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dc1774acf
DEMO MANUAL DC1774A-C
QUICK START PROCEDURE
Demo circuit 1774A-C can be set up to evaluate the per-
formance of the LTC6431-15. Refer to Figures 7 and 8, for
proper equipment connections and follow the procedure
below:
Single-Tone Measurement:
Connect all test equipment as suggested in Figure 7
1. The power labels of +5V and GND directly correspond
to the power supply. Typical current consumption of
the LTC6431-15 is about 90mA.
2. Apply an input signal to J7. A low-distortion, low noise
signal source with an external high order lowpass filter
will yield the best performance. (i.e. the input signal is
–10dBm. The Input is impedance matched to 50Ω).
3. Observe the output via J10. (The measured power at
the analyzer should be about +5dBm. The output is
impedance matched to 50Ω), suitable for the input of
a network or spectrum analyzer.
Two-Tone Measurement:
Connect all test equipment as suggested in Figure 8.
1. The power labels of +5V and GND directly correspond
to the power supply. Typical current consumption of
the LTC6431-15 is about 90mA.
2. Apply two independent signals f1 and f2 from SG1 and
SG2 at 240MHz and 241MHz respectively.
3. Monitor the output tone level on the spectrum analyzer.
Adjust signal generator levels such that output power
me2dBm/tone at the amplifier output J10, after
correcting for external cable losses and attenuators.
4. Change the spectrum analyzer’s center frequency and
observe the two IM3 tones at 1MHz below and above
the input frequencies. (i.e. the frequencies of IM3_LOW
and IM3_HIGH are 239MHz and 242MHz, respectively.
The measurement levels should be approximately
–90dBc; +47dBm is a typical performance of OIP3
at 240MHz). For this setup, the Rohde and Schwarz
FSEM30 spectrum analyzer was used. This SA has a
t20dBm third-order intercept point (TOI). So,
the SA input attenuation is set to 20dB with an external
20dB attenuation pad, resulting in an attenuation total
of 40dB. The system as described can measure OIP3
up to +50dBm.
Figure 1. LTC6431-15 Device Block Diagram
OUT
(PIN 18)
T-DIODE
(PIN 16)
GND
(PINS 8, 17, 23 AND EXPOSED PAD 25)
V
CC
(PINS 9, 22)
IN
(PIN 24)
dc1774ac F01
BIAS AND
TEMPERATURE
COMPENSATION