Differential Amplifier Source Resonance for Noise Cancellation
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Solution Overview
Problem
Designing a satisfactory amplifier for electronic devices with wireless communications capabilities is challenging due to noise interference that degrades performance.
Innovation Solution
The amplifier circuitry incorporates a differential capacitor configured to resonate with source inductors to cancel out differential noise, and optionally magnetically couples the source inductors for enhanced noise cancellation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional amplifier design is used, then the amplifier can provide basic signal amplification, but noise interference degrades the performance
Solution Approach 1:
The amplifier is divided into two separate amplification paths (first amplifier and second amplifier) with identical structures, each processing one phase of the differential signal. This segmentation allows independent noise cancellation for each path while maintaining overall signal integrity.
Solution Approach 2:
The noise cancellation circuit is configured to cancel differential noise before the noise degrades the amplifier performance. By using capacitors coupled between source terminals and configuring source inductors with specific impedance values, the circuit preemptively counteracts the harmful differential noise modes.
2Reliability
If noise cancellation circuitry is added to reduce noise interference, then amplifier performance improves, but circuit complexity increases
Solution Approach 1:
The noise cancellation functionality is merged into the existing differential amplifier structure by adding capacitors between source terminals and configuring source inductors. This integration allows noise cancellation without requiring completely separate cancellation circuits, reducing overall complexity.
Solution Approach 2:
The source inductors are configured with specific impedance values that simultaneously provide both signal amplification and noise cancellation. By carefully selecting the impedance parameters of the source inductors and coupling capacitors, the circuit achieves noise reduction while maintaining a relatively simple structure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration minimizes noise figure and improves amplifier performance by independently controlling common and differential mode source impedances, resulting in reduced noise interference.
Implementation Method 1
The capacitor can be configured to resonate with the first and second inductors
Implementation Method 2
The second inductor can be magnetically coupled to the first inductor in accordance with a magnetic coupling coefficient
Data Source
AI summary
Wireless circuitry can include amplifier circuitry. The amplifier circuitry can include a first input transistor having a gate terminal coupled to an input terminal, a second input transistor having a gate terminal coupled to the input terminal, a first inductor coupled to a source terminal of the first input transistor, and a capacitor having a first terminal coupled to the source terminal of the first input transistor and having a second terminal coupled to a source terminal of the second input transistor. The amplifier circuitry can further include a second inductor coupled between the source terminal of the second input transistor and a power supply line. The capacitor can be configured to resonate with the first and second inductors to provide noise cancelling at a target operating frequency.