Micrel touts high-sensitivity post amplifiers for optical receivers

Dec. 17, 2007

DECEMBER 17, 2007 -- The new devices are targeted at applications using low-cost transimpedance amplifiers and/or low gain PIN diodes, which occur in a wide variety of data and telecomm markets including PON, Gigabit Ethernet, SFP/SFF optical transceivers, 1X and 2X Fiber Channel, and SONET/SDH (OC-3/-12/-24/-48 and STM -1/-4/-8/-16 data rates).

DECEMBER 17, 2007 -- Micrel Inc. (search for Micrel) today added two new products to its growing family of Post Amplifiers. The SY88343HL and SY88289HL are high-sensitivity, low-power CML limiting post amplifiers, designed with twice the signal gain of the previously announced SY88343DL and SY88289CL, say company representatives.

The new devices are targeted at applications using low-cost transimpedance amplifiers and/or low gain PIN diodes, which occur in a wide variety of data and telecomm markets including PON, Gigabit Ethernet, SFP/SFF optical transceivers, 1X and 2X Fiber Channel, and SONET/SDH: OC3/12/24/48 - STM 1/4/8/16 data rates. Both devices are currently in volume production with pricing for 1K quantities starting at $2.49.

"Higher gain, high-sensitivity post amplifiers exhibit better Bit Error Rate (BER) performance as a result of bigger eye opening when detecting and receiving very weak signals," explains Thomas S. Wong, vice president, high-bandwidth products for Micrel. "These devices are recommended for systems that have stringent BER and low cost requirements."

In a fiber-optic module, the devices connect to typical trans-impedance amplifiers (TIAs). The linear signal output from TIAs can contain significant amounts of noise and may vary in amplitude over time. The SY88289HL and SY88343HL quantize these signals and output them in low-noise CML-level waveforms. The SY88343HL and SY88289HL both feature high input sensitivity and can amplify input signals as small as 4 mVpp to drive CML/PECL devices. The SY88343HL has the same footprint as all other Micrel Post Amplifiers, which allows for flexible upgrades and interchangeability, says the company.

According to Micrel, the new devices also feature high-sensitivity Loss-of-Signal circuits, which are ideal for detecting very small input signals. The new Post Amplifiers are intended for applications where Receiver Optical Subassemblies (ROSAs) with low-cost/low-gain transimpedance amplifiers and/or a PIN Photodiodes are used. The devices have wide bandwidth, high gain, and are optimized to operate over a range of data rates, from 155 Mbits/sec to 3.2 Gbits/sec.

Both Post Amplifiers have chatter-free open collector TTL LOS outputs with adjustable LOS level threshold. The ICs can amplify as low as 4-mv signals to drive devices with CML and PECL inputs. Each device operates from a single 3.3-V power supply over temperatures ranging from -40 ° C to +85 ° C and come in a tiny 3-mm x 3-mm 16-pin MLF package.

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