Trap Rich Polysilicon Layer Optimization for Harmonic Suppression in Front End Modules
Trap rich polysilicon layers freeze interface charges to hold high resistivity and suppress switch harmonics below minus eighty dBc.
Non-Linear Distortion
Meaning
Generation of spurious frequency components in an electronic system occurs when the output signal is not directly proportional to the input signal. The presence of non-linear distortion limits the spectral purity of radio-frequency transmitters and reduces the sensitivity of receivers. This effect is bounded by the compression point of the active device and the power level of the incoming signal, which defines the transition from linear amplification to saturation.
Harmonic Generation
Non-linearities in the transfer characteristic of a transistor generate integer multiples of the fundamental input frequency. These unwanted signals can fall within adjacent communication channels and cause interference. Designers utilize filtering and feedback to minimize these out-of-band emissions.
Substrate Influence
In high-frequency circuits, the voltage-dependent capacitance of the semiconductor substrate is a major source of this signal degradation. Modifying the substrate with trap-rich layers helps linearize the capacitance under high-power conditions. This structural change significantly reduces the generation of harmonic distortion.
Measurement Standard
Characterisation of distortion levels uses multi-tone test signals to measure intermodulation products. The third-order intercept point is a standard metric used to qualify the linearity of radio-frequency switches and amplifiers. Accurate prediction of this point allows system engineers to optimize the dynamic range of the transceiver.