The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 19, 2012
Filed:
Jul. 01, 2009
Radhakrishnan L. Nagarajan, Cupertino, CA (US);
Huan-shang Tsai, Cupertino, CA (US);
Radhakrishnan L. Nagarajan, Cupertino, CA (US);
Huan-Shang Tsai, Cupertino, CA (US);
Infinera Corporation, Sunnyvale, CA (US);
Abstract
Consistent the present disclosure, a receive circuit is provided that includes a balanced detector portion and a transimpedance amplifier (TIA). The anode of one photodiode is connected to the cathode of the other by a bonding pad, which supplies the sum of the currents generated in each photodiode to an input of the TIA. Thus, the TIA may, for example, have a single input, as opposed to multiple inputs, thereby reducing the number of connections so that the photodiodes and the TIA may be integrated onto a smaller die. In addition, since there are few connections, fewer TIAs are required and differential stages are unnecessary. Power consumption is thus reduced, and, since the photodiode current is fed through one input to the TIA, fewer feedback resistors are required, thereby reducing thermal noise. In addition, since the anode of one photodiode is connected to the cathode of the other, the dark current generated in each flows in opposite directions, and is therefore effectively cancelled out. Since one input is provided, impedance matching with other inputs is unnecessary, nor is additional DC biasing circuitry needed. As described in greater detail below, an example of the present disclosure includes a bonding pad, which connects the two photodiodes and provides the input current to the TIA.