Differential Amplifier Current Switching for Common-Mode Gain Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Amplifier circuits in semiconductor integrated circuits face challenges in maintaining small signal gain and signal band integrity due to fluctuations in input common-mode voltage, leading to potential deterioration in performance across varying power source voltages.
Innovation Solution
The implementation of a fully differential amplifier circuit with a detection circuit that controls electric current distribution between N-channel and P-channel input sections based on input common-mode voltage, using switch elements and multiple current sources to maintain optimal gain and signal band across different operation regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional amplifier circuit is used, then the circuit structure is simple, but the small signal gain and signal band deteriorate when input common-mode voltage fluctuates
Solution Approach 1:
The amplifier circuit dynamically adjusts the operating regions of N-channel and P-channel differential amplifier sections based on input common-mode voltage levels. A detection circuit monitors the common-mode voltage and controls switch elements to redistribute electric current between the two amplifier sections, ensuring optimal performance across varying voltage conditions without requiring a completely complex circuit redesign
Solution Approach 2:
The invention changes the operating parameters (electric current distribution, operating region) of the amplifier sections based on detected input common-mode voltage levels. By adjusting which section operates in saturation region and which in triode region according to voltage thresholds, the circuit maintains stable small signal gain and signal band across different power source voltages
2Reliability
If electric current is increased to maintain gain, then small signal gain is improved, but electric power consumption increases
Solution Approach 1:
The detection circuit monitors input common-mode voltage and dynamically adjusts the electric current distribution between N-channel and P-channel amplifier sections. When one section operates in saturation region, it receives higher current to maintain gain, while the other section operates in triode region with lower current, thus maintaining gain stability without excessive power consumption across all voltage conditions
Data Source
AI summary
According to one embodiment, the amplifier circuit includes a first and second differential amplifier. The first differential amplifier includes first and second transistors, a first current source, and a second current source that is configured to supply a current to the first and second transistors via a first switch element. The second differential amplifier includes third and fourth transistors, a third current source, and a fourth current source that is configured to supply a current to the third and fourth transistors via a second switch element. A first signal is input to the first and third transistors. The first switch elements are controlled by third and fourth signals, respectively. The third signal and the fourth signal are complementary.