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What is SuPA?

SuPA: Supply for Power Amplifier

“SuPA” = DC/DC converter that provides an adaptive, optimized output power supply for the RF PA to extend battery life and improve thermal performance

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Traditional Approach:Fixed Battery Supply to PA

More Efficient Approach:TI SuPA Adaptive Supply to PA

VBATT

RFIN

VCC

RFOUT

VCC

RFOUT

RFIN

SuPA

VBATT

VCTRL

VOUT

VOUT is optimized for given POUT

SuPA Benefit #1:Reduced Battery Current Draw• RF PAs have efficiencies between 4-40% TI SuPA solution can reduce

battery current by 20%-50%– Longer battery life– Smaller battery form factor– More voice/usage time

and coverage

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SuPA Benefit #2:Thermal Dissipation Improvement• TI SuPA solution reduces worst case hot temperature by up to 30ºC

– Reduced thermal constraints– Higher reliability– Thinner, lighter phone design

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With SuPAWithout SuPA

60.1˚C90.5˚C

30˙C Temperature Reduction + 33% Power Savings

SuPA Key Characteristics

Differences vs Standard DC/DC Converter

• Higher Switching Frequencies

• Bypass Mode: ACB (Active Current Bypass)

• ACLR, EVM RF Compliance

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Standard Buck vs. SuPA Buck

Digital core Buck SuPA Buck

No Vcon pin needed for changing output voltage

Vcon pin critical for changing output voltage

Typically operates at low duty cycles<25% to 60%

Operates over wide duty cycles10% to 100%

High efficiency over entire output current range

High efficiency over entire output voltage range

Iq critical since it spends more time in standby

Iq not that critical since PA is a constant load ~30mA to 50mA

Standard Buck vs. SuPA Buck (cont.)

Digital core Buck SuPA Buck

Current Limit designed to support max Iout

Designed for Vcon transients and max Iout

Transient response is optimized for Line/Load Transients

Optimized for Vcon transients (output voltage)

Start-up time not that critical as long as it’s below 700uS

Critical, it must be less than 50uS

Drop-out not critical and no need for a Bypass FET

Designed to provide low output ripple and smooth transition

ti.com/rfpower

SuPA: Supply for Power Amplifier

Benefits– Reduced Battery Current Draw– Thermal Dissipation Improvement

Different from a standard buck converter

Summary