User Guide

RH-26
2 - System Module CCS Technical Documentation
Page 40 ©Nokia Corporation Issue 1 02/04
Figure 21: RF frequency plan
DC characteristics
Regulators
The transceiver baseband section has a multi-function analogue ASIC, UEM, which con-
tains six pieces of 2.78 V linear regulators and a 4.8 V switching regulator. All the regula-
tors can be controlled individually by the 2.78 V logic directly or through a control
register. Normally, direct control is needed because of the switching speed requirement:
the regulators are used to enable the RF-functions which means that the controls must
be fast enough.
The use of regulators can be seen in the power distribution diagram. The seven regulators
are named from VR1 to VR7. VrefRF01 is used as the reference voltage for Helgo,
VrefRF01 (1.35V) for the bias reference.
The regulators (except for VR7) are connected to Helgo. Different modes of operation can
be selected inside Helgo according to the control information coming through the RFBus.