A Compact and Efficient RF Rectifier Using Series–Parallel LC Network for UHF Battery-Less RFIDs

This letter proposes a wide input power range compact and efficient rectifier for harvesting ambient radio frequency
$(\text{RF})$
energy from 915 MHz ultrahigh frequency
$(\text{UHF})$
. An
L
-match series and parallel topology have been designed and compared to not only boost the received input power but also to produce a highly efficient network to hold a broad input power range. This letter demonstrates theoretically and practically that a parallel network is more efficient than a series network due to greater harmonic suppression results in an improvement of 3%–8% efficiency throughout a power range of 26 to 12 dBm at a desired frequency. The design utilizes multidiode (SMS-7630, HSMS-2850, and HSMS-2862) approach to achieve higher efficiency over a wide input power range. From the measurements, the proposed series
L
-match rectifier achieves peak power conversion efficiency (PCE) of 75% at 4 dBm with 35 dB of wide input power range from −23 to 12 dBm with
$>20\%$
, respectively, whereas the proposed parallel
L-
match rectifier achieves peak power conversion efficiency of 79% at 4 dBm with 38 dB of wide input power range from −26 to 12 dBm with
$>20\%$
in an area of 1.8 × 2
$\text{cm}^{2}$
, respectively.