Back-Gate Differential Power Amplifier for Parasitic Neutralization
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Solution Overview
Problem
Existing RF/mmWave differential power amplifiers suffer from low gain, poor linearity, complex circuit layout, and increased parasitic charges due to cross-over routings, which degrade performance and efficiency.
Innovation Solution
A back-gate controlled differential circuit with auxiliary devices and a differential pair of transistors on a fully depleted semiconductor-on-insulator substrate, utilizing back-gate controls for gain boost and parasitic neutralization, maintaining independent front gate operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If two-cross capacitors are used to cancel phase delay, then gain is improved, but linearity is degraded due to capacitance variation with signal swing level
Solution Approach 1:
A back-gate controlled auxiliary transistor circuit is introduced as an intermediary mechanism to neutralize the parasitic capacitance effects of the two-cross capacitors. The auxiliary transistors are configured to provide counteracting capacitance that cancels the signal swing-dependent capacitance variation, thereby maintaining linearity while preserving the gain enhancement provided by the two-cross capacitor structure.
2Power
If reference source with two-cross capacitors is used, then gain is improved, but circuit complexity increases due to cross-over routings and parasitic charges
Solution Approach 1:
The auxiliary transistor circuit is merged with the existing two-cross capacitor structure by integrating the back-gate controlled devices directly into the signal path. This combination allows the parasitic neutralization function to be performed within the existing circuit topology without requiring separate neutralization circuits, thereby limiting the increase in complexity while achieving gain improvement.
3Power
If floating source circuit is used, then gain is improved, but oscillations increase at high swing levels
Solution Approach 1:
The back-gate controlled auxiliary transistors are configured to provide preliminary counter-action to the oscillatory tendencies that arise in floating source circuits at high swing levels. By pre-establishing the parasitic neutralization effect through the back-gate control mechanism, the circuit is stabilized before oscillations can develop, allowing high gain operation without excessive oscillations.
Data Source
AI summary
The present disclosure relates to semiconductor structures and, more particularly, to a differential circuit with automatic parasitic neutralization and gain boost and methods of manufacture. The structure includes a plurality of auxiliary circuit devices with back-gate controls to perform a boost gain, and a differential pair of circuit devices which are connected to the auxiliary circuit devices.