TUA6039XT Infineon Technologies, TUA6039XT Datasheet - Page 27
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TUA6039XT
Manufacturer Part Number
TUA6039XT
Description
Manufacturer
Infineon Technologies
Datasheet
1.TUA6039XT.pdf
(64 pages)
Specifications of TUA6039XT
Lead Free Status / Rohs Status
Compliant
of the PLL in the locked-in state. In this way different VCO gains can be compensated,
for example. Furthermore, in order to obtain best results for phase noise, reference
frequency rejection and PLL stability especially in a wideband system like a digital tuner,
it is necessary to set the charge pump current to different values depending on the band
and frequency used. This is to cope with the variations of the different parameters that
set the bandwidth. The selection can be done in the application and requires for each
frequency to program not only the divider ratios, but also the band and the best charge
pump current.
The software controlled ports P0 to P4 are general purpose open-collector outputs. The
test bits T2, T1, T0, OS = 0, 1, 0, 1 switch the test signals f
and f
The lock detector resets the lock flag FL if the width of the charge pump current pulses
is greater than the period of the crystal oscillator (i.e. 250 ns). Hence, if FL = 1, the
maximum deviation of the input frequency from the programmed frequency is given by
where I
frequency and C
pump pulses at i.e. 62.5 kHz (= f
the loop has lost lock state.
Once FL has been reset, it is set only if the charge pump pulse width is less than 250 ns
for eight consecutive f
set after the loop regains lock.
3.4.3
The RF AGC stage detects the level of the SAW filter driver output signal. If the detected
level is below the RF AGC take-over point, a external capacity will be charged with the
source current of 300 nA or 9 µA (release current). If the detected level is above the RF
AGC take-over point, the external capacity will be discharged with the sink current of
100 µA (attack current). The integrated current generates the AGC voltage for gain
control of the tuners input transistors. The RF AGC take-over and the time constant are
selectable by the I
An integrated RF AGC buffer allows to monitor the AGC voltage without any influence
on the tuner gain control.
3.4.4
Coming out of the SAW filter the IF signal is sent through a VGA (Variable Gain Amplifier)
which will set the differential IF output signal to the desired level (preferably 1 Vpp). The
gain of the VGA is determined by the DC-voltage at pin IFAMPAGC
Data Sheet
f =
ref
I
P
(i.e. 4 MHz / 64) to P0 and P1 respectively.
P
is the charge pump current, K
(K
RF AGC
IF AGC amplifier
VCO
/ f
1
, C
2
XTAL
C bus (see
2
the capacitances in the loop filter (see
ref
) (C1 + C2) / (C1 C2)
periods. Therefore it takes between 128 and 144 s for FL to be
Table
ref
), it takes a maximum of 16 s for FL to be reset after
13).
VCO
27
the VCO gain, f
TUA 6039-2, TUA 6039, TUA 6037
Section
div
Functional Description
Xtal
/ 2 (divided input signal)
Revision 2.6, 2007-08-20
the crystal oscillator
4.2). As the charge