Parallel Variable Gain Amplifier for High-Frequency Gain Resolution
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Variable gain amplifiers in the high-frequency region suffer from degraded characteristics due to increased parasitic capacitance with a large number of transistors, requiring a large number of transistors for improved gain resolution.
Innovation Solution
A variable gain amplifier design with a signal transmission circuit having parallel amplifying transistor units, a load circuit, a signal short circuit, and a constant-current source circuit, where a transistor control circuit selectively turns on transistor units to achieve high gain resolution with a smaller number of transistors, maintaining excellent high-frequency characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a large number of transistors are used to improve gain resolution, then gain accuracy is improved, but parasitic capacitance increases causing degradation of high-frequency characteristics
Solution Approach 1:
The signal transmission circuit is divided into multiple parallel branches, each containing a transistor unit. By segmenting the overall gain control into discrete parallel paths, the patent achieves fine gain resolution through selective activation of individual units rather than requiring a single large complex transistor structure. This segmentation allows gain adjustment while maintaining lower parasitic capacitance per branch.
Solution Approach 2:
The patent transitions from a single-series transistor configuration to a multi-branch parallel configuration, adding a dimensional aspect to the circuit topology. This dimensional change enables simultaneous achievement of high gain resolution (through multiple controllable branches) and reduced parasitic capacitance (by distributing the total transistor count across parallel paths rather than stacking them in series).
2Measurement precision
If a large number of transistors are used to improve gain resolution, then gain accuracy is improved, but device complexity increases
Solution Approach 1:
Multiple transistor units are merged into parallel branches where each branch processes a portion of the signal. The merging of these parallel paths at the output node allows the system to achieve high gain resolution through cooperative operation of multiple simpler units rather than relying on a single complex transistor structure, thereby reducing overall device complexity while maintaining precision.
Solution Approach 2:
The circuit employs dynamic control of transistor switching states to achieve variable gain. By dynamically activating or deactivating specific transistor units in each parallel branch based on desired gain levels, the system achieves fine gain resolution through temporal and spatial control rather than requiring all transistors to be permanently configured in a complex fixed structure, thus reducing device complexity.
Data Source
AI summary
A variable gain amplifier (1) includes: a signal transmission circuit (10, 20) including amplifying transistor units (111 to 11N, and 211 to 21N) connected in parallel between a signal input port (2P, 2N) and a signal output port (3P, 3N); a load circuit (40) connected between a supply line of power supply voltage (VDD) and an output end of the signal transmission circuit (10, 20); a signal short circuit (30) including a short-circuit transistor unit (31) connected between the supply line of the power supply voltage (VDD) and an input end of the signal transmission circuit (10, 20), a constant-current source circuit (42), and a transistor control circuit (46). The transistor control circuit (46) selects transistor units to be turned on, from among the amplifying transistor units (111 to 11N, and 211 to 21N) and the short-circuit transistor unit (31), and supplies control voltages for turning on the selected transistor units.