TDA8040T Datasheet, PDF (4/16 Pages) NXP Semiconductors – Quadrature demodulator

Philips Semiconductors
Quadrature demodulator
Objective specification
TDA8040T
PINNING
SYMBOL
V_CC(A)
I
GND(D)
RF A
RF B
V_CC(D)
Q
GND(A)
Q_in
Q_out
GND(V)
VCOA
VCOB
V_CC(V)
I_out
I_in
PIN
DESCRIPTION
1 supply voltage for I and Q amplifiers
2 I channel buffer output
3 demodulator ground
4 RF input A
5 RF input B
6 supply voltage for demodulator
7 Q channel buffer output
8 I and Q amplifiers ground
9 Q channel amplifier input
10 Q channel amplifier output
11 VCO ground
12 VCO tank circuit A
13 VCO tank circuit B
14 supply voltage for VCO
15 I channel amplifier output
16 I channel amplifier input
handbook, halfpage
VCC(A) 1
16 Iin
I2
15 Iout
GND(D) 3
14 VCC(V)
RF A 4
13 VCOB
TDA8040T
RF B 5
12 VCOA
VCC(D) 6
Q7
GND(A) 8
11 GND(V)
10 Qout
9 Qin
MGE510
Fig.2 Pin configuration.
FUNCTIONAL DESCRIPTION
The QPSK modulated RF signal is applied at the input of a
high gain RF amplifier. The amplified signal is then mixed
in a pair of mixers with two LO signals, which are
90 degrees out of phase, to produce the in-phase (I) and
quadrature (Q) signals. These two signals are separately
buffered to drive the external low-pass filters used for the
baseband filtering. The I and Q signals are then amplified
by two matched amplifiers designed to avoid crosstalk
between channels.
The VCO operates at twice the carrier frequency. Its output
signal is applied to a frequency divider (divide-by-2) to
produce the two LO signals which are 90 degrees out of
phase. The VCO is powered from the internal voltage
stabilizer to ensure good shift performance.
1996 Oct 08
4