Book contents
- Frontmatter
- Contents
- Notation
- Preface
- 1 Introduction to Highly Integrated and Tunable RF Receiver Front Ends
- 2 Active Blocker-Cancellation Techniques in Receivers
- 3 Impedance Transformation: Introduction to the Simplest On-Chip SAW Filter
- 4 Four-Phase High-Q Bandpass Filters
- 5 M-Phase High-Q Bandpass Filters
- 6 Design of a Superheterodyne Receiver Using M-Phase Filters
- 7 Impact of Imperfections on the Performance of M-phase Filters
- 8 M-phase Filtering and Duality
- Appendix A
- References
- Index
5 - M-Phase High-Q Bandpass Filters
Published online by Cambridge University Press: 05 July 2013
- Frontmatter
- Contents
- Notation
- Preface
- 1 Introduction to Highly Integrated and Tunable RF Receiver Front Ends
- 2 Active Blocker-Cancellation Techniques in Receivers
- 3 Impedance Transformation: Introduction to the Simplest On-Chip SAW Filter
- 4 Four-Phase High-Q Bandpass Filters
- 5 M-Phase High-Q Bandpass Filters
- 6 Design of a Superheterodyne Receiver Using M-Phase Filters
- 7 Impact of Imperfections on the Performance of M-phase Filters
- 8 M-phase Filtering and Duality
- Appendix A
- References
- Index
Summary
Introduction
The four-phase high-Q bandpass filter introduced in the previous chapter can integrate external SAW filters in many narrowband RF applications such as cellular. In addition, the previous chapter described the design of a SAW-less quad-band GSM receiver integrated as part of 2.5G SoC in which the receiver uses four-phase on-chip high-Q bandpass filters to handle strong out-of-band blockers. The receiver passes all 3G blocker specifications with some margin, except for folding blockers that are located at the third, fifth, and other odd-order harmonics of the LO, where exceptions must be taken. Although useful in cellular receivers or other narrowband applications, for wideband applications such as TV reception, the four-phase filter is not a proper choice because of the blocker folding issue at the third, fifth, and all other odd harmonics. Therefore, the four-phase high-Q BPF must evolve further to move the closest folding components up to the higher frequencies that are much larger than the third harmonic of the clock. In this chapter, we will see that an M-phase high-Q bandpass filter is the solution [60, 67–69], which shifts the closest folding frequency components to the (M − 1)th harmonic.
Moreover, we will show that, similar to the four-phase filters, the M-phase filter (with M being an integer multiple of four) can also use complex baseband impedances to frequency-translate them to the LO frequency. Additionally, we will see that high-Q image-rejection bandpass filters with quadrature RF inputs are also realizable with such values of M.
- Type
- Chapter
- Information
- Integration of Passive RF Front End Components in SoCs , pp. 90 - 116Publisher: Cambridge University PressPrint publication year: 2013