A High Gain Common Mode Feedback Loop Applied to High Impedance Current Source Load Differential Mode Amplifying Circuit

Abstract

The invention discloses a high gain common mode feedback loop applied to a high impedance current source load differential mode amplification circuit. The feedback loop comprises a common mode signal sampling circuit, a reference voltage source, a first level differential comparison amplification circuit and a second level amplification drive circuit; two input ends of the common mode signal sampling circuit are respectively connected with two output ends of an impedance current source load differential mode amplification circuit; an averaging output of the sampling circuit is connected with the input end of the first level differential comparison amplification circuit; the reference voltage source is connected with the other input end of the first level differential comparison amplification circuit; the single end output of the first level differential comparison amplification circuit is connected with the input of the second level amplification drive circuit. Gain of the common mode feedback loop is maximized under the condition that current consumption is not increased, the stability is ensured, a common mode DC (direct current) working point is maximized and stably output, the dynamic range of an output differential signal is effectively increased, and common mode spurious noise on a power supply, the ground and a signal line are inhibited.

Description

technical field [0001] The invention relates to a high-gain common-mode feedback loop applied to a high-impedance current source load differential-mode amplifying circuit. Background technique [0002] In various high-impedance differential output amplifier circuits with current source loads, the common-mode feedback loop has become a necessary auxiliary circuit, which is used to lock the output common-mode DC operating point, effectively increase the dynamic range of the output differential signal and suppress the power / Common-mode spurious noise on the ground / signal line, and the effects of these effects mainly depend on the gain of the common-mode feedback loop. The larger the gain, the better the effect. At present, the common-mode feedback loops used in various high-impedance differential amplifier circuits with current source loads To ensure the stability of the common-mode feedback loop, the common-mode feedback loop often uses a single-stage amplifier circuit with o...

AI Technical Summary

Problems solved by technology

At present, the common-mode feedback loops used in various high-impedance differential amplifier circuits with current source loads To ensure the stability of the common-mode feedback loop, the common-mode feedback loop often uses a single-stage amplifier circuit with only a single main pole. The loop gain is often made lower to prevent self-oscillation due to the presence of multiple sub-poles at higher frequencies, which weakens the effect of the common-mode feedback loop

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