PCF5079 datasheet(16/28 Pages) PHILIPS

16 / 28 page

2001 Nov 21

Philips Semiconductors

Product speciﬁcation

Dual-band power ampliﬁer controller for

GSM, PCN and DCS

PCF5079

handbook, full pagewidth

1 k

Ω

1 k

Ω

MGT337

PCF5079

VCG

CINT1

< 50 pF

CINT2

< 50 pF

RF SECTION

AUXDAC3

PCF5073x

VINT(N)

VCD

VS1

VS2

VSS

VDAC

0 to 2.3 V

VDD

Fig.13 Diagram showing external components required.

12.1

Ramp control

CODEKICK and Vhome define the starting conditions for

ramping-up. Ramping-up and ramping-down are defined

by VVDAC. CODEEND and CODESTART define the correct

shut-off of the power module.

The non-linear behaviour of the control curves of the

power modules has a large influence on the loop. Starting

conditions in the flat area of the control curve are critical

and need some attention. Initially the voltage on

pins VCD (VCG) will be at the home position.

Successively, the integrator is moved into the active part

of the control curve.

This is achieved by integrating CODEKICK. When

VCD (VCG) voltage has reached the active region of the

control curve, the loop is closed and the circuit can follow

the ramping function generated at pin VDAC. The top

value of VDAC voltage determines the power of the

transmit burst. Ramping-down is started according to the

decrease of VDAC voltage. The loop follows the leading

function for ramping-down until the RF sensor leaves its

active region. The reason for CODESTART and CODEEND

is to shorten the tail of the slope.

MGT338

handbook, halfpage

VVCD, VVCG

350

Ω

120 pF

Fig.14 Worst case load on control voltage pins

VCG and VCD.

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