CXA3355ERVQFN SONY [Sony Corporation], CXA3355ERVQFN Datasheet - Page 21

• Manufacturer Part Number: CXA3355ERVQFN
• Description: GPS Down Converter IC
• Manufacturer: SONY [Sony Corporation]

Description of Operation
Overview of Operation
This IC down-converts the GPS (Global Positioning System) frequency of 1.57542GHz to fo (fo: 1.023MHz) or
4fo (4fo: 4.092MHz).
The internal configuration is divided into the analog block, consisting of the amplifier, mixer and filters, and the
digital block (including the comparator block and the control block), which forms the PLL.
The analog block converts the frequency and amplifies the signal with the amplifier and the mixer, and
eliminates undesired components with the filters.
The digital block can switch the PLL frequency division ratio in order to down convert the output signal to fo or
4fo.
1. LNA
2. RF Amplifier, RF Mixer, IF Phase Shifter and Adder
The GPS signal that passes through the antenna is input to Pin 24 via a matching circuit as shown in the
figure below.
The input signal is amplified by the LNA, and then output from Pin 27.
Always use matching circuits for the LNA input pin (Pin 24) and the LNA output pin (Pin 27), and match at
1.57542GHz.
The signal amplified by the LNA passes through the SAW filter, and is then input to Pin 30 via a matching
circuit.
The input signal is amplified by the RF amplifier, and then down-converted by the RF mixer to the fo (1.023MHz)
or 4fo (4.092MHz) I and Q components. The IF signal down-converted to the I and Q components has the
image component eliminated by the phase shifter and the adder, and is then input to the IF filter.
Always use a matching circuit for the RF amplifier input pin (Pin 30), and match at 1.57542GHz.
SAW
Matching Circuit
Matching Circuit
Matching Circuit
24
27
30
31
– 21 –
LNA
1540fo
0˚
90˚
fo or 4fo
Phase
Shifter
fo: 1.023MHz
Adder
To the IF filter
CXA3355ER