Confidential
PMB 2208
preliminary
Reference
1) The mixer current decreases when no external resistors to ground are
connected at IF and IFX. In this case the typical value of ,MO+,MOX is 1mA.
2) Design hint. The settling time is determined by the time required to charge
the external capacitors.
3) Note: There are external resistors (82 Ohms) at IF and IFX to ground.
4) Application hint
5) Design hint
6) The carrier suppression can be optimized for a particular application using
offset voltages at the baseband inputs A/AX and B/BX. The optimum
values can be found iteratively by adjusting the A/AX and B/BX offsets
alternately until the carrier disappears into the noise floor. If the actual
offset voltages differ from their optimum values by ∆926$ and ∆926%, the
carrier suppression in dB is given by
ac
=
20 ⋅ log10
---------------------------V-----m-----------------------------
(∆VOSA)2 + (∆VOSB)2
where 9P is the peak value of the signal voltage at A/AX and B/BX.
7) DIM3 can be increased by reducing the amplitude of the modulator inputs
VA-AX and VB-BX.
Wireless Components
5-6
Specification, August 1999