RFIC – Atlanta June 15-17, 2008 RMO1C-3 An ultra low power LNA with 15dB gain and 4.4db NF in 90nm CMOS process for 60 GHz phase array radio Emanuel Cohen (12), Shmuel Ravid (1), and Dan Ritter (2) (1)Mobile Wireless Group, Intel Haifa, Israel (2)Department of Electrical Engineering, Technion, Haifa, Israel

RFIC – Atlanta June 15-17, 2008 Outline Design methodology flow and passives Circuit implementation options LNA measurements Conclusions

RFIC – Atlanta June 15-17, 2008 Motivation How low can we get power consumption in a mm-wave LNA without compromising gain NF and size? Typical LNA designed for 60GHz showed a power of 20mW gain). For a phase array with elements we end up with ~1Watt ! Power and size must go down for a full phase array system in commercial application

RFIC – Atlanta June 15-17, 2008 LNA Design Methodology 1.Choose the passive circuits and models 2.Choose the transistor width for optimized target 3.Choose best topology with optimized transistor width

RFIC – Atlanta June 15-17, 2008 Passive inductor design Ground ring on inductor improves isolation by 19dB No real impact on Q

RFIC – Atlanta June 15-17, 2008 Creating inductor simple model Build a model based on a library of inductors with EM simulation Then the design can be optimized without EM iterations Simple pi model

RFIC – Atlanta June 15-17, 2008 Full EM simulation Full EM possible in momentum - 8 hour run Excellent fit to stand alone inductor  proves good inductor isolation with ground ring

RFIC – Atlanta June 15-17, 2008 Capacitors MIM cap Finger Cap Parasitic capacitance [pf] Parasitic capacitance [pf] Q Q 200pf MIM cap Q~9 and finger cap Q >>10 Finger cap has ~8% parasitic (after optimizing and using 2-4 layers only) Finger cap was chosen for the design

RFIC – Atlanta June 15-17, 2008 Transistor size and circuit topology Transistor size is the key issue for low power design For Q~20 0.3dB max penalty, with full simulation even less ¼ of power consumption

RFIC – Atlanta June 15-17, 2008 LNA behavior with W change 3 stage CS design with different transistor sizes and same current density. Similar performance is achieved with W=10um and 3x10um No real BW degradation Different Transistors Have similar Q impedance

RFIC – Atlanta June 15-17, 2008 LNA with different topologies Using optimized flow to check different topologies without iterations All topologies designed for ~4mW W=1x10um

RFIC – Atlanta June 15-17, 2008 Low Noise Amplifier schematic Big inductors still maintain high SRF Have better Q

RFIC – Atlanta June 15-17, 2008 LNA Layout die 440 um x 320 um Size limited by pads- inner core (0.04mm 2 )

RFIC – Atlanta June 15-17, 2008 Measured and Simulated Performance Gmax=15dB NF=4.4dB Power consumption 4mW

RFIC – Atlanta June 15-17, 2008 NF set-up at 60Ghz [ S. Pellerano, Y. Palaskas, K. Soumyanath “A 64GHz 6.5dB NF 15.5dB Gain LNA in 90nm CMOS” in IEEE ESSCIRC 2007 ] Down converter NFA

RFIC – Atlanta June 15-17, 2008 Comparison with State of the Art LNAs Lowest power with smallest size at same Gain

RFIC – Atlanta June 15-17, 2008 Additional bias point characterization Bias point compromise –0.2dB in NF –3dB in Gain

RFIC – Atlanta June 15-17, 2008 NF, Gain vs. total power dissipation Maximum points align on the same line There is no difference between changing Vds or Ids Consumption can drop to 2mW for 12dB of gain

RFIC – Atlanta June 15-17, 2008 Compression point measure Max input signal ~ -25dBm for high data rates This is enough for a 60Ghz link budget

RFIC – Atlanta June 15-17, 2008 Conclusions Fast design flow with lumped inductor and ground ring was created The flow enabled a check of full circuits topology for a fair comparison on optimized results The CS and small transistor size 1x10um is the best tradeoff between power consumption Gain and NF. A record power consumption of 4mW achieved with best NF of 4.4dB 15dB gain and similar to smallest footprint published Lumped inductor enabled smallest size and no additional design complexity

RFIC – Atlanta June 15-17, 2008 Thank You

RFIC – Atlanta June 15-17, 2008 Input impedance with W Q is very similar 10um 40um