Abstract
In this paper, a comparative study of different types of mixer topologies
is presented. Gilbert cell is widely used as core of the mixer because it
provides high conversion gain, good port-to-port isolation and low
even-order distortion. It is found that the linearity of mixer is very good
for Multi-Tanh technique by incorporating multiple differential transconductance stage but it reaches to very low conversion gain whereas,
use of current bleeding technique increase linearity and conversion
gain of the mixer by adding current source to increase the bias current
at the expense of power consumption. A very low value of noise figure
can be achieved with the switched biasing technique by replacing
current source with parallel connected nMOS transistors but due to use
of the transistor in place of tail current source, linearity is degraded
and more power is consumed. Folded Cascode Technique is used to
reduce DC supply voltage by folding the LO switching stage with pMOS
transistors in switching stage but it degrades the noise figure. Bulkdriven technique can be employed to lower down the power
consumption by providing the switching action via the gate of LO (RF)
and amplification by the bulk of LO (RF) transistors, however it
reduces the linearity. High linearity is obtained by using CCPD (Cross
coupled post distortion) technique by cancelling of third order
derivatives but it decreases the conversion gain and consume more
power due to increase in the number of auxiliary transistors. MGTR
enables to achieve high linearity by incorporating auxiliary transistor
but it decreases the overall conversion gain and increases noise figure
of the mixer. So it is observed that there is a trade-off among the
performance metrics, i.e., conversion gain, noise figure linearity, and
power consumption of the mixer.
Citation
ID:
134476
Ref Key:
sharma2016ictacta