A 2.4-GHz 0.18-um CMOS Self-Biased Cascode Power Amplifier IEEE JOURNAL OF SOLID-STATE CIRCUITS, VOL. 38, NO. 8, AUGUST 2003 A 2.4-GHz 0.18-um CMOS Self-Biased Cascode Power Amplifier Tirdad Sowlati, Member, IEEE, and Domine M. W. Leenaerts, Senior Member, IEEE 指導老師:林志明 學生:黃政德 系級:積體所研一

Introduction (1) Oxide breakdown sets a limit on the maximum signal swing on drain. Hot carrier degradation is a reliability issue. It increases the threshold voltage and consequently degrades the performance of the device. Cascode configuration and thick-oxide transistors have been used.

Introduction (2) This work demonstrates a 0.18-um CMOS self-biased cascode RF power amplifier that operates at 2.4 GHz and provides 23 dBm from a 2.4-V supply voltage for Class-1 Bluetooth application. By using standard oxide thickness devices in the process, the design takes full advantage of the technology and its high Ft.

Conventional cascode amplifier and Voltage waveforms versus time

Self-biased cascode amplifier and Voltage waveforms versus time

Bootstrapped cascode amplifier and Voltage waveforms versus time

Two-stage self-biased cascode PA

Simulate output power, gain, and PAE

Conventional and Self-biased Cascode PA

Microphotograph of the PA

Measured Pout , gain, and PAE versus Pin

Pout versus time of continuous operation

Bluetooth spectrum at the output of the PA

SLIDING BIAS TECHNIQUE To improve the linearity of a PA: Operate the PA in class A/AB mode Use a bias boosting or gain boosting at the compression point Employ a de-biasing technique at low and intermediate power levels to have the same gain at the maximum power

Measured Gain and PAE versus Pout for constant/sliding gate bias voltages

Measured phase variations versus inputs power for constant/sliding bias

Conclusion A self-biased cascode topology was applied to reduce hot carrier effects. No performance degradation occurs after ten days of continuous operation under maximum output power conditions. Using a sliding biasing technique on both stages, improve the PAE at low/mid-power level and linearize the PA.