Radar MMIC Power Amplifier Shutdown With Constant Supply Current
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Solution Overview
Problem
Existing RF systems face performance issues when quickly stopping RF signal transmission due to rapid changes in supply current, leading to overshoot and undershoot of supply voltage, temperature distribution variations, and spectral purity impacts, particularly in millimeter-wave radar systems.
Innovation Solution
A method involving a phase shifter and power amplifier configuration that maintains a constant supply current by using a termination control signal to enable or disable RF signal transmission through the power amplifier, reducing power via scale factors and terminating the signal without changing the supply current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the RF transmitter is turned off during short periods between chirp signals, then transmission is stopped, but supply current changes cause voltage overshoot and undershoot
Solution Approach 1:
The patent applies preliminary action by gradually reducing the RF signal power through scaling factors before completely turning off transmission. This preparatory power reduction prevents abrupt current changes that would cause voltage overshoot and undershoot, while still achieving the goal of stopping transmission between chirp signals.
Solution Approach 2:
The patent implements dynamics by using dynamic scaling factors to continuously adjust the RF signal power level during the transition from active transmission to standby mode. This dynamic power adjustment allows smooth current changes rather than abrupt switching, maintaining voltage stability while enabling quick transmission stopping.
2Productivity
If the RF transmitter is turned off quickly, then transmission stops rapidly, but temperature distribution variations occur
Solution Approach 1:
The patent applies preliminary action by gradually reducing power through scaling factors before complete shutdown, allowing the semiconductor device to cool down progressively. This prevents sudden temperature distribution variations that would occur with abrupt switching, while still achieving rapid transmission stopping between chirp signals.
3Productivity
If the RF transmitter is turned off quickly, then transmission stops rapidly, but spectral purity is degraded
Solution Approach 1:
The patent implements dynamics by using dynamic scaling factors to continuously adjust the RF signal power during the transition to standby mode. This dynamic reduction smooths the signal envelope, preventing spectral regrowth and maintaining spectral purity while still achieving rapid transmission stopping between chirp signals.
Data Source
AI summary
A method of operating a monolithic microwave integrated circuit (MMIC) in a radar transmitter includes: sending a radio frequency (RF) signal to a power amplifier of the radar transmitter, where the power amplifier is controlled by a termination control signal, where when the termination control signal is de-asserted, the power amplifier is configured to pass the RF signal through the power amplifier for transmission by an RF antenna, where when the termination control signal is asserted, the power amplifier is configured to terminate the RF signal in the power amplifier; transmitting the RF signal by de-asserting the termination control signal; and after de-asserting the termination control signal, disabling transmission of the RF signal by: reducing a power of the RF signal; and asserting the termination control signal.