High Linearity Components Simplify Direct Conversion Receiver Designs:A direct conversion radio receiver takes a high frequency
input signal, often in the 800MHz to 3GHz frequency range,
and utilizes one mixer/demodulator stage to convert the
signal to baseband without going through an intermediate
frequency (IF) stage. The resulting low frequency (baseband)
signal spectrum has useful information at frequencies
from DC to typically a few tens of MHz. Designing
these receivers requires the use of very high performance
analog ICs. High performance direct conversion radio
receiver signal chains for applications such as cellular
infrastructure and RFID readers require high linearity,
low noise fi gure (NF), and good matching between the
in-phase and quadrature (I and Q) channels.