Abstract
An experimental filter was designed to operate at 3.6 GHz using mainstream 0.18 μm CMOS. In the design, the Q-enhancement technique was used to overcome the low-Q characteristics of the CMOS on-chip inductors. A sixth-order bandpass filter with a wide passband and a high image rejection was built by cascading three stages of second-order Q-enhanced filters. A combination of three biquads with offset in center frequency provides wider tuning frequency and bandwidth. This high-performance filter provides a 340 MHz tunable center frequency around 3.6 GHz, an image rejection of 50 dB and a tunable Q from 25 to 50 for a bandwidth adjustment from 95 MHz to 35 MHz. The filter achieves an 18 dB voltage gain while consuming 130 mW of power at 1.8 V DC supply. The chip occupies an area of 900×900μm2 including all the required bonding pads. The design provides a simple architecture to simplify tuning scheme for both frequency and bandwidth for practical use. The tunable ability of the design could be exploited in further study to be used as a channel-select filter in the gigahertz range.
Highlights
The rapid growth in wireless telecommunication systems necessitated research and development of monolithic bandpass filters for gigahertz radio frequencies
This paper presents an approach and design of a tunable 3.6 GHz CMOS bandpass filter to achieve the following characteristics: low-noise figure, wide-tuning range, high-voltage gain, and high-linearity
The Q tuning range depends on stability and pass band ripple of the filter
Summary
The rapid growth in wireless telecommunication systems necessitated research and development of monolithic bandpass filters for gigahertz radio frequencies. The integration of filters in GHz range faces many hurdles such as the design of high-Q on-chip inductors and capacitors and in particular, the accurate high-frequency CAD models for onchip passive components. The design of a wide tuning range and high-quality varactors in CMOS technology is a great challenge [8]. This paper presents an approach and design of a tunable 3.6 GHz CMOS bandpass filter to achieve the following characteristics: low-noise figure, wide-tuning range, high-voltage gain, and high-linearity. The filter is designed as a secondorder and cascade to form a sixth-order filter with a tuning capability in both center frequency and quality factor. These tunings offer frequency selection and bandwidth adjustment. Noise figure, and particular linearity of the filter are taken into considerations of the design
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
