UPC2533GS-01 NEC [NEC], UPC2533GS-01 Datasheet - Page 11

• Manufacturer Part Number: UPC2533GS-01
• Description: AM TUNER FOR ELECTRONIC TUNING CAR RADIOS
• Manufacturer: NEC [NEC]

2. Operation of Each Block
2.1 FR Amplifier Circuit Block
J-FET is used in the PC2533 to raise RF input impedance.
between the RF amplifier circuit and MIX1. Instead, it employs an LPF (about 6 MHz) consisting of L4, L5 and C3
to C5 between the RF amplifier circuit and MIX1 in order to cut image frequency (21.4 MHz or higher). Because this
allows a wide-band RF amplifier circuit to be configured without using a tuning circuit, frequency sensitivity deviation
can be minimized to a high degree.
transistor Q1. Use a low-noise transistor even with low current for the cascade transistor Q1 (if a high-noise one is
used, the S/N ratio deteriorates).
Note L
In the AM band, the capacitance of a car radio antenna depends on its length, diameter, cable length, etc. Therefore,
Since the PC2533 raises the first IF (intermediate frequency) to 10.71 MHz, there is no need for a tuning circuit
The AGC circuit consists of RF AGC1 by the PIN diode connected to the FET gate and RF AGC2 by the cascade
Remark Set bias voltage for cascade transistor Q1 to V
DX : 1 V or lower
O
L1
: 3 V or higher
L2
C1
L3
Q2
Q1
V
CC
R1
R2
C9
C2
+
C8
C3
Fig. 2-1 RF Ampliier Circuit
L4
LPF
C4
L5
C5
C
C6
+
> V
C7
B
.
33
30
35
36
34
RF AGC
MIX1
From MIX2
L
O
/DX
4
Note
PC2533
11