Active All-Pass Lattice Phase Shifter for Wideband Low-Noise Control
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Solution Overview
Problem
Existing phase-shifting techniques in RADAR and wireless communications, such as switched-line and high/low-pass filtering, are passive and incur signal losses, with limited bandwidth and precision challenges as desired bandwidths and frequencies increase.
Innovation Solution
A low-noise wideband active phase shifter is developed using transconductance cells with transistors, feedback networks, and tunable LC series networks forming an all-pass lattice network, enabling precise phase control across a wide frequency range with reduced noise and increased gain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional passive phase-shifting techniques (switched-line, filtering) are used, then device complexity is reduced, but signal loss increases and bandwidth is limited
Solution Approach 1:
The patent replaces passive mechanical/electrical switching mechanisms with an active all-pass lattice network using transconductance cells and tunable LC networks. This substitution transforms the phase-shifting mechanism from passive component switching to active signal processing, thereby reducing signal loss while accepting increased circuit complexity.
Solution Approach 2:
The patent employs tunable LC networks where inductance and capacitance values can be adjusted to achieve different phase shifts. By changing the parameters of the LC networks rather than switching between fixed configurations, the system maintains continuous signal flow (reducing loss) while achieving variable phase control.
2Adaptability or versatility
If traditional passive phase-shifting techniques are used, then ease of manufacture is improved, but bandwidth is limited and precision deteriorates at high frequencies
Solution Approach 1:
The patent uses dynamically tunable LC networks where the inductance and capacitance can be adjusted during operation. This dynamic capability allows the phase shifter to adapt to different frequency ranges and maintain precision across a wide bandwidth, overcoming the static limitations of traditional switched-line approaches.
Solution Approach 2:
The all-pass lattice network configuration provides inherent feedback mechanisms that maintain signal integrity and phase accuracy across wide bandwidths. The feedback structure compensates for variations and maintains precision even as operating conditions change.
3Loss of energy
If active components are introduced to reduce signal loss, then noise increases
Solution Approach 1:
The patent acknowledges that active components introduce noise but converts this potential harm into a benefit by using the active all-pass lattice network to simultaneously provide gain compensation. The noise from active components is offset by the overall signal amplification, resulting in a net improvement in signal-to-noise ratio compared to passive lossy approaches.
Data Source
AI summary
Apparatus and associated methods relate to a low-noise wideband active phase shifter. The low-noise wideband active phase shifter includes first and second transconductance cells, a fixed LC series network and a tunable LC series network configured to form an all-pass lattice network. The first and second transconductance cells, each include a transistor, a feedback network, and a transistor biasing network. The transistor has an input terminal and an output terminal. The negative feedback network electrically couples the input and output terminals of the transistor. The biasing network provides input and output biasing of the transistor. The fixed LC series network connects between the first and the second transconductance cells. The tunable LC series network connects between the first and the second transconductance cells.