10-GHZ MMIC PREDISTORTION CIRCUIT FOR IMPROVED DYNAMIC-RANGE OF BROAD-BAND ANALOG FIBEROPTIC LINK

A MMIC predistortion circuit that operates at up to 10 GHz and improve s the spurious free dynamic range of a broadband analog fiber-optic li nk from 108 dB/Hz(2/3) to 111 dB/Hz(2/3) is developed. The experimenta l results agree with the performed theoretical analysis, indicating th at the link dynamic range improvement through the predistortion techni que is limited by the high driving voltage of a standard LiNbO3 Mach-Z ehnder modulator, that is, by the third-order intercept point of comme rcial microwave broadband power amplifiers. To overcome this limitatio n a low-voltage modulator should be employed. (C) 1996 John Wiley & So ns, Inc.