Design Of Broadband Radio Frequency LC Voltage Controlled Oscillator

As a kind of important information transmission medium, radio has experienced 100 years of development, and has already changed from analog to digital modulation. Digital Radio Mondiale(DRM) and Digital Audio Broadcasting(DAB) these kinds of standards has become research direction of many RF researchers. It’s of great significance to design wireless communication Integrated Circuit that is compatible with DRM/DAB.The DRM/DAB receiver accepts the architecture of dual-conversion low-IF system. As a monolithic transceiver system, it is necessary to produce a stable and reliable Local Oscillation (LO). The key of a high performance transceiver is to devise an outstanding Phase Lock Loop (PLL). Voltage Controlled Oscillator (VCO) as the core of PLL is studied in this paper as well as it architecture and performance, such as its oscillation condition and noise. A broad-band VCO containing 16 sub-bands is designed. Meanwhile, in consideration of the locking time of PLL, an Auto Frequency Calibration system is devised and optimized for the VCO.DRM standard which includes AM band (148.5kHz-27MHz) and FM band (78-108 MHz) is suitable for large scale broadcast. DAB standard which includes III band (174-240 MHz) and L band (1452-1492 MHz) is suitable for local broadcast. To cover all the bands the VCO should have an oscillation ranger of 1.9-3.1 GHz, the relative bandwidth is 48%. In the control word of four bits, the VCO is divided into 16 sub-bands.In aim to get a quick location of sub-band, based on full-custom analog counter, a kind of AFC utilizing binary search is devised. The searching time is controlled in four clock cycle and the simulated locking time of AFC is 0.8 μs.VCO and AFC are designed and manufactured in standard 0.18-pμm RF-CMOS process. The circuits are tested and the results meet the targets.