MAX2450

19-0455; Rev 1; 9/98 KIT ATION EVALU E L B AVAILA 3V, Ultra-Low-Power Quadrature Modulator/Demodulator General Description ____________________________Features o Combines Quadrature Modulator and Demodulator o Integrated Quadrature Phase Shifters o On-Chip Oscillator (Requires External Tuning Circuit) o On-Chip Divide-by-8 Prescaler o Modulator Input Bandwidth Up to 15MHz o Demodulator Output Bandwidth Up to 9MHz o 51dB Demodulator Voltage Conversion Gain o CMOS-Compatible Enable o 5.9mA Operating Supply Current 1µA Shutdown Supply Current MAX2450 The MAX2450 combines a quadrature modulator and quadrature demodulator with a supporting oscillator and divide-by-8 prescaler on a monolithic IC. It operates from a single +3V supply and draws only 5.9mA. The demodulator accepts an amplified and filtered IF signal in the 35MHz to 80MHz range, and demodulates it into I and Q baseband signals with 51dB of voltage conversion gain. The IF input is terminated with a 400Ω thinfilm resistor for matching to an external IF filter. The baseband outputs are fully differential and have 1.2Vp-p signal swings. The modulator accepts differential I and Q baseband signals with amplitudes up to 1.35Vp-p and bandwidths to 15MHz, and produces a differential IF signal in the 35MHz to 80MHz range. Pulling the CMOS-compatible ENABLE pin low shuts down the MAX2450 and reduces the supply current to less than 1µA. To minimize spurious feedback, the MAX2450’s internal oscillator is set at twice the IF via...