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Download Audio Presentation â Continuous Sigma TM April 2015
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INDICE Semiconductor High Resolution Digital amplifiers enabled by Continuous Sigma April 2015 CONTINUOUS SIGMA ENCODING A breakthrough in high resolution, switched amplifiers Continuous Sigma is Indice’s proprietary power control algorithm that is able to remove switch-mode bridge error and noise in real time, offering a breakthrough in high resolution audio whilst maintaining ultra high efficiency. We address the limitations of Class D amplifiers which inherently introduce inter-modulation and harmonic distortion due to the carrier frequency modulation and inadequate adaptation rates. Indice’s amplifier uses a multi-feedback system which naturally rejects switching and power supply noise. WHY CHOOSE INDICE? Indice’s proprietary continuous sigma control offers the following benefits covered in the slides: •High Resolution audio (HRA) ready •High frequency adaption rate •Flat gain curve •Spread spectrum EMI profile •Bridge Tied load (BTL) standard offering •Multiple feedback nodes •High efficiency High Resolution – Fast adaptation rate The unique nature of Continuous Sigma is it is adapting at the switching rate which enables more accurate reproduction of the source music •Algorithm: Continuous Sigma •Decision speed: 1MHz •Sample b/w: 192KHz Traditional Class D ~44KHz 44KHz Switching frequency comparison Continuous Sigma enables INDICE to make switching decisions at the carrier frequency delivering superior performance and a high resolution audio experience Class D decision speed 44KHz Class D switching frequency 200KHz 400KHz INDICE switching speed and decision speed 600KHz 800KHz 1MHz Class-AB amplifier crossover distortion INDICE’s Continuous Sigma amplifiers do not suffer from crossover distortion that is experienced in Class-AB amplifiers INDICE delivers a flat gain curve Continuous sigma enables a very flat gain curve to accurately reproduce the source music with the clarity of Class A but with the efficiency of a digital amplifier. Continuous sigma does not suffer compression like other switching amplifiers which leads to higher THD. Green = INDICE Highly uniform frequency response The flat gain curve and highly linear nature of Continuous Sigma delivers an highly uniform frequency response INDICE amplifiers are BTL (Bridge Tied Loads) All INDICE amplifiers are BTL which means that they can run from a single supply rail, reducing system cost while maintaining excellent frequency response and performance. Amplifiers that are not BTL have to factor in higher system costs for the additional power supply rail. EMI filter advantages Most Class D amplifiers require the carrier to be present at the speaker, Indice’s amplifiers do not as the feedback network is before the output stage filter enabling a higher attenuation filter to reduce speaker cable RF emissions Class D feedback node INDICE feedback node Spread spectrum EMI profile Continuous sigma is asynchronous so there is no fixed carrier frequency that leads to a large EMI peak or subsequent harmonics. Traditional Class D INDICE High Efficiency gives freedom for design Continuous sigma enables efficiency >96% which reduces heatsink design, in many applications the external heatsink can be eliminated or reduced in size EXTERNAL HEATSINK FREE INDICE Blade TAS5611A >96% ~89% 4W 11W Efficiency: Pd @ 100WRMS: Precise speaker position control The BLADE has a very high damping factor (DF) enabling very precise control of the speaker and fast attack and fade Incredible audio fidelity THD+N performance in a very cost effective package INDICE BLADE IN81 vs TI TAS5611A D-CLASS IC Description of Feature INDICE Texas Instruments BLADE IN81 TAS5611A Control technique Continuous Sigma PurePath HD Power Bandwidth 50KHz / 100KHz* 44KHz Rated power (1% THD into 4Ω) 91W (without heatsinking) 60W (heatsinked) Maximum power rating (1% THD) 364W @1Ω 125W @2Ω Efficiency (80% load, 4Ω) 96% 89% Signal to Noise Ratio (Supply = 24V, Load = 4Ω, A-weighted) 122dB 100dB THD+N (Supply = 24V, Load = 4Ω) 0.004% 0.05% Idle Power consumption (Control circuit only) 200mW 750mW Output noise (VCC = 24V) 34uV 168uV Differential input range 4VRMS 0 – 5Vp-p Power supply ripple rejection (PSSR) -77dB (Vripple=1VRMS@100Hz) Not specified Switching frequency Asynchronous up to 1.2MHz 400KHz www.indicesemi.com 15
