On-Chip Harmonic Filter Tuning for Bond Wire Emission Control
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Solution Overview
Problem
Conventional harmonic filtering techniques for RF communications, particularly in high-efficiency power amplifiers, fail to effectively mitigate electromagnetic radiation from bond wires, leading to unwanted out-of-band emissions, which complicates meeting regulatory requirements without compromising transmit efficiency and receive noise figure and linearity.
Innovation Solution
An on-chip harmonic filtering system using a filter circuit with a first inductance, a variable capacitance, and a second inductance, where the capacitance is controlled to tune filtering for harmonics of the transmit output signal, shunting harmonic current to ground, thereby reducing radiated emissions from bond wires.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional off-chip harmonic rejection filters are used, then out-of-band emissions are reduced, but device complexity and area increase
Solution Approach 1:
The patent combines the harmonic rejection filter with the impedance matching network into a single integrated circuit block. This merging eliminates the need for separate off-chip filter components, reducing device complexity and area while maintaining the ability to suppress out-of-band emissions through the combined network's resonant characteristics.
Solution Approach 2:
The patent extracts the harmonic filtering function from external off-chip components and integrates it directly into the on-chip matching network. By taking out the filtering capability and embedding it within the existing circuit architecture, the solution reduces external component requirements while preserving emission suppression performance.
2Use of energy by moving object
If high-efficiency power amplifiers are used, then transmit efficiency is improved, but electromagnetic radiation from bond wires increases
Solution Approach 1:
The patent converts the harmful electromagnetic radiation from bond wires into a beneficial filtering mechanism. By designing the on-chip matching network to create resonant nulls at harmonic frequencies, the circuit naturally suppresses the radiated emissions that would otherwise be problematic, turning the high-efficiency amplifier's strong output into an opportunity for effective on-chip filtering.
Solution Approach 2:
The on-chip matching network acts as an intermediary between the high-efficiency power amplifier and the antenna. This intermediate circuit block provides impedance transformation while simultaneously filtering harmonic frequencies, mediating between the amplifier's high-power output and the antenna's requirements while suppressing unwanted emissions.
3Area of stationary object
If on-chip filtering is implemented, then device area is reduced, but filtering effectiveness for bond wire radiation may be compromised
Solution Approach 1:
The patent changes the electrical parameters of the on-chip matching network to achieve resonant frequencies that create nulls at harmonic frequencies. By adjusting the L/C ratios and component values, the network is tuned to specifically target and suppress the frequencies at which bond wire radiation occurs, maintaining filtering effectiveness within the constrained on-chip area.
Solution Approach 2:
The patent implements a reconfigurable on-chip matching network that can dynamically adjust its characteristics. This dynamic capability allows the network to optimize its filtering performance for different operating conditions and frequency ranges, ensuring effective suppression of bond wire radiation across varying transmit powers and frequencies while maintaining compact integration.
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
The on-chip harmonic filtering solution effectively suppresses unwanted emissions from bond wires while maintaining transmit efficiency and receiver performance, particularly for high-power applications, by filtering out harmonics without significant loss at the fundamental frequency.
Implementation Method 1
The capacitance amount for the variable capacitance is controlled to tune filtering for the filter circuit to a harmonic of a frequency for a transmit output signal
Implementation Method 2
The filter circuit includes a first inductance, a variable capacitance, and a second inductance
Implementation Method 3
The filter circuit includes a first inductance, a variable capacitance, and a second inductance
Data Source
AI summary
Systems and methods are disclosed for on-chip harmonic filtering for radio frequency (RF) communications. For disclosed embodiments, a filter circuit is coupled between a first internal node and a connection pad for an integrated circuit. The filter circuit includes a first inductance, a variable capacitance, and a second inductance. The capacitance amount for the variable capacitance is controlled to tune filtering for the filter circuit to a harmonic of a frequency for a transmit output signal. A power amplifier outputs the transmit output signal to the connection pad without passing through the filter circuit. The filter circuit filters the harmonic of the frequency for the transmit output signal, shunting harmonic current to ground. For one embodiment, the filtered harmonic is a third harmonic of the transmit frequency. For one embodiment, the transmit output signal has an output power greater than or equal to 15 dBm.