Type-C SPDT Switch Circuit With Reverse Bias for Audio and Bandwidth
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Solution Overview
Problem
Existing single-pole double-throw switch circuits with Type-C interfaces face a conflict between achieving good Total Harmonic Distortion (THD) performance in the analog audio path and maintaining high bandwidth in the digital path, as increasing the size of field effect transistors to improve THD leads to increased turn-off capacitance, which reduces digital path bandwidth.
Innovation Solution
A single-pole double-throw switch circuit with a Type-C interface that includes a reverse bias voltage module to reduce the capacitance of the PN junction, allowing for a larger field effect transistor size while maintaining high digital path bandwidth by generating a reverse bias voltage across a diode, thereby improving both THD performance and digital path bandwidth simultaneously.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the size of the field effect transistor in the analog audio path is increased to improve THD performance, then the THD performance is improved, but the turn-off capacitance increases which causes the bandwidth of the digital path to decrease
Solution Approach 1:
The patent applies reverse bias voltage to the PN junction of the field effect transistor in the analog audio path. This parameter change (applying reverse bias) reduces the turn-off capacitance of the transistor, allowing the transistor to be sized larger for better THD performance without sacrificing digital path bandwidth. The reverse bias voltage modifies the electrical characteristics of the PN junction to achieve lower capacitance.
2Adaptability or versatility
If a dedicated analog switch chip with two single-pole double-throw switch circuits is used to support time-sharing of D+ and D- pins, then the adaptability for different signal types is improved, but the device complexity increases
Solution Approach 1:
The patent designs the analog switch chip with two single-pole double-throw switch circuits that share common components (COM ports and PN junctions). This universal design allows the same physical infrastructure to handle both digital USB signals and analog audio signals through time-sharing, reducing overall device complexity while maintaining adaptability for different signal types.
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 solution effectively reduces ground capacitance when the diode is turned off, preventing bandwidth reduction and allowing for simultaneous improvement of THD performance and digital path bandwidth, resolving the conflict between the two.
Implementation Method 1
the reverse bias voltage module is connected between the first diode for generating a reverse bias voltage across the first diode
Data Source
AI summary
The present invention provides a single-pole double-throw switch circuit with a Type-C interface, an analog switch chip and an electronic device, which can generate a reverse bias voltage across a first diode, so that a capacitance value of a PN junction can be significantly reduced after the reverse bias voltage is applied to the PN junction. Further, a ground capacitance corresponding to a COM point when the first diode is turned off can be effectively reduced, avoiding the reduction of a bandwidth of a digital path due to excessive capacitance. It can be seen that the present invention can realize a large size of a first field effect transistor and a high bandwidth of the digital path simultaneously, thereby facilitating the simultaneous improvement of the THD performance of an analog audio path and the bandwidth of the digital path, and avoiding conflicts between the two.