Dual Transformer Injection Locked Frequency Divider Using GaAs E/D-Mode PHEMTs Process

This letter proposes a new divide-by-2 pHEMT injection locked frequency divider (ILFD) fabricated by 0.5-mum GaAs ED-Mode pHEMTs process and describes the operation principle of the dual-transformer ILFD. First transformer was applied to replace two inductors of cross-couple iC-tank oscillator circuit. The injection signal of ILFD transmits into a transistor through the second transformer which consisted of a band-pass filter achieving a high injection signal power and wide locking range. The measurement results show that the divider's free-running frequency were from 6.47 to 9.54 GHz (32.2%) with 3 V supply voltage. With an incident power of 0 dBm, the locking range is 3.04 GHz from the incident frequency 16.41 to 19.45 GHz (15.6%). The measured phase noise of free running VCO is -92.2 dBc/Hz at 1 MHz offset frequency at 9.45 GHz and this value of the locked ILFD is -128.4 dBc/Hz ,which is 36.2 dB lower than the free running VCO. The core power consumption was 42 mW.