M08035 Datasheet, PDF (22/49 Pages) M/A-COM Technology Solutions, Inc. – SD, HD, 3G Multi-rate Reclocker

Functional Description
Figure 4-3. Self Biasing the Input of M08035/M08045
AV_DDO 2.5V– 3.3V
50 Ω
0.1 µF per
AVDDI pin
AV_DDI do not supply
a voltage
50 Ω
DC coupled only,
Do not use internal
voltage regulator
Upstream
Device
M08035 /M08045
NOTE:
1. For self bias applications, no voltage must be applied to the AV_DDI pin. Every AV_DDI pin should be decoupled to GND with a 0.1 µF
capacitor as shown in Figure 4-3.
A Loss of Signal (LOS) detector monitors each input and issues an alarm when the input signal level dips below the
detection threshold set in register 06h. See Section 4.3 for more information on the LOS circuit.
In order to correct any duty cycle distortion (DCD) in the input signal, or any DC offset buildup in the internal signal
path, a DC correction loop has been added. Programming register 0Dh bit 1 to a '1' will disable the DC correction
loop for all inputs.
The M08035/M08045 include a 4:1 multiplexer. This allows any one of the four input signals to be routed to the
reclocker. By default SDI0 is selected to be routed to SDO0. The selected input can be set using MUX control
register 07h.
By default, only the selected input is powered up, with all other inputs powered down. When an input is powered
down, its associated LOS circuitry is disabled. If required, all the other inputs can also be powered up by setting
bit[3] in register 0Dh. This will allow a faster response if rapid input switching is required as there is no delay waiting
for the circuitry to power-up and adjust to the input signal, but has the disadvantage of consuming more power.
With all inputs enabled, the power consumption increases by 100 mW.
4.3
LOS (Loss of Signal)
The M08035/M08045 have integrated LOS circuits on each of their four high-speed inputs. This circuit monitors the
input amplitude and if it falls below the detection threshold it asserts the LOS alarm bit by setting this to a logic
high. These alarm bits are latched and will need to be reset with the CLR_ALARMS, register 85h, by setting bit 0 to
a high and back to a low. Hysteresis is built into the LOS circuit to avoid chattering. The LOS threshold can be set
to a different level by using the bits[7:5] in register 06h, this changes the level on all four inputs.
By default, the LOS alarm mutes the signal from that particular input. Setting register 06h bit[3] to a high will disable
this feature.
M08035, M08045 Data Sheet V1
MACOM™
22
080x5-DSH-001