On-Chip RF Filter Amplifier for Multi-Standard Receiver Front Ends
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Solution Overview
Problem
Current radio receiver technologies require multiple external RF pre-selection filters for multi-standard or multi-mode applications, leading to increased cost, complexity, and noise figure due to fixed center frequencies of SAW/BAW filters, which cannot be integrated on silicon, and result in reduced integration and higher bills-of-material for printed circuit boards.
Innovation Solution
An integrated circuit design incorporating a radio-frequency amplifier with an on-chip RF filter, where the amplifier input impedance is matched to the antenna impedance, and the feedback signal from the filter provides attenuation of out-of-band signals, using switching mechanisms controlled by oscillator signals to selectively connect impedances and achieve frequency selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple external RF pre-selection filters are used for multi-standard applications, then frequency selectivity is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines the RF filter and amplifier into a single integrated circuit module, where the filter is implemented using on-chip inductors and capacitors rather than external SAW/BAW filters. This merging eliminates the need for multiple external filters and switches, reducing device complexity while maintaining multi-standard reception capability through electronic tuning of the integrated filter parameters.
Solution Approach 2:
The integrated RF filter amplifier is designed to handle multiple frequency standards (GSM, WCDMA, LTE) within a single device. The filter uses voltage-controlled oscillators and variable capacitors to dynamically adjust its frequency response, providing universal functionality across different communication standards without requiring separate external filters for each standard.
2Object-affected harmful factors
If external RF pre-selection filters are used, then out-of-band signal filtering is improved, but noise figure increases due to filter loss
Solution Approach 1:
The amplifier is integrated within the same chip as the RF filter, allowing the amplifier to be positioned immediately after the filter in the signal path. This integration minimizes the distance between filter output and amplifier input, reducing additional loss paths. The amplifier's high gain compensates for the filter's inherent loss, maintaining a lower overall noise figure compared to discrete external filter configurations.
3Adaptability or versatility
If multiple RF input pins are used for multi-standard reception, then adaptability is improved, but device complexity and integration level decrease
Solution Approach 1:
The integrated RF filter amplifier provides a single universal RF input that can handle multiple frequency bands and modes. The device achieves multi-standard reception capability through internal electronic tuning mechanisms, including voltage-controlled oscillators and variable reactive elements, rather than requiring separate physical input pins for each standard. This single input approach maintains high integration while providing adaptability across GSM, WCDMA, LTE and other standards.
Data Source
AI summary
An integrated circuit for a radio receiver comprising a radio-frequency amplifier and a radio-frequency filter is described. The amplifier receives radio-frequency signals from an antenna, the filter is connected to the amplifier output, and the output of the filter is provided to a processing stage of the receiver. The amplifier comprises an amplifying stage controlled by a radio-frequency input signal and a signal fed back from the filter. The amplifier input impedance is substantially matched to the antenna impedance at a frequency band of interest. The signal fed back from the filter providing attenuation of signals outside the frequency band of interest at the amplifier input. The filter comprises one or more filter components. A filter component comprises a first input and a second input for receiving the amplifier output, a first switch arranged to selectively connect the first input to a first impedance, a second switch arranged to selectively connect the first input to a second impedance, a third switch arranged to selectively connect the second input to the first impedance, and a fourth switch arranged to selectively connect the second input to the second impedance. The first and fourth switches are controlled by a first oscillator signal and the second and third switches are controlled by a second oscillator signal that is 180° out of phase with the first oscillator signal.