Integrated LNB Down-Conversion Chip With Polyphase Image Suppression
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Solution Overview
Problem
Traditional LNB frequency down conversion circuits face issues with frequency stability due to temperature drift, occupy valuable PCB space with band-pass filters, and are cumbersome for manufacturing and debugging due to numerous discrete components.
Innovation Solution
An integrated LNB frequency down conversion chip circuit incorporating a pre-amplifier, quadrature voltage-controlled oscillator, quadrature frequency mixer, In-phase/Quadrature intermediate frequency amplifier, and polyphase filter to enhance noise suppression and eliminate minor image signals, while integrating most discrete components for improved stability and reduced PCB area usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If discrete components are used for LNB frequency down conversion, then the circuit can be easily assembled and repaired, but the frequency stability deteriorates due to temperature drift
Solution Approach 1:
The patent integrates multiple discrete components including HF amplifier, band-pass filter, DRO, frequency mixer, MF amplifier, voltage stabilizing unit, bias circuit, negative voltage generating circuit, and 22 kHz frequency detection circuit into a single integrated circuit chip. This merging eliminates temperature drift issues between discrete components and ensures consistent frequency stability while maintaining manufacturing efficiency through standardized chip production.
2Object-affected harmful factors
If passive band-pass filter is used to filter out-of-band signals, then the noise performance improves, but the PCB area occupied increases
Solution Approach 1:
The band-pass filter function is integrated directly into the IC chip alongside the frequency down conversion components. This eliminates the need for separate external band-pass filters on the PCB, reducing PCB area occupation while maintaining the noise filtering performance through on-chip signal conditioning.
3Adaptability or versatility
If numerous discrete components are used in LNB, then the circuit design is flexible, but the manufacturing and debugging complexity increases
Solution Approach 1:
All essential LNB frequency down conversion components are merged into a single integrated circuit chip, dramatically reducing the number of discrete components needed. This simplifies manufacturing assembly, reduces debugging complexity, and eliminates soldering issues associated with multiple small components while maintaining circuit functionality through integrated design.
Solution Approach 2:
The integrated circuit chip performs multiple functions including HF amplification, band-pass filtering, frequency oscillation, frequency mixing, MF amplification, voltage stabilization, bias generation, and frequency detection. This multi-functionality consolidates what would otherwise require numerous separate discrete components into a single universal chip, reducing overall system complexity.
Data Source
AI summary
The present invention discloses a type of LNB frequency down conversion integrated circuit. The present invention frequency-down-converts the RF signal with the Quadrature local oscillation signal (LO) and Quadrature Mixer. Then the 90 degree phase-shifting of the quadrature intermediate frequency (IF) signal after mixed is done by the use of passive Polyphase filter. The present invention further discloses a LNB frequency down conversion chip, a LNB frequency down circuit adopting the LNB frequency down conversion chip circuit and a method of LBN frequency down. The invention ensures the elimination of the minor image signal and the realization of the minor image suppression function.