LA1780M
AM
This section analyzes the gain in each of the blocks in the LA1780 when the Sanyo recommended circuit is used.
Test conditions
Ambient temperature:
26°C
Antenna and mixer 1 input frequency: 1 MHz
Mixer 2 input frequency:
10.71 MHz
IF and detector input frequencies: 450 kHz
An AM dummy is attached.
When an input level such that the output becomes –35 dBm is determined, the I/O characteristics of each stage were
determined to be as follows:
Antenna input: 9.5 dBµ
Mixer 1 input: 25.6 dBµ
Mixer 2 input: 29.5 dBµ
IF input:
36.0 dBµ
Detector input: 102.0 dBµ
These values allow the gains in each block to be calculated as follows.
RF gain: 16.1 dB
Mixer 1 gain: 3.9 dB
Mixer 2 gain: 6.5 dB
IF gain: 66.0 dB
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