Fiber Optic Receiver with Quantizer and
Clock Recovery and Data Retiming
a
AD807
FEATURES
Meets CCITT G.958 Requirem ents
for STM-1 Regenerator—Type A
frequency acquisition without false lock. T his eliminates a reli-
ance on external components such as a crystal or a SAW filter,
to aid frequency acquisition.
Meets Bellcore TR-NWT-000253 Requirem ents for OC-3
Output J itter: 2.0 Degrees RMS
155 Mbps Clock Recovery and Data Retim ing
Accepts NRZ Data, No Pream ble Required
Phase-Locked Loop Type Clock Recovery—
No Crystal Required
T he AD807 acquires frequency and phase lock on input data
using two control loops that work without requiring external
control. T he frequency acquisition control loop initially acquires
the frequency of the input data, acquiring frequency lock on
random or scrambled data without the need for a preamble. At
frequency lock, the frequency error is zero and the frequency
detector has no further effect. T he phase acquisition control
loop then works to ensure that the output phase tracks the input
phase. A patented phase detector has virtually eliminated pat-
tern jitter throughout the AD807.
Quantizer Sensitivity: 2 m V
Level Detect Range: 2.0 m V to 30 m V
Single Supply Operation: +5 V or –5.2 V
Low Pow er: 170 m W
10 KH ECL/ PECL Com patible Output
Package: 16-Pin Narrow 150 m il SOIC
T he device VCO uses a ring oscillator architecture and patented
low noise design techniques. Jitter is 2.0 degrees rms. T his low
jitter results from using a fully differential signal architecture,
Power Supply Rejection Ratio circuitry and a dielectrically
isolated process that provides immunity from extraneous signals
on the IC. T he device can withstand hundreds of millivolts of
power supply noise without an effect on jitter performance.
P RO D UCT D ESCRIP TIO N
T he AD807 provides the receiver functions of data quantiza-
tion, signal level detect, clock recovery and data retiming for
155 Mbps NRZ data. T he device, together with a PIN
diode/preamplifier combination, can be used for a highly inte-
grated, low cost, low power SONET OC-3 or SDH ST M-1
fiber optic receiver.
T he user sets the jitter peaking and acquisition time of the PLL
by choosing a damping factor capacitor whose value determines
loop damping. CCIT T G.958 T ype A jitter transfer require-
ments can easily be met with a damping factor of 5 or greater.
T he receiver front end signal level detect circuit indicates when
the input signal level has fallen below a user adjustable thresh-
old. T he threshold is set with a single external resistor. T he sig-
nal level detect circuit 3 dB optical hysteresis prevents chatter at
the signal level detect output.
Device design guarantees that the clock output frequency will
drift by less than 20% in the absence of input data transitions.
Shorting the damping factor capacitor, CD, brings the clock out-
put frequency to the VCO center frequency.
T he AD807 consumes 140 mW and operates from a single
power supply at either +5 V or –5.2 V.
T he PLL has a factory trimmed VCO center frequency and a
frequency acquisition control loop that combine to guarantee
FUNCTIO NAL BLO CK D IAGRAM
CF1 CF2
QUANTIZER
PIN
COMPENSATING
ZERO
LOOP
FILTER
Φ
∑
DET
NIN
PHASE-LOCKED LOOP
VCO
SIGNAL
THRADJ
LEVEL
F
CLKOUTP
CLKOUTN
DET
DETECTOR
LEVEL
DATAOUTP
DATAOUTN
RETIMING
DEVICE
DETECT
COMPARATOR/
BUFFER
AD807
SDOUT
REV. A
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use, nor for any infringem ents of patents or other rights of third parties
which m ay result from its use. No license is granted by im plication or
otherwise under any patent or patent rights of Analog Devices.
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© Analog Devices, Inc., 1997