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M02140 Datasheet, PDF (1/2 Pages) M/A-COM Technology Solutions, Inc. – Low Power 3.3 Volt Limiting Amplifier for Applications up to 12.5 Gbps
Low Power 3.3 Volt Limiting Amplifier for
Applications up to 12.5 Gbps
M02140
Low power, high sensitivity 12.5 Gbps
limiting amplifier in 4X4 MLF package
The M02140 is a high-gain limiting amplifier for applications
> KEY FEATURES
> Wide dynamic range with
5.5 mV typical input sensitivity
at 10 Gbps
up to 12.5 Gbps, and incorporates a limiting amplifier, a CML
buffer and an input signal level detection circuit. The M02140
> Received signal strength
indicator (RSSI)
also features a fully integrated DC-offset cancellation loop
that does not require any external components.
> Programmable input signal
level detect
> Operates with +3.3 V supply
> CML data outputs with
typical 23 ps rise and fall time
> Wide -40 to +85 °C operating
temperature range
> On-chip DC offset
cancellation circuit
The user is provided with the flexibility to set the output
amplitude levels and the signal detect threshold. Optional
output buffer disable (squelch/jam) can be implemented
using the power down (PWDN) input.
The data inputs are internally biased to VCC via 50Ω
resistors, and may be AC or DC-coupled. Note that if the
inputs are AC-coupled, the coupling capacitor should be of
sufficient value to pass the lowest frequencies of interest,
bearing in mind the number of consecutive identical bits, and
the input resistance (The use of a 2 to 10 nF capacitor is
recommended). The coupling capacitor should also be of
sufficient quality as to pass the high frequency content of
the input data stream.
The M02140 contains internal DC feedback requiring no
external components to remove the effects of DC offsets
and to act as a DC auto-zero circuit. This circuit is config-
ured such that the feedback is effective only at frequencies
well below the lowest frequency of interest. The low
frequency cut off is typically less than 50 kHz.
The output swing is linearly proportional to the value of
RAMPSET. It is possible to set the output voltage swing linearly
between 400 mVpp differential and 800 mVpp differential,
when the outputs are properly terminated. See the applica-
tions information section for further details on setting the
output swing amplitude.
The RSSI output voltage is proportional to the log of the
input signal amplitude (the RSSI output voltage is linearly
proportional to the optical modulation amplitude (OMA)). An
external 4.7 nF capacitor must be connected from the RSSI
output to VCC. The capacitor integrates the RSSI output
and also sets the loss of signal reaction time. The RSSI
voltage is compared with a selectable reference to deter-
mine loss of signal as described in the next section.
Using an external resistor, RLOS, between pin LOSSET and VCC,
the user can program the input signal threshold. The signal
detect status is indicated on the LOS and ST open-drain
output pins. The LOS signal is active when the signal is below
the threshold value, ST is active when the signal is above the
threshold value.
>