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US-12627263-B1 - Systems and methods for low voltage and low power transimpedance amplifier (TIA) design

US12627263B1US 12627263 B1US12627263 B1US 12627263B1US-12627263-B1

Abstract

In part, exemplary systems and methods are disclosed for maintaining low voltage and low power in a transimpedance amplifier (TIA). One system includes a sensor (e.g., a photodetector); the TIA; and a dummy TIA. The TIA includes a front end stage, a detector, and a back end stage. In some embodiments, the front end stage is configured to receive a current output from the sensor. In many embodiments, a reading of the detector is used to monitor the current output from the sensor. The back end stage is configured to convert the current to an output voltage in various embodiments. The dummy TIA is coupled to the sensor and diverts the current output from the sensor when the current exceeds a predetermined threshold in some embodiments.

Inventors

  • Mahdi Parvizi
  • Toshira Omori
  • Bahar Jalali Farahani
  • Ricardo Aroca

Assignees

  • CISCO TECHNOLOGY, INC.

Dates

Publication Date
20260512
Application Date
20230202

Claims (20)

  1. 1 . A system for maintaining low voltage and low power in a transimpedance amplifier (TIA), the system comprising: a sensor; a main TIA comprising a front end stage, a detector, and a back end stage, wherein the front end stage is configured to receive a current output from the sensor, wherein a received signal strength indicator (RSSI) at the detector is used to monitor the current output from the sensor, wherein the back end stage is configured to convert the current output to an output voltage; and a dummy TIA coupled to the sensor, wherein the dummy TIA diverts the current output from the sensor when the current output exceeds a first predetermined threshold, and wherein comparing the RSSI to a second predetermined threshold indicates whether the current output exceeds the first predetermined threshold.
  2. 2 . The system of claim 1 , wherein the sensor comprises a photodetector.
  3. 3 . The system of claim 1 , wherein the detector comprises one or both of: a root mean square (RMS) amplitude detector, or a peak amplitude detector.
  4. 4 . The system of claim 1 , wherein the current output from the sensor exceeds the predetermined threshold when the RSSI reading is below a second predetermined threshold.
  5. 5 . The system of claim 1 , wherein the main TIA further comprises a main signal path, wherein the main signal path transfers the current output from the sensor to the front end stage of the TIA when the current output from the sensor does not exceed the predetermined threshold.
  6. 6 . The system of claim 1 , wherein the dummy TIA comprises a second front end stage and a current bleeding path, wherein the current bleeding path diverts the current output from the sensor to the second front end stage when the current output from the sensor exceeds the predetermined threshold.
  7. 7 . The system of claim 6 , wherein the dummy TIA further comprises a control gain reduction switch coupled to the current bleeding path.
  8. 8 . The system of claim 7 , wherein, when the current output from the sensor exceeds the predetermined threshold, the control gain reduction switch calibrates an extent of the current output diverted to the second front end stage.
  9. 9 . The system of claim 8 , wherein the extent of the current output diverted is proportional to an extent that the current output from the sensor exceeds the predetermined threshold.
  10. 10 . The system of claim 8 , wherein the control gain reduction switch is an n-bit digital control gain reduction switch, wherein the extent of the current output diverted is discretely proportional to an extent that the current output from the sensor exceeds the predetermined threshold, wherein the extent of the current output can be one of n discrete levels.
  11. 11 . The system of claim 7 , wherein the control gain reduction switch is controlled via a digital to analog converter (DAC).
  12. 12 . The system of claim 1 , wherein, for a given amount of current output from the sensor and diverted to each of the main TIA and the dummy TIA, an impedance of the main TIA matches, to a predetermined tolerance level, an impedance of the dummy TIA.
  13. 13 . The system of claim 1 , wherein, for a given amount of current output from the sensor and diverted to each of the main TIA and the dummy TIA, the impedance of the dummy TIA is less than the impedance of the main TIA.
  14. 14 . The system of claim 1 , wherein, for a given amount of current output from the sensor and diverted to each of the main TIA and the dummy TIA, the power consumed by the dummy TIA is less than the power consumed by the main TIA.
  15. 15 . The system of claim 1 , further comprising an automatic gain control (AGC) in electrical communication with the dummy TIA, wherein the main TIA further comprises a variable gain amplifier (VGA), the VGA in electrical communication with the front end stage and the back end stage, wherein the VGA is in electrical communication with the AGC, wherein the AGC comprises the detector.
  16. 16 . A method for maintaining low voltage and low power in a transimpedance amplifier (TIA), the method comprising: receiving, via a main signal path of the main TIA, a current output from a sensor; converting, by the main TIA, the current output from the sensor to an output voltage; determining that the current output from the sensor is above a predetermined threshold; and diverting, responsive to the current output from the sensor being above the predetermined threshold, the current output from the sensor to a dummy TIA via a current bleeding path coupled to the sensor, wherein the dummy TIA comprises a control gain reduction switch coupled to the current bleeding path.
  17. 17 . The method of claim 16 , further comprising, after the current output from the sensor is determined to be above the predetermined threshold: calibrating, via the control gain reduction switch, an extent of the current being diverted to the dummy TIA.
  18. 18 . The method of claim 17 , wherein the extent of the current being diverted is proportional to an extent that the current output from the sensor exceeds the predetermined threshold.
  19. 19 . The method of claim 17 , wherein the control gain reduction switch is an n-bit digital control gain reduction switch, wherein the extent of the current being diverted is proportional to an extent that the current output from the sensor exceeds the predetermined threshold, wherein the extent of the current is one of n discrete levels.
  20. 20 . The method of claim 16 , wherein the impedance of the TIA matches, to a predetermined tolerance level, an impedance of the dummy TIA.

Description

FIELD This disclosure relates generally to the field of communications and transimpedance amplifiers (TIA). BACKGROUND Contemporary telecommunications systems make extensive use of integrated circuits that are advantageously mass-produced in various configurations for various purposes. SUMMARY In part, in one aspect, the disclosure relates to a system for maintaining low voltage and low power in a transimpedance amplifier (TIA). In some embodiments, the system includes a sensor (e.g., a photodetector), the TIA (also referred to as “main TIA”), and a dummy TIA. In various embodiments, the main TIA includes a front end stage, a detector, and a back end stage. In some embodiments, the front end stage is configured to receive a current output from the sensor. A reading of the detector is used to monitor the current output from the sensor. In some embodiments, the back end stage is configured to convert the current to an output voltage. In various embodiments, the dummy TIA coupled to the sensor and diverts the current output from the sensor when the current exceeds a predetermined threshold. In some embodiments, the detector includes a received signal strength indicator (RSSI). In various embodiments, the RSSI may be coupled to the front end stage of the main TIA. In some aspects, the current output from the sensor may exceed the predetermined threshold when the RSSI reading is below a second predetermined threshold. Also or alternatively, the detector may be coupled to the back end stage (e.g., to read an output waveform of the main TIA). For example, the detector may further include one or both of a root mean square (RMS) amplitude detector, or a peak amplitude detector. In many embodiments, the main TIA further includes a main signal path. The main signal path may transfer the current output from the sensor to the front end stage of the main TIA when the current output from the sensor does not exceed the predetermined threshold. Furthermore, the dummy TIA includes a second front end stage and a current bleeding path in some embodiments. In many embodiments, the current bleeding path may divert the current output from the sensor to the second front end stage when the current output from the sensor exceeds the predetermined threshold. In many embodiments, the dummy TIA may include a control gain reduction switch coupled to the current bleeding path. In some embodiments, the control gain reduction switch may be digital or analog. In various embodiments, when the current output from the sensor exceeds the predetermined threshold, the control gain reduction switch calibrates an extent of the current diverted to the second front end stage. For example, in some embodiments, the extent of the current diverted may be proportional to an extent that the current output from the sensor exceeds the predetermined threshold. Also or alternatively, the control gain reduction switch may be an n-bit digital control gain reduction switch in some embodiments. In some embodiments, as the extent of the current diverted is proportional to the extent that the current output from the sensor exceeds the predetermined threshold, the extent of the current can be one of n discrete levels (e.g., corresponding to one of the n-bits of the n-bit digital control gain reduction switch). In at least one aspect, the control gain reduction switch can be controlled via a digital to analog converter (DAC). In various embodiments, for a given amount of current output from the sensor and diverted to each of the main TIA and the dummy TIA, the impedance of the dummy TIA is less than the impedance of the main TIA. Furthermore, for a given amount of current output from the sensor and diverted to each of the main TIA and the dummy TIA, the power consumed by the dummy TIA is less than the power consumed by the main TIA in some embodiments. In some embodiments, the system may further include an automatic gain control (AGC) in electrical communication with the dummy TIA, wherein the main TIA further includes a variable gain amplifier (VGA), the VGA in electrical communication with the front end stage and the back end stage, wherein the VGA is in electrical communication with the AGC, wherein the AGC includes the detector. In yet another aspect, the disclosure relates to a method for maintaining low voltage and low power in a transimpedance amplifier (TIA). In some embodiments, the method may include: receiving, via a main signal path of the main TIA, a current output from a sensor; converting, by the main TIA, the current output from the sensor to an output voltage; determining that the current output from the sensor is above a predetermined threshold; and diverting, responsive to the current output from the sensor being above the predetermined threshold, the current output from the sensor to a dummy TIA via a current bleeding path coupled to the sensor. In some embodiments, the dummy TIA may further include a control gain reduction switch coupled to the cu