deliver excellent phase noise performance, with HMC764 achieving approximately -102 dBc/Hz at a 10 kHz offset and RMS jitter as low as 196 fs in fractional mode.
For applications requiring even better performance, HitTIte provides PLL chips without integrated VCOs, such as HMC440, HMC698, HMC699, HMC700, HMC701, and HMC702. These allow greater customization through external components. For example, the HMC700 features a serial port interface and can achieve spurs as low as -100 dBc with proper isolation in the peripheral circuit—far exceeding typical industry standards of -80 dBc.
If extreme phase noise performance is required, the HMC440 is an ideal choice. Designed specifically for low-phase-noise applications, it achieves a remarkable -153 dBc/Hz at a 10 kHz offset when using a 100 MHz reference frequency. This makes it suitable for demanding applications such as precision measurement, scientific research, and advanced radar systems.
HitTIte’s innovative design ensures that its PLL products offer superior performance in terms of phase noise, spurs, and integration. As electronic technology continues to evolve, the demand for high-quality frequency sources is increasing. With its low-phase-noise PLL solutions, HitTIte is well-positioned to support a wide range of applications, including physics, astronomy, radio communications, radar, aviation, aerospace, and precision instrumentation. Its products are set to play a vital role in the future of high-performance electronic systems.
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