RCV1551 RGR1551 AN-1125 TGR1155 MIL-STD-883C 5966-0450E - Datasheet Archive

 

155 Mb/s Fiber Optic "Light to Logic"TM Receivers for OC3/STM1 Application Note AN-1125 Introduction This application

 

RCV1551 RCV1551, RGR1551 RGR1551 155 Mb/s Fiber Optic "Light to Logic"TM Receivers for OC3/STM1 Application Note AN-1125 AN-1125 Introduction This application note details the operation and usage of the RCV1551 RCV1551 and RGR1551 RGR1551 Light to Logic SONET/SDH modules. Both models are 155 Mb/s, multi-sourced, SONET/SDH modules, capable of operating in a temperature range of -40°C to +85°C. Care should be taken to avoid transients and overvoltage. Overvoltage above the maximum specified in both the RCV1551 RCV1551 and RGR1551 RGR1551 data sheets may cause permanent damage. It should not be assumed that more than one maximum condition can be applied at a time. The RGR1551 RGR1551 has data and clock recovery function, the RCV1551 RCV1551 does not. Both parts are suitable for long reach applications. They both also have the facility of using independent biasing (0 V or -5 V) of the PIN diode to allow average power in the fiber pigtail to be sensed. In these receivers, the PIN supply provides bias and allows photocurrent measurement for monitoring purposes. It is recommended that a series inductor of at least 500 µH be inserted in the PIN bias line for optimum performance. If this facility is not required, the pin should be connected to the lowest voltage rail. The RCV1551 RCV1551 and RGR1551 RGR1551 convert optical signals into differential positive ECL (PECL) level outputs, they also provide complementary alarms to indicate loss of optical signal. Noise Immunity The receiver includes internal circuit components to filter power supply noise. The receivers are comprised of an InGaAs PIN photodiode, a high sensitivity, wide dynamic range transimpedance amplifier is capacitively coupled, in the case of the RCV1551 RCV1551, to a limiting amplifier stage. In the case of the RGR1551 RGR1551 the transimpedance amplifier is capacitively coupled to a PLL based clock recovery circuit. The latter stages of both parts convert low level signals to complementary PECL levels for RCV1551 RCV1551 data outputs and both data and clock outputs for the RGR1551 RGR1551. Under some conditions of EMI and power supply noise, external power supply filtering may be necessary. If receiver sensitivity is found to be degraded by power supply noise, the filter network shown in Figure 1, when positioned in close proximity to the device supply pins, may be used to improve performance. The values of the filter components are general recommendations and may be changed to suit a particular system environment. Shielded inductors are recommended. Electrical Characteristics Tables 5 and 6 provide a description of the function and use of each device pin for the RCV1551 RCV1551 and RGR1551 RGR1551 respectively. Data and Clock Outputs Power Supply Both receivers require a positive +5 V supply to operate all the internal circuitry. As previously indicated, the receivers have an output pin 10 that can be taken to a negative potential to externally bias the PIN diode. The part also meets specification with pin 10 grounded. The RGR1551 RGR1551 provides complementary recovered Clock outputs in addition to the data outputs provided by the RCV1551 RCV1551. These PECL outputs are 10 KH ECL compatible and must be correctly terminated as any mismatch will significantly degrade performance. Some typical termination techniques are shown in Figure 3. The receiver's Data (and RGR1551 RGR1551 Clock) outputs are not affected by the status of the loss of light alarm. Under loss of light conditions, the RGR1551 RGR1551 Clock outputs will not remain at their operating speed. Their frequency will vary as the circuit hunts for a signal to lock to. The Data outputs will switch randomly until the input signal rises to a detectable level. The RGR1551 RGR1551 CLOCK output falling edge occurs coincident with the edges of the Received Data output. The rising edge occurs in the middle of the Received Data baud period as shown in Figure 2. 1.0 µH Pin 11 10 µF 100 nF +5 V 100 nF Figure 1. BAUD INTERVAL V OH RD V OL V OH Layout Due to the relatively high frequencies and low noise levels involved, it is important that good RF techniques are used for the PCB layout. The use of ground planes and 50 ohm transmission line interconnects is required for PECL outputs. Jitter Tolerance SONET standards currently specify jitter tolerance as the jitter amplitude that increase by 1 dB the signal input level at which the network element will operate at a BER of 1 x 10-10. Table 1 shows a typical jitter tolerance performance for the RGR1551 RGR1551. The envelope column represents the minimum amount of jitter the device must tolerate at a given frequency. RD V OL V OH CLK V OL V OH CLK V OL CLOCK PERIOD Figure 2. Relative timing relationship between output re-timed data and recovered clock signals Table 1. Typical Jitter Tolerance Results for RGR1551 RGR1551 Frequency (kHz) 1 2 7 50 500 1000 2 Envelope (UI) 1.5 1.5 1.5 0.15 0.15 0.15 -40°C 24 18 4.8 0.75 0.39 0.39 Results (UI) @ -5 V +25°C +85°C 24 24 19 17 4.8 4.4 0.77 0.71 0.41 0.39 0.41 0.39 Option 1 - 50 ohms PECL Connection +5 V Z1 +5 V D R1 0V Z1 P-ECL VCC -2 V D -5 V R1 * 0V VCC -2 V Z1 = 50 ohm Interconnect R1 = 50 ohms * Photodiode Bias Option (0 V or -5 V) Option 2 - 50 ohms ECL Connection 0V Z1 +5 V D C1 0V -5 V Z1 0V D EC L R2 R1 C1 V BB R2 R1 * -5.2 V 0V Z1 = 50 ohm Interconnect R1 = 510 ohms R2 = 50 ohms C1 = 100 nF * Photodiode Bias Option (0 V or -5 V) 0V Option 3 - Differential Connection to ECL Z1 +5 V D C1 R2 R1 0V -5 V Z1 0V D 0V C1 R1 * 0V C1 = 100 nF R1 = 510 ohms R2 = 50 ohms Z1 = 50 ohm Interconnect * Photodiode Bias Option (0 V or -5 V) Figure 3. RCV1551 RCV1551 and RGR1551 RGR1551 termination options 3 50 Terminated Test Equipment R2 0V Notes: 1. Options 1 to 3 show termination configurations for DATA and DATA outputs. CLOCK and CLOCK outputs should be terminated in the same way. 2. 50 to -2 V may be replaced by the Thevenin equivalent 82 to VCC and 130 to VEE. Alarm Output Table 2. Typical Power Consumption The RCV1551 RCV1551 and RGR1551 RGR1551 contain circuitry to detect loss of input optical signal. The circuit monitors signal amplitude at the output of the preamplifier and therefore detects loss of modulation as well as loss of optical signal. -40°C +25°C +85°C The RGR1551 RGR1551 provides complementary CMOS alarm outputs and requires no output termination. The RCV1551 RCV1551 provides complementary PECL alarm outputs which require standard PECL termination's. The ALARM outputs (pins 12 and 14) are complementary with a HIGH level indicating normal operation and a LOW level indicating loss of light or modulation. -5 V +5 V Total Power Dissipation 1 mA 1 mA 1 mA 110* mA 120* mA 130* mA 555 mW 605 mW 655 mW *Current with DATA, DATA, ALARM, ALARM terminated as shown in Figure 3 is not included. Table 3. Fiber Pigtail Typical Parameters Core Diameter Cladding Diameter Concentricity Nominal Coating Diameter Outer Cladding Diameter PIN Photocurrent Monitoring Power Dissipation/Heatsinking The current drawn from pin 10 will be proportional to the optical signal level at the device. Additional circuitry may be added to use this as a means of actively monitoring the optical power. The current drawn from pin 10 will be approximately 1 nA for no signal rising to 250 µA at maximum input power. Responsivity of the pin diode is between 0.7 A/W and 1.0 A/W. The RCV1551 RCV1551 and RGR1551 RGR1551 are 20 pin DIP packaged components. The maximum operating temperatures are the maximum ambient temperatures. The typical power consumption is shown in Table 2. Care should be taken to avoid injecting noise onto this pin. A low impedance current measuring source should be used to minimize voltage drop. 4 Wavelength Range The RCV1551 RCV1551 and RGR1551 RGR1551 contain a planar InGaAs PIN photodiode and will detect an optical signal in the range 1200 nm to 1600 nm. Over this range the performance is substantially unchanged. However, due to the normal change in the PIN diode responsivity with wavelength, the sensitivity is likely to increase slightly (