Title | High linearity integrated silicon bipolar modulator for wideband FM CATV transmission |
Publication Type | Conference Paper |
Year of Publication | 1999 |
Authors | Rosales, R., and M. K. Jackson |
Conference Name | Nanostructures and Quantum Dots/WDM Components/VCSELs and Microcavaties/RF Photonics for CATV and HFC Systems, 1999 Digest of the LEOS Summer Topical Meetings |
Pagination | IV11 -IV12 |
Keywords | bipolar analogue integrated circuits, cable television, circuit tuning, current mirror, differential amplifiers, driver circuits, dynamic response, emitter-coupled multivibrator core, fully-differential circuits, high linearity, high-frequency layout, impedance-matched linearized amplifier, integrated silicon bipolar modulator, intensity modulation, limiter circuits, linear transadmittance amplifier, modulators, multivibrators, optical communication equipment, optical fibre subscriber loops, output driver circuits, phase noise, Si, single-ended multitransistor circuit, static tuning, time-domain waveform, wide linear tuning range, wideband FM CATV transmission |
Abstract | Lightwave CATV transmission based on intensity modulation by a multichannel CATV signal is simple, but requires very linear components and high received powers. Alternatively, the multichannel signal can be FM-modulated onto one RF carrier, and transmitted with conventional intensity modulation. However, optoelectronic modulators reported to date are complex and bulky, and an electronic approach is needed. We describe a wideband FM modulator with record linearity over a wide tuning range, and phase noise equal to the best optoelectronic modulator results. An emitter-coupled multivibrator (ECM) core coupled to a linear transadmittance amplifier drives fully-differential limiter and output driver circuits. With an ECM very wide linear tuning range can be achieved if appropriately-designed collector loads are used. The circuit was fabricated in Nortel's NT-25 silicon bipolar process; the high-frequency layout is fully differential and physically symmetric. The ECM core operates at currents around 1 mA, optimized in conjunction with transistor sizing, and a -4.5 V power supply is used. The linearized transadmittance amplifier is a single-ended multitransistor circuit with passive feedback and single-pole stabilization. We report results for two versions: in mod1a the ECM current is set by a current mirror, while mod2a includes the 50 Omega;-matched linearized amplifier, which consumes 150 mW total |
URL | http://dx.doi.org/10.1109/LEOSST.1999.794729 |
DOI | 10.1109/LEOSST.1999.794729 |