The VSC7969 is a 3.125Gb/s transimpedance amplifier IC with a built-in limiting amplifier, a signal detect
feature and a photocurrent monitor. The VSC7969 does not require any external electrical components in the
construction of a high performance optical receiver such as for SONET/SDH applications. The analog output is
a differential sig nal with a min imum amplitude of 200mVp-p ( singl e-ended). The VSC7969 opera tes with a single power supply with a maximum power dissipation of 300mW. A PIN photodiode or APD can be connected
and separately biased to provide optimal performance.
The VSC7969 provides filt ered bias f or MSM and PIN phot odete ctors; appli cations u sing an APD ph otodetector must supply bias separately. The VSC7969 also provides a photocurrent monitor whose output is linearly
proportional to the input photocurrent.
The VSC7969 can operate from a single +3.3V supply or a +5V or -5.2V supply. The VSC7969 is offered
in die form and in a 16-pin plastic thin-shrink small outline package (TSSOP-16). A fully tested TO-46 outline
packaged receiver with a photodetector is also available.
operation. Only one power
supply pin should be connected.
VCCD
GND
Outputs need to
be AC-coupled
VOUTP
VOUTN
SD_OUT
SD_ADJ
IMON
0.1µF
0.1µF
VITESSE
SEMICONDUCTOR CORPORATION
3.125Gb/s Integrated Transimpedance
Advance Product Information
and Limiting Amplifier with Signal Detect
Electrical Characteristics
Table 1: AC Specifications
SymbolParameterMinTypMaxUnitsConditions
∆I
PH
I
PHS-AVG
I
PHS-PEAK
∆V
OUT-SE
∆V
OUT-DIFF
t
, t
R
F
(1)
Z
T
(1)
∆Z
T
BWUpper -3dB Bandwidth2.22.53.0GHz
F
L
Z
O
PSRRPower Supply Rejection RatioTBD
I
NOISE
C
PD
SD
H
SD
A-OPEN
SD
D-OPEN
SD
A-SHORT
SD
D-SHORT
SD
HIGH
SD
LOW
Input Photocurrent Swing2.2mA
A verage Photocurrent Sensitivity4µA
Peak Input Photocurrent Sensitivity8µA
Single-Ended Ou tput Voltage
Amplitude
Differential Output Vo ltage Am plitude400500600mV
Rise and Fall Time60100ps
Transimpedance Gain20k27k40kΩDifferential measurement
Ripple in Passband Transimpedance1dB
Lower -3dB Cutoff Frequency100kHz
Output Impedance50ΩSingle-ended
Input-Referred rms Noise Current500nA30kHz to 2.5GHz
Photodetector Capacitance0.40.60.8pFBias vo ltage on detector at 2.0V
Signal Detect Hysterisis124dBElectrical meas urement on SD pin
Signal Detect Assertion L evel359µA
Signal Detect Deasseration Level1.02.23.0µA
Signal Detect Asseration Level61018µA
Signal Detect Deasseration Level2.04.46.0µA
Signal Detect HIGH Logic Level
Signal Detect LOW Logic Level0.50.8V
200250300mV
V
CCS
- 0.3
Peak-to-peak AC current
amplitude
-23dBm average optical power
with a detector responsitivity of
0.8A/W.
-23dBm average optical power
with a detector responsitivity of
0.8A/W.
Single-ended peak-to-peak
measurement, I
Differential peak-to-peak
measurement, IIN >20µA.
At 2.2mAp-p input photocurrent
NOTE: (1) CAUTION: Stresses listed under “Absolute Maximum Ratings” may be applied to devices one at a time without caus-
ing permanent damage. Functionality at or above the values listed is not implied. Exposure to these values for extended
periods may affect device reliability.
Recommended Operating Conditions
Positive Voltage Supply (V
Positive Voltage Supply (V
Negative Voltage Rail (GND) ............................................................................................................................ 0V
GND1130250Negative power supply rail (typically 0V)
BG_VREF2130375Band Gap voltage reference 1.24V for testpoint, no connect
GND3130500Negative power supply rail (typically 0V)
SD_TP4130625Signal Detect test point, DO NOT CONNECT.
SD_ADJ5130750
VOUTN6137875
SD_OUT7280875
GND8405875Negative power supply rail (typically 0V)
VOUTN9530875
GND10655875Negative power supply rail (typ ically 0V)
VOUTP11780875Positive logic output (logic HIGH when photocurrent is HIGH)
GND12905875Negative power supply rail (typ ically 0V)
IMON131030875Photocurrent Monitor
VOUTP141173875Positive logic output (logic HIGH when photocurrent is HIGH)
GMD151180750Negative power supply rail (typically 0V)
CSDN161180625Test point for Signal Detect capacitor. DO NOT CONNECT.
CSDP1 71180500Test point for Signal Detect capacitor. DO NOT CONNECT.
GND181180375Negative power supply rail (typically 0V)
GND191180250Negative power supply rail (typically 0V)
GND201030125Negative power supply rail (typically 0V)
GND21905125Negative power supply rail (typ ically 0V)
FILTER22780125Photodetector cathode connection (filtered V
IN23530125Photodetector anode connection
GND24405125Negative power supply rail (typ ically 0V)
VCCS25280125Positive power supply rail for 3.3V operation
VCCD26137125Positive power supply rail for 5V operation
Pad
Number
Coordinates (µm)
XY
Description
Signal Detect threshold adjustment (see Application am d Usage
section)
Complementary logic output (logi c LOW when photocurrent is
HIGH)
Signal detect output (logic HIGH when photocurrent exceeds
)
SD
A
Complementary logic output (logi c LOW when photocurrent is
HIGH)