Four-Channel Multiplexed Transimpedance Amplifier with Output Multiplexing

The LTC6561 is a low-noise four-channel, transimpedance amplifier (TIA)with 220MHz bandwidth. The LTC6561 multi-channel transimpedance amplifier’s low noise, high transimpedance, and low power dissipation are ideal for LIDAR receivers using Avalanche Photodiodes (APDs). The amplifier features 74kΩ transimpedance gain and 30µA linear input current range. Using an APD input circuit with a total capacitance of 2pF, the input current noise density is 4.5pA/√Hz at 200MHz. With lower capacitance, noise and bandwidth improve further. Only a 5V single supply is needed and the device consumes only 200mW. Utilizing the internal 4-to-1 MUX along with the LTC6561’s output MUX; multiple 4-channel LTC6561 devices can be combined to directly interface with 8, 12, 16 and 32-channel APD arrays. The LTC6561’s fast overload recovery and fast channel switchover make it well suited for LIDAR receivers with multiple APDs. Its single-ended output can swing 2VP-P on a 100Ω load. While its low impedance op amp-style output can drive back-terminated 50Ω cables.

The LTC6561 is packaged in a compact 4mm × 4mm 24-pin leadless QFN package with an exposed pad for thermal management and low inductance.

Applications

* LIDAR Receiver

* Industrial Imaging

* 220MHz –3dB Bandwidth with 2pF Input Capacitance

* Single-Ended Output

* 74kΩ Transimpedance Gain

* 4.8pA/√Hz Input Current Noise Density at 200MHz (2pF)

* 64nARMS Integrated Input Current Noise Over 200MHz (2pF)

* Linear Input Range 0µA to 30µA

* Overload Current > ±400mA Peak