An Efficient V-Band Frequency Tripler With Back-to-Back Connected Varactors

A
$V$
-band frequency tripler is presented, consisting of both passive and active frequency triplers. The passive tripler is composed of back-to-back connected accumulation-mode MOS (AMOS) varactors and generates third-order harmonics (
$3f_{0}$
) from a fundamental (
$f_{0}$
) input. The input of the active tripler is shunted to the passive one and also generates
$3f_{0}$
from
$f_{0}$
input. Simultaneously,
$3f_{0}$
generated from the passive tripler is amplified by the active core and added to the output. This enables the tripler to have high dc-to-RF efficiency. It is implemented in a 28-nm bulk CMOS process, achieving output power of −1.3 dBm and 5.2% conversion efficiency (CE) while consuming 9.4 mW of power from a 1.1-V supply.