Log-domain channel-select filters for multistandard wireless receivers

The design of log-domain building block circuits immune to multiple DC operating points is investigated. The circuits are used to implement a 6^th-order multistandard channel-select filter for wireless applications in a SiGe BiCMOS process. The filter performs channel selection for the WCDMA, GSM, and IS-95 standards, and realizes a frequency range spanning 100 kHz to 20.05 MHz. The filter core operates with a supply voltage as low as 1.2 V, and consumes a maximum power of 12.9 mW for the WCDMA standard. By incorporating dynamic biasing techniques, the spurious free dynamic range (SFDR) of the filter is extended from SFDR = 39 dB to SFDR = 48 dB at 20.05 MHz.