Push-Pull Amplifier Topology for Wideband Harmonic Rejection
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Solution Overview
Problem
Wideband power amplifiers face performance degradation due to harmonic frequencies and intermodulation products falling within the carrier frequency band, requiring complex band-specific filters and resulting in inefficient operation.
Innovation Solution
A circuit topology for push-pull amplifiers with separated ground planes and specific connections between amplifier devices allows for low impedance at common mode over a large bandwidth, enabling efficient operation with reduced distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If wideband power amplifier is operated to cover multiple frequency bands, then bandwidth capability is improved, but harmonic frequencies and intermodulation products fall within the carrier frequency band causing performance degradation
Solution Approach 1:
The patent segments the output circuit into separate common-mode and differential-mode paths. The push-pull amplifier configuration naturally separates even-order harmonics (common-mode) from the fundamental frequency (differential-mode), allowing independent termination strategies for each mode without requiring band-specific filters.
Solution Approach 2:
The patent converts the harmful effect of even-order harmonics falling within the band into a beneficial feature by utilizing the push-pull topology's inherent common-mode rejection. The harmonics that would normally degrade performance are automatically routed to a common-mode termination, transforming a performance problem into a design advantage.
2Object-affected harmful factors
If band-specific filters are added to reject harmonic frequencies and intermodulation products, then emission standards compliance is improved, but device complexity and inventory requirements increase
Solution Approach 1:
The patent implements a universal termination network that handles all frequency bands simultaneously through the common-mode/differential-mode separation. A single push-pull amplifier configuration with shared termination components complies with emission standards across multiple bands without requiring band-specific filters, reducing both complexity and inventory requirements.
3Reliability
If push-pull amplifier uses complementary device techniques (n-type and p-type), then even order tones can be short-circuited, but performance of p-type transistors is limited making them no option for high performance applications
Solution Approach 1:
The patent employs identical n-type amplifier devices in both branches of the push-pull configuration, eliminating the need for p-type transistors. The homogeneous device selection maintains full performance capabilities while simplifying manufacturing and component selection, as the common-mode/differential-mode separation still effectively rejects even-order harmonics.
4Ease of manufacture
If push-pull amplifier uses only n-type devices, then manufacturing is simplified, but the output network must fulfill Z11=Z22=−Z12 which is very challenging over a large bandwidth
Solution Approach 1:
The patent segments the impedance requirements into separate common-mode and differential-mode terminations. This segmentation transforms the challenging broadband impedance matching requirement (Z11=Z22=−Z12) into two independent, simpler termination designs that can be achieved over wide bandwidths using standard techniques.
Data Source
AI summary
The present disclosure relates to an amplifier arrangement (1, 100, 200) comprising a first amplifier device (2, 102, 202) and a second amplifier device (3, 103, 203) where each amplifier device (2, 3; 102, 103; 202, 203) is connected to an input circuit (8, 108) and has a first type output terminal (4, 6; D) and a second type output terminal (5, 7; S), where the output terminals (4, 6, D; 5, 7, S) are connected to an output circuit (9, 109, 109′). The first type output terminal (4, D) of the first amplifier device (2, 102, 202) is connected to the second type output terminal (7, S) of the second amplifier device (3, 103, 203) by means of a first connection (10, 110), and the first type output terminal (6, D) of the second amplifier device (3, 103, 203) is connected to the second type output terminal (5, S) of the first amplifier device (2, 102, 202) by means of a second connection (11, 111). The first type output terminal (4, D) of the first amplifier device (2, 102, 202) and the first type output terminal (6, D) of the second amplifier device (3, 103, 203) are electrically separated in the output circuit (9, 109, 109′), and the second type output terminal (5, S) of the first amplifier device (2, 102, 202) second type output terminal (7, S) of the second amplifier device (3, 103, 203) are electrically separated in the output circuit (9, 109, 109′).