Wideband differential amplifier comprising a high frequency gain-drop compensator device
AssigneeSTMicroelectronics S.r.l.
InventorsClaude Renous, François Van-Zanten
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Abstract
A wideband differential amplifier includes a first differential stage connected to a Miller stage allowing an open-loop gain increase. The Miller stage includes a current source and a resistive-capacitive network causing a feedback into the current source. The feedback includes a portion of a Miller stage output signal having a high frequency range to move a bias point of the current source within the high frequency range. Thus, a gain of the Miller stage significantly increases towards the bias point.
Claims23
A differential amplifier circuit for operating within a frequency band and having first and second input terminals and first and second output terminals, the differential amplifier circuit comprising:
- a first stage comprising
- first and second transistors,
- first and second mirror current sources for feeding said first and second transistors, respectively, and
- a control circuit for controlling said first and second mirror current sources;
- and a second stage comprising
- third and fourth transistors for receiving output signals from said first stage,
- third and fourth current sources for feeding said third and fourth transistors, respectively, and
- a resistive-capacitive circuit for feeding back a portion of the output signals for controlling said third and fourth current sources such that bias points thereof are moved to increase a gain of said second stage towards an upper end of the frequency band.
A differential amplifier circuit for operating within a frequency band and having first and second input terminals and first and second output terminals, the differential amplifier circuit comprising:
- a first stage comprising
- first and second transistors,
- first and second mirror current sources for feeding said first and second transistors, respectively, and
- a control circuit for controlling said first and second mirror current sources;
- a second stage comprising
- third and fourth transistors for receiving output signals from said first stage,
- third and fourth current sources for feeding said third and fourth transistors, respectively, and
- a resistive-capacitive circuit for feeding back a portion of the output signals for controlling said third and fourth current sources such that bias points thereof are moved to increase a gain of said second stage towards an upper end of the frequency band;
- and
- a cascode stage connected between said first stage and said second stage.
An ATM-type or XDSL-type data communicating device comprising:
- a differential amplifier circuit and operating within a frequency band and having first and second input terminals and first and second output terminals, said differential amplifier circuit comprising:
- a first stage comprising
- first and second transistors,
- first and second mirror current sources for feeding said first and second transistors, respectively, and
- a control circuit for controlling said first and second mirror current sources;
- and a second stage comprising
- third and fourth transistors for receiving output signals from said first stage,
- third and fourth current sources for feeding said third and fourth transistors, respectively, and
- a resistive-capacitive circuit for feeding back a portion of the output signals for controlling said third and fourth current sources such that bias points thereof are moved to increase a gain of said second stage towards an upper end of the frequency band.
Dependencies are inferred from the claim text.