Mobile Phone Testing using Impedance Tuners

Transcription

1 Mobile Phone Testing using Impedance Tuners Roman Meierer and Steve Dudkiewicz Your Complete Measurement & Modeling Solutions Partner 1

2 We Live in a 50 World The components have been designed for ideal 50Ω operation! 2

3 When are we not at 50? 1) Antennas are not always 50Ω by design How much mismatch between phone and antenna can be tolerated? 2) Non-ideal reception conditions mimic non-50ω conditions Driving inside tunnel Talking inside elevator Broken antenna How much mismatch between phone and antenna/outside-world can be tolerated? How can we even test outside of 50Ω? 3

4 Mobile Phone Testing Beyond 50Ω It is not enough to test a phone at ideal 50Ω, it must be tested under realistic conditions! Agilent Acts as base station - Sets active channel and power levels - Measures power, BER, ACPR Maury MT98x Tuner - Sets non-50ω impedance Maury AMTS Software - Controls 8960 and tuner - De-embeds VSWR and power levels to DUT reference - Controls variable DC supply to mimic battery voltages - Automates measurements 4

5 What is the Agilent 8960? The Agilent 8960 is your one-box solution for wireless device development, manufacturing and repair - today and tomorrow Agilent Technologies Important Tests using 8960: TX Power Test at specific PCL levels RX Sensitivity BER testing ACPR Output Spectrum Note: 8960 testing is at 50Ω condition only 5

6 Tuner emulates mismatched antenna In order to emulate all non-50ω conditions, we remove the antenna from the phone and replace with cable connected to impedance tuner. Impedance tuners can create any VSWR magnitude between 1:1 and ~10-200:1 and phase between

7 Easily Reproducible Test Conditions No anechoic chamber or reference antenna needed Compact laboratory desktop setup results in easily reproducible test systems and results Test multiple modules under identical conditions in a fraction of the time, at multiple site locations! 7

8 The SLIDE-SCREW TUNER 8

9 Automatic Tuner or Manual Tuner? 14 Maximum Phone Power Maximum 8960 Power Power or Loss (db) Phone Power Tuner Loss 8960 Power 2 Tuner Loss Tuner Reflection 9

10 The Pre-Calibrated Automated Tuner Motors 2 & 3 (Probes) Motor 1 (Carriage) Slabline 10

11 Maury Repeatability Data a b c db a) specification b) Worst case repeatability c) average repeatability 11

12 Tuner Characterization (Calibration) S-parameters are recorded for various X-Y positions of the tuner at each frequency of interest loss is calculated in real-time instant DUT de-embedding 12

13 Fixed Source Power LP V ds = 5.0 V I dsq = 150 ma Freq = 835 MHz At maximum PAE of 70% the power is 33 dbm At maximum power of 38 dbm the PAE is 51% 13

14 AMTS Software for Agilent

15 TX Power Testing - Set Frequency/Channel - Set PCL transmit power level - Set VSWR magnitude and phase - Set DC voltage Measure power delivered to antenna port as function of VSWR magnitude and phase 15

16 RX Sensitivity Testing - Set Frequency/Channel - Set required BER (2% or other) - Set VSWR magnitude and phase - Set DC voltage Measure sensitivity of phone for given BER as function of VSWR magnitude and phase 16

17 Automation through Scripting Pre-define list of frequencies/channels, power levels, battery voltages, VSWR settings Automatically measure each line as a separate test intelligent sequencing 17

18 What do we do with the results? 1) Antennas are not always 50Ω by design Tell the antenna designer how much mismatch is acceptable based on real-life tests (did 2:1 VSWR at all phases meet requirements? 3:1?...) 2) Non-ideal reception conditions mimic non-50ω conditions - Did our mobile phone pass minimum requirements under pre-defined VSWR and voltage conditions? - After a large VSWR sweep plan, does the phone return to same performance at 1:1 VSWR? (performance may degrade db!) - Are there thermal stability issues? (performance may degrade db inside burst check for smooth curves) - Is the phone design acceptable or must we redesign a component? - Is this a batch manufacturing issue? These are only suggestions on how to analyze the data, the possibilities are endless! 18

19 Mobile Phone Test System 19