Stacked CMOS Driver Amplifier Stage Without Inter-Stage Matching
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Solution Overview
Problem
The elevated frequencies of 5G-NR cellular standards pose challenges for power amplifiers in mobile communication devices, requiring improved signal transmission capabilities and increased efficiency, particularly in reducing the need for inter-stage impedance matching networks which consume space, power, and impose bandwidth limitations.
Innovation Solution
A driving amplifier stage with low output impedance is achieved by using stacked transconductance devices, specifically complementary metal oxide semiconductor (CMOS) field effect transistors (FETs), which reuse supply current to provide an intermediate signal with high current and moderate voltage swing, eliminating the need for inter-stage impedance matching circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an inter-stage impedance matching network is used between the driving amplifier stage and the output amplifier stage, then impedance matching is achieved, but device complexity, area, and power consumption increase
Solution Approach 1:
The patent removes the inter-stage impedance matching network from the transmission chain by redesigning the driving amplifier stage to inherently provide the necessary impedance transformation through stacked transconductance devices, thereby eliminating the separate matching network component
Solution Approach 2:
The stacked transconductance devices in the driving amplifier stage serve multiple functions: they provide voltage amplification, current buffering, and impedance transformation simultaneously, replacing what previously required separate dedicated impedance matching circuits
2Reliability
If an inter-stage impedance matching network is used, then signal transmission is optimized, but area and physical costs increase
Solution Approach 1:
The patent merges the impedance matching function into the driving amplifier stage itself by using stacked transconductance devices, combining what were previously separate functions (amplification and impedance matching) into a single integrated stage, thereby reducing total circuit area
3Power
If an inter-stage impedance matching network is used, then power amplification is achieved, but power consumption increases
Solution Approach 1:
The stacked transconductance devices utilize the supply current efficiently by having the first and second amplifiers share the same current source, allowing the circuit to self-regulate power distribution and eliminate the additional power consumption that would be required by a separate impedance matching network
4Reliability
If an inter-stage impedance matching network is used, then signal quality is maintained, but bandwidth is limited
Solution Approach 1:
The stacked transconductance configuration provides dynamic impedance transformation that adapts to the signal frequency, maintaining signal quality across a broader frequency range without the bandwidth limitations imposed by fixed-impedance matching networks
Data Source
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AI summary
A driving amplifier (200) with low output impedance is disclosed. In one aspect, a driving amplifier stage (202) that does not need an inter-stage impedance matching network between the driving amplifier stage (202) and an output amplifier stage (208) in a transmission chain may be achieved by providing stacking transconductance devices within the driving amplifier stage (202) and reusing a supply current to provide an intermediate signal with high current but moderated voltage swing to drive the output amplifier stage (208). In specifically contemplated aspects, the stacked transconductance devices may be complementary metal oxide semiconductor (CMOS) field effect transistors (FETs).