SAW-less RF front-ends

  SAW-less RF front-ends Copyright: RWTH IAS

The high integration level in CMOS facilitates implementation of different radio standards like GSM, UMTS, and LTE in a single chip. Thus a small form factor, a low bill of materials, and low cost can be maintained for a phone serving different standards. Conversely, each band and standard require a dedicated external surface acoustic wave filter to suppress out-of-band interferers which would otherwise desensitize the receiver and render signal reception impossible. With an increased number of bands and standards, form factor and cost will ultimately be limited by the number of external components.

This projects aims at reducing RF front-end complexity by replacing external filters by an on-chip interference cancellation scheme: An interfering signal is sensed and an interferer replica signal is extracted which is subsequently subtracted from the incoming interfering signal. Thus the interference level for subsequent blocks in the receive chain can be reduced.

The concept has been explored and implemented in 65 nm and 90 nm CMOS processes ranging from a concept prototype to a complete receive chain.

Tobias Werth < >