Integrated sensor cuts costs

Phyworks has introduced a single chip transceiver in CMOS which combines an integrated +/-3C temperature sensor and diagnostic reporting for 10GBASE-SR and 1G to 8G Fibre Channel SFP+ optical applications. The PHY3070 can be used with an external junction-temperature monitoring transistor to improve module temperature sensing accuracy. This reduces measurement variance due to the influence of IC temperature. Integrating the sensor also cuts cost and saves space. The device combines enhanced diagnostics with a 1 to 10.6Gbps VCSEL driver and a high performance, limiting amplifier. To help reduce operating and environmental costs it has been designed to enable sub 750mW modules.

The PHY3070 replaces many functions normally handled in an external microcontroller by providing accurate readings of temperature, transmit power, receive power, bias current and supply voltage. Reporting is via the chip’s two-wire serial interface, with only a low cost 8-bit microcontroller now required for SFF-8472 compliant digital diagnostics monitoring and device setup.
The transmitter output stage will drive four-terminal VCSEL TOSAs differentially using AC coupling and provides comprehensive safety shutdown functions.

The driver delivers a maximum peak-to-peak modulation current of 12mA and offers two laser control modes: open loop or digital mean-power, the latter using an integrated automatic power control (APC) loop which further reduces the functions and cost of an external microcontroller and improves start-up time by removing an external interface and associated delay.

On the receiving side, a high performance-limiting amplifier with a 100 differential input termination is directly ac-coupled to a transimpedance amplifier. The receiver chain includes a low pass filter with programmable cut off frequency, enabling the PHY3070 to support five discrete data rates in the range 1Gbps to 10.6Gbps. The output of the PHY3070 receiver employs programmable pre-emphasis to equalize the distortion associated with the SFP+ module PCB and connector.

The PHY3070 transceiver is provided in a 32-pin 5mm x 5mm QFN package with an operating temperature range of -40C to +95C. The device is priced at $2.00 USD in volume and with its high levels of integration it offers the highest performance, lowest cost and lowest power solution available. The PHY3070 is supported by a reference module, schematics , Gerber files, SFP+ host board with GUI and firmware. The chip can also be made available as a bare die to suit specific custom build requirements