To optimise audio performance, high-end consumer and pro-audio equipment makers typically build discrete AM/FM receiver designs from manually tuned inductors and multiple active components. These complicated, hand-crafted receiver designs result in limited configurability, fewer end-customer features, higher cost, and extensive manufacturing overhead and test time. The discrete approach also suffers from overload in strong signal environments, causing degradation in audio quality, particularly for weaker signals. Silicon Labs” highly integrated AM/FM receiver design improves robustness and delivers improved audio quality in all reception conditions while reducing system cost and complexity.
The Si477x family includes two feature-rich, single-chip devices: the Si4770, a global multiband AM/FM receiver, and the Si4777, an AM/FM receiver supporting HD Radio tuner functionality. Silicon Labs designed the Si477x receivers to reduce the bill of materials (BOM) for high-end consumer and pro-audio applications while enhancing design flexibility and delivering outstanding performance. The Si477x family leverages Silicon Labs” patented digital low-intermediate-frequency (low-IF) architecture to deliver superior audio quality under the most demanding environments.
The Si477x family offers improved RF sensitivity, adjacent and alternate channel selectivity, linearity and audio fidelity through advanced DSP algorithms. With -3.5 dBµV sensitivity, the Si477x receivers can tune to signals down to 0.67 µV, picking up stations up to 100 miles away.
Featuring a highly linear RF front end and sophisticated RF and IF automatic gain control (AGC) coupled with a state-of-the-art dynamic bandwidth control algorithm, the Si477x receivers optimize sensitivity and selectivity in strong signal environments, enabling outstanding reception at all times and conditions. The Si477x family”s best-in-class selectivity (65 dB at ±100 kHz and 72 dB at ±200 kHz frequency offset from the desired station) sets a new standard for tuning weaker stations buried among stronger ones in today”s crowded spectrum.
The Si477x receivers also feature an on-chip “prosumer” FM channel equalizer designed to eliminate multipath fading and deliver optimal performance under complex multipath interference conditions present in urban settings. The equalizer”s patented adaptation algorithm corrects for multipath fading, which occurs when a radio station”s signal reaches the receiver along with time-shifted versions of the station”s same signal reflected off of buildings and other large objects. The equalizer significantly reduces audio distortion with fewer sound-compromising mitigation fixes applied to the audio. This high-performance FM channel equalizer is the first of its kind in the audio industry.
The Si4770 and Si4777 receiver products are pin compatible, simplifying system design efforts across multiple high-end audio equipment platforms. Since the device footprints are identical, developers can design one board and use either the Si4770 or Si4777 with a different back end to scale between HD Radio and non-HD Radio solutions.