With the advent and fast-paced development of ultrahighspeed digital interconnects for next-generation computing systems, low-latency broadband wireless communications for fifth generation and beyond, high-resolution imaging techniques and emerging parametric sensing systems for medical/biomedical and security applications, material and structure analyses and evaluations, and deep-space radio astrophysics, and so on, the search for system solutions with larger bandwidth has sparked a growing research in expanding the electromagnetic spectrum into the terahertz (THz) regime. Generally, the THz frequency covers 300 GHz through 10 THz, which presents the most fundamental spect rum gap between elect ronics and photonics.

An active bandpass filter topology with transformer-feedback Q-enhancement technique in 0.18 μm CMOS technology is presented for IEEE 802.11a Wireless LAN applications. The novel transformer-feedback Q-enhancement technique utilizes the turns ratio of the primary coil and the secondary coil of the transformer for efficient loss compensation. The active bandpass filter is designed, simulated and laid out in a 0.18 μm CMOS process to illustrate the concept. The simulated results show that the center frequency of the active bandpass filter is 5.2 GHz and a bandwidth of 93 MHz. A 35-dB attenuation at 100 MHz away from the center frequency is achieved. The simulated input 1 dB compression point (P1dB) and noise figure are −6 dBm and 16.8 dB at center frequency, respectively. While showing a minimum gain of 1.5 dB of the entire passband, the active bandpass filter consumes 12.2 mA from a 1 V supply voltage.