A 0.13-μm CMOS Current-Mode All-Pass Filter for Multi-GHz Operation

A CMOS wide-bandwidth first-order current-mode all-pass filter (APF) is discussed. The circuit consists of one transistor, a resistor, a grounded inductor, and a load. When used with a current mirror as the load, the current-mode filter exhibits a high output impedance, which is advantageous from an integration point of view and enables this configuration to be cascaded with current-mode circuits. The operation of the proposed circuit is experimentally validated. The APF implemented in IBM 0.13-mu m CMOS was measured to have the pole-zero pair located at 8.32 GHz and to achieve a 55 ps group delay while consuming 19 mW from a 1.5-V supply. This paper experimentally demonstrates a CMOS APF that operates at multi-GHz frequencies and achieves the highest delay-bandwidth products of the published CMOS first-order APFs known to the authors.