COMPACT AND BLOCKER-TOLERANT LOW-NOISE AMPLIFIER FOR SATELLITE RADIO

Abstract
Satellite Digital Audio Radio Service’s (SDARS) reception over 2320- 2345MHz can be blocked by cellular transmissions in the neighbouring bands. In vehicles, the blocking is exacerbated by SDARS sharing a common radome with cellular aerials. Considering the SDARS satellites are ~40,000km away, this is an extreme example of the nearfar problem. Among cellular services, the Wireless Communications Service’s (WCS) 2305-2320MHz and 2345-2360MHz bands are the most disruptive because they sandwich SDARS without any guard band. As SDARS aerial on the car roof is connected to the receiver through a long coaxial cable, an outboard low noise amplifier (LNA) is necessary to overcome cable loss. A compact LNA is required because of the small radome. Conventionally, a band-select filter before the LNA (pre-filter), is used to defend against blockers, but the filter’s insertion loss can significantly degrade the overall noise figure. Furthermore, the space constraint necessitates a miniature filter which accentuates the loss. To reject WCS, the filter must possess narrow fractional bandwidth (~1%) and steep skirts. To reduce component count, we integrated amplifiers, biasing, impedance matching and filters into a 5×5mm2 multi-chip on board (MCOB) module. The conflicting requirements for low noise and blocking immunity are satisfied by relocating the filter to mid-LNA. In conclusion, this design achieves previously unattainable miniaturization and blocking performance.

Authors
Chin Leong Lim
Avago Technologies, Malaysia

Keywords
Satellite Digital Audio Radio Service Low Noise Amplifier, Blocker Tolerant, Cellular Coexistence, Miniaturize
Published By :
ICTACT
Published In :
ICTACT Journal on Microelectronics
( Volume: 5 , Issue: 2 )
Date of Publication :
July 2019

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