VCO Control Voltage Compensation at Low Supply Voltage
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Solution Overview
Problem
Voltage-controlled oscillators (VCOs) in portable or wearable electronic devices face challenges with voltage headroom due to temperature and supply voltage variations, especially at low supply voltages, which limits their frequency range and power efficiency.
Innovation Solution
Incorporating a voltage-to-current converter, a current-controlled oscillator, and a compensation circuit that generates currents varying in opposite directions to temperature and supply voltage changes, stabilizing the first voltage and enabling multiple frequency points at low supply voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If low supply voltage is provided to VCO to reduce power consumption, then power efficiency is improved, but voltage headroom becomes insufficient leading to limited frequency range
Solution Approach 1:
The patent changes the operating parameters of the VCO by introducing a compensation current that dynamically adjusts the control voltage range. This allows the VCO to maintain its frequency tuning capability across the full range even when operating at low supply voltages, effectively decoupling the frequency range from the supply voltage level.
Solution Approach 2:
The compensation circuit acts as an intermediary element that mediates between the low supply voltage condition and the VCO's frequency tuning requirement. By injecting a compensation current proportional to the control voltage, it creates an artificial voltage headroom that enables full frequency range operation without requiring high supply voltage.
2Duration of action of stationary object
If low supply voltage is used to achieve low power consumption, then battery life is extended, but voltage headroom limitation occurs
Solution Approach 1:
The compensation circuit implements a feedback mechanism where the compensation current is generated based on the control voltage applied to the VCO. This feedback loop ensures that the control voltage remains within the valid range required for proper VCO operation, thereby maintaining reliability even at low supply voltages.
Solution Approach 2:
The patent dynamically adjusts the effective control voltage range by adding a compensation component that scales with the control voltage. This parameter transformation allows the system to maintain adequate voltage headroom for reliable operation while keeping the actual supply voltage low to extend battery life.
3Loss of energy
If control voltage range is limited at low supply voltage, then power consumption is reduced, but frequency tuning capability is degraded
Solution Approach 1:
The compensation current serves as an intermediary that bridges the gap between the limited control voltage range at low supply voltage and the full frequency tuning capability requirement. By adding this intermediate compensation signal, the system achieves both low power consumption and full frequency tuning range.
Data Source
AI summary
Some aspects of the present disclosure relate to an apparatus, a PLL and an electronic device. The apparatus comprises a voltage-to-current (V2I) converter, a current controlled oscillator and a compensation current. The V2I converter is operable to receive a first voltage and generate a first current based on the first voltage. The current controlled oscillator is coupled to the V2I converter and operable to generate an oscillation signal based on a second current from or to the V2I converter. The compensation circuit is coupled to the V2I converter and operable to receive a third current from or to the V2I converter. The second and third currents vary in response to at least one of temperature variation and supply voltage variation of the apparatus. Variation direction of the third current is opposite to variation direction of the second current and different frequencies may be provided for a low supply voltage domain.