Figure 1 shows the general models of the FPD and TPD that are used in direct-conversion receiver architectures.
Since then, the field of applications of six-port systems has been extended to measurement of direction of arrival (DoA) of multiple signals [2, 3], phase/frequency discriminator for automobile radars [4, 5], microwave and millimeter-wave sensing , and demodulators in direct-conversion receivers [7-20].
To avoid the severe flicker noise, dc offset and [IIP.sub.2] problems of a direct-conversion receiver
[8,9], a low-IF receiver is also widely chosen and implemented [10-13].
A series of tests is designed to identify the limiting stage in a fully integrated direct-conversion receiver (DCR).
In this article, the third-order nonlinearity of a direct-conversion receiver (DCR) is evaluated with a set of well-designed tests.
An example of an UTRA/FDD direct-conversion receiver
is shown in Figure 6.
With the tremendous advances in RFIC technology, over the last few years, direct-conversion receiver
ICs are fast becoming popular with pager designers.
Laskar, "Design and analysis of low flicker-noise CMOS mixers for direct-conversion receivers
" IEEE Transactions on Microwave Theory and Techniques, vol.
Raman, "DC offsets in direct-conversion receivers
: Characterization and implications," IEEE Microwave Magazine, Vol.
Obviously, direct-conversion receivers
require no expensive and bulky external filter for analog channel selectivity.
Tanimoto, "A 2 GHz Balanced Harmonic Mixer for Direct-conversion Receivers
," 1997 IEEE Custom IC Conference, pp.
Good mixer balancing is also important in a receiving mixer to suppress LO noise, especially at very low intermediate frequencies or in direct-conversion receivers
. Finally, good mixer balancing is also required in a vector modulator in a transmitter to suppress the residual carrier.