M02040-15 Datasheet, PDF (15/31 Pages) M/A-COM Technology Solutions, Inc. – 3.3 5V Limiting Amplifier for Applications to 2.125 Gbps

M02040-15
3.3/5V Limiting Amplifier for Applications to 2.125 Gbps
Rev V4
3.3.4
Loss of Signal (LOS)
The M02040-15 features input signal level detection over an extended range. Using an external resistor, R_ST,
between pin ST_SET and V_CC3 (Figure 3-5) the user can program the input signal threshold. The signal detect status
is indicated on the LOS output pin shown in Figure 3-4. The LOS signal is active when the signal is below the
threshold value. The signal detection circuitry has the equivalent of 3.5 dB (typical) electrical hysteresis.
Figure 3-4. LOS Output
V_CC
80 kΩ
LOS
R_ST establishes a threshold voltage at the ST_SET pin as shown in Figure 3-5. Internally, the input signal level is
monitored by the Level Detector (which also outputs the RSSI_PP voltage). As described in the RSSI_PP section, this
voltage is proportional to the input signal peak to peak value. The voltage at ST_SET is internally compared to the
signal level from the Level Detector. When the Level Detect voltage is less than V_(STSET), LOS is asserted and will
stay asserted until the input signal level increases by a predefined amount of hysteresis. When the input level
increases by more than this hysteresis above V_(STSET), LOS is deasserted. See the applications information sec-
tion for the selection of R_ST.
Note that ST_SET can be left open if the loss of signal detector function is not required. In this case LOS would be
low.
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