U2730B-NFSG1 Atmel, U2730B-NFSG1 Datasheet - Page 6

• Manufacturer Part Number: U2730B-NFSG1
• Description: IC DOWN-CONV FOR DAB RCVR 28SSOP
• Manufacturer: Atmel
• Series: U2730r

Specifications of U2730B-NFSG1

• Mfg Application Notes: U2731B
• Rf Type: Broadcast Radio, DAB
• Frequency: 1.4GHz ~ 1.55GHz
• Number Of Mixers: 1
• Package / Case: 28-SSOP
• Operating Temperature (min): -40C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Industrial
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Supply: -
• Voltage - Supply: -
• Gain: -
• Noise Figure: -
• Secondary Attributes: -
• Lead Free Status / Rohs Status: Not Compliant

Overall Properties of the
Signal Path
Power Save Mode
Frequency Synthesizer
Reference Oscillator
6
U2730B-N
The overall gain of this circuit amounts to 24 dB, the gain-control range is about 30 dB.
With a new AGC concept in the amplifier and mixer, the U2730B-N reaches better inter-
modulation distances (DIM3) at higher IF output power levels.
For VPSM > 2 V (pin 1) the power consumption in the analog part (gain-controlled
amplifier and mixer and gain-controlled circuitry) is reduced by 80%. The VCO and the
PLL is not influenced by the power-down mode.
The frequency synthesizer block consists of a reference oscillator, a reference divider, a
LO divider in order to divide the frequency of the internal oscillator, a tri-state phase
detector, a lock detector, a programmable charge pump, a loop filter amplifier, a control
interface and a test interface. The control interface is accessed by three control pins, CI,
SI1 and SI2. The test interface provides test signals which represent output signals of
the reference and the LO divider.
The purpose of this unit is to lock the frequency f
quency f
according to the following relation:
f
where: SF = 2464,
SF
Table 1. Scaling Factors of the Reference Frequency
An on-chip crystal oscillator generates the reference signal which is fed to the reference
divider. By connecting a quartz crystal to pins OSCE and OSCB according to Figure 10,
this oscillator generates a highly stable reference signal. The U2731B (Atmel’s one-chip
front-end IC) offers the reference signal at pin FREF. This reference signal (LC-filtered
to suppress harmonics) can be used to overdrive the oscillator. In this application (see
Figure 11) the reference signal has to be applied to the pin OSCB and the pin OSCE
must be left open.
VCO
Voltage at Pin SI1
ref
= SF ´ f
is the scaling factor of the reference divider according to Table 1
OPEN
OPEN
OPEN
GND
GND
GND
VCC
VCC
VCC
ref
of the reference signal applied to the input pin OSCB phase-locked loop
ref
/SF
ref
Voltage at Pin SI2
OPEN
OPEN
OPEN
GND
GND
VCC
VCC
GND
VCC
SF
36
33
48
65
63
64
35
32
49
ref
VCO
of the internal VCO on the fre-
Reference Oscillator
17.920 MHZ
18.432 MHz
24.576 MHz
32.768 MHz
16.384 MHz
Frequency
–
–
–
–
4719A–DAB–05/03