TFF11101HN All information provided in this document is subject to legal disclaimers. © NXP B.V. 2013. All rights reserved.
Product data sheet Rev. 1 — 28 March 2013 6 of 17
NXP Semiconductors
TFF11101HN
Low phase noise LO generator for VSAT applications
10.2 Output buffer
The output consists of a differential pair with 50 collector resistors R
BUF_P
and R
BUF_N
. If
only one output is used, terminate the non used output with the same impedance as the
load (see Figure 8
)
10.3 Lock detector
The lock detector is the output of a window detector. The window detector compares the
output voltage over the charge pump. This voltage is identical to VTUNE when a
type 2 loop filter is used (see Figure 4
). In case of a type 3 loop filter this voltage is filtered
by R2/C3 (see Figure 5
). Due to this filtering the attack and decay time will decrease.
The lower window detector threshold voltage is 7 % of the output voltage on
VREGVCO (pin 1), the upper window detector threshold voltage is 93 % of the output
voltage on VREGVCO (pin 1). The hysteresis is 0.1 V. The output is 2.5 V CMOS
compliant. The values are shown in Table 6
. The timing diagram is shown in Figure 6.
At start-up the LCKDET (pin 7) will be LOW until the circuit has acquired lock.
Fig 4. Type 2 loop filter Fig 5. Type 3 loop filter
001aal727
10 pF
C2
C1
R1
30 pF
3
VTUNE
2
CPOUT
1
VREGVCO
2.7 V
001aal728
10 pF
C2
C3
R2
C1
R1
30 pF
3
VTUNE
2
CPOUT
1
VREGVCO
2.7 V
Table 5. Component values used for characterization
f
i(ref)
Divider value C1 C2 C3 R1 R2
(MHz) (nF) (pF) (pF) () ()
38.750 to 39.570 256 27 82 33 470 560
77.500 to 79.141 128 18 82 33 330 560
155.000 to 158.281 64 18 120 33 270 560
310.000 to 316.563 32 33 270 33 120 560
620.000 to 633.125 16 68 560 33 68 560