Envelope Tracking Voltage Circuit With High-Order Delay Compensation
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Solution Overview
Problem
Envelope tracking (ET) amplifier systems in mobile communication devices face efficiency and linearity degradation due to group delay fluctuations caused by trace inductance, especially at higher modulation bandwidths, leading to increased power consumption and thermal dissipation.
Innovation Solution
An ET voltage tracker circuit is introduced, featuring a target voltage processing circuit that pre-processes time-variant target voltages using high-order transfer functions, such as second-order complex-pole transfer functions, to maintain group delay flatness and improve temporal alignment between the time-variant voltage and target voltage, thereby enhancing efficiency and linearity across wider modulation bandwidths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the modulation bandwidth is increased to achieve higher data rates, then the output power of RF signals can be increased, but group delay fluctuations caused by trace inductance worsen, leading to efficiency and linearity degradation
Solution Approach 1:
The patent applies preliminary action by pre-processing the target voltage envelope signal through a transfer function circuit before it reaches the power amplifier. This pre-processing compensates for anticipated group delay effects, ensuring that the voltage envelope remains temporally aligned with the RF signal even at higher modulation bandwidths, thereby preventing efficiency and linearity degradation
2Power
If sophisticated power amplifiers are employed to increase output power of RF signals, then higher data rates can be achieved, but power consumption and thermal dissipation increase
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the supply voltage to the power amplifier based on the instantaneous power envelope requirements. By using envelope tracking to vary the voltage parameter in real-time, the amplifier operates more efficiently at lower power levels while still achieving high peak output power when needed, thereby reducing overall power consumption and thermal dissipation
3Speed
If the modulation bandwidth is increased to achieve higher data rates, then the output power of RF signals can be increased, but thermal dissipation increases
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the supply voltage to the power amplifier based on the instantaneous power envelope requirements. By using envelope tracking to vary the voltage parameter in real-time, the amplifier operates more efficiently at lower power levels while still achieving high peak output power when needed, thereby reducing overall power consumption and thermal dissipation
Data Source
AI summary
An envelope tracking (ET) voltage tracker circuit is provided. The ET voltage tracker circuit is configured to generate a time-variant voltage based on a time-variant target voltage, which further corresponds to a time-variant power envelope of a radio frequency (RF) signal. The time-variant voltage may be provided to an amplifier circuit(s) for amplifying the RF signal. The ET voltage tracker circuit includes a target voltage processing circuit configured to pre-process the time-variant target voltage. More specifically, the target voltage processing circuit is configured to pre-process the time-variant target voltage based on a high-order transfer function when the time-variant target voltage corresponds to a higher modulation bandwidth (e.g., >80 MHz). As a result, it may be possible to improve temporal alignment between the time-variant voltage and the time-variant target voltage at the amplifier circuit(s), thus allowing the amplifier circuit(s) to operate with improved efficiency and linearity.