US 12,170,525 B2
Power efficient transformer-based interface circuit to interface a differential current sinking DAC to laser anode
Juergen Hauenschild, Bochum (DE); Sachidanandam Sundarraju, Nuremberg (DE); and Jan Louis Sundermeyer, Nuremberg (DE)
Assigned to CISCO TECHNOLOGY, INC., San Jose, CA (US)
Filed by Cisco Technology, Inc., San Jose, CA (US)
Filed on Nov. 23, 2022, as Appl. No. 17/993,163.
Prior Publication US 2024/0171194 A1, May 23, 2024
Int. Cl. H03M 1/66 (2006.01); H01S 5/183 (2006.01); H01S 5/50 (2006.01)
CPC H03M 1/66 (2013.01) [H01S 5/183 (2013.01); H01S 5/5027 (2013.01)] 20 Claims
OG exemplary drawing
 
1. An apparatus to interface a digital-to-analog converter to a laser, comprising:
a first cascode amplifier configured to receive as input positive and negative differential outputs of the digital-to-analog converter and to provide a positive amplified output and a negative amplified output;
a second cascode amplifier having a positive input and a negative input, the positive input being coupled to the positive amplified output of the first cascode amplifier, wherein the second cascode amplifier is configured to generate a positive amplified current at a positive amplified output and to generate a negative amplified current at a negative amplified output, wherein the positive amplified output and the negative amplified output are connected together at an output node and the positive amplified current and the negative amplified current are combined to produce an output current that is provided as input to an anode of the laser; and
a transformer coupled between the negative amplified output of the first cascode amplifier and the negative input of the second cascode amplifier.