How a Radio Amplifier Saves Energy by Sharing Work

This patent describes a power amplifier design that dynamically adjusts the power supplied to two amplifier stages based on the strength of the incoming radio signal, making it more efficient.

What it covers

This patent describes a power amplifier that improves efficiency by dynamically adjusting how two internal amplifiers operate. It starts by splitting an incoming radio frequency (RF) signal into two parts: an "in-phase" signal and a "quadrature phase" signal using a power divider (Claim 1). A "carrier amplifier" boosts the in-phase signal, and a "peaking amplifier" boosts the quadrature phase signal (Claim 1). The clever part is how the power supplied to these amplifiers (their "bias inputs") is controlled. As the strength of the incoming RF signal changes, the bias to the carrier amplifier decreases while the bias to the peaking amplifier increases (Claim 1). This ensures that the amplifiers only work as hard as needed, saving energy. Finally, the boosted signals are combined to create the strong output signal (Claim 1). For example, when a cell phone transmits a weak signal, the carrier amplifier might handle most of the work, but for a strong signal, the peaking amplifier kicks in more to help.

What it doesn't cover

• —Does not cover power amplifiers that use only a single amplifier stage.
• —Does not cover power amplifiers where the bias inputs for the carrier and peaking amplifiers are fixed or adjusted independently without the inverse relationship described (carrier bias decreases as peaking bias increases).
• —Does not cover power amplifiers that split the RF input signal into more than two components (in-phase and quadrature phase).
• —Does not cover power amplifiers where the bias control signals are not derived from the magnitude of the RF input signal or the current drawn by the carrier amplifier.
• —Does not cover power amplifiers where the two amplified signals are not combined in additive phase.

The clever bit

The innovation lies in dynamically and inversely controlling the power (bias) to two separate amplifier stages based on the incoming signal's strength. This allows one amplifier to handle low-power signals efficiently, while the other steps in to provide additional power only when needed for stronger signals, preventing wasted energy.

Why it matters

Efficient power amplifiers are crucial for any device that transmits radio signals, like cell phones, Wi-Fi routers, and broadcast equipment. They consume a significant portion of a device's power, so improving their efficiency directly translates to longer battery life for mobile devices and reduced energy consumption for base stations. This patent describes a technique to achieve higher efficiency, especially when the signal strength varies, which is common in wireless communication.

Real-world examples

• 1.Cellular base station power amplifiers
• 2.Smartphone radio frequency front-ends
• 3.Wi-Fi access point transmitters
• 4.Satellite communication transceivers
• 5.Broadcast radio and TV transmitters