Agilent CMM Fixture Electronics Clock/Crystal Measurement Module

Transcription

1 Agilent CMM Fixture Electronics Clock/Crystal Measurement Module Slide # 1

2 Having problems with clock? Frequency too high, over 3070 spec > 20MHz for any hybrid receivers (rcva) > 60MHz for clock receivers (rcvc) Crystal does not oscillate. Crystal stops oscillating during test. False failures Keep adjusting detector threshold, but still cannot get stable measurement over a number of boards in production. Escapes (e.g. my test tolerance is too wide, 5%, that I cannot detect misplaced components, 24.5MHz vs 25MHz). Differential clock signals Slide # 2

3 Clock/Crystal Measurement Module (CMM) Model Test Application Input Frequency Output Frequency (Input divided by) Input Voltage Range (Max) Input Signal Amplitude (Min) CMM1-08 Single ended clock signal at 3.3V logic level, e.g. LVTTL, LVCMOS, 1 160MHz 8 0 to +3.3V 2Vp-p CMM2-02 Crystal 1 40MHz 2 0 to +3.3V 1Vp-p CMM2L-02 32kHz Crystal 32kHz 2 0 to +3.3V 1Vp-p CMM3-16 Differential clock signals, e.g. ECL, PECL, LVPECL, LVDS, 1 350MHz 16 0 to +3.3V 400mVp-p Slide # 3

4 Measuring High Frequency Clock with CMM1 +3.3V 100MHz LVTTL Clock EN 100MHz OSC OUT Use twisted pair to ground If wire is long (> 3 ) Input CMM1 GND +3.3V Output 12.5MHz Clock - + Personality Pins 3070 Testhead Slide # 4

5 Clock Measurement Module (CMM1-08) Feature highlights: 1 x 0.5 x to 160MHz (rcva) Built in disconnect relay for powered test simplifies wiring and test development. Slide # 5

6 Easy to wire DUT test point 3070 personality pin Remove the wire assigned by IPG and connect through the clock divider DUT test point 2 Input Output personality pin Ground +3.3V 3 1 Digital ground Low High DUT power supply Slide # 6

7 CMM1-08 Block Diagram Behaves like a wire during unpowered test. Divider Input Clock Output Clock Digital GND V DUT Power Supply Slide # 7

8 Why can t I test my crystal with 0.01% (100ppm) accuracy? Not even 5%? Loading kills oscillation. Especially kHz RTC (Real Time Clock). If the amplitude is only 200~500mVp-p, chances are you re measuring NOISE! (Crystal is a tuned filter, it will filter fixture noise to make it look like signal) Noise coupling in your fixture wiring. Capacitive loading shifted the frequency of oscillation. Slide # 8

9 Typical Crystal Oscillator (on chip) Clock Generator IC Clock out Xtal in C1 15pF Y1 8MHz Xtal out C2 15pF Measure Clock at Clock out. May require removing probe at Xtal in and Xtal out for more stable and accurate measurement in production. Measure Clock at Xtal out May require removing probe at Xtal in. Measure Clock at Xtal in. Slide # 9

10 Typical Crystal Oscillator (on chip) Microcomputer IC Xtal in C1 15pF Y1 8MHz Xtal out C2 15pF Less options for IC without a separate clock output pin. Measure Clock at Xtal out May require removing probe at Xtal in. Care must be taken to keep the fixture wire very short. Usually test is unstable on long wire side of dual well fixture. This is becoming more and more unstable as designers use lower power components. Widen test limits but still high false failures in production!!! Slide # 10

11 Even Worse with 32KHz Crystal Peripheral IC Clock out Xtal in C1 10pF R1 1M Y1 32,768Hz Xtal out C2 10pF Measure Clock at Clock out. Requires removing both probes at Xtal in and Xtal out for more stable and accurate measurement in production. Measure Clock at Xtal out Measure Clock at Xtal in. Slide # 11

12 Measuring Clock at Crystal using CMM2 Microcomputer IC Xtal in Xtal out CMM2 buffers and isolates the test probes on the crystal, and divides by 2 the output to Stable test results in volume production even for low power crystal and low power oscillator circuits. Y1 8MHz 4MHz Clock C1 10pF C2 10pF DUT Xtal out DUT Xtal in GND CMM Xtal out GND 3070 Xtal in / Freq Out Personality Pins 3070 Testhead Slide # 12

13 Use CMM2L for 32KHz Crystal Peripheral IC Xtal in R1 1M Y1 32,768Hz Xtal out CMM2L is specially designed for low power 32,768 crystal with extra stability. Stable test results in volume production even for low power crystal and low power oscillator circuits. 16,384Hz Clock C1 10pF C2 10pF DUT Xtal out DUT Xtal in GND CMM2L Xtal out GND 3070 Xtal in / Freq Out Personality Pins 3070 Testhead Slide # 13

14 Measuring Differential Clock with CMM3 Vcc EN 156MHz OSC P N 156MHz Differential Clock Input+ Input- GND Unpowered Output+ Unpowered Output- CMM3 - + Freq Out GND 9.75MHz Clock Personality Pins 3070 Testhead Slide # 14

15 No more problems with clock High false failure rate on measuring 27MHz crystal on ATi Video Controller. Use CMM2 false failure reduced to zero. Use CMM3 to measure 212.5MHz differential clock signal. Use CMM1 to measure 100MHz clock signal. Use CMM2 to measure 24.5MHz and 25MHz crystals with 1% test limit to detect wrong parts. Slide # 15

16 Many used Worldwide since 2003 CMM1-04 CMM3-08 CMM1-08 CMM CMM2-02 CMM2L -02 Originally designed and used by Agilent Test Solution Centers for customer applications. Due to customer request, we start selling to customer and 3 rd parties as a standard custom product since We continue to look for opportunity for more as technology continues to progress. Tell us what you need now and in the future. Slide # 16

17 How to order CMM? Ask your fixture vendor to use Agilent CMM and they will order and install it inside the fixture for you. Just specify where and which one in your fixture document. You can also order directly from Agilent Business Center. Technical assistance contact or your local AE. Slide # 17