Abstract: This paper presents post-layout simulated results of an analog baseband chain for mobile and multimedia applications in a 0.13-μm SiGe BiCMOS process. A programmable 7th-order Chebyshev low pass filter with a calibration circuit is used in the analog baseband chain, and the programmable bandwidth is 1.8/2.5/3/3.5/4 MHz with an attenuation of 26/62 dB at offsets of 1.25/4 MHz. The baseband programmable gain amplifier can achieve a linear 40-dB gain range with 0.5-dB steps. Design trade-offs are carefully considered in designing the baseband circuit, and an automatic calibration circuit is used to achieve the bandwidth accuracy of 2%. A DC offset cancellation loop is also introduced to remove the offset from the layout and self-mixing, and the remaining offset voltage is only 1.87 mV. Implemented in a 0.13-μm SiGe technology with a 0.6-mm² die size, this baseband achieves IIP3 of 23.16 dBm and dissipates 22.4 mA under a 2.5-V supply.

Key words: multimedia, baseband, low pass filter, leapfrog, programmable gain amplifier, frequency calibration, DC negative feedback loop