Method and system for process and temperature compensation in a transimpedance amplifier using a dual replica

1. A method comprising:

in a transimpedance amplifier (TIA) circuit comprising:

a first TIA, a second TIA, and a third TIA, the first TIA comprising a fixed feedback resistance and the second and third TIAs each comprising a configurable feedback impedance, and

a gain stage with inputs coupled to outputs of the first and second TIAs and with an output coupled to the configurable feedback impedances of the second and third TIAs:

configuring a first gain level of the first TIA based on the fixed feedback resistance and a reference current applied at an input to the first TIA;

configuring a second gain level of the second and third TIAs based on a control voltage generated by the gain stage; and

amplifying a received electrical current to generate an output voltage using the third TIA.

2. The method according to claim 1 , wherein the reference current generates a reference voltage at one of the inputs of the gain stage.

3. The method according to claim 2 , wherein the reference voltage controls the output of the gain stage that is coupled to the configurable feedback impedances of the second and third TIAs.

4. The method according to claim 1 , further comprising compensating for gain level changes with temperature of the second and third TIAs via the configurable feedback impedances of the second and third TIAs, respectively.

5. The method according to claim 1 , wherein the configurable feedback impedances of the second and third TIAs each comprise a fixed resistor and a voltage-controlled resistance.

6. The method according to claim 5 , further comprising configuring the configurable feedback impedances of the second and third TIAs by configuring a gate voltage of a transistor of the voltage-controlled resistance via the output of the gain stage.

7. The method according to claim 1 , further comprising coupling the output voltage to a first input of a second gain stage wherein a second input of the second gain stage is coupled to an output of a fourth TIA.

8. The method according to claim 7 , further comprising generating a differential signal via the output voltage and an output of the fourth TIA.

9. The method according to claim 7 , further comprising configuring the output of the second gain stage by configuring an input current of the third TIA.

10. The method according to claim 1 , further comprising receiving the received electrical current from a photodetector.

11. A transimpedance amplifier (TIA) circuit comprising:

a first TIA, a second TIA, and a third TIA, the first TIA comprising a fixed feedback resistance and the second and third TIAs each comprising a configurable feedback impedance, and

a gain stage with inputs coupled to outputs of the first and second TIAs and with an output coupled to the configurable feedback impedances of the second and third TIAs, the TIA circuit being operable to:

configure a first gain level of the first TIA based on the fixed feedback resistance and a reference current applied at an input to the first TIA;

configure a second gain level of the second and third TIAs based on a control voltage generated by the gain stage; and

amplify a received electrical current to generate an output voltage using the third TIA.

12. The TIA circuit according to claim 11 , wherein the reference current generates a reference voltage at one of the inputs of the gain stage.

13. The TIA circuit according to claim 12 , wherein the reference voltage controls the output of the gain stage that is coupled to the configurable feedback impedances of the second and third TIAs.

14. The TIA circuit according to claim 11 , wherein the TIA circuit is operable to compensate for gain level changes with temperature of the second and third TIAs via the configurable feedback impedances of the second and third TIAs, respectively.

15. The TIA circuit according to claim 11 , wherein the configurable feedback impedances of the second and third TIAs each comprise a fixed resistor and a voltage-controlled resistance.

16. The TIA circuit according to claim 15 , wherein the TIA circuit is operable to configure the configurable feedback impedances of the second and third TIAs by configuring a gate voltage of a transistor of the voltage-controlled resistance via the output of the gain stage.

17. The TIA circuit according to claim 11 , wherein the TIA circuit is operable to couple the output voltage to a first input of a second gain stage wherein a second input of the second gain stage is coupled to an output of a fourth TIA.

18. The TIA circuit according to claim 17 , wherein the TIA circuit is operable to generate a differential signal via the output voltage and an output of the fourth TIA.

19. The TIA circuit according to claim 17 , wherein the TIA circuit is operable to configure the output of the second gain stage by configuring an input current of the third TIA.

20. A

transimpedance amplifier (TIA) circuit, the TIA circuit comprising:

a first TIA comprising a fixed feedback resistor and an output coupled to a first input of a first gain stage;

a second TIA comprising a first configurable impedance and an output coupled to a second input to the first gain stage; and

a third TIA comprising a second configurable impedance, an input for receiving an input electrical current, and an output that generates an output voltage of the TIA circuit,

wherein the output of the first gain stage is coupled to the first configurable impedance and the second configurable impedance for stabilizing gain of the third TIA with temperature changes.