Single-VCO Frequency Synthesizer for Wideband UMTS Coverage
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Solution Overview
Problem
Conventional frequency generation solutions for RF communication systems, such as those used in UMTS transceivers, require multiple Voltage Controlled Oscillators (VCOs) to support a wide range of frequency bands, leading to increased silicon area usage, cost, and noise challenges, while existing Delay Locked Loop (DLL) synthesizers suffer from quantization noise and require impractically small delay increments.
Innovation Solution
A semiconductor device with synthesized frequency generation logic that uses a programmable divider and programmable oscillator control logic to generate a range of frequencies from a single VCO, allowing for frequencies that are not limited to integer multiples of the reference signal, thereby reducing the need for multiple VCOs and minimizing quantization noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple VCOs are used to support a wide range of frequency bands, then the frequency coverage is improved, but the silicon area consumption and cost increase
Solution Approach 1:
The patent implements a single VCO that can generate multiple frequency bands (up to 11 UMTS bands) by combining it with a programmable divider and delay elements. This universal frequency generation approach eliminates the need for multiple dedicated VCOs, thereby reducing silicon area while maintaining wide frequency coverage capability
Solution Approach 2:
The patent segments the frequency generation function into separate components: a single VCO for base frequency generation, a programmable divider for frequency multiplication/division, and delay elements for phase control. This segmentation allows one VCO to effectively serve multiple frequency band requirements through digital control
2Adaptability or versatility
If multiple VCOs are used to support a wide range of frequency bands, then the frequency coverage is improved, but the current consumption increases
Solution Approach 1:
A single VCO is designed to provide frequency coverage for multiple UMTS bands through digital frequency synthesis techniques. This universal VCO approach consumes less current compared to running multiple separate VCOs, each dedicated to specific frequency bands, while achieving the same overall frequency coverage
3Manufacturing precision
If delay increments are made smaller to reduce quantization noise, then the quantization noise is reduced, but the delay elements become impractically large
Solution Approach 1:
The patent transitions from purely analog delay elements to a hybrid approach combining digital delay control with analog delay circuits. The delay amount is controlled digitally through programmable logic that selects from discrete delay stages, achieving fine resolution without requiring impractically small analog delay increments
Data Source
AI summary
A semiconductor device comprises synthesized frequency generation logic arranged to receive a reference signal, and to generate a synthesized frequency signal from the reference signal. The synthesized frequency generation logic comprises programmable divider logic arranged to receive the reference signal and to generate a divided signal comprising a frequency with a period substantially equal to N times that of the reference signal, where N comprises a programmable integer value. The synthesizer frequency generation logic is arranged to generate the synthesized frequency signal comprising a frequency with a period substantially equal to 1/M that of the divided signal, where M comprises a further programmable integer value.