U2893B Datasheet, PDF (9/14 Pages) TEMIC Semiconductors – Modulation PLL for GSM, DCS and PCS Systems

Application Hints
For some of the baseband ICs it may be necessary to
reduce the I/Q voltage swing so that it can be handled by
the U2893B. In those cases, the following circuitry can be
used.
R1
I
I
NI
Baseband IC
Q
NQ
R2
R1
R1
R2
R1
NI
U2893B
Q
NQ
12496
Figure 12. Interfacing the U2893B to I/Q baseband circuits
U2893B
U2893B
GND
CPC
R1 R2
1 nF
R1 = 2230 R
R2 = 1160 R (incl. rds_on of FET)
4 mA
2 mA
12497
Figure 14. Programming the charge pump current
Application examples for programming different modes.
U2893B
U2893B
VS2
VS2
MC
a) single mode
MC
RMODE 1
RMODE 2
b) any mode & mode 5
U2893B
VS2
U2893B
VS2
MC
MC
RMODE
36k or
10k
c) any mode
d) mode 5 & mode 3 or mode 4
Figure 13. Mode control
TELEFUNKEN Semiconductors
9 (14)
Rev. A1, 29-Jan-97
Preliminary Information