In-Phase Detect i on
In this section, an in-phase coupled CON architecture is proposed to improve
the sensitivity of SRX. As shown in Figure 11.1, the input power is ampliﬁed
by two oscillators, which are coupled in phase in a positive feed-back loop.
Then, the output voltage envelope is detected, indicating the input power
level. The main design challenge is how to realize in-phase coupling between
The key idea of this paper is using a zero phase shifter (ZPS) to couple two
quench-controlled oscillators in phase. Compared to the transformer-coupling
metho d , the ZPS approach does not introduce the extra phase between
two oscillators, as shown in Figure 11.1(a). As a result, the SRX sensitivity
can be improved in terms of bo th reduced noise ﬁgure (NF) and increased
oscillator y ampliﬁcation.
The proposed SRX with ZPS-coupled CON is designed in 65nm CMOS at
131.5GHz with a core area of 0.06mm
. The c ircuit measurement shows that
the receiver features a sensitivity of -84dBm, a noise equivalent power (NEP)
, a NF of 7.26dB and a power of 8.1 mW.
11.2 SRX Sens itivity Enhancement by ZPS-
In this section, the fundamentals of the SRX circuit are described at ﬁrst and
then, the sensitivity enhancement by the ZPS-coupled CON is discussed.