A modulator using RF CMOS T-type attenuator for TH-UWB communications

作者：Duan Jihai^*; Wang Zhigong; Li Zhiqun

来源：Journal of Southeast University (english Edition), 2009, 25(4): 435-438.

• Carrier frequency
• Chip sizes
• Complementary metal oxide semiconductors
• Modulated signal
• Modulator chips
• On-off keying
• On-off keying (OOK)
• Oscillating frequencies
• Output impedance
• Output matching network
• Output ports
• Power Consumption
• Radio frequencies
• Return loss
• RF CMOS technology
• RF CMOS transistors
• RF-CMOS
• Time hopping
• pulse position modulations
• Time-hopping
• UWB communication

The insertion loss (IL) of a T-type attenuator is theoretically analyzed. A T-type RF (radio frequency) CMOS (complementary metal-oxide-semiconductor) attenuator is designed as an on-off keying (OOK) modulator in a time-hopping ultra wide-band (TH-UWB) communication with a carrier frequency of 4 GHz. In the topology of the OOK modulator circuit, there are three parts, an oscillator with an oscillating frequency of 4 GHz, a T-type attenuator constructed by RF CMOS transistors, and an output impedance matching network with a L-type LC structure. The modulator is controlled by a time-hopping pulse position modulation (TH-PPM) signal. The envelope of the modulated signal varies with the amplitude of the controlling signal. Meanwhile, an output matching network is also designed to match a 50 Ω load. In 0.18 μm RF CMOS technology, a modulator is designed and simulated. The implemented modulator chip has 65 mV of the output amplitude at a 50 Ω load from a 1.8 V supply, and the return loss (S11) at the output port is less than -10 dB. The chip size is 0.7 mm × 0.8 mm, and the power consumption is 12.3 mW.

• 出版日期2009
• 单位东南大学