Differential gm-boosting circuit and applications
View Patent ↗A fully-differential circuit includes a differential gm-boosting circuit and/or a differential output circuit. The use of differential gm-boosting and output circuits improves input common-mode and power-supply noise rejection relative to the prior art. The fully differential gm-boosted circuit may be used in a wide variety of applications.
1. An electronic circuit comprising:
a pair of differential gm-boosted input transistors; and
a differential gm-boosting circuit coupled between source and drain terminals of the pair of differential gm-boosted input transistors configured to boost a gm of the pair of differential gm-boosted input transistors such that the electronic circuit is fully differential;
wherein the differential gm-boosting circuit includes a mirrored pair of gm-boosting components and a current source shared by the mirrored pair of gm-boosting components.
2. The electronic circuit of claim 1 , wherein the electronic circuit is configured to receive a differential voltage input.
3. The electronic circuit of claim 1 , wherein the electronic circuit is configured to receive a differential current input.
4. The electronic circuit of claim 1 , wherein the electronic circuit is configured to generate a differential voltage output.
5. The electronic circuit of claim 1 , wherein the electronic circuit is configured to generate a differential current output.
6. The electronic circuit of claim 1 , wherein a differential current input is received at a source or at a drain of the gm-boosted transistors.
7. The electronic circuit of claim 1 , wherein the gm-boosting circuit is responsive to a difference in voltage between sources or between drains of the pair of gm-boosted transistors.
8. The electronic circuit of claim 1 , further comprising:
a pair of mirrored resistors each disposed between a source of one of the pair of differential gm boosted transistors and an output of the differential gm-boosting circuit, respectively.
9. The electronic circuit of claim 1 , further comprising:
a resistor disposed between sources of the pair of differential gm boosted input transistors.
10. The electronic circuit of claim 1 , further comprising:
a pair of mirrored resistors each disposed between an input of the electronic circuit and a source of one of the input gm-boosted transistors, respectively.
11. The electronic circuit of claim 1 , further comprising a fully differential output circuit configured to provide a differential output proportional to a differential input received by the fully-differential gm-boosted circuit.
12. The electronic circuit of claim 11 , wherein the output circuit includes a current source shared by a mirrored pair of output transistors.
13. The electronic circuit of claim 12 , wherein each of the output transistors is configured to provide one side of a differential output of the circuit, respectively.
14. The electronic circuit of claim 1 , further comprising a common-mode feedback circuit.
15. The electronic circuit of claim 1 , wherein the gm-boosting circuit is configured such that power supply noise from a power supply of the gm-boosting circuit is rejected from an output of the electronic circuit.
16. A differential amplifier comprising:
a first fully-differential gm-boosted circuit;
a second fully-differential gm-boosted circuit;
a plurality of switches configured to control gain of the differential amplifier by selectively including the second fully-differential gm-boosted circuit in an output path of the differential amplifier; and
a digital logic circuit configured to control the plurality of switches, the digital logic circuit and the first fully-differential gm-boosted circuit being disposed on a same semiconductor substrate.
17. The differential amplifier of claim 16 , wherein the first fully-differential gm-boosted circuit includes a current source shared by a mirror pair of output components.
18. The differential amplifier of claim 17 , wherein each of the output components is configured to provide one side of a differential output of the first fully-differential gm-boosted circuit respectively.
19. The differential amplifier of claim 16 , wherein the differential amplifier is configured to receive a differential voltage input and to supply a differential current output.
20. The differential amplifier of claim 1 , wherein the differential amplifier is configured to receive a differential voltage input and to supply a differential voltage output.
21. The differential amplifier of claim 16 , wherein the differential amplifier is configured to receive a differential voltage input and to supply a differential current output.
22. The differential amplifier of claim 16 , wherein the differential amplifier is configured to receive a differential current input and to supply a differential voltage output.
23. The differential amplifier of claim 16 , wherein the differential amplifier is configured to receive a differential current input and to supply a differential current output.
24. An integrated circuit comprising:
a signal generation circuit for generating a differential input signal;
a first fully-differential gm-boosted circuit configured to receive the differential input signal and to supply a differential analog output signal along an output path;
a second fully-differential gm-boosted circuit configured to receive the differential analog output signal and to supply an additional differential analog output signal along the output path, the first and second fully-differential gm-boosted circuits and the signal generation circuit being disposed on a same semiconductor substrate; and
a switch configured to selectively include the second fully-differential gm-boosted circuit in the output path.
25. The integrated circuit of claim 24 , further comprising a digital logic circuit configured to control the switch and disposed on the same semiconductor substrate.
26. The integrated circuit of claim 24 , wherein the first fully-differential gm-boosted circuit include a fully-differential transconductor.
27. A method comprising:
receiving a differential input at a pair of differential gm-boosted input transistors;
boosting the gm of the differential gm-boosted input transistors using a differential gm-boosting circuit coupled between source and drain terminals of the pair of differential gm-boosted input transistors, the differential gm-boosting circuit comprising a current source shared by a pair of mirrored gm boosting components; and
providing a differential output proportional to the differential input.
28. The method of claim 27 , wherein providing the differential output includes providing current from a shared current source to a mirrored pair of output components.
29. The electronic circuit of claim 1 , wherein the gm-boosting circuit includes a differential voltage to current converter.