Design Consideration for Future RF Circuits Circuits and Systems, ISCAS IEEE International Symposium 27 May 2007 Author : Behzad Razavi Presenter : Kyungjin Yoo

I.Introduction RF circuits - 2 trends  Device level: speed, noise  System level: System-on-chips New paradigm  Multi-band, multi-mode transceivers  Baseband processors Issues in this paper  Technology scaling  Design techniques

II.Impact of Technology Scaling 1. Lower supply voltages 2. Higher gate leakage currents 3. Lower transistor output impedances

Supply Voltage Scaling Noise, linearity, gain Trade off  Mixer  Oscillator  VCO

Transistor Output Impedance Lower the Q of oscillators deQing effect of ro >> Rp  Negligible in 90-nm technology : ro=2.3 Kohm  Problematic in 65-nm and 45-nm generation

Gate Leakage Current Gate leakage current in 90-nm tech : 10~100pA/micrometer^2 90-nm : IG/Cp microV/ns  Tin=50ns causes mVpp ripple

III.Design Techniques 1. Low-Voltage Active Mixers 2. Multi-Band Techniques

Low-Voltage Active Mixers Principle : bias current to the switching pair and the loads < bias current to the RF transconductor device

Multi-Band Techniques Goal  Minimize area  avoid long interconnects at high freq. Layout compaction  Stacked inductors: LNA,VCO  Nested inductors: dual-band oscillator

Thank you! Q&A