Transistor-Cascaded Circuit With AC Enhancement for Bias Shift Loss
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Solution Overview
Problem
Existing amplifier circuits with parasitic capacitors experience signal attenuation during bias voltage adjustment, leading to reduced bandwidth and performance, especially when operating at low supply voltages.
Innovation Solution
A transistor-cascaded circuit with an AC signal enhancement circuit that compensates for signal attenuation by sampling the voltage difference between differential input signals, using capacitors and switches to enhance the AC signal without significantly increasing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a level shifter is used to adjust the bias voltage level of input signals to ensure optimal transistor operation, then transistor performance is improved, but the input signal undergoes attenuation due to parasitic capacitors, reducing overall bandwidth and amplifier performance
Solution Approach 1:
An AC signal enhancement circuit is introduced as an intermediary between the level shifter and the transistors. This circuit uses capacitors and switches to detect the voltage difference between differential input signals and generate an enhancement signal that compensates for the attenuation caused by parasitic capacitors, thereby restoring the AC signal magnitude while maintaining the bias adjustment function
Solution Approach 2:
The AC signal enhancement circuit implements a feedback mechanism by continuously monitoring the voltage difference between the differential input signals and adjusting the enhancement signal accordingly. This feedback loop ensures that the AC signal attenuation is dynamically compensated, maintaining signal integrity across varying operating conditions
2Power
If multiple transistors are used in the input stage to increase transconductance value, then amplifier gain is improved, but the complexity of bias voltage management increases, requiring additional level shifters and signal enhancement circuits
Solution Approach 1:
The AC signal enhancement circuit serves multiple functions simultaneously: it compensates for signal attenuation, maintains AC signal magnitude, and works seamlessly with the level shifter to manage bias voltages. This multi-functionality reduces the need for separate compensation circuits and simplifies the overall bias management architecture
Solution Approach 2:
The level shifter and AC signal enhancement functions are merged into a closely integrated circuit architecture. The enhancement circuit shares capacitors and switches with the level shifter, allowing both bias adjustment and signal compensation to be achieved through a unified structure rather than separate independent circuits
Data Source
AI summary
A transistor-cascaded circuit is provided. The transistor-cascaded circuit includes a first transistor, a second transistor, a level shifter and an alternating current (AC) signal enhancement circuit. The level shifter is configured to receive a first input signal of a pair of differential input signals and shift the first input signal to a shifted bias voltage level, in order to generate a shifted input signal to at least one of a gate terminal of the first transistor and a gate terminal of the second transistor. In addition, the AC signal enhancement circuit is configured to enhance an AC signal of the shifted input signal according to a voltage difference between the first input signal and a second input signal of the pair of differential input signals. More particularly, one of the first transistor and the second transistor is an N-type transistor, and the other one is a P-type transistor.