Tri-State Lookup Table for RF Linearity Compensation
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Solution Overview
Problem
Integrated circuits face challenges in compensating for non-ideal responses in radio-frequency devices due to substrate area limitations and non-linearity, particularly when implementing lookup tables, which require balancing area with bit resolution and often lack radiation hardening and adjustability.
Innovation Solution
A hard-wired lookup table is implemented within an integrated circuit, using a bus structure with value cells comprising open drain transistor cells, where metallization connections define the compensation function, allowing for improved digital control input resolution and radiation tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a prior art lookup table is implemented on an integrated circuit, then compensation for non-linearity is achieved, but substrate area is excessive
Solution Approach 1:
The lookup table is segmented into multiple value cells, each containing a pair of bit-control transistors. This segmentation allows the table to be implemented using fewer transistors per entry compared to conventional approaches, reducing overall substrate area while maintaining compensation functionality.
Solution Approach 2:
The value cells use open drain transistor cells with tri-state output capability, allowing dynamic configuration of the lookup table contents through metallization connections. This dynamic approach enables flexible compensation functions with reduced area requirements compared to static implementations.
2Measurement precision
If bit resolution is increased to improve compensation accuracy, then transfer response closer to ideal is achieved, but substrate area increases
Solution Approach 1:
The lookup table is divided into multiple value cells that can be independently configured. This segmentation allows high bit resolution to be achieved through clever arrangement and selection of values in the cells rather than using a straightforward proportional increase in transistor count, thereby reducing area.
Solution Approach 2:
The invention changes the implementation parameters by using metallization connections to define the compensation function rather than traditional logic gate arrangements. This parameter change enables high bit resolution with reduced area by optimizing the physical layout and connection strategy.
3Measurement precision
If lookup table components are made adjustable for tuning, then compensation accuracy is improved, but device complexity increases
Solution Approach 1:
The lookup table is pre-configured with compensation values during manufacturing through metallization connections. This preliminary action eliminates the need for post-manufacturing adjustment mechanisms, reducing device complexity while maintaining high compensation accuracy through factory-set optimal values.
Solution Approach 2:
The lookup table uses hard-wired metallization connections that are automatically configured during fabrication, making the system self-configure without requiring external adjustment mechanisms. This self-service approach reduces complexity by eliminating adjustment hardware and procedures.
Data Source
AI summary
An integrated circuit device can include a radio-frequency device and a hard-wired lookup table. The radio-frequency device can have an analog input, a digital control input, and an analog output. An unadjusted transfer response of the analog output relative to the analog input and the digital control input can differ from an ideal transfer response. The hard-wired lookup table can be connected to the digital control input of the radio-frequency device to generate a modified digital control input based on a predetermined function. This can have the effect that the adjusted transfer response of the analog output relative to the analog input and the modified digital control input is closer to the ideal transfer response than the unadjusted transfer response of the analog output relative to the analog input and the digital control input. The predetermined function can be defined by metallization connections within the integrated circuit device.