A direct-conversion receiver for 900 MHz (ISM band) spread-spectrum digital cordless telephone

A single chip direct-conversion receiver for use in the 900 MHz ISM (industrial-scientific-medical) band has been fabricated in a 25 GHz f/sub T/ silicon-bipolar process. The receiver has a maximum gain of 105 dB with more than 80 dB of gain-control range. Integrated quadrature mixers and phase-shift networks are included. The typical phase error of the I/Q outputs is less than 1 degree. A class-AB servo amplifier is used to reduce dc offset while maintaining a turn-on time of 200 /spl mu/s. An integrated filter is included to improve channel selectivity. The integrated circuit operates on a supply voltage range of 2.7 to 5.0 V and draws 50 mA of supply current.