Austin, Tex.—Touting a step advance in Class D audio amplifiers, JamTech's JM2020 True Fidelity digital amp includes its new sub-ranging pulse width modulator (PWM) technology to significantly extend linearity and dynamic range. It claims best-in-class audio fidelity for flat-panel and compact audio applications at a price comparable to both traditional Class D amplifiers (analog, using a DAC) and delta-sigma PWM digital amplifiers.
The two-channel JM2020, working from a 10-13.2 VDC source, delivers 8 watts per channel into an 8-ohm load. It touts 16-bit audio quality with a 98 dB range of linearity, 100 dB true dynamic range, 100 dB SNR, and an overall efficiency of 80 percent.
The sub-ranging concept
The JM2020's sub-ranging PWM architecture, key to the performance enhancements, claims an equivalent precision of 17-18 bits (102-108 dB) to extend linearity, reduction of zero-crossing distortion by more than two orders of magnitude, and instantaneous transient performance. This technique, initially developed for data converters, divides the input data into the sum of coarse and fine signal components, which are converted separately and recombined at the output. As a result, the output signal driving the output stage has significantly higher precision for even the smallest audio inputs. The company points to a water bucket analogy using both a large diameter hose (most signficant bits) and a small diameter hose (least significant bits), each connected to a time controlled (pulse-width-modulation) valve. The large hose fills the bucket quickly, and the small hose fine-tunes the level very precisely.
Click here for the product brief. The JM2020 is currently available in production in a 64-pin QFN package and costs $3.10 each in 1000 unit quantities.