sky74100-21 Skyworks Solutions, Inc., sky74100-21 Datasheet - Page 3

• Manufacturer Part Number: sky74100-21
• Description: Sky74100-21 Dual-band Receiver For Cdma And Pcs Femtocell Applications
• Manufacturer: Skyworks Solutions, Inc.

Technical Description
LNAs
Due to noise and isolation considerations, the CDMA and PCS
LNAs are contained on the SKY74092 (refer to the device Data
Sheet, document number 103205, for further information).
Mixers
Two mixers with separate differential inputs accommodate CDMA
and PCS modes of operation.
Serial Bus Interface
The SKY74100-21 has two read/write, three-wire serial bus
interfaces (Auxiliary and Receive). The Auxiliary bus is used for
writing to and reading from the UHF VCO and PLL. The Receive
bus is used for writing to and reading from the receive path. The
Receive bus is shared with the SKY74092 LNA.
Fully Integrated VCO
The VCO is designed to operate at twice the frequency of the PCS
receive band and four times the frequency of the CDMA receive
band. The carrier frequency and quadrature are then achieved by
dividing the VCO signal by either two or four.
The analog tuning range is sufficient to cover frequency variations
due to supply and temperature changes under normal operating
conditions. This ensures that the PLL is always locked.
Continuous Time Low Pass Filters
The receive filter has two primary tasks: to set the receive
bandwidth, and to reject adjacent and alternate channel blockers.
These functions are formalized by the requirements placed on the
900 kHz and 1.25 MHz blockers for the cellular and PCS bands,
respectively, with further attenuation requirements at 1.7 MHz
and 2.05 MHz.
There are two identical receive filters, one for the I channel and
one for the Q channel. A 15 dB gain step is provided in the filter,
programmed either through the three-wire bus or through the
MIX_GAINSTEP signal (pin 13).
DC Offset Correction (DCOC)
DCOC is provided as part of the baseband filter transfer function.
A high pass cut-off is provided in the signal path. No external
components are required. However, the high pass cut-off
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [e-mail] • www.skyworksinc.com
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frequency can be adjusted from 640 Hz to 1.91 kHz using the
Auxiliary serial bus.
RF PLL
The RF PLL is fully integrated with the exception of the loop filter
components. The pre-scalar has been designed to directly use the
VCO frequency to maintain resolution without impacting settling
time.
A power on reset signal is generated on start-up. This is used to
reset all flip-flops in the PLL and as a reference to enable on-chip
tuning sequences.
Package and Handling Information
Since the device package is sensitive to moisture absorption, it is
baked and vacuum packed before shipping. Instructions on the
shipping container label regarding exposure to moisture after the
container seal is broken must be followed. Otherwise, problems
related to moisture absorption may occur when the part is
subjected to high temperature during solder assembly.
The SKY74100-21 is rated to Moisture Sensitivity Level 3 (MSL3)
at 260 C. It can be used for lead or lead-free soldering. For
additional information, refer to the Skyworks Application Note,
PCB Design & SMT Assembly/Rework Guidelines for RFLGA
Packages, document number 103147.
Care must be taken when attaching this product, whether it is
done manually or in a production solder reflow environment.
Production quantities of this product are shipped in a standard
tape and reel format.
Electrical and Mechanical Specifications
Signal pin assignments and functional pin descriptions are
described in Table 1. The absolute maximum ratings of the
SKY74100-21 are provided in Table 2. The recommended
operating conditions are specified in Table 3 and electrical
specifications are provided in Tables 4 through 7.
An application schematic diagram for the SKY74100-21 is shown
in Figure 3. A PCB footprint drawing is provided in Figure 4,
package dimensions for the 40-pin LGA are shown in Figure 5,
and the tape and reel dimensions are provided in Figure 6.
DATA SHEET • SKY74100-21 CDMA RECEIVER
3