An Injection Lock
An Injection Locked Ring VCO with Enhanced Phase Noise for 2.4GHz Band ZigBee Applications
Fatemeh Talebi 1, Hassan Ghafoorifard 1, Samad Sheikhaei 2, Elias Soleiman 2
1. Electrical Engineering Department, Amirkabir University of Technology, Tehran, Iran
2. School of Electrical and Computer Engineering, University of Tehran, Tehran, Iran
Abstract: A low power low phase noise ring voltage controlled oscillator (ring VCO) with subharmonic injection locking is proposed for low power applications in 2.4GHz ISM band, such as ZigBee systems. The injection signal to this VCO comes from a PLL, in which, a replica ring VCO is used. The PLL operates at 1/4th of target frequency and through locking to an available exact reference frequency, provides the control voltage for the second ring VCO. Due to operating at lower frequencies, PLL produces less phase noise, and through injection locking, reduces the phase noise of the second ring VCO that operates at 4× frequency. The target application in this paper, is 2.4GHz band ZigBee, however, it can be used in other applications with similar specifications. The circuit is designed in TSMC 0.18 μm CMOS technology. The phase noise at 3.5 and 10 MHz offsets is -117 and -119 dBc/Hz, respectively, and total circuit consumes 6.1 mW from a 1.8 V supply.
[Fatemeh Talebi, Hassan Ghafoorifard, Samad Sheikhaei, Elias Soleiman. An Injection Locked Ring VCO with Enhanced Phase Noise for 2.4GHz Band ZigBee Applications. J Am Sci 2013;9(6): 431-437]. (ISSN: 1545-1003).http: //www. jofamericanscience.org.
Keywords: ZigBee; Frequency Synthesizer; Voltage Controlled Oscillator; Injection Locking. Full Text 53