Variable Gain Amplifier Linearity Compensation Across Gain Settings
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Solution Overview
Problem
Cascode variable gain amplification circuits suffer from impedance variations that lead to waveform distortion, failing to maintain linearity across different gain settings.
Innovation Solution
A variable gain amplification circuit with a linearity compensation mechanism, comprising an amplification circuit with a lower and upper branch, amplification control circuits, and a gain adjustment circuit with adjustment transistors and a first voltage adjustment circuit, which adjusts the impedance and cross-voltage relation to maintain linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the circuit configuration is varied to adjust the gain in a cascode variable gain amplification circuit, then the gain can be changed, but the impedance varies resulting in waveform distortion and loss of linearity
Solution Approach 1:
The patent introduces a linearity compensation circuit that includes compensation transistors and control circuits as intermediary elements. These components mediate between the gain control mechanism and the output to counteract the impedance variations caused by gain adjustment, thereby maintaining waveform linearity across different gain settings
Solution Approach 2:
The patent dynamically adjusts circuit parameters including impedance and voltage relationships through the linearity compensation circuit. By changing these parameters in response to gain adjustments, the system maintains optimal linearity performance while allowing gain variability
2Adaptability or versatility
If the circuit configuration is varied to adjust the gain, then different gain levels can be achieved, but the impedance variation causes distortion of the output voltage waveform
Solution Approach 1:
The linearity compensation circuit employs feedback mechanisms where the output signal is monitored and fed back through control circuits to adjust the compensation transistors. This feedback loop detects waveform distortion caused by impedance variations and automatically compensates for it, eliminating the harmful distortion effect
Solution Approach 2:
The compensation transistors and control circuits serve as intermediary components between the gain adjustment mechanism and the output stage, isolating the output from the harmful impedance variations while still allowing gain control to function
Data Source
AI summary
The present invention discloses a variable gain amplifier circuit having linearity compensation mechanism is provided. A lower amplification transistor of a lower branch of an amplification circuit is controlled by an AC input signal. Upper amplification transistors of an upper branch generate an AC output signal at an amplification output terminal. An amplification control circuit controls the turn-on and turn-off of the upper amplification transistor according to an amplification control voltage. An inductor is electrically coupled between a power supply terminal and the amplification output terminal. In a gain adjustment circuit, each of adjustment control circuits controls the turn-on and turn-off of each of adjustment transistors according to a adjustment control voltage. A first voltage adjustment circuit adjusts an impedance of each of the adjustment transistors to further adjust an AC cross voltage relation between the lower amplification transistor and the upper amplification transistors.