Abstract: A method of manufacturing a microphone using epitaxially grown silicon. A monolithic wafer structure is provided. A wafer surface of the structure includes poly-crystalline silicon in a first horizontal region and mono-crystalline silicon in a second horizontal region surrounding a perimeter of the first horizontal region. A hybrid silicon layer is epitaxially deposited on the wafer surface. Portions of the hybrid silicon layer that contact the poly-crystalline silicon use the poly-crystalline silicon as a seed material and portions that contact the mono-crystalline silicon use the mono-crystalline silicon as a seed material. As such, the hybrid silicon layer includes both mono-crystalline silicon and poly-crystalline silicon in the same layer of the same wafer structure. A CMOS/membrane layer is then deposited on top of the hybrid silicon layer.

Abstract: A method of manufacturing a microphone using epitaxially grown silicon. A monolithic wafer structure is provided. A wafer surface of the structure includes poly-crystalline silicon in a first horizontal region and mono-crystalline silicon in a second horizontal region surrounding a perimeter of the first horizontal region. A hybrid silicon layer is epitaxially deposited on the wafer surface. Portions of the hybrid silicon layer that contact the poly-crystalline silicon use the poly-crystalline silicon as a seed material and portions that contact the mono-crystalline silicon use the mono-crystalline silicon as a seed material. As such, the hybrid silicon layer includes both mono-crystalline silicon and poly-crystalline silicon in the same layer of the same wafer structure. A CMOS/membrane layer is then deposited on top of the hybrid silicon layer.

Abstract: An upstream programmable gain amplifier (PGA) (114, 214) for a cable modem (100) having a programmable bias current. PGA (114, 214) includes a bias current-setting circuit (140, 240) coupled to a power amplifier stage (136, 236), the bias current-setting circuit (140, 240) adapted to program the bias current Ibias of the power amplifier stage (136, 236). The bias current-setting circuit (140) includes a bandgap generator (130, 230) having an external bias resistor R1 at the input. The bias current-setting circuit (140) may include a variable gain amplifier (VGA) (134), a digital-to-analog converter (DAC) (132), and a bias code generator (138). The bias current-setting circuit (240) may alternatively include a plurality of programmable resistors R1a, R1b . . . R1x coupled to a bias code generator (238).