Floating-Control Multi-Stage Amplifier Without Level Shifters
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Solution Overview
Problem
Conventional multi-stage amplifier circuits suffer from bandwidth loss and increased power consumption due to the presence of extra parasitic poles and level shifter circuits, which also lead to signal distortion and stability issues.
Innovation Solution
A multi-stage amplifier circuit with a floating control circuit that uses sub-floating control circuits and AC positive feedback loops to control transistors without affecting stability, reducing bandwidth loss and power consumption by eliminating the need for extra level shifter circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a level shifter circuit is used to generate driving signals for the output stage, then the gate-source voltages of the transistors can be controlled, but extra parasitic poles are introduced which reduce the bandwidth
Solution Approach 1:
The invention extracts and eliminates the level shifter circuit from the amplifier structure, directly using the output of the pre-stage amplifier to control the output stage transistors. This removes the source of parasitic poles while maintaining the necessary voltage control function through direct coupling.
Solution Approach 2:
The invention segments the control function by using separate control paths for the upper and lower output transistors, with each transistor controlled directly by the pre-stage amplifier output without requiring a unified level shifter circuit, thereby avoiding the introduction of additional parasitic poles.
2Stability of the object's composition
If the constant offset current of the level shifter circuit is increased to ensure stability with large transistors, then stability is improved, but power consumption increases
Solution Approach 1:
By removing the level shifter circuit entirely, the invention eliminates the constant offset current requirement, thereby reducing power consumption while maintaining stability through direct control of the output stage transistors by the pre-stage amplifier.
3Ease of operation
If a level shifter circuit is used to cancel gate-source voltages, then the transistors can be driven, but gate-source voltage mismatches occur which affect the output common-mode range and increase signal distortion
Solution Approach 1:
The invention removes the level shifter circuit that caused voltage mismatches, allowing each output transistor to be controlled directly by the pre-stage amplifier output, thereby eliminating gate-source voltage mismatches and reducing signal distortion.
Data Source
AI summary
A multi-stage amplifier circuit includes a pre-stage amplifier circuit and a floating control circuit. The pre-stage amplifier circuit amplifies a voltage difference between its input terminals, to generate plural pre-stage transconductance currents flowing through corresponding plural pre-stage transconductance nodes. The floating control circuit includes: a floating reference transistor configured as a source follower and a floating amplifier. The floating amplifier and the floating reference transistor are coupled to form feedback control and to generate an upper driving signal and a lower driving signal according to a floating reference level in the floating control circuit. The upper driving signal is higher than the lower driving signal with a predetermined voltage difference. The floating control circuit is electrically connected to the plural pre-stage transconductance nodes and is floating in common mode relative to the pre-stage transconductance nodes.