TDA8040T Datasheet, PDF (8/16 Pages) NXP Semiconductors – Quadrature demodulator

Philips Semiconductors
Quadrature demodulator
Objective specification
TDA8040T
4. The phase and gain error between the I and Q channel outputs is measured as follows:
a) the oscillator is tuned at f_i(VCO) = 140 MHz
b) a sine wave signal f_i(RF) = ¹â„₂f_i(VCO) + 500 kHz (70.5 MHz) is applied at the IF input
c) the higher frequencies (140.5 MHz) are filtered out.
Under these conditions, in each I and Q channel, a sine wave with a frequency of 500 kHz will be present.
These sine waves should be 90 degrees out of phase.
The phase error is defined as the phase quadrature imbalance between the I and Q channels.
The gain error is defined as the gain difference between the I and Q channels.
5. The tilt is defined as the difference between the maximum and the minimum channel gain measured in a frequency
band of 25 MHz around f_i(RF). The specified tilt is the maximum tilt value found in one of the I or Q channels.
6. The specified noise figure is the maximum value obtained from I and Q channel noise measurement. The noise meter
is tuned to 10.7 MHz.
7. The specified intermodulation distortion is the minimum value obtained from intermodulation measurements in the
I and Q channels. Intermodulation is measured with two sine wave signals at f_i(RF) = 79 MHz and f_i(RF) = 81 MHz with
an amplitude of 67 dBµV for each tone. The difference in level between the converted carriers (9 MHz and 11 MHz)
and the intermodulation products after frequency conversion (7 MHz and 13 MHz) is defined as IM3 (see Fig.3).
8. The temperature for the VCO frequency drift is defined for ∆T_amb = 25 °C. It is measured in the application circuit of
Fig.10 with the following component values for the tank circuit:
a) L1: 22 nH (TOKO NE545BNA5 - 100082)
b) C1: 15 pF NP0
c) C2: 33 pF N220 (220 ppm/°C)
d) C3 and C4: 1 nF
e) C5: 3.3 µF
f) D1 and D2: BB133
g) R1 and R2: 100 kΩ
h) R3: 1 kΩ.
9. The phase noise is measured at the oscillator frequency (140 MHz). Due to the frequency divider, the phase noise
at the input of the mixers is 6 dB better (111 dBc/Hz at 100 kHz).
10. Output amplifiers are measured separately with an external DC bias applied at pins 9 and 16. The gain is measured
for an output signal of 500 mV (p-p) at f_i = 500 kHz.
11. The specified intermodulation distortion is the minimum value obtained from intermodulation measurements in the
I and Q output amplifier. Intermodulation is measured with two sine wave signals at f_i = 9 MHz and f_i = 11 MHz at an
output level of 500 mV (p-p) for each tone.
12. The crosstalk between the I and Q amplifiers is defined as the ratio between the wanted output signal and the
disturbing signal from the other channel. To measure the crosstalk of the I and Q amplifiers, a sine wave
15 MHz, 0.1 V (p-p) is applied at the I input and a sine wave 15.5 MHz, 0.1 V (p-p) is applied at the Q input. For each
output, the difference in level is measured between the 15 MHz and the 15.5 MHz component. This difference is the
value of the crosstalk between the I and Q amplifiers.
1996 Oct 08
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