SDARS-GNSS LNA THAT CAN COEXIST WITH CELLULAR

ICTACT Journal on Microelectronics ( Volume: 4 , Issue: 4 )

Abstract

vioft2nntf2t|tblJournal|Abstract_paper|0xf4ff93cf290000001c36010001000900
The 2320-2345MHz band is licensed to Sirius XM for broadcasting Satellite Digital Audio Radio Service (SDARS). Out-of-band (OOB) transmissions can disrupt SDARS reception through blocking. The blocker can either emanate from nearby vehicles, or can be selfinflicted because the vehicular SDARS aerial often share a common radome with cellular aerials. Among cellular bands, the Wireless Communications Service’s (WCS) 2305-2320MHz and 2345-2360MHz are the most disruptive because they sandwich SDARS without any guard band. As the SDARS aerial is connected to the receiver through 15-20 feet of coaxial cable, an outboard low noise amplifier (LNA) is necessary to overcome cable loss. Due to stringent noise requirement, the LNAs are predominantly discrete designs which necessitate many components and large printed circuit boards (PCB), but vehicular aesthetic and aerodynamic demand small and unobtrusive radomes. When reception of global navigation satellite system (GNSS) is also required, the additional aerial and LNA further increase the space pressure. A dual-band aerial can eliminate one aerial, but still requires a diplexer to interface with two LNAs. Narrowband receivers conventionally employ a band-select filter before the LNA, i.e. prefilter, as the primary defence against OOB blockers. However, the insertion loss of a miniature microwave filter is incompatible with the SDARS LNA’s noise requirement. The pre-filter will also prevent GNSS reception. In order to reject WCS blockers, the filter must possess narrow fractional bandwidth (~1%) and steep skirts. Most prior arts utilize either surface acoustic wave (SAW) or dielectric filters because they have the required selectivity but they add cost and PCB space. To reduce component count, we integrated RF amplifiers, active biasing, impedance matching and band-filtering into a 5×5mm2 multichip on board (MCOB) module. To save on a separate GNSS LNA, the module is dual-band capable; hence eliminating the need for a diplexer between aerial and LNA. The conflicting requirements for low noise and blocking immunity are satisfied by relocating the filter to mid-LNA and distributing the gain optimally. An SDARS LNA’s blocking tolerance is reported for the first time. In conclusion, this design achieves previously unattainable miniaturization and blocking performance.

Authors

Chin-leong Lim
Avago Technologies, Malaysia

Keywords

SDARS GNSS Low Noise Amplifier, Wireless Communications Service Blocker Tolerant, Cellular Coexistence, Miniaturize

Published By
ICTACT
Published In
ICTACT Journal on Microelectronics
( Volume: 4 , Issue: 4 )
Date of Publication
Januray 2019
Pages
681-686

ICT Academy is an initiative of the Government of India in collaboration with the state Governments and Industries. ICT Academy is a not-for-profit society, the first of its kind pioneer venture under the Public-Private-Partnership (PPP) model

Contact Us

ICT Academy
Module No E6 -03, 6th floor Block - E
IIT Madras Research Park
Kanagam Road, Taramani,
Chennai 600 113,
Tamil Nadu, India

For Journal Subscription: journalsales@ictacademy.in

For further Queries and Assistance, write to us at: ictacademy.journal@ictacademy.in