By Linear Technology 27
ADI's LTC6560 and LTC6561 are low-noise, transimpedance amplifiers (TIA) with 220 MHz bandwidth. The LTC6560 is a single channel, and the LTC6561 is a four (quad) channel TIA ideal for LIDAR receivers using avalanche photodiodes (APDs). These amplifiers feature 74 kΩ transimpedance gain and 30 μA linear input current range. Using an APD with a total input capacitance of 2 pF, the input current noise density is 4.8 pA/√Hz and 4.5 pA/√Hz respectively at 200 MHz. With lower capacitance, noise, and bandwidth improve further. The LTC6560 operates from a single 5 V supply and consumes only 90 mW. The LTC6561 consumes 200 mW.
Utilizing the LTC6560's output MUX, multiple LTC6560 devices can be combined to a single output, whereas the LTC6561 has a 4-to-1 MUX. LTC6561 devices can be combined to directly interface with 12-channel, 16-channel, and 32-channel APD arrays. The LTC6560's and LTC6561's fast overload recovery and fast output MUXing make them well suited for LIDAR receivers with multiple APDs. These amplifiers single-ended output can swing 2 VP-P on a 100 Ω load. Its low impedance op amp style output has been designed to drive back-terminated 50 Ω cables.
The LTC6560 and LTC6561 are packaged in 16-pin and 24-pin leadless QFN packages with exposed pads for thermal management and low inductance.